Precambrian Geology, Northern Swayze Greenstone Belt

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Precambrian GeologyNorthern Swayze Greenstone Belt

Ontario Geological SurveyReport 297

1995

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Northern OntarioDevelopment Agreement

Entente de développementdu nord de l'Ontario

CANADAONTARIO

M i n e r a l s • M i n é r a u xNO

DA

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NO

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This publication was funded under the Minerals program of the Canada-Ontario Northern Ontario Development Agreement (NODA), a four year joint initiative signed November 4, 1991.

Ontario Geological SurveyReport 297

J. A. Ayer

1995


© Queen’s Printer for Ontario, 1995 ISSN 0704-2582ISBN 0-7778-3813-3

Publications of the Ontario Geological Survey and the Ministry of Northern Developmentand Mines are available from the following sources. Orders for publications should beaccompanied by cheque or money order payable to the Minister of Finance.

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Canadian Cataloguing in Publication Data

Ayer, John AlbertPrecambrian geology, Northern Swayze Greenstone belt

(Ontario Geological Survey report, ISSN 0704-2582; 297)Includes bibliographic references.ISBN 0-7778-3813-3

1. Geology-Ontario-Swayze Region. 2. Geology, Stratigraphic-Precambrian. 3. Greenstone belts-Ontario-SwayzeRegion. I. Ontario. Ministry of Northern Development and Mines. II. Ontario Geological Survey. III. Title. IV. Series.

QE191.A93 1995 551.7’1’09713133 C95-964027-4

Every possible effort is made to ensure the accuracy of the information contained in thisreport, but the Ministry of Northern Development and Mines does not assume any liabilityfor errors that may occur. Source references are included in the report and users may wishto verify critical information.

If you wish to reproduce any of the text, tables or illustrations in this report, please write forpermission to the Director, Ontario Geological Survey, Ministry of Northern Developmentand Mines, Willet Green Miller Centre, 933 Ramsey Lake Road, Sudbury, Ontario P3E 6B5.

Cette publication est disponible en anglais seulement.

Parts of this publication may be quoted if credit is given. It is recommended that referencebe made in the following form:

Ayer, J.A. 1995. Precambrian geology, northern Swayze greenstone belt; Ontario GeologicalSurvey, Report 297, 57p.

Critical Reader: P.C. Thurston

Edited/Produced by: Geomatics International Inc.

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Contents

Introduction .................................................................................................................. 3Mineral Exploration ................................................................................ 3Previous Geological Work ...................................................................... 4Present Geological Survey...................................................................... 4Acknowledgments .................................................................................. 4

General Geology .......................................................................................................... 6Archean ................................................................................................................ 7

Ultramafic Metavolcanic Rocks .................................................................... 7Mafic Metavolcanic Rocks ............................................................................ 8Intermediate Metavolcanic Rocks ................................................................ 9Felsic Metavolcanic Rocks ............................................................................ 9Clastic Metasedimentary Rocks .................................................................... 10Chemical Metasedimentary Rocks ................................................................ 10Metamorphosed Ultramafic Cumulate Rocks .............................................. 11Metamorphosed Mafic Intrusive Rocks ........................................................ 12Felsic to Mafic Plutonic Rocks...................................................................... 12

Kapuskasing Structural Zone ................................................................ 13Nat River Granitoid Complex ................................................................ 13Kenogamissi Batholith .......................................................................... 14Tom Smith Lake Granitic Complex ...................................................... 14Kukatush Pluton .................................................................................... 15Hoodoo Lake Pluton .............................................................................. 15Ivanhoe Lake Pluton .............................................................................. 16

Alkalic Mafic Intrusive Rocks ...................................................................... 16Proterozoic ............................................................................................................ 16

Mafic Intrusive Rocks .................................................................................. 16Phanerozoic .......................................................................................................... 17

Pleistocene and Recent .................................................................................. 17Metamorphism ...................................................................................................... 17Alteration .............................................................................................................. 18

Silicification .................................................................................................. 18Chloritoid-bearing Volcanic Rocks .............................................................. 18Carbonatization .............................................................................................. 18Epidotization .................................................................................................. 18

Geochemistry................................................................................................................ 20

Structural Geology ...................................................................................................... 43Kapuskasing Structural Zone ................................................................................ 43North Swayze Greenstone Belt Zone .................................................................. 43

Folding .......................................................................................................... 43Faulting .......................................................................................................... 44

Ductile Faults ........................................................................................ 45Brittle-Ductile Faults .............................................................................. 45Brittle Faults .......................................................................................... 45

Economic Geology ...................................................................................................... 46Gold ...................................................................................................................... 46

Arkell ............................................................................................................ 46BHP-Utah Mines Limited .............................................................................. 46B.P. Resources Limited .................................................................................. 46Bromley.......................................................................................................... 47Card Lake Copper Mines Limited ................................................................ 47Hoodoo-Patricia ............................................................................................ 47Joburke Mine ................................................................................................ 47

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Johnson Wright .............................................................................................. 48Jonsmith ........................................................................................................ 48Kalbrook ........................................................................................................ 49Little Long Lac Gold Mines Limited ............................................................ 49Mining Corp .................................................................................................. 49Nib Yellowknife ............................................................................................ 49Tremblay ........................................................................................................ 49Unigold Resources Limited .......................................................................... 49

Copper and Zinc .................................................................................................... 50Dome Exploration .......................................................................................... 50Hudbay Mining Limited ................................................................................ 51Karvinen ........................................................................................................ 51Keevil Mining Group Limited ...................................................................... 51Noranda Exploration Company Limited ...................................................... 51United MacFie Mines Limited ...................................................................... 51

Nickel and Platinum Group Elements .................................................................. 52Akweskwa Lake ............................................................................................ 52Amax Minerals Limited ................................................................................ 52International Norvalie .................................................................................... 52Ireland ............................................................................................................ 52McIntyre Johnson .......................................................................................... 52Norduna.......................................................................................................... 52

Iron ........................................................................................................................ 53Nat River ........................................................................................................ 53Radio Hill ...................................................................................................... 53

Asbestos ................................................................................................................ 53Reeves Mine .................................................................................................. 53

Talc ........................................................................................................................ 54Penhorwood Mine .......................................................................................... 54

Barite .................................................................................................................... 54Cryderman Mine ............................................................................................ 54

Silica .................................................................................................................... 54Horwood Mine .............................................................................................. 54Roseval Mine ................................................................................................ 54

References .................................................................................................................... 55

Metric Conversion Table .............................................................................................. 57

FIGURES

1. Key map showing the location of the synoptic area. .......................................... 3

2. General geology of the northern Swayze greenstone belt. .................................. 6

3. Jensen cation plot of ultramafic volcanic samples. .............................................. 20

4. Chondrite-normalized REE plot of ultramafic volcanic samples. ........................ 20

5. Jensen cation plot of mafic volcanic samples. ...................................................... 21

6. Chondrite-normalized REE plot of mafic volcanic samples. .............................. 21

7. Jensen cation plot of intermediate to felsic volcanic samples. ............................ 22

8. Chondrite-normalized REE plot of intermediate to felsic volcanic samples. ...... 22

9. Jensen cation plot of ultramafic cumulate and gabbroic samples. ...................... 22

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10. Chondrite-normalized REE plot of samples from the Reeves ultramafic to gabbroic body. .................................................................................................. 23

11. Chondrite-normalized REE plot of samples from the ultramafic to gabbroic body hosting the Ireland nickel showing. .............................................. 23

12. Jensen cation plot of altered mafic volcanic samples from the Joburke Mine. .. 24

13. Chondrite-normalized REE plot of altered mafic volcanic samples from the Joburke Mine. ........................................................................................ 24

14. Pearce and Cann plot of volcanic samples from the northern Swayze greenstone belt. ........................................................................................ 24

15. Pearce and Cann plot of altered mafic volcanic samples from the Joburke Mine. ................................................................................................ 24

TABLES

1. Lithologic units for the northern Swayze greenstone belt. .................................. 7

2. Lithogeochemical sample descriptions and locations. ........................................ 25

3. Whole-rock geochemical data from Foleyet and Ivanhoe townships. ................ 28

4. Whole-rock geochemical data from Muskego and Keith townships. .................. 34

5. Whole-rock geochemical data from Reeves, Penhorwood, Sewell and Kenogaming townships. ...................................................................................... 37

GEOLOGICAL MAPS

Map 2627 - Precambrian Geology, Northern Swayze Greenstone Belt ..........back pocket

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Abstract

This report is a synopsis and compilation of the geology of Foleyet, Ivanhoe, Muskego,Keith, Reeves, Penhorwood, Sewell and Kenogaming townships at a scale of 1:50 000. Itcovers most of the northern Swayze greenstone belt within the southwestern part of theAbitibi Subprovince and a small part of the eastern margin of the Kapuskasing StructuralZone.

The oldest rocks in the area consist of northeasterly trending paragneiss and amphi-bole gneiss, intruded by both the Shawmere anorthosite complex and granitoid gneiss,within the Kapuskasing Structural Zone, on the western margin of the synoptic area.Tonalite gneiss associated with the Shawmere complex has been dated at 2765 Ma.Kapuskasing Structural Zone rocks have been metamorphosed to granulite facies condi-tions and are interpreted to be a segment of Archean lower crust thrust eastwards over theAbitibi Subprovince along the Ivanhoe Lake cataclastic zone.

East of the Ivanhoe Lake cataclastic zone, the northern Swayze greenstone belt con-sists of easterly trending supracrustal rocks subdivided into 3 distinct assemblages. TheMuskego–Reeves assemblage in the northern part of the belt consists of mafic flows inter-calated with ultramafic volcanic flows, iron formations, clastic sedimentary rocks andlocalized accumulations of intermediate to felsic flows and pyroclastic rocks. Conglomerate,wacke and mudstone occur in an extensive clastic sedimentary unit in the uppermoststratigraphic reaches of the Muskego–Reeves assemblage in the northwest part of the belt.The Horwood assemblage lies to the south. It consists predominantly of tholeiitic maficflows with minor intercalations of fine-grained clastic sedimentary rocks, calc-alkalicpyroclastic rocks and ultramafic flows. The Hanrahan assemblage consists of intermediateto felsic pyroclastic rocks and flows capped by iron formation, within the Hanrahan anti-form in the southeast part of the belt.

Extensive sill-like bodies of massive, medium-grained, cumulate-textured ultramaficrock occur in all the assemblages. Locally, in the Muskego–Reeves assemblage, the cumulate-textured ultramafic units grade along strike into ultramafic flows and thus may representproximal-facies flows or feeder intrusions. Differentiation into an uppermost gabbroicunit occurs in the northern part of the Reeves ultramafic body.

Granitoid intrusions include both early foliated and late massive rock units. Earlyintrusions tend to be more sodic and are predominantly tonalite and granodiorite. They aremost abundant in the large granitic complexes outside the supracrustal sequence, includingthe Kenogamissi batholith, the Nat River granitic complex and the Tom Smith Lakegranitic complex. Smaller, early intrusions of foliated porphyry, granodiorite and graniteoccur within the supracrustal assemblages. Late intrusions include bodies such as theIvanhoe Lake, Hoodoo Lake and Kukatush plutons, within the supracrustal rocks, andparts of the larger external granitic complexes mentioned above. Late granitic phases con-sist predominantly of massive to weakly foliated granodiorite, granite and monzonite,with minor diorite, syenite, gabbro and clinopyroxenite. Late intrusive phases of the TomSmith Lake granitic complex and the Hoodoo Lake pluton have been dated at 2680 and2684 Ma, respectively.

Lithogeochemical data indicate the mafic volcanic rocks are magnesium and irontholeiites. The tholeiitic mafic and the komatiitic ultramafic flows are depleted in lightrare earth elements, suggesting derivation from a long-term depleted ensimatic Archeanmantle at a constructive plate margin. These geochemical patterns are most similar tothose of modern basalts formed at mid-oceanic ridges. The intermediate to felsic volcanicrocks are calc-alkalic with highly enriched light rare earth elements. They were most like-ly derived from destructive plate margins associated with Archean island arc environ-ments. The cumulate-textured ultramafic bodies have geochemical patterns which suggestan origin common to that of the ultramafic flows.

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Polyphase deformation has resulted in at least 5 separate fabric generations.Generations D1 to D3 are related to regional folding events, with or without associatedductile deformation. Generations D4 and D5 are spatially associated with regional shearzones and are interpreted to be related to late ductile deformation. Three distinct generationsof faulting are distinguished. Faults associated with D4 and D5 are designated as ductileand brittle-ductile faults. Late northerly trending brittle faults are Proterozoic in age andmay be associated with the Matachewan diabase dikes.

A number of significant gold occurrences and a past-producing gold mine indicategood potential for gold mineralization in the northern Swayze greenstone belt. TheJoburke mine produced about half a million tons of ore grading approximately 0.11 ounceAu per ton. All of the gold mineralization is spatially associated with ductile deformationzones. Typically the mineralization occurs in quartz veins in highly deformed and car-bonatized mafic volcanic rocks.

Two types of exhalative copper-zinc mineralization are present in the area: 1) localizedconcentrations of sphalerite and chalcopyrite within sulphide-facies iron formations; and2) lenses of strata-bound, massive to disseminated sulphides with minor sphalerite andchalcopyrite, in sequences containing calc-alkalic felsic, tholeiitic mafic and komatiiticultramafic volcanic rocks. Hydrothermal alteration consisting of chloritoid-bearing volcanicrocks and silicification is locally associated with the stratabound sulphide mineralization.

Potential may also exist for magmatic nickel-copper-platinum group elementdeposits. Documented occurrences are predominantly associated with the ultramaficcumulate bodies in the Hanrahan assemblage. Asbestos and talc are also associated withthe ultramafic rocks. Two ore bodies occur in the Reeves ultramafic unit. The Reevesasbestos mine produced about 140 000 tons of asbestos and the Penhorwood talc mine iscurrently milling 450 tons per day of talc. Industrial minerals, including barite and silica,have been produced from veins closely associated with granitic intrusions in theHardiman deformation zone, in southwestern Penhorwood Township.

Ayer, J.A. 1995. Precambrian geology, northern Swayze greenstone belt; Ontario Geological Survey,Report 297, 57p.

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J. A. Ayer

Geoscientist, Precambrian Geoscience Section, Ontario Geological Survey.

Report approved for publication by B. Dressler, Section Chief, PrecambrianGeoscience Section, Ontario Geological Survey. This report is published with thepermission of John Wood, Director, Ontario Geological Survey.

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an estimated 27 million tons of 29% total iron in the NatRiver iron formation in Penhorwood Township. A thirdiron formation extends about 10 km with an east-northeasttrend across the north-central part of Keith Township. Thisiron formation, identified as the Palomar iron formation,has been explored by a number of companies but as it isrelatively thin throughout its length, resource tonnage figureswere never calculated.

PREVIOUS GEOLOGICAL WORK

The earliest geological reference to the map area is byParks (1900) who produced the first map of the area sur-rounding Ivanhoe and Horwood lakes. Tanton (1917) out-lined the distribution of the “greenstones” in the map areain a reconnaissance survey along the Canadian NationalRailway (CNR) line between Gogama and Oba. A geolog-ical map by Harding (1937), at a scale of 1:63 360, includedall of Ivanhoe and Keith townships and the southern thirdof Foleyet and Muskego townships. A regional-scale map-ping project, published at a scale of 1:250 000 by Thurstonet al. (1977), included all of the map area. The westernhalf of the map area is also included in a 1:100 000 scalemap by Percival (1981).

Previous detailed mapping, predominantly conductedat a scale of 1:15 840, covered substantial parts of the maparea and includes 1) the northern half of Keith Townshipand the southern part of Muskego Township by Prest(1951) at a scale of 1:12 000; 2) Reeves, Penhorwood,Sewell and Kenogaming townships by Milne (1972); 3)the southern half of Keith Township by Breaks (1978); and4) the northwestern part of Foleyet Township by Riccio(1981).

The area was covered by an airborne magnetic surveyat a 400 m line spacing and was published in 1963 at ascale of 1:63 360 (ODM–GSC 1963a-d). A higher resolu-tion airborne magnetic and electromagnetic survey at a200 m line spacing includes the parts of the map areaunderlain by supracrustal rocks and was published at ascale of 1:20 000 (OGS 1990)

PRESENT GEOLOGICAL SURVEY

This synoptic report is part of a continuing project toupdate the geological database of the northern Swayzegreenstone belt (NSGB). The initial phases of the projectwere funded by the Northern Ontario DevelopmentAgreement (NODA) and were focussed on detailed mapping(1:15 840 scale) of Foleyet and Ivanhoe townships in 1991(Ayer 1993), and Keith and Muskego townships in 1992(Ayer and Theriault 1992). Reeves, Penhorwood, Sewelland Kenogaming townships were investigated in 1993,with detailed mapping at a scale of 1:20 000 focussed onspecific areas with regard to special geological, structural,geochemical or metallogenic problems. The accompanyingsynoptic geological map (Map 2627, back pocket) is at ascale of 1:50 000 and represents a compilation of informa-

tion derived from the detailed mapping outlined above,previous mapping projects and from data contained inmineral exploration files. Exploration work filed forassessment credit is on file at the Resident Geologist’soffice in Timmins and is now available in a summarizedformat in Geological Data Inventory Folios (GDIF) for allof the 8 townships across the NSGB.

Diamond-drill core stored at a number of locations inTimmins, including the Ministry of Northern Develop-ment and Mines drill core library, and at FalconbridgeLimited and Placer Dome Canada Limited, was examinedand in some places sampled. Diamond-drill hole locationswere derived from the GDIFs available as open files in theResident Geologist’s office, Timmins, and from the relevantcompany files for those holes not located on the GDIFs.The geological coding of rock units which were not directlyobserved by the author have been derived from the drilllogs and are prefixed by the letter “D” on Map 2627(back pocket).

Geological data were recorded in the field on acetateoverlays superimposed on 1:15 840 scale aerial photo-graphs. The data were subsequently transferred to cronaflexbase maps prepared by the cartography section of theOntario Ministry of Natural Resources.

Data from airborne total intensity and electromagneticsurveys (OGS 1990) were utilized to derive colour-contouredmagnetic susceptibility and vertical derivative maps.These maps enhance subtle geological and structural featuresand greatly aided in geological interpretation, particularlyin areas with extensive overburden cover. The geologicalcoding of units interpreted from the geophysical maps areprefixed by the letter “G” on Map 2627 (back pocket).

A number of regional-scale geological projectsfocussing on the Swayze greenstone belt are also currently inprogress. These are as follows: 1) a mineral deposit study(Fumerton 1992, 1993); 2) surficial geological mappingand drift geochemistry (Kaszycki 1992; Bernier and Goff1993); 3) a regional-scale bedrock mapping andgeochronology study (Heather 1993; Heather and vanBreemen 1994); and 4) computer-assisted compilation andanalysis of a wide range of digital data using GeographicInformation System technology (Harris et al. 1994).

ACKNOWLEDGMENTS

M. Puumala and R. Theriault served as senior assistants in1991 and 1992, respectively. Their contribution to the map-ping and the development of geological concepts appliedto the resulting map is very much appreciated. S. Beauchamp,C. Lang, T. Searcy, Y. Rappaport, T. Hearty, S. Connelland S. Morrison are gratefully acknowledged for theircapable assistance as junior assistants during the 3 years ofmapping.

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Appreciation is also extended to the staff of the ResidentGeologist’s office and drill core library in Timmins for logis-tical support. Members of the geological staff of NorandaExploration Company Limited, Falconbridge Limited, PlacerDome Canada Limited, Marshall Minerals Corporation and

Cominco Limited are thanked for access to diamond-drillcore and proprietary exploration data, and for many fruitfuldiscussions about the geology of the synoptic area. I wouldalso like to thank G. Ross of Foleyet for his time and insighton a number of property tours in and around the map area.

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NORTHERN SWAYZE GREENSTONE BELT

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Jackson et al. (1994) define supracrustal assemblagesas regional map units that contain rocks sharing some,but not all, of the following properties: lithic attributes,geochemistry, facies association, geophysical signature,structural style and age. The units contained within anassemblage need not be stratigraphically related, and anassemblage may either be in fault or depositional contactwith other assemblages.

The MRA is confined to the northern part of the beltand is composed of tholeiitic mafic volcanic rocks withlesser components of komatiitic ultramafic volcanic rocks,calc-alkalic intermediate and felsic volcanic units, andclastic and chemical sedimentary units. The HWA extendssouth of the synoptic area into the central part of theSwayze greenstone belt. It consists predominantly oftholeiitic mafic volcanic rocks, with minor intercalationsof fine-grained clastic and chemical sedimentary rocks,calc-alkalic felsic pyroclastic rocks and komatiitic ultra-mafic flows. The HNA is confined to the southeastern partof the NSGB and consists predominantly of calc-alkalicintermediate and felsic volcanic rocks that have beenintruded by extensive ultramafic and gabbroic sills. A lat-erally extensive, but relatively thin, unit of iron formationcaps the HNA and delineates much of the boundarybetween the HNA and the MRA.

Table 1 is a presentation of the main rock units within thesynoptic area. These units are discussed in more detail below.

ARCHEAN

Ultramafic Metavolcanic Rocks

Previous mapping in the synoptic area took place prior tothe general recognition of the existence of ultramaficextrusive rocks and thus all ultramafic rocks were classi-fied as intrusions (e.g., Prest 1951; Milne 1972; Breaks1978). However, current mapping has shown many ofthese ultramafic units to be of extrusive origin. The closespatial relationship of the komatiite flows (unit 1, Map2627, back pocket) with massive, medium-grained cumu-late-textured serpentinite bodies of more enigmatic origin(unit 7, Map 2627, back pocket) suggests a cogenetic rela-tionship which is not as yet fully understood.

Komatiitic ultramafic flows (unit 1, Map 2627, backpocket) represent an estimated 5% of the MRA, 1% of theHWA and were not observed within the HNA. A numberof these units in the MRA are laterally extensive. The mostextensive unit occurs in Penhorwood and eastern Keithtownships, with dimensions of about 15 km (length) by upto 1 km (width). In central Keith Township, a number oflenticular units 1 to 2 km long appear to lie along the samestratigraphic horizon, suggesting the lenticular morphologymight represent basinal areas of komatiite accumulationseparated by areas of higher paleorelief without komatiitedeposition. This observation is supported by the common

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Table 1. Lithologic units for the northern Swayze greenstone belt.

PHANEROZOICCENOZOIC

QUATERNARYPLEISTOCENE AND RECENT

Glacial, glaciofluvial, lacustrine and fluvialdeposits

Unconformity

PRECAMBRIANPROTEROZOIC

Mafic Intrusive RocksDiabase dikes

ARCHEANAlkalic Mafic Intrusive Rocks

Lamprophyre dikes

Late Felsic to Mafic Plutonic Intrusive RocksGranodiorite, quartz monzodiorite, granite, tonalite, quartzdiorite, gabbro, clinopyroxenite, pegmatite, porphyry, felsite

Early Felsic to Mafic Plutonic Intrusive RocksTonalite, quartz diorite, granodiorite, quartz monzodiorite,granite, diorite, gabbro, porphyry, felsite

Metamorphosed Mafic Intrusive RocksGabbro, melagabbro, leucogabbro, diorite, anorthosite,anorthositic gabbro

Metamorphosed Ultramafic Cumulate RocksDunite, peridotite, pyroxenite

Chemical Metasedimentary RocksMagnetite iron formation, siderite iron formation, sulphideiron formation, graphitic mudstone, chert

Clastic Metasedimentary RocksSandstone, siltstone, mudstone, conglomerate, tuffaceouswacke, paragneiss

Felsic Metavolcanic RocksTuff, lapilli tuff, tuff breccia, massive flow, brecciated flow

Intermediate Metavolcanic RocksTuff, lapilli tuff, tuff breccia, pillowed flow, massive flow,amygdaloidal flow, brecciated flow

Mafic Metavolcanic RocksMassive flow, pillowed flow, variolitic flow, amygdaloidalflow, brecciated flow, plagioclase-phyric flow, pyroxene-spinifex-textured flow, tuff, lapilli tuff, tuff breccia

Ultramafic Metavolcanic RocksMassive flow, spinifex-textured flow, polyhedral-jointedflow, brecciated flow

association of the komatiitic flows with sulphidic iron for-mation and fine turbidites, which implies relatively deep-water deposition.

The extrusive origin of these ultramafic rocks isindicated by features such as spinifex textures. In somewell-preserved areas, flow units and top criteria are deter-minable based on the classic distribution of uppermostflow-top breccias, fine, random spinifex grading downwardsinto coarse oriented spinifex (A zone) and a lowermostcumulate unit of equigranular ultramafic rock (B zone;Donaldson 1982). Flow units range from 1 to 10 m thickin the map area. Many of the flows are massive, fine- tomedium-grained cumulate-textured units commonly dis-playing well-developed polyhedral jointing, with or withoutassociated spinifex textures. Massive komatiitic flowsrange from equigranular to porphyritic. The rocks typicallyfeel talcose when powdered and have a wide variety ofweathered surface colours, ranging from green to orange-brown. Where highly strained, the ultramafic volcanicrocks have been altered to chlorite-talc-carbonate schists,with or without a bright green fuchsitic mica.

In komatiites with olivine spinifex, the relict olivinecrystals have blade-like morphologies (pseudomorphed byserpentine, chlorite or amphibole) with an interstitialgroundmass of fine-grained plumose pyroxene (replacedby amphibole and/or chlorite), with or without intergrownplagioclase and opaque minerals. The olivine spinifex maybe randomly oriented and fine grained near the tops offlow units to extremely coarse grained with a preferredorientation roughly perpendicular to the orientation of theflow units. In the lowermost parts of the flow units(B zone), orthocumulate textures predominate. Cumulusolivine (pseudomorphed by serpentine, chlorite and/oramphibole) occurs as equant, medium-grained euhedralcrystals with fine-grained intergranular intergrowths ofplumose pyroxene and opaque minerals, very similar inhabit to the interstitial textures within the spinifex parts ofthe flow.

Rare komatiitic flow units consisting of pyroxenespinifex were observed. A good example of this komatiitetype occurs in the ultramafic volcanic unit immediatelynorth of the Radio Hill iron formation, east of theGroundhog River. In these units, the uppermost part of theflow units (A zone) consists of acicular, skeletal amphi-bolitized pyroxenes in an interstitial groundmass of veryfine-grained amphibolitized pyroxene, plagioclase andopaque minerals. In the lower part of the flow unit(B zone), an orthocumulate texture is preserved consistingof medium-grained, equant, euhedral, skeletal, tremolitizedpyroxenes in a goundmass similar to the spinifex part ofthe flow unit.

An unusual heterolithic breccia occurs in ultramaficvolcanic rocks located north of the CNR tracks about 1 kmwest of Palomar siding in Keith Township. The brecciasare surrounded to the south, west and north by a large areaof massive, medium-grained, adcumulate-textured ultra-mafic rocks (unit 7, Map 2627, back pocket). The breccia

consists of angular to subrounded clasts of spinifex-tex-tured komatiite, and amygdaloidal mafic and intermediatevolcanic rocks. Clast types vary within the unit from dom-inantly intermediate flow clasts to dominantly ultramaficflow clasts. Brecciated clasts are supported in a sparsematrix of finely comminuted material largely derived fromthe clasts. Locally, thin, spinifex-textured to massivekomatiite flows are interbedded with breccia units. Thisfeature indicates the breccia is synvolcanic, rather thantectonic as was originally suggested by Prest (1951).

Mafic Metavolcanic Rocks

Mafic volcanic rocks represent about 70% of the MRA,90% of the HWA and do not occur within the HNA, withthe possible exception of mafic units east of the MindedoCreek fault in eastern Kenogaming Township. Amphi-bolitic remnants represent about 10% of the KapuskasingStructural Zone and are probably mafic volcanic unitsand/or synvolcanic mafic intrusions metamorphosed togranulite facies (Riccio 1981).

Amphibolites in the Kapuskasing Structural Zoneoccur as isolated rafts intruded by a variety of graniticgneisses. These rafts occur both as large mappable unitsand as outcrop-scale inclusions. The mappable units arecommonly surrounded by granitic gneiss with abundant,unassimilated amphibolite inclusions. The amphibolitesare fine- to medium-grained, dark grey to black rocks withstrongly foliated to gneissic textures. They are mainlycomposed of hornblende and plagioclase. Accessory mineralsinclude clinopyroxene, garnet, quartz and opaque minerals.

Mafic volcanic rocks in the Swayze greenstone beltvary from light green, to dark green to black on weatheredsurfaces. They range from soft and chloritic to relativelyhard and amphibolitic. Massive flows are the most commonmafic volcanic rock type and vary from fine to mediumgrained. Pillowed flows occur in gradational contact withthe massive flows. Pillows average 30 to 50 cm in lengthwith thick selvages (up to 2 to 3 cm) that are darker greenin colour and more rusty than the pillow interiors. Themafic volcanic rocks are predominantly aphyric in handspecimen. Rare exceptions occur in a few outcrops ofplagioclase-megaphyric mafic volcanic rocks adjacent tothe Nat River granitoid complex in southeastern MuskegoTownship and northeastern Penhorwood Township.Vesicles infilled with quartz, carbonate and/or epidote arewidespread in the pillowed flows. They typically range upto 2 to 3 mm in diameter and are concentrated in the outerparts of the pillows. Variolitic flows consist of abundant,light grey, 1 to 5 cm varioles which tend to coalesce in theinterior parts of pillows. In thin section, the varioles con-sist of radiating to concentric intergrowths of fine-grained,acicular, amphibolitized pyroxene with very fine-grained,intergranular anhedral plagioclase. They have slight protu-berances on their outer surfaces (visible in thin section),suggesting an origin as devitrification spherulites ratherthan immiscible liquids.

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Relict subophitic textures are preserved in some medium-grained massive flows. Massive mafic flows containingpyroxene spinifex textures occur locally in northern KeithTownship. Lower cumulate-textured bases (B zone) werenot observed in these spinifex-textured basaltic flows.Rather, the central parts of these flow units exhibit a fine toextremely coarse spinifex texture, with crystals orientedroughly perpendicular to the flow direction. Textures in thespinifex-textured mafic flows are microscopically similar tothe ultramafic pyroxene spinifex-textured flows (describedabove), except that the content of fine-grained interstitialplagioclase is sufficiently high (up to 30%) to suggest abasaltic composition. Pyroxene spinifex textures also occursporadically in the coarser grained massive mafic flows.They consist of actinolitized pyroxene in large, acicular,dendritic grains in a groundmass of finer grained plagioclaseand amphibole.

Breccias consisting of brecciated pillows or autoclasticflow breccias in massive flows are locally present. Maficpyroclastic rocks consisting of tuff, lapilli tuff and tuffbreccia are very rare. These units are largely reported indiamond-drill core logs and could possibly be misidentifiedflow breccia.

Mineralogically, the mafic volcanic rocks predominantlyconsist of amphibole and plagioclase. Throughout much ofthe area, the mineral assemblage of actinolite and albite, withor without accessory epidote, sericite, carbonate, quartz,chlorite, leucoxene and opaque minerals, indicates they areof mid- to upper-greenschist metamorphic facies. Locally,the presence of garnet, biotite, hornblende and plagioclase ofoligoclase to andesine composition indicate the maficvolcanic rocks were recrystallized to amphibolite metamor-phic facies within 1 to 2 km of the contacts with the largegranitoid bodies, and throughout much of southern IvanhoeTownship.

Intermediate Metavolcanic Rocks

Intermediate volcanic rocks constitute about 10% of theMRA with much of these occurring in the northwestern partof the assemblage. They represent about 5% of the HWA and75% of the HNA.

The intermediate volcanic rocks are medium to lightgreen-grey on weathered surfaces. In the northwestern partof the MRA, the majority of the intermediate volcanic rocksare flows which are typically plagioclase-phyric and amyg-daloidal. Pillowed flows have thin dark grey to dark greenpillow selvages. Amygdules may constitute up to 20% of therock and range up to several centimetres in diameter. Theyare typically infilled with carbonate, quartz, epidote, biotiteand/or chlorite. Plagioclase and rarely pyroxene (replaced byamphibole) phenocrysts may constitute up to 20% of theflows. They occur in a very fine-grained groundmass ofrecrystallized amphibole, chlorite, epidote, opaque mineralsand/or biotite, commonly with plagioclase microlites eitherin random pilotaxitic or aligned trachytic orientations.

Pillow breccia, autoclastic flow breccia and highlyvesicular flows are abundant east of the Ivanhoe Lakepluton. This is also an area of extensive hydrothermalsilicification that probably occurred as a consequence ofthe original porosity of these rocks. Pillow breccias aremore abundant than pillowed flows in this area and consistof light grey, irregularly shaped, amygdaloidal pillow frag-ments in a medium grey, sericitic hyaloclastite matrix.

Intermediate fragmental rocks consisting of tuff, lapillituff and tuff breccia are common within the HNA, but rel-atively uncommon within the MRA. Clast populationswithin the fragmented units range from monolithic to het-erolithic. The fragments are composed of various aphyricto porphyritic, nonvesicular to highly vesicular, intermediatevolcanic clasts (possibly pumiceous in texture). Thesefragmental rocks are light to medium grey-green and rela-tively hard. Fine- to medium-grained plagioclase crystals(constituting 5 to 30% of the rock) are common and minorquartz crystals may also be present. Plagioclase, amphibole,biotite and quartz are essential minerals, while accessoryminerals may include chlorite, sericite, carbonate, epidoteand opaque minerals. With a few exceptions, the fragmentalunits of the HNA are poorly sorted without any visiblebedding or grading. Rare interbeds of finely laminatedsiltstone and normal grading occur in the northern marginof the HNA. Massive to laminated, amygdaloidal interme-diate flows and flow breccias were also observed in anumber of localities within the HNA.

Felsic Metavolcanic Rocks

Felsic volcanic rocks constitute about 5% of the MRA in anumber of isolated lenticular units scattered throughoutthe assemblage. Minor felsic units also occur in the HWAand HNA.

The felsic volcanic units are light grey on weatheredsurfaces and are typically quartz- and/or feldspar- phyric.Felsic volcanic rocks are massive to fragmented.Pyroclastic units are subdivided into tuff, lapilli tuff andtuff breccia. Felsic flows are exposed in a small outcrop onthe southeast side of Highway 101. They are massive andgenerally nondescript, but locally contain zones of angularflow breccia and isolated miarolitic cavities infilled byvery fine-grained quartz. Felsic volcanic rocks commonlycontain up to 25% plagioclase and quartz phenocrysts in avery fine-grained groundmass of recrystallized quartz,feldspar, sericite, biotite, chlorite, carbonate and epidote.

Some of the felsic units appear to be complexes ofintrusive and extrusive origin, possibly in an exogenousdome-like setting. The Groundhog Lake felsic complex isa large enclave (3 by 5 km) within the Kukatush pluton.The complex consists, for the most part, of a weakly foli-ated, homogeneous, porphyritic, very fine-grained, massivefelsic rock. Subordinate felsic to intermediate pyroclasticrocks and interbedded wackes occur along the southernmargin of the body. The massive felsic rock is typically

9


composed of 1 to 2% feldspar phenocrysts (1 to 3 mm indiameter) in a very fine-grained, equigranular groundmassof anhedral quartz and feldspar with 2 to 10% muscovite,biotite, chlorite and epidote. Microscopic examination of asample from the south-central part of the complexrevealed that muscovite grains are partially replaced byfibrolitic sillimanite. This feature indicates the complexhas experienced metamorphism to amphibolite facies.Irregular patches of coarser-grained granitic material werelocally observed, likely produced by the escape of a related,volatile-rich phase. Minerals within the coarser phase aresimilar, but with a higher proportion of biotite to muscovite(i.e., 8% biotite, 2% muscovite) and about 5 to 10% micro-cline. The microcline occurs in subhedral crystals in thegroundmass and as rare rapakivi-textured phenocrysts,consisting of microcline cores surrounded by finer, euhedral,plagioclase crystal-rich rims. Miarolitic cavities wereobserved within the porphyritic rock along the west shoreof Groundhog Lake.

Clastic Metasedimentary Rocks

Clastic sedimentary rocks represent about 10% of the MRAand are a very minor component of the HWA and HNA.A wide variety of sedimentary types are present. Clasticsedimentary rocks of the MRA, consisting of conglomerate,sandstone, siltstone and mudstone, are poorly exposed in aunit up to 4 km wide that extends across the northwest andcentral part of the map area and terminates against thecumulate-textured ultramafic to gabbroic unit hosting theReeves and Penhorwood mines. The conglomerate unitsare heterolithic and composed of well-rounded to subangularclasts of felsic porphyry, volcanic clasts of varying com-position (i.e., ultramafic to felsic) and up to 5% of a fine,sugary-textured quartzose material which could representeither recrystallized chert or vein quartz. Conglomeratebeds are up to 1 m thick and are typically in contact withinterbedded, fine- to medium-grained sandstone beds up to50 cm thick. Normal grading and interbedded siltstone andmudstone units are locally evident.

A relatively proximal provenance is suggested for thisclastic sedimentary unit. It is most likely that the sedimentswere derived from local volcanic edifices and deposited byturbidity currents in submarine fans. This is indicated bythe proportion and variety of volcanic clasts, and thechanges in dominant clast types in different locations. Forexample, conglomerates observed along the IvanhoeRiver, in Foleyet Township, contain clasts of spinifex-textured ultramafic volcanic rocks and massive sulphideswhere the sedimentary unit overlies a thick ultramaficvolcanic unit in the vicinity of a number of known massive-sulphide lenses (Ayer 1993). In contrast, the conglomeratesand wackes south of Slate Rock Lake, in Keith Township,contain relatively abundant quartz-phyric felsic clasts andquartz sand immediately east of a 500 m thick unit ofquartz-phyric felsic volcanic rocks.

Another clastic unit, up to 1 km wide, lies north of themain clastic unit in the southwestern part of MuskegoTownship. It is not well exposed and lies within the SlateRock deformation zone. This unit appears to lack con-glomerates and consists of turbiditic sandstone, siltstoneand mudstones with a considerable intermixture of inter-mediate volcanic rocks. North of Slate Rock Lake, wackeswithin this northern unit are thickly bedded and normallygraded. They consist of feldspathic wacke with a frameworkof mainly plagioclase grains and subordinate quartzgrains, in a matrix of finer-grained feldspar and quartzwith accessory sericite, chlorite, opaque minerals, biotite,epidote and zircon.

A third clastic unit lies immediately south of theRadio Hill iron formation. Its width is somewhat conjec-tural, as there are only a few outcrops of thickly beddedwacke occurring sporadically immediately south of theRadio Hill iron formation.

Less extensive clastic sedimentary units are scatteredthroughout the map area. They consist of thinly to thicklybedded wacke, siltstone, mudstone and minor conglomerate.In general, these units are intimately intermixed with ultra-mafic to felsic volcanic units and in some localities withchemical sedimentary rocks. The coarser parts of the unitsare composed of minor conglomerate and feldspathic andlithic wacke.

Siltstones are light grey to dark grey, and mudstonesare dark grey to dark green on weathered surfaces. Bothare typically schistose and thinly laminated. Silty layersare composed of very fine-grained recrystallized feldspar,quartz, chlorite, sericite, carbonate and biotite. Mudstoneshave a higher proportion of micaceous minerals.Tourmaline porphyroblasts occur in turbidites interbeddedwith ultramafic to intermediate volcanic rocks northeast ofPalomar Lake, in northeastern Keith Township.

Chemical Metasedimentary Rocks

Chemical sedimentary rocks, consisting of banded mag-netite-, sulphide-, graphite-, siderite- and chert-facies ironformation occur scattered throughout the map area in allthe supracrustal assemblages. Three extensive units ofmagnetite iron formation are the Palomar, the Radio Hilland the Nat River iron formations which are described inmore detail below. Sulphide iron formation consists offine-grained, laminated pyrite or beds of concretionarypyrite nodules interbedded with graphitic mudstonesand/or chert. These sulphide iron formations and graphiticmudstones occur in units with fine-grained wacke andsiltstone and are interbedded with mafic and ultramaficvolcanic rocks in a number of localities throughout themap area, many of which have been identified by geo-physical surveys and diamond drilling. The sulphides are pre-dominantly pyrite and/ or pyrrhotite and may also includesphalerite and chalcopyrite (see “Economic Geology”).

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OGS REPORT 297

A banded magnetite-chert iron formation unit, termedthe Palomar iron formation (Ayer, in press), occurs northof the MacKeith fault in Keith Township. The iron forma-tion is about 10 km long and up to several hundred metresthick. The unit consists of a number of separate ironformation units up to 12 m thick, interbedded with mas-sive and pillowed mafic flows. Magnetite-rich beds offine-grained euhedral magnetite intergrown with anhedralquartz are up to several centimetres thick. Chert beds ofsimilar thickness consist of recrystallized anhedral togranular quartz and commonly contain radiating sprays ofprismatic tremolite porphyroblasts. Locally, a distinctiveblue magnetite-chert banded iron formation was intersectedin diamond-drill core. This unit is distinguished by thepresence of porphyroblasts of a blue amphibole of possiblesodic composition (riebeckite?).

The Radio Hill iron formation has a strike length ofabout 10 km with a maximum thickness of 500 m in thevicinity of Radio Hill, in Penhorwood Township.Throughout much of its length it is overlain by komatiiteflows to the north and underlain by thickly bedded wacke.Milne (1972) indicates 2 seams of iron formation separatedby felsic volcanic rocks on the western margin ofPenhorwood Township. Only the southern seam appears tocontinue westward into Keith Township. East of Lead-beater Lake in Penhorwood Township, the 2 units coalesceand thicken (probably in an isoclinal F1 fold nose) to forma single zone about 200 m thick. East of this, in theRadio Hill area, the iron formation is folded into an iso-clinal S-shaped fold about 500 m thick (F2 folding?),plunging north-northwest at about 50° (Milne 1972).

The unit consists of magnetite, siderite, sulphide, silicate(minnesotaite), hematite (jasper) and graphite iron forma-tion typically interbedded with chert. A number of distinctivefacies changes occur in the Radio Hill iron formation. Inthe Radio Hill area in Penhorwood Township, the unitconsists of magnetite, siderite, sulphide, silicate, hematiteand graphite iron formation. West of the Groundhog Riverin Keith Township, the magnetite and silicate facies areabsent. Milne (1972) has characterized 4 major verticalfacies transitions in the Radio Hill area. They are, fromsouth to north (hanging wall to footwall), 1) sulphide, sil-icate and carbonate facies, 0 to 50 m in thickness; 2) oxidefacies with minor carbonate and silicate facies, 30 to 100 min thickness; 3) carbonate and silicate facies, 10 to 80 m inthickness; and 4) sulphide facies, 0 to 25 m in thickness.

The Nat River iron formation caps the HNA and thusoutlines much of the boundary between the HNA and theMRA in Penhorwood and Kenogaming townships. Itextends about 20 km and ranges from 30 to 60 m in thick-ness. The iron formation consists of magnetite, sulphide,silicate and graphite iron formation interbedded withchert. Magnetite-chert iron formation is the predominantfacies type and its continuous presence is indicated by astrong aeromagnetic response along its margins to aboutthe Nat River. East of the Nat River, the magnetic responseis attenuated along the south margin, but a response con-tinues to the east on airborne geophysical surveys. This

feature suggests a facies change to sulphide and/orgraphite facies. Sporadic lenses of magnetite-facies alsooccur further to the east at the HNA-MRA contact, south-west and south of Crawford Lake. The iron formation doesnot appear to continue east of Crawford Lake.

Metamorphosed UltramaficCumulate Rocks

Cumulate-textured ultramafic bodies represent about 20%of the HNA and 2% of the MRA. The units are up to 15km in length and 500 m in width. The interpreted settingof these rocks is somewhat enigmatic and the unit may becomposed of both flows and sills. The rocks of this unitwere originally mapped as intrusions (Prest 1951; Milne1972). Many of these massive cumulate-textured unitswithin the MRA grade laterally, and rarely vertically, intospinifex-textured komatiitic flows. Recent research onrocks with similar textures and chemistry in other Archeanterranes has indicated that some of these cumulate-texturedultramafic rocks are a proximal facies of komatiitic flows(Hill et al. 1990). Others, such as the numerous ultramaficcumulate bodies within the HNA, may be sills. These unitsdo not grade into spinifex-textured komatiites and may besubvolcanic intrusions related to the same magmaticevents which resulted in the komatiite flows found in theMRA.

The ultramafic cumulates are fine- to medium-grainedmassive rocks that range in colour from white to darkgreen on weathered surfaces. They are strongly magneticand where undeformed, are relatively resistant to weathering.Where they have experienced strong ductile deformation,they are soft, talcose and may contain green fuchsiticmica. Ubiquitous irregular joints related to serpentinizationoutline polyhedral columns from 10 to 100 cm in diameter.Primary textures are dominantly net-textured adcumulateto mesocumulate and rarely orthocumulate. Forsteritecores within serpentinized rims, surrounded by thin inter-stitial rinds rich in opaque minerals, have been microscop-ically observed in some of the adcumulates. Rocks withmesocumulate textures contain serpentinized, anhedralolivine crystals with a higher proportion of interstitialmaterial consisting of talc, serpentine, carbonate andopaque minerals. Preserved orthocumulates, in whichserpentinized cumulate olivine grains are isolated in agroundmass of intercumulus material, are rare within thisunit but are commonly observed in the cumulate portionsof spinifex-textured flows. North of the CNR tracks andwest of Palomar siding in Keith Township, rare sphericalstructures up to 1 cm in diameter are infilled with serpentineand sulphides. These features are suggestive of amygdulesand may be further evidence of an extrusive origin forsome of the massive, cumulate-textured ultramafic rocks.

An extensive cumulate-textured body, hosting boththe Reeves asbestos mine and the Penhorwood talc mine,occurs in northern Penhorwood and southern Reevestownships. The unit has a northerly trend which is distinctly

11


variant from the overall easterly trend of most rock unitsin the NSGB. The northern part of the unit is folded abouta northerly trending F2 antiformal syncline. Exposure isbest in the northwestern part of the unit in the vicinity ofthe Reeves Mine, where based on the differentiation trends(see “Geochemistry”), the ultramafic body faces to the east.It is underlain by poorly exposed komatiitic volcanic rockson the west and mafic volcanic rocks to the north. Thekomatiite unit is up to about 150 m wide. The basal portionconsists of talc-carbonate schists in highly strained contactwith schistose clastic sedimentary rocks to the west. Theschists are succeeded to the east by spinifex-texturedflows grading into brecciated flows. The komatiite unit isoverlain by a thick unit of massive, serpentinized adcumu-late dunite capped by about 3 m of pyroxenite grading intoa thick gabbroic unit in the core of the antiformal syncline.

Metamorphosed Mafic Intrusive Rocks

The most extensive mafic intrusion within the map area isthe Shawmere anorthosite. It is located in the northwesternportion of the map area within the Kapuskasing StructuralZone. Within the NSGB, less extensive mafic intrusiverocks represent about 5% of the HWA and HNA, and lessthan 1% of the MRA. Some of these are intrusive units, asindicated on previous maps (Prest 1951; Milne 1972;Breaks 1978). Others, however, may be extrusive in origin,representing large ponded and locally differentiated flows.

The Shawmere anorthosite complex is a deformedand metamorphosed Archean basement-type anorthositewithin the Kapuskasing Structural Zone. It underlies thewestern part of Foleyet Township in a northeast-trendingcomplex about 50 by 10 km in size (Thurston et al. 1977).Riccio (1981) subdivided the intrusion into a main zoneand a marginal zone. In the map area, the main zone con-sists largely of leucogabbro and anorthosite, with smalleramounts of gabbro, melagabbro and ultramafic rocks. Themarginal zone consists of foliated, garnetiferous amphibo-lite cut by anorthosite and gabbro dikes. The gabbroicrocks typically consist of plagioclase megacrysts in a fine-to medium-grained recrystallized matrix of plagioclase,amphibole and pyroxene with or without minor opaqueminerals, quartz and garnet. Anorthositic rocks consist ofa medium-grained granulated mosaic of plagioclase andonly rarely contain plagioclase megacrysts. Mafic mineralsconsist largely of hornblende, but may also include garnet,titanite, epidote, chlorite and biotite. Gneissic textures pre-dominate in the margins and clotty and coronitic texturesin the central parts.

The compositional and textural similarity of the maficintrusions in the Swayze belt with the volcanic rocksstrongly suggests that they are synvolcanic and that somemay be thick massive flows that cooled slowly. However,locally crosscutting contacts indicate that at least some ofthese are intrusions. Some of the gabbro bodies are closelyassociated with the cumulate-textured ultramafic units.

In the Reeves unit there is a gradational contact betweenan underlying ultramafic unit and the overlying gabbro,indicating the gabbros are differentiates. Differentiationwas also observed in the serpentinite unit overlying theNat River iron formation in northern KenogamingTownship. The unit is about 250 m thick at the eastern end,where it appears to consist of several units gradingupwards from olivine orthocumulates into garbbroic zonesand spinifex-textured pyroxenites. Locally, the gabbroicportion of these differentiated bodies have randomspinifex textures consisting of elongate branching pyrox-enes in a groundmass of fine-grained plagioclase. Thesetextures are similar to the gabbroic central zones of largedifferentiated komatiite flows such as the Boston Creekflow in the Kirkland Lake area of the Abitibi greenstonebelt (Stone et al. 1987).

Mafic intrusions include dark green, medium- tocoarse-grained gabbro and minor melagabbro. Light grey-green, medium- to coarse-grained leucogabbro may formisolated bodies, such as the lenticular intrusion west ofMuskego Lake in northeastern Ivanhoe Township, oroccur more commonly as minor differentiates closelyassociated with gabbroic to ultramafic bodies. Inequi-granular textures composed of randomly oriented, acicular,amphibolitized pyroxenes in a finer plagioclase-richgroundmass are common. Relict subophitic textures werealso observed in thin section.

The elliptical Cornice Creek gabbro occurs in thesouthwestern part of Keith Township. The intrusion is wellfoliated along its margin, and locally contains felsic tomafic volcanic xenoliths. The rock is characterized bylarge clusters (5 to 10 mm) of hornblende crystals set in afiner grained matrix dominated by plagioclase. Such textureis typical of many other gabbroic bodies in KeithTownship. Microscopically, the rock displays a subophitictexture with coarse-grained, subhedral, amphibolitizedpyroxene crystals that partially to totally enclose subhedralto euhedral plagioclase crystals.

Felsic to Mafic Plutonic Rocks

The relative age of the plutonic rock units indicated onMap 2627 (back pocket) is based on the absence or presenceof a tectonic fabric and its intensity of development, asthere are only a few precise U-Pb zircon age determinationson the plutonic bodies within the area. The reader isadvised that these criteria should only be considered asguidelines to relative age. Previous U-Pb age determinations(Percival and Krogh 1983; Frarey and Krogh 1986) suggestthat the plutonic rocks of the Kapuskasing Structural Zone(KSZ), with a minimum crystallization age of 2765 Ma,are generally older than those of the NSGB. Initial resultsof an ongoing U-Pb geochronological study focussed onthe Swayze greenstone belt (SGB) and surrounding grani-toids also suggest younger ages for the plutonic suites ofthe SGB, but also show a wider range of ages than was

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OGS REPORT 297

previously recognized. For example, results of the studyindicate an age of 2740 Ma for the Chester biotite trond-hjemite pluton in the southeastern part of the SGB(Heather and van Breemen 1994). In addition, the studyreveals that the Kenogamissi batholith is composed ofphases with a wide range of ages, from 2713 to 2665 Ma.

The more extensive granitic complexes and plutonsare described below. Smaller intrusions consist of early tolate granitic stocks and dikes within the supracrustal rocksof the NSGB and are not described in any detail. Earlyfoliated porphyritic dikes and intrusions are foundthroughout the map area, but they are most abundant in thepredominantly sedimentary rocks of northern Keith andnorthwestern Penhorwood townships. The intrusions arepredominantly of plagioclase porphyry with subordinateamounts of plagioclase-quartz porphyry. Plagioclase por-phyry consists of medium- to coarse-grained, oscillatory-zoned, euhedral plagioclase phenocrysts in a very fine-grained groundmass of anhedral-granoblastic quartz andfeldspar, with lepidoblastic biotite or chlorite (afterbiotite?) and minor amounts of epidote, carbonate andopaque minerals. The plagioclase phenocrysts have beenmoderately altered to sericite, epidote and/or carbonate.

KAPUSKASING STRUCTURALZONE (KSZ)

Located west of the Ivanhoe Lake cataclastic zone, thegranitoid gneisses of the KSZ are compositionally vari-able, consisting mainly of tonalite and granodiorite. Atonalite gneiss body within the Shawmere anorthositecomplex on the western margin of Foleyet Township maybe coeval with or intrudes the Shawmere anorthosite. Thetonalite gneiss has a minimum Pb-Pb age of 2765 Ma, thusproviding a lower limit for the age of the complex and theassociated paragneisses and amphibolites of the KSZ(Percival and Krogh 1983).

In general, tonalite and diorite gneiss occurs adjacentto, and within, the Shawmere anorthosite complex, whereasgranodiorite intermixed with tonalite gneiss is concentratedfurther east in the KSZ. The tonalite gneiss commonlycontains abundant amphibolite xenoliths. Minor quartz-saturated phases consisting of diorite and monzonitegneiss occur adjacent to the Shawmere anorthosite com-plex in southwestern Foleyet Township. Tonalite gneiss islight grey and contains plagioclase (andesine), quartz,biotite, with or without hornblende and accessory alkalifeldspar, apatite, epidote and opaque minerals. Granodioritegneiss is a light pinkish grey with 5 to 15% alkali feldsparand biotite as the main mafic mineral. Diorite gneiss isdark grey with plagioclase (andesine), quartz, hornblende,with or without biotite, and accessory alkali feldspar,apatite, epidote and opaque minerals.

NAT RIVER GRANITOID COMPLEX

The Nat River granitoid complex marks the northernboundary of the north Swayze greenstone belt and extendsfrom the Ivanhoe Lake cataclastic zone eastward acrossthe map area. The distribution of this complex is largelybased on the interpretation of aeromagnetic patterns. Thisinterpretation, supported by sparse outcrop, also indicatesthat the early felsic to intermediate intrusions have lowerand less variable magnetic susceptibilities. The complexconsists of 1) both early, strongly foliated to gneissic,hornblende-biotite tonalite to granodiorite and late, mas-sive to weakly foliated, biotite granodiorite; 2) weaklyfoliated pegmatite and aplite dikes; and 3) massive granitedikes.

Early phases are predominantly strongly foliated togneissic tonalites and granodiorite. The tonalite is lightgrey on weathered surfaces and consists of plagioclase(oligoclase), quartz and biotite, with accessory epidote andtitanite. In eastern and western Muskego Township, thedominant rock type is medium-grained, moderately toweakly foliated pink-weathering hornblende-biotite gran-odiorite and biotite granodiorite. These early intrusivephases are cut by diorite, felsite and pegmatite, and locallycontain minor inclusions of tonalite and diorite. Typicallythe hornblende-biotite granodiorite consists of 35 to 40%plagioclase (moderately altered to sericite and epidote),20 to 25% quartz, 10 to 20% microcline, 15 to 20% horn-blende, 1 to 5% chloritized biotite and trace amounts oftitanite, opaque minerals, epidote and zircon. Biotite gran-odiorite consists of 60 to 70% plagioclase, 20% quartz,10% biotite and 5% alkali feldspar. The minor hornblendediorite probably represents a more primitive intrusivephase, closely associated with the granodiorite in south-western Muskego Township. Hornblende diorite consistsof 40 to 60% plagioclase (moderately to strongly altered tosericite and epidote), 20 to 40% hornblende, less than5% biotite, less than 5% quartz, less than 5% opaque min-erals and less than 5% epidote.

Compositions of the late granitic intrusions within theNat River granitoid complex are generally more potassicthan the early foliated to gneissic granitoids. They are pre-dominantly granite and granodiorite, with or without coarse-grained, tabular alkali-feldspar phenocrysts. A large latefelsic pluton intrudes the foliated granodiorite and dioritewithin the Nat River granitoid complex in MuskegoTownship and northeastern Foleyet Township. It consistsof a massive to weakly foliated, equigranular to porphyritic,medium-grained biotite granite and granodiorite with orwithout muscovite. Compositionally, these late-stagegranitic intrusions are distinguished from the surroundingearly granitoids by their higher potassium content, signif-icant differences in mafic mineral composition and commonporphyritic nature. Typically they consist of 35 to 40%microcline, 30 to 35% quartz, 15 to 25% plagioclase, 5%biotite, less than 2% muscovite, less than 2% titanite andtrace amounts of epidote, apatite and opaque minerals.Porphyritic granite is common south of Beatty Lake, where

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it contains 5 to 10%, zoned alkali-feldspar phenocrysts 1 to5 cm in size. Large inclusions of massive, coarse-grained,alkalic melagabbro occur within the granite on the south-west side of Beatty Lake. The melagabbro consists of 60to 70% hornblende, 15 to 20% plagioclase (moderatelyaltered to sericite and epidote), 10 to 15% microcline, 2 to3% titanite and trace amounts of apatite and opaque miner-als. The alkalic gabbro probably represents a composition-ally primitive early phase of the granitic magma.

Foliated, medium-grained hornblende gabbro withaccessory magnetite is seen in outcrop along theGroundhog River north of Highway 101. Granitic inclusionsand crosscutting aplite dikes suggest the gabbro is an earlyintrusive phase of the complex. Airborne magnetic surveydata indicate the gabbro is about 2 km wide along thesouthern margin of the complex. Another unit of perhapssimilar chronology occurs along the southern margin ofthe Nat River granitoid complex in western Reeves andSewell townships. This unit was not observed in the syn-optic mapping and thus has been compiled from Milne(1972). He describes the unit as a mixture of biotite-horn-blende granodiorite and diorite. The diorite is composed of30 to 40% hornblende with coarse-grained plagioclase andinterstitial quartz, with accessory titanite, magnetite andapatite, and secondary epidote, chlorite, carbonate, sericiteand pyrite. Because the exposure is very poor in this partof the map area, the unit has been largely interpreted fromaeromagnetic maps, as it has a markedly higher magneticresponse than the surrounding foliated tonalite and gran-odiorite.

In northeastern Foleyet and northwestern Muskegotownships, the Nat River granitoid complex consists oftonalitic gneiss, paragneiss and amphibolite intruded bybiotite-muscovite granite and pegmatite. The granite con-sists of plagioclase (oligoclase), microcline, quartz, biotiteand muscovite, with trace amounts of epidote, titanite,opaque minerals and rarely garnet, which is suggestive ofan aluminous “S type” granite. The pegmatite dikes con-sist of graphic-textured intergrowths of perthite andquartz, biotite, muscovite, and may also contain minorfine-grained garnet. Locally, plagioclase within the granitein the northwestern part of Muskego Township has under-gone significant epidotization suggesting propylitic alter-ation, perhaps as a result of the intrusion of abundantgranitic pegmatite dikes in the area. Similar dikes cut foli-ated granodiorite along Highway 101 in west-centralMuskego Township. In this locality, however, the peg-matite dikes also contain minor quantities of chalcopyriteand molybdenite, which are also suggestive of porphyry-type mineralization.

KENOGAMISSI BATHOLITH

Within the synoptic area, the Kenogamissi batholithoccurs in the southern part of Penhorwood Township, the

southern and eastern parts of Kenogaming Township andthe southeastern part of Reeves Township. It is a large,elliptical granitoid complex that separates the Swayzegreenstone belt from the Abitibi greenstone belt. Recon-naissance mapping by Heather (1993) has documented acomplex sequence of at least 6 intrusive phases which rangefrom early foliated to late massive granitic phases.Geochronological studies by Heather and van Breemen(1994) have revealed a large range of ages, including 1)foliated hornblende tonalites at 2713 Ma; 2) foliated biotitetonalite to granodiorite at 2697 Ma; 3) massive to foliated,potassium-feldspar megacrystic, hornblende granodiorite at2692 Ma; and, 4) massive biotite granite at 2665 Ma.

Only marginal phases were observed in the presentstudy. These range from biotite tonalite in the southwest tohornblende-biotite tonalite and biotite granodiorite in thesoutheast. These southern marginal phases are strongly foli-ated, with northerly dips becoming progressively steepertowards the east. A septum of foliated hornblende monzodi-orite, crosscut by biotite tonalite and aplite dikes, joins thebatholith with the Nat River granitoid complex in south-central Sewell Township. Moderately foliated biotite graniteoccurs in the batholith south of a large supracrustal inclusionin southeastern Sewell Township.

A late granite phase is indicated within theKenogamissi batholith south of Montgomery Lake, insoutheastern Penhorwood and southwestern Kenogamingtownships. Milne (1972) indicated this phase is continuouswith a septum of granitic rocks joining the batholith with theKukatush pluton. High resolution aeromagnetic maps indi-cate that this granitic septum is more likely a series of sep-arate intrusions, as is indicated on Map 2627 (back pocket),that are most likely satellite bodies or apophyses of thebatholith. Milne (1972) described the granite (or ratherquartz monzonite in Milne’s classification scheme) as beingmassive and inequigranular with coarse-grained plagioclasein a medium-to fine-grained groundmass. The mineralogy isdescribed as mainly oscillatory-zoned oligoclase, micro-cline and quartz, with minor biotite and muscovite, acces-sory titanite, magnetite and apatite, and secondary sericiteand epidote.

TOM SMITH LAKE GRANITIC COMPLEX

A complex of early foliated tonalite and granodiorite, latefoliated monzonite and diorite and massive granite andgranodiorite, located east of the Ivanhoe Lake cataclastic zonein western Ivanhoe Township, is herein identified as theTom Smith Lake granitic complex. Compositions are highlyvariable and mainly include tonalite, granodiorite, graniteand quartz-saturated, alkalic intrusions. Foliated tonalite islight grey and consists of plagioclase (oligoclase), quartz andbiotite with minor alkali feldspar, titanite, apatite and epidote.Foliated granodiorite typically contains up to 10% coarse-grained alkali-feldspar phenocrysts in a finer grained ground-mass of plagioclase (oligoclase), microcline, quartz andbiotite, with minor myrmekite, titanite and opaque minerals.

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OGS REPORT 297

Late monzonite, syenite and diorite, with gabbro andclinopyroxenite xenoliths, occur in 2 separate bodies: 1)along the Ivanhoe Lake cataclastic zone in southwesternFoleyet Township; and 2) south of the broad part ofIvanhoe Lake in west-central Ivanhoe Township.

The phases along the Ivanhoe Lake cataclastic zonehave a strongly developed cataclastic fabric defined byelongate alkali-feldspar augen. Intrusive phases alongIvanhoe Lake contain medium-grained alkali-feldsparphenocrysts and are only moderately to weakly foliated.Percival (1981) interpreted the alkalic intrusions in these 2areas as a narrow continuous body. Aeromagnetic datafrom these areas indicate isolated magnetic highs separatedby magnetic lows. Thus, a more likely interpretation isthat of 2 isolated alkalic intrusions separated by a largeunexposed area, which is probably underlain by early foli-ated tonalite and/or granodiorite. Geochronological sam-pling of a diorite from south of the broad part of IvanhoeLake indicates a U-Pb age of 2680 +3

-2 Ma (Percival andKrogh 1983).

Foliated syenite and monzonite are pinkish-grey, typ-ically with up to 10% coarse-grained alkali-feldspar augenwhere the rock is strongly deformed. The phenocrystsconsist of perthitic alkali feldspar surrounded by anhedral,recrystallized alkali feldspar and plagioclase in the matrixwith clinopyroxene, biotite and accessory apatite andopaque minerals. Foliated diorite is dark grey, with medium-grained plagioclase (oligoclase) crystals in a finer ground-mass of hornblende, quartz and biotite, with accessorytitanite, opaque minerals, apatite and epidote.

Gabbro and clinopyroxenite occur as inclusions orlarge rafts in the monzonite and syenite intrusions. Thesemafic intrusions manifest a tectonic foliation but theirmineralogy indicates a relatively unmetamorphosednature, in contrast with the mafic and ultramafic intrusiverocks in the supracrustal sequences discussed above.Gabbros are dark grey to black and contain 50% normallyzoned plagioclase (oligoclase), 25% augite, 12% horn-blende and 12% biotite and trace amounts of titanite,epidote, carbonate and zircon. Clinopyroxenite is dark greyand medium grained, with coarse-grained hornblende pheno-crysts. A typical clinopyroxenite consists of 70% augite,20% hornblende and 10% plagioclase, with trace amountsof titanite and apatite.

In the southwest part of Ivanhoe Township, the mainphase of the complex is a homogeneous biotite graniteconsisting of microcline, plagioclase (oligoclase), quartzand biotite with trace amounts of apatite, epidote andopaque minerals. Numerous pegmatite dikes, consisting ofgraphic-textured intergrowths of perthite and quartz,intrude the granite.

KUKATUSH PLUTON

The Kukatush pluton is a 5 by 15 km, elongate, east-trending body, located in southeastern Keith and south-

western Penhorwood townships. It is a homogeneousintrusion consisting of a massive, equigranular, medium-grained hornblende monzonite. In contrast to the lowmagnetic susceptibilities of the Hoodoo Lake pluton andthe Groundhog Lake felsic complex, the Kukatush plutonexhibits a positive aeromagnetic anomaly which, in con-junction with limited exposure, indicates a more extensivedistribution to the west into Hoodoo Lake than indicatedon previous maps (Thurston et al. 1977; Breaks 1978). Thehigh-resolution aeromagnetic maps also suggest modifica-tion of the interpreted contacts of Milne (1972) in south-western Penhorwood Township.

The most abundant phase of the pluton consists of amassive, equigranular, medium-grained hornblende mon-zonite. As seen in thin section, monzonite typically consistsof 40 to 50% plagioclase (slightly altered to sericite andepidote), 20 to 30% microcline, 0 to 5% quartz, 10 to 20%hornblende, less than 5% biotite (chloritized with epido-tized rims), less than 3% magnetite, less than 3% titaniteand trace amounts of epidote, apatite and zircon. A moredifferentiated hornblende-biotite quartz monzonite, con-taining 10% alkali-feldspar phenocrysts (1 cm in size) and10 to 20% quartz, occurs locally as a marginal phase. Bothphases commonly contain a significant proportion ofmafic volcanic xenoliths (5 to 10%). Inclusions of fine-grained, felsic volcanic rock were also observed in thevicinity of the Groundhog Lake felsic complex.

A number of small intrusions with northeast elongation,located between the Kukatush pluton and the Kenogamissibatholith, are most likely satellites of the Kenogamissibatholith. These bodies consist of biotite granodiorite,muscovite granite and quartz-feldspar porphyry. They arestrongly foliated, dip gently to the northwest, and are insheared contact with the supracrustal rocks on their south-eastern margins. This suggests that southeasterly directedthrusting along the northwestern contact of the Keno-gamissi batholith may have created the structural site of theveins hosting the quartz and barite open pit mines in this area.

HOODOO LAKE PLUTON

The Hoodoo Lake pluton is a 5 by 10 km northeast-trendingovoid, in western Keith and eastern Ivanhoe townships.Although exposures are restricted to the southeastern mar-gin, intrusive contacts are well defined by a distinct nega-tive aeromagnetic anomaly. The surrounding mafic vol-canic rocks are metamorphosed to amphibolite facies, withfoliations paralleling the intrusive contact and dipping intowards the centre of the pluton. U-Pb zircon geo-chronology indicates a crystallization age of 2684±3 Ma(Frarey and Krogh 1986). It is a massive, homogeneous,porphyritic biotite granodiorite characterized by largealkali-feldspar phenocrysts (1 to 3 cm in size) set in amedium-grained groundmass. The granodiorite consists of50 to 60% subhedral, oscillatory-zoned plagioclase (slightlyaltered to sericite and epidote), 15 to 25% quartz, 10 to 15%microcline, less than 5% biotite and minor amounts oftitanite, epidote, apatite, opaque minerals and zircon.

15


IVANHOE LAKE PLUTON

The Ivanhoe Lake pluton is a triangular intrusion about 8 kmacross. The western part is a massive, pinkish-grey weath-ering, alkali-feldspar porphyritic, biotite granodiorite con-sisting of plagioclase (andesine), quartz, microcline andbiotite, with trace amounts of opaque minerals, titanite,epidote, sericite and carbonate. The eastern part of the plutonconsists of massive, light grey weathering, alkali-feldsparporphyritic, biotite-quartz monzodiorite composed ofstrongly saussuritized plagioclase, microcline, quartz andbiotite with trace amounts of titanite and opaque minerals.Abundant, grey weathering, equigranular tonalite dikesintrude the surrounding country rock on the southeastmargin of the pluton.

Alkalic Mafic Intrusive Rocks

Alkalic mafic intrusions consist of lamprophyre dikes toosmall to be portrayed on Map 2627 and are therefore notincluded on the map’s legend (back pocket). The dikes aremost abundant in the 4 western townships in close prox-imity to the KSZ. They have a consistent northeasterlytrend. The suite is interpreted to be Archean, but may alsoinclude intrusions associated with alkalic magmatismfocussed along the KSZ, which occurred over a protractedperiod in the Proterozoic and Paleozoic eras (Sage 1991).Some of these dikes may be genetically related to a 40 cmkimberlitic dike reported in core from diamond drilling byDome Exploration (Canada) Limited, in Keith Townshipwest of the Horwood Lake road and north of the Kukatushpluton. Watson et al. (1978) indicated the dike consistsmainly of olivine (40%), phlogopite (25%) and carbonateminerals (20%), and lesser amounts of spinel, ilmenite,clinopyroxene, serpentine, perovskite and apatite.

The dikes range from mafic to ultramafic in composi-tion. They are commonly porphyritic and typically containbiotite. Massive biotite lamprophyre dikes up to 20 cmthick occur in foliated monzonite along the west side ofIvanhoe Lake and in the massive granite pluton in south-western Ivanhoe Township. The dikes are carbonate-rich,weather recessively and are rusty brown in colour. Theyconsist of fine-grained pyroxene and biotite phenocrysts,extensively replaced by carbonate, in a very fine-grainedgroundmass whose original mineralogy is obscured byextensive carbonate alteration. Phenocrysts (0.5 to 2 cm)of clinopyroxene (30%; moderately altered to amphibole)and biotite (20%) in a groundmass of fine-grained ortho-clase (30%), carbonate (15%) and opaque minerals (5%)were identified by thin section examination of a samplefrom a 30 cm dike cutting granitoids, along Highway 101west of Scorch Creek. A 5 m ultramafic lamprophyre dikeobserved in core from a diamond-drill hole on the east sideof Muskego Lake, consists of phenocrysts of enstatite 1 to5 cm in size (40%; partially altered to talc and serpentine)in a groundmass of phlogopite (20%), tremolite (25%),serpentine (10%) and opaque minerals (5%).

PROTEROZOIC

Mafic Intrusive Rocks

Diabase dikes occur scattered throughout the map areaand are genetically related to 3 Proterozoic magmaticevents: 1) a northwest-trending Matachewan swarm with aU-Pb age of 2454±2 Ma; 2) a northeast-trending swarmrestricted to the KSZ with an Ar-Ar age of 2043 Ma; and3) an east-northeast-trending Abitibi swarm with a U-Pbage of 1140±2 Ma (Osmani 1991).

A large number of tholeiitic diabase dikes (unit 11,Map 2627, back pocket) occur throughout the map area,but are most abundant in the 4 eastern townships. All dikesof this set have a northwesterly to northerly trend, areslightly to moderately magnetic and are interpreted asmembers of the Matachewan swarm. They are most readilydetected on vertical gradient or second derivative magneticsurvey maps and in many places have their location pos-tulated on the basis of magnetic interpretation. The dikesare dark grey to black on weathered surfaces near their fine-grained contact margins and are brown-weathering, medium-grained and diabasic-textured in their central parts.Exposed dikes range up to 80 m in width and some are plagio-clase-phyric. Thin section examination of a sample of por-phyritic diabase indicates it consists of 20% bytownite phe-nocrysts (An80), 2 to 10 mm in size and strongly altered tosericite and epidote, in a subophitic groundmass of normallyzoned labradorite (50%), hypersthene (25%; moderatelyaltered to amphibole and chlorite) and opaque minerals (5%).

Two large east-northeast-trending olivine diabasedikes (unit 12, Map 2627, back pocket), found in thesoutheastern part of the synoptic area, are part of theAbitibi swarm. The southern dike is up to 130 m wide andmay extend for a total length of over several hundred km(Milne 1972). The dikes are characterized by very highmagnetic susceptibility and thus their position on Map2627 (back pocket) is largely based on aeromagnetic inter-pretation. The diabase is very susceptible to weatheringand thus outcrops typically consist of a veneer of largelyunconsolidated masses of pea-sized sand. The fresh rock islight grey coloured. The central parts of the dikes are verycoarse grained and subophitic textured, with lathes oflabradorite, interstitial titanaugite and accessory olivine,biotite, magnetite and apatite.

Within the Kapuskasing Structural Zone the diabasedikes (not shown on Map 2627, back pocket) are up to 10 mwide and trend east to northeast. They are interpreted to bepart of the Kapuskasing swarm of diabase dikes (Percival1990). The dikes are tholeiitic quartz diabase. They arefine to medium grained, brown weathering, and have asubophitic texture. They consist of plagioclase (normallyzoned from andesine to oligoclase) and clinopyroxenewith minor opaque minerals and quartz.

The larger Matachewan diabase dikes have envelopesof epidote alteration and locally have associated sulphide

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OGS REPORT 297

mineralization. Milne (1972) indicates 3 such sulphideoccurrences in the eastern part of the synoptic area: 1) dis-seminated bornite and chalcopyrite in the serpentiniteadjacent to the diabase dike cutting the Reeves asbestosdeposit; 2) disseminated chalcopyrite and pyrrhotite asso-ciated with the diabase in the iron formation outcrop southof Crawford Lake, in Kenogaming Township; and 3) scat-tered veinlets containing stibnite in mafic volcanic rocksassociated with the diabase dike in southwestern SewellTownship.

PHANEROZOIC

Pleistocene and Recent

The map area lies within the Abitibi upland of the JamesBay region which exhibits moderately rolling relief, with ele-vations averaging between 300 and 400 m (Kaszycki 1992).All surface drainage is northward into Hudson Bay via theGroundhog River and its tributaries. The map area isextensively covered by drift and is characterized by a gentlyrolling till plain.

A number of esker systems with a southerly trendtransect the synoptic map area. Extensive deposits of out-wash sand, reworked into rolling hills by eolian processes,are evident in the central parts of Ivanhoe Township andare closely associated with the main esker meandering ina southerly trend across central Foleyet and Ivanhoe town-ships. This esker represents an extensive esker system witha regional extent of over 75 km (Thurston et al. 1977). Theesker is up to 100 m wide and rises up to 30 m above thesurrounding countryside. Two other significant eskersystems bisect the map area. One extends from the north-western boundary of Reeves Township to the southeasternboundary of Keith Township. The esker rises up to about20 m above the surrounding country where it parallels theGroundhog River in eastern Keith Township. A third eskertrends from the northwestern boundary of SewellTownship to the southeastern boundary of PenhorwoodTownship. The esker rises to over 60 m above the sur-rounding terrain in east-central Penhorwood Township.Associated subaqueous fan and eolian sand and graveldeposits parallel these esker systems and they have locallybeen quarried for their aggregate.

Glacial striae observed throughout the map area indi-cate the main direction of ice flow was to the southwest at190° to 200°. This feature is related to the main directionof ice transport during the Late Wisconsinan between 10 700and 11 500 years BP (Prest 1970). Other, more obscure,trends of ice movement have also been identified locallywithin the map area (Kaszycki 1992). The older trendingstriae may reflect a pre-Wisconsinan glaciation (Bird andCoker 1987).

Much of the map area is covered by glacial till up to35 m thick. Laminated silt and clay occurs in topographiclows in river valleys and along the shore of Horwood Lake

(Kaszycki 1992). Varved clay and sand deposits are alsovisible in the banks of the Ivanhoe River.

Recent swamp and muskeg deposits occur throughoutthe map area. They are extensive in low areas, particularlyin northwestern Keith and southwestern Muskego town-ships. Investigations of the economic potential for peat inthis area indicated a number of sites with potentially com-mercial resources, with a depth averaging between 2 and 3 m(Dendron Resource Surveys Ltd. 1984).

METAMORPHISM

Mineral assemblages in paragneiss and amphibolite gneissindicate granulite-facies metamorphic conditions prevailedin the Kapuskasing Structural Zone. Geothermometry andgeobarometry by Percival (1990) indicate metamorphicconditions increase eastward across the KSZ, representingthe exposure of progressively deeper, lower crustal rocks.He estimates maximum temperatures in the range of 700to 800°C and pressures in the 8 to 9 kilobar range in theeasternmost part, adjacent to the Ivanhoe Lake cataclasticzone.

All supracrustal rocks with the NSGB have been sub-jected to greenschist- or amphibolite-facies metamorphicconditions. Greenschist-facies mineral assemblages areevident throughout most of the belt. Mineral assemblagesindicative of amphibolite facies occur throughout southernIvanhoe Township, south of the Muskego River fault.Contact metamorphism of the supracrustal rocks within1 km of the external granitoid intrusions and 500 m of thelarger internal plutons has also produced amphibolite-facies mineral assemblages. This metamorphic upgradingis most evident as a colour change from dark green toblack in mafic volcanic rocks. Typical mineral assem-blages in greenschist-facies mafic volcanic rocks includealbite, actinolite, chlorite and epidote, while amphibolite-facies rocks contain oligoclase, quartz, hornblende, andepidote with localized development of medium-grained,feathery hornblende porphyroblasts or equant garnet por-phyroblasts.

Mineral assemblages consisting of biotite, muscovite,garnet and andalusite in the pelitic sedimentary rockssouth of the Ivanhoe Lake pluton are also indicative oflower amphibolite-facies metamorphism. Porphyroblasticgrowth is locally evident in sedimentary rocks and felsicvolcanic rocks. Hornblende porphyroblasts occur in amudstone metamorphosed to amphibolite facies in closeproximity to the contact with the Nat River granitoid com-plex, in southwestern Muskego Township. Amphibole andtourmaline porphyroblasts were observed in greenschist-facies chert beds and turbidites, respectively, in KeithTownship. Chloritoid porphyroblasts in schistose felsicvolcanic rocks indicate that upper greenschist-faciescontact-metamorphic conditions occurred about 1 km southof the Nat River granitoid complex in south-centralMuskego Township. The chloritoid porphyroblasts are

17


randomly oriented and overprint an S1 and S2 tectonic fab-ric, within the Slate Rock deformation zone, indicating thatthe contact metamorphic event came relatively late in thetectonic history of the area.

Contact strain aureoles also appear to have developedin conjunction with contact metamorphism, as thesupracrustal rocks surrounding the Hoodoo Lake andKukatush plutons have a well-developed tectonic foliationwhich parallels the plutonic contacts and dips steeplyinwards towards the pluton centres. The latter feature sug-gests erosion has removed much of the upper part of theplutons.

ALTERATION

Mineral assemblages indicative of alteration are evident ina number of localities in the NSGB. Four distinct types aredocumented:

1) hydrothermal silicification of volcanic rocks

2) hydrothermal alteration producing chloritoid-bearingvolcanic rocks

3) carbonatization associated with ductile deformation

4) epidotization associated with metamorphism andhydrothermal alteration

Silicification

Hydrothermal silicification was observed in a number oflocalities in the northwestern part of the Muskego–Reevesassemblage. The most extensive is a northeast-trendingzone of silicification, exposed over an area of 1 by 5 km,in northeastern Ivanhoe Township (Ayer 1993). It occurswithin intermediate to mafic flows cut by the southeasternmargin of the Ivanhoe Lake pluton. Silicification has onlyoccurred to a moderate degree in much of the zone and ismost evident in pillow breccia, where the fragments arelight grey in a darker grey schistose matrix. Silicificationin these zones appears to have been controlled by earlyporosity, as the most intense bleaching is concentratedaround amygdules. This is also supported by the lack ofsilicification evident in the minor non-amygdaloidal orunbrecciated flows occurring within the silicified zone.Intense silicification is only exposed in the western part ofthe zone. In these areas, the silicification is manifested bylight grey to white rock in which the original volcanic tex-tures have been largely destroyed by multiple generationsof fracturing, pervasive silicification and quartz veining.

Thin section examination of both types of silicificationindicate a considerably higher proportion of very fine-grained quartz, feldspar, sericite and biotite than is evidentin the unsilicified mafic flows. Numerous dikes of tonalitecut the silicified zone and foliated silicified inclusions inmassive quartz monzodiorite locally occur in intrusivebreccias near the southeastern margin of the Ivanhoe Lakepluton. These relationships indicate the silicification

occurred prior to deformation and was cut by the posttec-tonic Ivanhoe Lake pluton. This and the early porositycontrol of the moderate silicification strongly suggests thatsilicification was synvolcanic.

Patchy zones of silicification also occur in an outcropof quartz- and feldspar-phyric felsic pyroclastic rockssoutheast of Highway 101, in the main felsic unit in south-eastern Foleyet Township. A felsic flow in the same uniton the southeast side of the highway also appears to besilicified and is cut by abundant quartz veins and cavitiesinfilled with very fine-grained silica.

Chloritoid-bearing Volcanic Rocks

Chloritoid porphyroblasts are found in drill core of car-bonatized mafic flows associated with a subeconomicstrata-bound sulphide zone and in carbonatized felsic tuffsalong the Ivanhoe River, in southeastern Foleyet Township(Ayer 1993). An extensive zone of chloritoid alteration, upto about 500 m wide and with an apparent strike length of4 km also occurs in Muskego Township (Ayer, in press).Fine feathery chloritoid is visible on cleavage surfaces ina plagioclase-phyric felsic schist north of Keith Lake.Along strike with this unit, to both the east and west,medium-grained, black tabular porphyroblasts of chloritoidin felsic carbonatized schists were observed in diamond-drill core. As chloritoid in greenschist-facies metavolcanicrocks has been documented to be the result of hydrothermalalteration (Lockwood 1986), it is assumed that this zonerepresents a zone of conformable hydrothermal alterationwhich could be associated with sulphide mineralization.Of economic significance, chloritoid-bearing altered vol-canic rocks are associated with a number of Archean vol-canogenic massive-sulphide deposits (Franklin et al. 1975).

Carbonatization

Extensive carbonatization is characteristic of ductiledeformation zones in the NSGB. The carbonate is com-monly a rusty-weathering iron-magnesium carbonate orlight grey weathering calcium carbonate. The most intensecarbonatization appears to be associated with highly schis-tose rocks with chlorite and/or sericite, and may occur inbroad zones up to 1 km wide in major shear zones such asthe Slate Rock deformation zone.

Epidotization

Rounded, epidote-rich clots occur within amphibolite-facies mafic volcanic rocks in south-central IvanhoeTownship. Epidotization is also evident within and sur-rounding large diabase dikes. In addition, epidote wasobserved as fine-to coarse-grained euhedral crystals withinquartz-carbonate veins in ultramafic volcanic rocks cut bygranodiorite dikes west of the Hoodoo Lake pluton, inIvanhoe Township. The above types of epidotization are

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OGS REPORT 297

probably related to remobilization of alkali elements bycontact metamorphism.

Pervasive epidotization, possibly related to propylitichydrothermal alteration, occurs in the foliated graniticrocks along the southwestern side of the open part ofIvanhoe Lake. In addition, plagioclase in the granite locatedin the northwestern part of Muskego Township has under-

gone significant epidotization, suggesting propylitic alter-ation, perhaps as a result of the intrusion of abundantgranitic pegmatite dikes in the area.

Epidotization is also locally evident in ductile defor-mation zones. In the deformation zone on the west side ofIvanhoe Lake, the evidence suggests it occurred prior tocarbonatization (Ayer 1993).

19


The lithogeochemical features of the synoptic area arebased on whole-rock analyses of 136 samples. Samplelocations are displayed on Map 2627 (back pocket) andsample descriptions indexed by township and UTM co-ordinates are provided in Table 2. Tables 3, 4 and 5 presentanalytical results for samples collected in 1991, 1992 and1993, respectively. Whole-rock sample analyses were per-formed by the Geoscience Laboratories of the OntarioGeological Survey, Toronto, for the 1991 samples (Table 3),X-Ray Assay Laboratories, Toronto, for the 1992 samples(Table 4), and the Geoscience Laboratories, GeoservicesBranch, Sudbury, for the 1993 samples (Table 5). Majoroxide contents were determined by X-ray fluorescence(XRF). Loss-on-ignition (LOI) was determined by gravi-metric methods; carbon dioxide and sulphur contents weredetermined by infrared spectrometry. Trace elements weredetermined by atomic adsorption (AA), X-ray fluores-cence, inductively coupled plasma optical emission spec-trometry (ICP-OES), and inductively coupled plasma massspectrometry (ICP-MS).

The ultramafic volcanic rocks of the Muskego–Reevesassemblage (MRA) range in MgO contents from 17 to 40%.They all plot in the komatiitic fields on a Jensen cationplot (Figure 3), and display a wide range in Mg-Fe-Almajor oxide variation from peridotitic komatiites (PK) tobasaltic komatiites (BK). A number of paired samples areplotted on Figure 3. These represent 2 samples from singleflow units: one representing the spinifex-textured rock inthe chilled upper part of the flow, and the second from thelower, cumulate-textured part of the same flow. Thesepaired samples show the cumulate portion to be moreprimitive than the chilled spinifex-textured part of theflow. In general, the olivine spinifex-textured peridotitickomatiite flows demonstrate a smaller range in Mg-Fe-Almajor oxide variation than do the pyroxene spinifex-tex-tured basaltic komatiite flows. Figure 4 displays the chon-drite-normalized rare earth element (REE) values for anumber of the PK and BK samples. The figure demon-strates that all the PK samples show distinct light rareearth element (LREE) depletion ([La/Lu]N = 0.5), negativeEu anomalies and flat heavy rare earth element (HREE)patterns at values 2 to 4 times that of chondrite. On Figure4, sample 93-1108 is from the spinifex-textured top andsample 93-1109 is from the cumulate base of the sameflow. The cumulate sample is more primitive, with lowerREE values, but the parallel trend of the REE patterns ofthese 2 samples demonstrates that there has been negligibleREE fractionation between the chilled upper margin of theflow, which presumably closely resembled the original liquidcomposition, and the cumulate base. The BK samples aredistinctive from those of the PK, with more fractionatedREE values in the 6 to 10 times chondrite range, slightlyelevated LREE values ([La/Lu]N = 1.5) and no Eu anomalies.

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OGS REPORT 297

Geochemistry

BK

PK

93-1014 pyroxene spinifex

91-119 talc-chlorite schist

92-231 polyhedral joints

91-1010 olivine spinifex

91-1215 cumulate base

92-249 pyroxene spinifex






Individual Flow Samples Paired Flow Samples

2 3Al O MgO

FeO + TiO 2

PK - Peridotitic komatiiteBK - Basaltic komatiite

La

Ce Pr

Nd

Sm Eu

Gd

Tb

Dy

Ho Er

Tm Yb

Lu

10

93JAA-1108

93JAA-1109

93JAA-1121

20

Basaltic komatiites

Peridotitic komatiites

Ro

ck/C

ho

nd

rite

1

91JAA-0039

93JAA-1014

93JAA-1035

93JAA-1033

Figure 3. Jensen (1976) cation plot of ultramafic volcanic samples. Manyof the samples are paired, representing a spinifex top and cumulate basefrom the same flow.

Figure 4. Chondrite-normalized REE plot of ultramafic volcanic samples.

Comparison with the geochemistry of komatiites inNewton Township (Cattell and Arndt 1987), in the south-ern Swayze greenstone belt (SSGB) indicates many simi-larities between the 2 areas. In both areas the olivinespinifex-textured komatiites show distinctive LREEdepletion, but in the northern Swayze greenstone belt(NSGB) the REE values range to lower values suggestingmore primitive magmas. This is also indicated by higherabsolute values of MgO and Ni in the NSGB. In addition,in both areas the komatiitic basalts range to moderatelyLREE-enriched values.

The potential for nickel-copper deposits in the MRAkomatiites appears to be favourable, as their geochem-istry is similar to that of the host rocks of nickel-copperdeposits in the Abitibi greenstone belt. Barrie et al. (1993)state that nickel-copper deposits in the Abitibi Subprovinceare hosted exclusively in komatiite flows and hypabyssalsills, represented by chill compositions (i.e., spinifex-textured) with high MgO contents (20 to 35%, anhydrous),very low incompatible element contents and LREE-depleted signatures ([La/Lu]N = 0.5 to 0.8 and Zr/Y lessthan 2.5). In comparison, most barren komatiites have lessprimitive compositions, higher absolute values of REEand flat to elevated LREE patterns.

Mafic volcanic rocks from the MRA and Horwoodassemblage (HWA) dominantly plot in the tholeiitic fieldon a Jensen cation plot (Figure 5). Magnesium tholeiitespredominate and consist of pillowed and massive flows,including some pyroxene spinifex-textured flows. Irontholeiites are volumetrically subordinate and consist ofpillowed and massive flows lacking spinifex. Both ironand magnesium tholeiites are dominantly LREE depleted([La/Lu]N = 0.6), with or without slight Eu depletion (Figure6). However, iron tholeiites generally have higher REEvalues (e.g., sample 91JAA-1047, Figure 6).

The overall depleted LREE patterns in the komatiiteand mafic volcanic samples from the MRA and HWAsuggest derivation from the same source region of depletedArchean mantle. These same LREE-depleted patterns areevident in the ultramafic and mafic volcanic rocks ofNewton Township in the SSGB (Cattell and Arndt 1987).A depleted Archean mantle source is also indicated in aSm-Nd isotopic study of the Newton Township ultramaficand mafic lavas, with epsilon Nd values of +1.6 to +4.2(Cattell et al. 1984). These features suggest that the extensivemafic to ultramafic volcanic suites of the NSGB andSSGB developed in a rift environment, with little or noinvolvement of continental crust, and may be an Archean-equivalent tectonic setting to mid-oceanic ridge or back-arcbasin volcanism in modern environments.

Similarities also exist between mafic volcanic and koma-tiite REE patterns in the MRA and HWA with those of theKidd–Munro assemblage. The tholeiitic mafic volcanicrocks in the 2 areas also have similar patterns to modernmid-oceanic ridge basalts with depleted LREE values formagnesium and iron tholeiites, but with higher absolutevalues for the iron tholeiites (Jackson et al. 1994).

Intermediate to felsic volcanic samples from theHanrahan assemblage (HNA) and MRA plot within thecalc-alkalic field on the Jensen cation plot and show ratioswhich range from calc-alkalic basalts to rhyolites (Figure 7).All display a high degree of LREE fractionation ([La/Lu]N

= 10), flat to concave-upward HREE patterns, with orwithout slight Eu depletion (Figure 8). What appears to belacking, in comparison with Abitibi assemblages such asthe Kidd–Munro assemblage, are the tholeiitic felsic dif-ferentiates or rhyolites designated as FIII-type by Lesheret al. (1986). All intermediate to felsic volcanic rocks sam-pled to date in the NSGB show high degrees of REE frac-tionation with highly elevated LREE and depleted HREE

21


HFT

CB HMT

HFT

HMT

CB

- High-iron tholeiite

- High-magnesium tholeiite

- Calc-alkalic basalt

2 3Al O MgO

FeO + TiO 2

91JAA-0008

91JAA-0196

93JAA-1112

93JAA-1107

91JAA-1047

20

10

Ro

ck/C

ho

nd

rite

4

Iron tholeiite Magnesium tholeiites

La

Ce Pr

Nd

Sm Eu

Gd

Tb

Dy

Ho Er

Tm Yb

Lu

Figure 5. Jensen (1976) cation plot of mafic volcanic samples. Figure 6. Chondrite-normalized REE plot of mafic volcanic samples.

patterns typical of calc-alkalic FI-type rhyolites (Lesher etal.1986). In modern day volcanism these rocks are moretypical of destructive-margin tectonics than the rifting-typeenvironment suggested by the tholeiitic felsic and interme-diate volcanic rocks of the Kidd–Munro assemblage(Barrie et al. 1993).

Thus, volcanism in the NSGB can be characterized ashaving occurred in 2 distinct tectonic environments. Theultramafic and mafic suites of the HWA and the MRAappear to have been derived from a depleted mantle sourcewith the mafic flows most similar to modern mid-oceanicridge basalts. The intermediate to felsic suites of the HNAand the MRA are clearly calc-alkalic in their affinity anddemonstrate a more evolved magmatic source, most similarto modern island arcs forming at destructive continentalmargins.

Samples from the ultramafic cumulates and associatedgabbroic differentiates of the MRA (Figure 9) show a sim-ilar range to the ultramafic and mafic volcanic samples onthe Jensen cation plots (see Figures 3 and 5), and are mostprobably synvolcanic sills or large ponded flows. Analysesof samples from the Reeves ultramafic to gabbroic bodyare displayed on Figure 10. Two dunite samples are veryprimitive, with similar REE patterns at 0.2 to 0.4 timeschondrite values and slightly fractionated LREE values([La/Lu]N = 1.5 to 2). Sample 93JAA-1119 is the mostprimitive and occurs at the base of the unit, while sample93JAA-1118 occurs about 50 m above the base. Sample93JAA-1122 is a pyroxenite sample which occurs at thetop of the ultramafic part of the body, an estimated 100 mabove the base of the unit. In contrast to the underlyingdunites, the pyroxenite sample displays moderate LREEdepletion ([La/Lu]N = 0.6) but with relatively primitive

REE values of 0.3 to 0.9 times chondrite. Samples fromthe overlying gabbroic part of the body (93JAA-1124,93JAA-1006 and 93JAA-1005) have flat REE patterns atvalues 1 to 10 times chondrite with either Eu enrichmentor depletion. These patterns indicate that besides olivineand pyroxene, plagioclase must have crystallized on theliquidus at some stage in the magma evolution and wasconcentrated in the gabbroic differentiates. The 3 ultra-mafic samples all have Eu values below detection limitsand thus these rocks would most likely display Eu depletionanomalies on Figure 10, if their absolute Eu values wereknown.

22

OGS REPORT 297

CBCA

CDCR

CB

CA

CD

CR


- Calc-alkalic andesite

- Calc-alkalic dacite

- Calc-alkalic rhyolite

2 3Al O MgO

FeO + TiO 2

1

93JAA-1062

92JAA-0258

91JAA-0184

91JAA-0170

92JAA-0194

92JAA-1134

93JAA-1071

100

10

Ro

ck/C

ho

nd

rite

La

Ce Pr

Nd

Sm Eu

Gd

Tb

Dy

Ho Er

Tm Yb

Lu

HFT

HMT

BK

PK



- Basaltic komatiite

- Peridotitic komatiite

HFT

HMT

BK

PK

2 3Al O MgO

FeO + TiO 2

Figure 7. Jensen (1976) cation plot of intermediate to felsic volcanicsamples.

Figure 8. Chondrite-normalized REE plot of intermediate to felsic vol-canic samples.

Figure 9. Jensen (1976) cation plot of ultramafic cumulate and gabbroicsamples.

Samples collected from the differentiated body host-ing the Ireland nickel showing in northeastern Keno-gaming Township are shown on Figure 11. Three samplesfrom the northeastern part of the body represent peri-dotite (93JAA-1096), pyroxenite (93JAA-1097) and gab-bro (93JAA-1095). All 3 samples show similar patterns,with significant to moderate LREE depletion ([La/Lu]N =0.35 to 0.85). In contrast, peridotite and gabbro samplesfrom the western end of the body (93JAA-1068 and93JAA-1069) display flat to slight LREE enrichment pat-terns ([La/Lu]N = 0.8 to 1.4). This difference may havesome economic significance, as the western samples werecollected in the immediate vicinity of known concentra-tions of nickel, copper and platinum group element (PGE)mineralization. It is possible that the samples enriched inLREE were contaminated by the assimilation of underlyingunits enriched in LREE, such as the felsic rocks of theHNA (e.g., see sample 93JAA-1071, Figure 8) and/or theNat River iron formation. This may have provided a mech-anism for sulphur saturation and thus the concentration ofnickel sulphides in this area (see “Economic Geology”).

Alteration has had a significant effect on whole-rockgeochemical patterns and in particular has affected themore mobile elements, such as the incompatible elementsiron and magnesium. In sampling for the synoptic project,the effect of alteration was minimized as much as possibleby collecting only samples without evident alteration, andby the removal of weathered surfaces and veining prior tosample submission. Figures 12 and 13 illustrate the effectof hydrothermal alteration on a suite of highly carbonatizedmafic samples collected in the immediate vicinity of theJoburke Mine, in Keith Township. The altered sampleswere provided by Noranda Exploration Company Limitedand were analyzed at X-Ray Assay Laboratories, in Toronto.Locations and results of individual samples are providedby Hall and Plant (1992a, 1992b). Figure 12, a Jensencation plot, illustrates that many of the altered mafic vol-

canic samples from the Joburke Mine plot in the interme-diate to basaltic parts of the iron tholeiite field. This is incontrast to the patterns of the unaltered mafic volcanicsamples collected throughout the NSGB (see Figure 5) inwhich only a minor number of the mafic suite samples areiron tholeiites. This iron enrichment is most probably theresult of hydrothermal alteration and the resultant mobilityof iron and magnesium. Similar shifts (not shown) werealso evident in carbonatized volcanic samples (bearingchloritoid) from other parts of the synoptic area (i.e., sam-ples 91JAA-0170, 92JAA-0109, and 92JAA-0221, Tables3 and 4).

The intense hydrothermal alteration around theJoburke Mine may also be evident in the REE patterns.Figure 13 shows that while the LREE values are in thenormal range for MRA mafic volcanic rocks, the middlerare earth element (MREE) and HREE values are distinctlydepleted, probably as a result of the alteration. Strongdepletion in HREE has been documented in carbonatizedmetabasic schists adjacent to auriferous veins at the DomeMine in Timmins and has been attributed to leaching bycarbonate- and potassium-rich hydrothermal fluids(Kerrich and Fryer 1979). In distinct contrast, Schandl andGorton (1992) document mobility in the LREE in thehydrothermally altered host rocks of Superior Provincemassive-sulphide deposits. Hall and Plant (1992b), how-ever, suggest that depletion in HREE values could also bean artifact of the analytical technique if there has beenincomplete digestion of refractory minerals in the ICPanalysis.

Tectonic environment interpretations are illustratedin Figures 14 and 15, in which the mafic volcanic sam-ples collected from the NSGB plot within the field ofocean floor basalts. If the field of unaltered mafic vol-canic rocks on Figure 14 is compared with those ofaltered mafic volcanic samples from the Joburke Mine

23


93JAA-1005

93JAA-1006

93JAA-1118

93JAA-1119

93JAA-1122

93JAA-1124

10

1

.1

Ro

ck/C

ho

nd

rite

La

Ce Pr

Nd

Sm Eu

Gd

Tb

Dy

Ho Er

Tm Yb

Lu

93JAA-1068

93JAA-1069

93JAA-1095

93JAA-1096

93JAA-1097

Ro

ck/C

ho

nd

rite

10

1

La

Ce Pr

Nd

Sm Eu

Gd

Tb

Dy

Ho Er

Tm Yb

Lu

Figure 11. Chondrite-normalized REE plot of samples from the ultramaficto mafic body hosting the Ireland showing.

Figure 10. Chondrite-normalized REE plot of samples from the Reevesultramafic to gabbroic body.

area (Figure 15), the “blurring” to the left and right of theocean floor basalt field in the Joburke samples is mostlikely an effect of hydrothermal alteration resulting inmobility of the high field strength elements (HFSE),which are generally considered to be immobile. In par-ticular, Figure 15 demonstrates that there is considerablymore mobility in yttrium as the deviation is focussed

along a line parallel to the yttrium axis with little devia-tion towards the zirconium or titanium axes. This con-firms the above-observed REE mobility, as yttrium is arelatively more compatible HFSE and is thus geochemi-cally more similar to the HREE, while zirconium is a rel-atively incompatible HFSE and is thus geochemicallymore similar to the LREE.

24

WPB

OFB

LKT

CAB

WPB

OFB,LKT,CAB

CAB

LKT

- with plate basalts

- ocean floor basalts

- low potassium tholeiites

- calc-alkalic basalts

Ti/100

Yx3Zr

Figure 15. Pearce and Cann (1973) plot of the altered mafic volcanicsamples from the Joburke Mine.

Ti/100

Yx3Zr

WPB

OFB

LKT

CAB

WPB

OFB, LKT, CAB

LKT

CAB

- with plate basalts

- ocean floor basalts

- low potassium tholeiites

- calc-alkalic basalts

Figure 14. Pearce and Cann (1973) plot of mafic volcanic samples fromthe northern Swayze greenstone belt.

HFT

HMT

TA

TD

CD

CA CB

HMT

CB

CA

CD

- Tholeiitic dacite

- Tholeiitic andesite


TD

TA

HFT



- Calc-alkalic andesite

- Calc-alkalic dacite

2 3Al O MgO

FeO + TiO 2

Figure 12. Jensen (1976) cation plot of altered mafic volcanic samplesfrom the Joburke Mine.

Ro

ck/C

ho

nd

rite

1

10

La

Ce Pr

Nd

Sm Eu

Gd

Tb

Dy

Ho Er

Tm Yb

Lu

Figure 13. Chondrite-normalized REE plot of altered mafic volcanic sam-ples from the Joburke Mine. Representative samples from analyses pro-vided by Noranda Exploration Company Limited.

25


91JAA-0006 pillowed mafic flow Ivanhoe 390237 5329160


91JAA-0009 massive granodiorite Ivanhoe 387492 5338216

91JAA-0039 massive komatiite flow Ivanhoe 384931 5335133

91JAA-0049 foliated tonalite Ivanhoe 380532 5333195

91JAA-0057 massive granodiorite Ivanhoe 381876 5330026

91JAA-0066 massive granite Ivanhoe 381584 5324022


91JAA-0073 polyhedral jointed komatiite flow Ivanhoe 394003 5332466

91JAA-0077 polyhedral jointed komatiite flow Ivanhoe 394071 5332272

91JAA-0094 massive quartz monzodiorite Ivanhoe 391294 5335062

91JAA-0102 intermediate amygdaloidal flow Ivanhoe 393075 5335410

91JAA-0105 leucogabbro Ivanhoe 393914 5336075

91JAA-0109 intermediate plagioclase-phyric tuff Ivanhoe 393914 5336075

91JAA-0113 massive mafic flow Ivanhoe 393820 5336406

91JAA-0119 altered schistose ultramafic with chloritoid Foleyet 392034 5339710

91JAA-0124 plagioclase-phyric felsic lapilli tuff Foleyet 392034 5339710

91JAA-0127 massive mafic flow with medium-grained pyroxene needles Ivanhoe 393260 5338193





91JAA-0149 polyhedral jointed komatiite flow Foleyet 393906 5340575

91JAA-0155 quartz-phyric felsic tuff Foleyet 391888 5340270

91JAA-0161 plagioclase-phyric felsic tuff Ivanhoe 387581 5334572

91JAA-0163 syenite gneiss Foleyet 385555 5339690

91JAA-0168 massive intermediate flow Foleyet 391992 5338863

91JAA-0170 altered quartz-phyric felsic tuff with chloritoid Foleyet 393375 5339814

91JAA-0173 massive mafic flow Foleyet 391345 5342700


91JAA-0184 quartz-phyric brecciated felsic flow Foleyet 391560 5340715

91JAA-0185 intermediate plagioclase & quartz-phyric tuff Foleyet 392532 5342797

91JAA-0193 massive mafic flow with medium-grained pyroxene needles Foleyet 393498 5338502

91JAA-0196 massive mafic flow with medium-grained pyroxene needles Ivanhoe 391368 5334494

91JAA-0197 silicified amygdaloidal flow Ivanhoe 391746 5334088


91JAA-1010 spinifex-textured komatiite flow Ivanhoe 390706 5331830

91JAA-1024 polyhedral-jointed komatiite flow Ivanhoe 391380 5333030

91JAA-1047 amphibolitized mafic flow Ivanhoe 388549 5324646

91JAA-1060 gabbro Ivanhoe 391154 5326347


91JAA-1095 mafic flow Ivanhoe 392326 5327271


91JAA-1136 amygdaloidal mafic flow Ivanhoe 395155 5329397

91JAA-1168 tonalite gneiss Foleyet 383389 5340869

Table 2. Lithogeochemical sample descriptions, township and UTM co-ordinates. (All UTM values are within Grid Zone 17.)

Sample No. Sample description Township Easting Northing

26

OGS REPORT 297

91JAA-1174 granodiorite gneiss Foleyet 384127 5341206

91JAA-1215 polyhedral-jointed komatiite flow Ivanhoe 390706 5331830

91JAA-1218 silicified flow Ivanhoe 391345 5334295

91JAA-2007 paragneiss Foleyet 395738 5348736

92JAA-0018 adcumulate dunite Keith 399128 5334137

92JAA-0045 massive mafic flow Keith 401684 5334388

92JAA-0047 pillowed mafic flow Keith 400588 5333080

92JAA-0066 amygdaloidal pillowed intermediate flow Keith 397575 5337317

92JAA-0109 altered felsic schist with chloritoid Muskego 403836 5338692


92JAA-0142 amygdaloidal intermediate flow Keith 405170 5335847

92JAA-0151 spinifex pyroxenite at base of differentiated flow Keith 406826 5335432

92JAA-0173 massive mafic flow Muskego 406602 5338400

92JAA-0194 quartz- and feldspar-phyric felsic schist Keith 403426 5332611

92JAA-0198 variolitic pillowed mafic flow Keith 406359 5331941


92JAA-0221 altered felsic schist with chloritoid Muskego 402615 5338435


92JAA-0231 polyhedral-jointed komatiite flow Keith 408401 5332430


92JAA-0248 polyhedral base of pyroxene spinifex ultramafic flow Keith 409188 5334010

92JAA-0249 pyroxene spinifex top of komatiite flow Keith 409188 5334010

92JAA-0250 massive mafic flow with medium-grained pyroxene needles Keith 408765 5333780

92JAA-0252 polyhedral komatiite flow with olivine phenocrysts Keith 406549 5335450


92JAA-0258 intermediate lapilli tuff Keith 406906 5335697


92JAA-1030 quartz-phyric felsic flow Keith 397775 5336805


92JAA-1052 pyroxene spinifex mafic flow Keith 397882 5334681

92JAA-1053 variolitic pillowed mafic flow Keith 398400 5334590


92JAA-1097 plagioclase megaphyric mafic flow Muskego 409387 5341716

92JAA-1116 massive granite Muskego 404032 5341240

92JAA-1134 plagioclase-phyric felsic porphyry Keith 404845 5328884

92JAA-1143 plagioclase-phyric felsic porphyry Keith 406874 5328984

92JAA-1144 monzonite Keith 407364 5327536

92JAA-1156 polyhedral-jointed komatiite flow Keith 404963 5324471


92JAA-1162 felsic schist Keith 402310 5324715

92JAA-1170 massive intermediate flow Keith 403425 5325310

92JAA-1180 granodiorite Keith 400203 5326416

92JAA-1193 quartz-phyric felsic tuff Keith 395718 5326151

93JAA-1001 massive mafic flow Reeves 419426 5339535

93JAA-1005 gabbro Reeves 419622 5338572

93JAA-1006 gabbro Reeves 419800 5337983

Table 2. Continued.


27


93JAA-1008 pillowed mafic flow Penhorwood 419952 5337110

93JAA-1014 spinifex-textured komatiite flow Reeves 419114 5339035


93JAA-1020 polyhedral-jointed komatiite flow Penhorwood 420479 5334444


93JAA-1027 pillowed intermediate flow Reeves 422227 5338688

93JAA-1033 spinifex-textured komatiite flow Penhorwood 415708 5333601

93JAA-1035 massive komatiite flow Penhorwood 414827 5332014

93JAA-1041 plagioclase porphyry Penhorwood 416389 5336332

93JAA-1042 massive mafic flow Penhorwood 415854 5326847

93JAA-1043 massive orthocumulate ultramafic Penhorwood 413405 5325923

93JAA-1046 spinifex-textured komatiite flow top Penhorwood 412158 5326030

93JAA-1055 quartz- and feldspar-phyric felsic tuff Penhorwood 424430 5331663

93JAA-1059 plagioclase-phyric intermediate flow Penhorwood 423757 5334659

93JAA-1062 plagioclase-phyric intermediate brecciated flow Penhorwood 424071 5334218

93JAA-1068 melagabbro Kenogaming 429624 5335890

93JAA-1069 adcumulate ultramafic Kenogaming 429624 5335890

93JAA-1071 plagioclase-phyric felsic tuff Kenogaming 429613 5336024

93JAA-1078 intermediate flow Kenogaming 430510 5333250

93JAA-1083 intermediate tuff breccia Kenogaming 428146 5331775

93JAA-1085 massive mafic flow Kenogaming 427703 5330244

93JAA-1086 intermediate lapilli tuff Kenogaming 430495 5331525

93JAA-1090 pillowed mafic flow Sewell 424652 5339400

93JAA-1095 gabbro Kenogaming 431667 5337092

93JAA-1096 spinifex-textured ultramafic pyroxenite Kenogaming 431550 5337093

93JAA-1097 orthocumulate ultramafic peridotite Kenogaming 431550 5337093


93JAA-1101 mafic flow Reeves 411582 5339468

93JAA-1102 intermediate Reeves 411828 5338207


93JAA-1106 intermediate flow Reeves 417042 5340935

93JAA-1107 plagioclase-phyric mafic flow Reeves 420238 5341136

93JAA-1108 spinifex-textured komatiite from flow top Penhorwood 418116 5332918

93JAA-1109 polyhedral-jointed komatiite from base of flow Penhorwood 418116 5332918

93JAA-1111 polyhedral-jointed komatiite flow Penhorwood 417639 5333293



93JAA-1114 spinifex-textured komatiite from flow top Penhorwood 419546 5333942

93JAA-1115 polyhedral-jointed komatite from base of flow Penhorwood 419546 5333942


93JAA-1118 adcumulate about 50 m above base of ultramafic unit Reeves 419187 5339845

93JAA-1119 adcumulate at base of ultramafic unit Reeves 419079 5338894

93JAA-1121 brecciated komatiite flow Reeves 418878 5338772

93JAA-1122 pyroxenite at top of ultramafic unit Reeves 419895 5338730

93JAA-1124 gabbro at bottom of gabbroic unit Reeves 419895 5338730

Table 2. Continued.


28

OGS REPORT 297

91JA

A-0

006

51.6

60.

8715

.78

11.0

70.

177.

238.

973.

320.

170.

080.

8610

0.18

91JA

A-0

008

54.4

60.

7913

.92

11.3

80.

217.

837.

433.

390.

100.

060.

2399

.80

91JA

A-0

009

64.8

60.

4916

.32

3.67

0.05

1.46

3.05

4.42

3.21

0.18

1.96

99.6

7

91JA

A-0

039

44.9

90.

356.

7510

.09

0.19

22.3

07.

170.

140.

030.

035.

7597

.79

91JA

A-0

049

70.4

70.

1716

.75

0.90

0.01

0.51

2.25

5.69

1.91

0.05

0.74

99.4

5

91JA

A-0

057

68.6

10.

4015

.89

2.35

0.03

0.89

1.62

4.33

4.44

0.13

1.08

99.7

7

91JA

A-0

066

72.5

10.

1714

.65

1.32

0.02

0.37

1.21

3.98

4.54

0.05

0.51

99.3

3

91JA

A-0

068

51.8

00.

7914

.06

11.6

50.

186.

379.

722.

840.

270.

071.

9099

.65

91JA

A-0

073

45.3

10.

336.

5911

.39

0.17

21.8

58.

220.

440.

040.

035.

0299

.39

91JA

A-0

077

43.7

60.

356.

8411

.33

0.18

23.0

47.

350.

510.

070.

035.

3998

.85

91JA

A-0

094

65.4

10.

4615

.55

3.58

0.05

1.59

2.79

4.21

3.38

0.17

1.02

98.2

1

91JA

A-0

102

61.5

90.

5616

.36

5.95

0.07

3.97

5.72

3.58

1.36

0.11

0.77

100.

04

91JA

A-0

105

49.5

30.

6411

.64

8.72

0.16

8.71

14.0

71.

320.

400.

054.

4299

.66

91JA

A-0

109

57.6

70.

7417

.54

7.73

0.07

4.64

4.40

1.54

2.83

0.18

2.31

99.6

5

91JA

A-0

113

54.5

51.

3014

.32

11.5

00.

145.

005.

833.

340.

190.

222.

5998

.98

91JA

A-0

119

34.9

70.

316.

0810

.16

0.17

16.6

015

.41

0.13

0.03

0.04

11.6

995

.59

91JA

A-0

124

72.1

50.

2715

.69

1.32

0.06

0.97

2.81

2.99

2.22

0.06

1.60

100.

14

91JA

A-0

127

48.7

41.

0313

.64

12.6

90.

238.

8010

.09

1.45

0.14

0.11

2.92

99.8

4

91JA

A-0

135

57.0

21.

2814

.72

11.1

30.

273.

867.

772.

970.

260.

110.

4299

.81

91JA

A-0

136

51.2

70.

7614

.53

12.3

20.

206.

7211

.20

1.66

0.16

0.06

0.67

99.5

5

91JA

A-0

137

51.0

90.

8313

.87

12.7

90.

206.

909.

881.

580.

860.

071.

2099

.27

91JA

A-0

139

51.4

61.

1715

.87

12.5

80.

215.

127.

273.

720.

950.

071.

0499

.46

91JA

A-0

149

46.5

00.

406.

6412

.13

0.18

18.3

49.

560.

210.

160.

034.

5098

.65

91JA

A-0

155

75.9

40.

1413

.26

0.51

0.03

0.32

2.98

4.26

0.86

0.06

1.04

99.4

0

91JA

A-0

161

73.8

20.

1814

.11

1.64

0.03

0.70

0.62

1.78

5.21

0.05

1.35

99.4

9

91JA

A-0

163

56.8

70.

8917

.58

5.66

0.08

3.07

4.82

5.17

4.44

0.54

0.55

99.6

7

Tabl

e 3.

Who

le-r

ock

geoc

hem

ical

dat

a fr

om F

oley

et a

nd I

vanh

oe to

wns

hips

. Maj

or e

lem

ent o

xide

val

ues

in w

eigh

t %, t

race

and

rar

e ea

rth

elem

ent v

alue

s in

ppm

.

Sam

ple

No.

SiO

2T

iO2

Al 2O

3F

e 2O

3M

nOM

gOC

aON

a 2O

K2O

P2O

5L

OI

Tota

l

Met

hod

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

29


91JA

A-0

168

56.0

40.

7816

.85

8.64

0.12

4.89

4.80

4.52

1.03

0.16

1.77

99.6

0

91JA

A-0

170

49.9

00.

4711

.48

15.0

20.

411.

979.

180.

450.

320.

1110

.53

99.8

4

91JA

A-0

173

50.8

61.

6413

.09

17.3

50.

234.

367.

383.

470.

280.

130.

8699

.65

91JA

A-0

176

50.3

20.

8715

.86

12.0

30.

365.

3811

.14

1.27

0.23

0.09

2.10

99.6

5

91JA

A-0

184

75.2

60.

1412

.97

1.21

0.04

0.58

0.91

0.20

6.19

0.05

1.74

99.2

9

91JA

A-0

185

63.9

90.

9017

.44

4.44

0.11

1.38

2.62

6.03

1.07

0.18

1.12

99.2

8

91JA

A-0

193

51.3

91.

1014

.39

10.1

80.

187.

1010

.81

2.26

0.14

0.11

1.89

99.5

5

91JA

A-0

196

49.4

90.

7214

.85

10.4

20.

207.

1613

.19

1.40

0.38

0.07

1.58

99.4

6

91JA

A-0

197

62.7

40.

5214

.87

6.39

0.10

4.35

5.80

2.61

1.24

0.10

1.32

100.

04

91JA

A-0

198

52.0

90.

9715

.34

9.70

0.22

6.11

9.60

2.56

1.19

0.07

1.60

99.4

5

91JA

A-1

010

44.7

50.

366.

8911

.07

0.17

22.5

26.

950.

270.

050.

035.

7998

.85

91JA

A-1

024

51.3

50.

265.

359.

930.

2217

.07

12.2

00.

880.

100.

031.

9699

.35

91JA

A-1

047

50.2

31.

3913

.42

16.4

20.

244.

889.

212.

690.

330.

100.

3499

.25

91JA

A-1

060

50.9

41.

7413

.03

18.2

90.

264.

388.

542.

200.

240.

130.

1399

.88

91JA

A-1

074

50.2

31.

3913

.42

16.4

20.

244.

889.

212.

690.

330.

100.

3499

.25

91JA

A-1

095

53.0

80.

7113

.90

10.7

70.

196.

8511

.17

1.99

0.13

0.07

0.70

99.5

6

91JA

A-1

116

50.6

00.

5611

.15

11.7

50.

2110

.61

11.5

61.

370.

140.

051.

1099

.10

91JA

A-1

136

53.9

60.

8514

.96

8.76

0.24

6.13

11.4

61.

840.

270.

071.

1699

.70

91JA

A-1

168

66.2

30.

5416

.44

3.52

0.05

1.56

3.66

4.71

1.70

0.38

0.95

99.7

4

91JA

A-1

174

67.9

30.

2316

.99

2.08

0.03

1.03

4.16

5.04

1.23

0.12

0.63

99.4

7

91JA

A-1

215

38.9

90.

255.

069.

290.

1823

.67

8.91

0.09

0.03

0.03

12.7

899

.28

91JA

A-1

218

70.5

40.

4414

.47

2.80

0.04

1.29

3.61

2.69

1.99

0.09

1.39

99.3

5

91JA

A-2

007

70.6

20.

3915

.16

2.15

0.06

0.87

5.38

3.42

0.56

0.12

0.52

99.2

5

Tabl

e 3.

Con

tinue

d.

Sam

ple

No.

SiO

2T

iO2

Al 2O

3F

e 2O

3M

nOM

gOC

aON

a 2O

K2O

P2O

5L

OI

Tota

l

Met

hod

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

30

OGS REPORT 297

91JA

A-0

006

800.

3571

4050

270

2084

1.0

2.0

3.0

100

201.

394.

66

91JA

A-0

008

730.

3667

3947

270

6189

1.0

2.0

4.0

9518

1.92

5.59

91JA

A-0

009

131.

6713

95

5014

880.

00.

02.

010

407

49.7

098

.61

91JA

A-0

039

1830

0.20

1379

8824

135

2658

7.0

10.0

3.0

507

0.36

1.10

91JA

A-0

049

172.

2310

42

95

400.

00.

02.

056

53

4.30

8.73

91JA

A-0

057

192.

048

53

2319

540.

00.

00.

094

011

77.3

114

2.51

92JA

A-0

066

01.

705

42

127

370.

00.

00.

089

04

27.2

752

.68

91JA

A-0

068

600.

3870

4347

267

136

135

0.0

0.0

3.0

9515

2.10

6.11

91JA

A-0

073

1860

0.24

1149

8322

132

1683

5.0

9.0

0.0

506

0.30

1.03

91JA

A-0

077

2200

0.36

974

7719

145

3764

9.0

11.0

2.0

115

60.

461.

39

91JA

A-0

094

321.

3218

94

4712

730.

00.

00.

093

07

56.4

911

1.76

91JA

A-0

102

630.

7861

1916

101

4669

0.0

0.0

0.0

250

1513

.89

29.0

7

91JA

A-0

105

490

0.29

182

5246

239

9411

667

.017

.03.

014

513

1.51

4.25

91JA

A-0

109

187

0.81

6221

1711

622

870.

00.

00.

036

5618

14.9

235

.73

91JA

A-0

113

670.

6650

2924

187

451

0.0

0.0

0.0

7532

13.5

634

.10

91JA

A-0

119

1630

0.32

1190

7821

121

5855

5.0

6.0

2.0

145

60.

551.

43

91JA

A-0

124

100.

976

33

513

643

0.0

0.0

2.0

490

1126

.07

58.0

1

91JA

A-0

127

276

0.31

8946

3623

014

572

7.0

7.0

2.0

3523

3.75

10.4

2

91JA

A-0

135

119

0.31

8944

4228

512

293

0.0

0.0

2.0

145

274.

1211

.68

91JA

A-0

136

870.

1871

3947

254

110

860.

00.

04.

060

192.

126.

09

91JA

A-0

137

830.

2167

3944

258

128

114

0.0

0.0

3.0

145

182.

096.

15

91JA

A-0

139

131

0.38

5834

2617

433

840.

00.

03.

017

019

2.79

7.24

91JA

A-0

149

450.

1454

367

2816

111

666.

08.

00.

045

90.

471.

61

91JA

A-0

155

301.

063

21

24

430.

00.

00.

034

011

23.1

151

.94

91JA

A-0

161

00.

993

22

34

250.

00.

00.

085

011

24.4

251

.31

91JA

A-0

163

171.

0115

169

9369

741.

02.

02.

012

8016

79.4

017

9.68

Tabl

e 3.

Con

tinue

d.

Sam

ple

No.

Cr

Be

Ni

Co

ScV

Cu

Zn

Pd

Pt

Au

Ba

YL

aC

e

Met

hod

AA

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-OE

SA

AA

AA

AA

AIC

P-M

SIC

P-M

SIC

P-M

S

31


91JA

A-0

168

840.

5384

2516

9520

880.

00.

02.

022

016

8.38

21.5

0

91JA

A-0

170

530.

3032

1319

9014

137

0.0

0.0

6.0

7010

11.5

626

.21

91JA

A-0

173

450.

3336

4344

366

3497

0.0

0.0

0.0

6034

4.69

13.0

1

91JA

A-0

176

283

0.23

120

4031

213

101

745.

05.

00.

013

015

2.82

7.76

91JA

A-0

184

01.

013

21

24

360.

00.

00.

054

513

27.1

256

.05

91JA

A-0

185

01.

1218

1610

9013

770.

00.

00.

033

513

15.1

034

.73

91JA

A-0

193

294

0.35

8340

3822

895

8810

.08.

00.

012

522

3.88

10.8

9

91JA

A-0

196

340

0.19

100

3838

209

137

6718

.018

.02.

095

161.

715.

03

91JA

A-0

197

580.

5754

1816

9053

700.

00.

04.

019

515

12.0

525

.76

91JA

A-0

198

197

0.32

7234

4226

099

865.

05.

03.

050

520

2.47

7.06

91JA

A-1

010

1920

0.18

737

6923

129

113

6610

.08.

02.

040

70.

441.

37

91JA

A-1

024

1700

0.14

1009

6818

872

996.

06.

02.

060

50.

190.

75

91JA

A-1

047

640.

3655

4139

304

5513

20.

00.

03.

080

273.

6010

.29

91JA

A-1

060

140.

5223

3940

322

792

0.0

0.0

5.0

6538

3.08

9.58

91JA

A-1

074

990.

3067

3640

264

3267

0.0

0.0

6.0

125

222.

838.

20

91JA

A-1

095

123

0.21

5837

4222

111

276

13.0

14.0

3.0

4517

2.62

7.21

91JA

A-1

116

210

0.15

127

4349

220

105

721.

01.

08.

045

131.

393.

95

91JA

A-1

136

900.

2269

3644

231

107

680.

01.

05.

020

020

2.40

6.80

91JA

A-1

168

341.

2023

94

3612

650.

00.

00.

058

06

29.5

663

.86

91JA

A-1

174

261.

5011

64

2138

400.

00.

00.

033

53

13.7

128

.02

91JA

A-1

215

1600

0.10

961

6818

8840

527.

07.

00.

045

70.

611.

74

91JA

A-1

218

740.

6523

88

356

270.

00.

00.

059

011

11.0

724

.64

91JA

A-2

007

200.

699

55

327

390.

00.

00.

019

06

12.5

728

.76

Tabl

e 3.

Con

tinue

d.

Sam

ple

No.

Cr

Be

Ni

Co

ScV

Cu

Zn

Pd

Pt

Au

Ba

YL

aC

e

Met

hod

AA

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-OE

SA

AA

AA

AA

AIC

P-M

SIC

P-M

SIC

P-M

S

32

OGS REPORT 297

91JA

A-0

006

0.76

4.78

1.82

0.86

2.77

0.45

3.29

0.80

2.18

0.34

2.26

0.35

91JA

A-0

008

0.90

5.19

1.80

0.64

2.54

0.44

3.19

0.74

2.16

0.33

2.19

0.33

91JA

A-0

009

10.7

439

.92

6.09

1.38

3.32

0.37

1.69

0.28

0.63

0.09

0.52

0.08

91JA

A-0

039

0.22

1.35

0.64

0.10

0.94

0.17

1.31

0.28

0.85

0.12

0.84

0.12

91JA

A-0

049

1.01

4.26

0.84

0.23

0.64

0.07

0.39

0.06

0.19

0.02

0.22

0.03

91JA

A-0

057

13.8

945

.71

6.24

1.02

3.68

0.44

2.36

0.40

1.03

0.15

0.96

0.13

91JA

A-0

066

4.76

15.1

81.

880.

471.

130.

110.

600.

090.

290.

030.

290.

04

91JA

A-0

068

0.95

4.97

1.71

0.63

2.10

0.37

2.75

0.64

1.87

0.30

1.99

0.29

91JA

A-0

073

0.20

1.31

1.59

0.14

0.88

0.16

1.21

0.25

0.71

0.08

0.60

0.07

91JA

A-0

077

0.25

1.45

0.58

0.21

0.92

0.15

1.22

0.26

0.81

0.11

0.82

0.12

91JA

A-0

094

11.2

642

.38

5.76

1.40

3.25

0.34

1.61

0.26

0.59

0.07

0.52

0.07

91JA

A-0

102

3.35

13.7

12.

860.

842.

770.

402.

740.

541.

540.

221.

530.

21

91JA

A-0

105

0.66

3.82

1.41

0.47

1.88

0.33

2.43

0.51

1.49

0.21

1.48

0.22

91JA

A-0

109

4.23

17.0

33.

831.

103.

460.

553.

600.

671.

910.

251.

730.

21

91JA

A-0

113

4.49

21.7

75.

611.

466.

220.

996.

161.

263.

450.

503.

210.

47

91JA

A-0

119

0.23

1.34

0.55

0.17

0.81

0.14

1.02

0.22

0.68

0.09

0.68

0.10

91JA

A-0

124

6.18

22.5

53.

620.

892.

540.

341.

960.

381.

090.

151.

040.

17

91JA

A-0

127

1.57

8.66

2.72

0.92

3.74

0.59

4.30

0.95

2.70

0.38

2.41

0.35

91JA

A-0

135

1.78

9.58

3.11

1.18

3.82

0.66

4.77

1.07

3.10

0.47

3.08

0.43

91JA

A-0

136

0.97

5.27

1.86

0.72

2.37

0.43

3.23

0.74

2.16

0.31

2.33

0.32

91JA

A-0

137

0.98

5.45

1.90

0.68

2.56

0.46

3.27

3.27

3.27

0.31

2.18

0.31

91JA

A-0

139

1.05

5.59

2.06

0.88

2.98

0.52

3.49

3.49

3.49

0.30

2.08

0.30

91JA

A-0

149

0.29

1.84

0.81

0.34

1.18

0.20

1.58

1.58

1.58

0.12

0.81

0.09

91JA

A-0

155

6.05

23.0

15.

870.

832.

640.

341.

931.

931.

930.

151.

100.

16

91JA

A-0

161

5.60

19.5

03.

170.

622.

060.

291.

731.

731.

730.

151.

260.

19

91JA

A-0

163

21.7

391

.67

15.7

93.

7710

.15

1.10

5.16

5.16

5.16

0.22

1.30

0.18

Tabl

e 3.

Con

tinue

d.

Sam

ple

No.

Pr

Nd

SmE

uG

dT

bD

yH

oE

rT

mY

bL

u

Met

hod

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

33


91JA

A-0

168

2.83

13.2

33.

331.

123.

140.

493.

020.

611.

590.

221.

560.

22

91JA

A-0

170

2.89

13.2

32.

830.

722.

710.

331.

800.

361.

180.

181.

610.

24

91JA

A-0

173

1.96

10.3

73.

471.

124.

600.

815.

711.

293.

610.

543.

490.

53

91JA

A-0

176

1.10

5.87

1.89

0.70

2.34

0.38

2.65

0.59

1.71

0.25

1.76

0.24

91JA

A-0

184

6.16

22.5

73.

620.

832.

380.

332.

000.

411.

170.

181.

330.

19

91JA

A-0

185

4.12

17.0

23.

491.

012.

760.

402.

570.

501.

390.

181.

200.

16

91JA

A-0

193

1.57

8.55

2.67

0.96

3.33

0.57

3.91

0.85

2.33

0.33

2.20

0.30

91JA

A-0

196

0.84

4.55

1.67

0.63

2.31

0.41

2.85

0.65

1.74

0.26

1.71

0.29

91JA

A-0

197

3.02

12.4

72.

690.

772.

640.

412.

660.

561.

500.

231.

450.

24

91JA

A-0

198

1.14

6.24

2.13

0.80

2.98

0.51

3.43

0.75

2.05

0.31

1.92

0.31

91JA

A-1

010

0.26

1.55

0.64

0.21

1.03

0.19

1.32

0.28

0.72

0.10

0.73

0.10

91JA

A-1

024

0.17

1.07

0.47

0.16

0.74

0.13

0.99

0.21

0.55

0.08

0.55

0.08

91JA

A-1

047

1.62

8.82

3.05

1.13

4.06

0.70

4.95

1.11

3.03

0.47

3.14

0.48

91JA

A-1

060

1.54

9.21

3.63

1.32

5.28

0.92

6.28

1.35

3.91

0.61

4.08

0.60

91JA

A-1

074

1.28

2.83

2.22

0.80

3.04

0.54

3.76

0.83

2.34

0.34

2.34

0.36

91JA

A-1

095

1.07

5.47

1.76

0.69

2.43

0.41

2.94

0.66

1.83

0.29

1.86

0.29

91JA

A-1

116

0.64

3.43

1.16

0.45

1.88

0.31

2.27

0.51

1.43

0.21

1.47

0.23

91JA

A-1

136

1.02

5.77

1.97

0.65

2.57

0.45

3.31

0.72

2.15

0.31

2.10

0.29

91JA

A-1

168

6.87

26.4

94.

300.

862.

810.

291.

430.

230.

530.

060.

360.

05

91JA

A-1

174

3.08

12.4

02.

270.

831.

470.

160.

720.

100.

230.

020.

180.

02

91JA

A-1

215

0.28

1.61

0.63

0.23

0.92

0.16

1.25

0.26

0.76

0.10

0.74

0.10

91JA

A-1

218

2.82

11.6

72.

430.

742.

230.

301.

930.

381.

130.

151.

050.

17

91JA

A-2

007

2.70

10.3

61.

900.

601.

490.

191.

070.

200.

530.

070.

470.

05

Tabl

e 3.

Con

tinue

d.

Sam

ple

No.

Pr

Nd

SmE

uG

dT

bD

yH

oE

rT

mY

bL

u

Met

hod

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

34

OGS REPORT 297

92JA

A-0

018

36.8

00.

121.

348.

070.

1037

.80

0.23

0.01

-0.0

10.

0214

.70

99.1

892

JAA

-004

554

.00

1.13

14.9

08.

320.

186.

579.

142.

660.

120.

122.

4599

.59

92JA

A-0

047

48.4

00.

8215

.00

11.6

00.

187.

6311

.00

1.90

0.03

0.07

2.40

99.0

392

JAA

-006

655

.30

0.64

17.1

09.

360.

223.

266.

942.

890.

830.

172.

0098

.71

92JA

A-0

109

75.9

00.

2012

.60

1.52

0.04

0.76

2.03

2.84

1.44

0.07

1.60

99.0

092

JAA

-014

139

.10

0.13

1.51

8.24

0.13

36.8

01.

37-0

.01

-0.0

10.

0312

.30

99.5

992

JAA

-014

264

.30

0.54

16.1

04.

030.

062.

273.

807.

050.

480.

121.

1099

.85

92JA

A-0

151

43.7

00.

428.

3511

.70

0.23

20.6

07.

740.

030.

030.

055.

2098

.05

92JA

A-0

173

51.1

00.

9613

.00

13.3

00.

218.

037.

760.

760.

020.

085.

3210

0.54

92JA

A-0

194

75.0

00.

3114

.40

1.57

0.06

0.39

0.37

3.88

2.32

0.08

1.45

99.8

392

JAA

-019

850

.80

0.69

13.3

011

.80

0.27

7.31

12.9

02.

010.

240.

050.

9510

0.32

92JA

A-0

199

54.6

01.

4814

.50

11.4

00.

235.

028.

682.

170.

700.

141.

0099

.92

92JA

A-0

221

39.7

00.

8211

.10

10.3

00.

225.

2113

.30

0.76

0.34

0.07

18.4

010

0.22

92JA

A-0

229

52.1

00.

7514

.10

12.0

00.

206.

978.

922.

750.

590.

060.

7599

.19

92JA

A-0

231

38.1

00.

202.

898.

420.

1234

.00

1.87

0.01

0.02

0.02

12.4

098

.05

92JA

A-0

237

51.3

00.

7513

.90

11.5

00.

257.

539.

181.

360.

070.

062.

4598

.35

92JA

A-0

248

44.5

00.

427.

7413

.30

0.21

19.9

07.

980.

070.

020.

045.

1099

.28

92JA

A-0

249

49.0

00.

6911

.70

11.2

00.

1712

.30

6.77

3.21

0.05

0.06

3.00

98.1

492

JAA

-025

050

.80

0.86

13.8

011

.90

0.19

7.12

10.3

03.

310.

210.

081.

8510

0.42

92JA

A-0

252

39.0

00.

101.

357.

990.

1540

.00

0.33

-0.0

10.

040.

0211

.50

100.

4792

JAA

-025

353

.50

1.34

15.2

012

.00

0.17

3.49

5.39

4.53

-0.0

10.

113.

6599

.37

92JA

A-0

258

67.6

00.

5714

.40

3.95

0.05

1.86

2.20

8.71

0.05

0.13

0.60

100.

1292

JAA

-101

735

.40

0.12

1.50

12.4

00.

1735

.20

0.82

-0.0

1-0

.01

0.02

13.0

098

.61

92JA

A-1

030

73.9

00.

0914

.30

1.64

0.03

0.46

1.36

3.84

2.65

0.04

1.40

99.7

192

JAA

-104

346

.60

0.87

13.7

020

.70

0.62

5.32

9.35

1.20

0.23

0.09

1.20

99.8

792

JAA

-105

248

.80

0.84

13.8

012

.60

0.18

7.88

9.33

2.42

0.04

0.08

2.65

98.6

292

JAA

-105

347

.60

0.73

11.8

012

.40

0.19

11.8

06.

862.

650.

140.

073.

2097

.43

92JA

A-1

073

53.0

00.

8714

.70

8.44

0.15

7.96

8.06

3.12

1.57

0.36

1.10

99.3

392

JAA

-109

748

.00

0.75

15.6

012

.30

0.20

7.84

11.6

01.

400.

420.

061.

1099

.27

92JA

A-1

116

73.1

00.

1215

.20

1.10

0.03

0.36

2.04

5.74

1.93

0.05

0.20

99.8

792

JAA

-113

474

.70

0.29

12.6

01.

830.

040.

901.

382.

323.

220.

070.

9098

.25

92JA

A-1

143

69.8

00.

3415

.80

2.24

0.04

0.78

2.67

4.90

2.56

0.12

0.80

100.

0592

JAA

-114

460

.70

0.48

16.7

03.

940.

082.

594.

225.

703.

280.

280.

3598

.32

92JA

A-1

156

42.6

00.

355.

9511

.30

0.19

26.1

05.

650.

370.

030.

036.

7599

.32

92JA

A-1

157

51.6

00.

7414

.30

11.9

00.

217.

5711

.00

2.17

0.21

0.06

0.80

100.

5692

JAA

-116

266

.50

0.36

12.0

04.

860.

132.

436.

813.

541.

170.

082.

2010

0.08

92JA

A-1

170

56.8

01.

8016

.10

9.11

0.14

3.85

5.83

3.68

1.45

0.16

0.75

99.6

792

JAA

-118

069

.10

0.25

16.6

01.

520.

040.

983.

055.

752.

530.

100.

3510

0.27

92JA

A-1

193

69.4

00.

3615

.30

2.93

0.08

1.59

2.58

6.78

0.80

0.08

0.65

100.

55

Tabl

e 4.

Who

le-r

ock

geoc

hem

ical

dat

a fr

om M

uske

go a

nd K

eith

tow

nshi

ps. M

ajor

ele

men

t oxi

de v

alue

s in

wei

ght %

, tra

ce a

nd r

are

eart

h el

emen

t val

ues

in p

pm.

Sam

ple

No.

SiO

2T

iO2

Al 2O

3F

e 2O

3M

nOM

gOC

aON

a 2O

K2O

P2O

5L

OI

Tota

l

Met

hod

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

35


92JA

A-0

018

0.80

6680

710

124.

00-1

.00

17.0

07.

008

8115

1.00

2.0

80.

100.

100.

3092

JAA

-004

51.

1049

745

8910

9-3

.00

-1.0

0-3

.00

-5.0

09

149

213

20.0

04.

080

0.80

0.10

3.80

92JA

A-0

047

1.50

227

4010

490

5.00

-1.0

08.

00-5

.00

947

157

10.0

02.

058

0.90

0.07

3.20

92JA

A-0

066

1.70

013

103

128

-3.0

01.

00-3

.00

-5.0

042

183

371

14.0

04.

016

31.

800.

5015

.20

92JA

A-0

109

0.90

474

445

-3.0

0-1

.00

-3.0

0-5

.00

6949

916

711

.00

2.0

153

2.20

0.60

11.3

092

JAA

-014

10.

8017

109

2025

6.00

-1.0

0-3

.00

-5.0

011

8030

1.00

2.0

70.

100.

100.

3092

JAA

-014

21.

1011

19

2497

-3.0

0-1

.00

-3.0

0-5

.00

1445

337

49.

007.

016

72.

100.

6017

.20

92JA

A-0

151

1.40

2410

3342

110

5.00

-1.0

0-3

.00

8.00

1010

831

19.0

02.

023

90.

0092

JAA

-017

31.

6022

542

7689

4.00

-1.0

030

.00

-5.0

07

5522

122

.00

2.0

620.

900.

103.

4092

JAA

-019

41.

1017

43

30-3

.00

-1.0

0-3

.00

-5.0

061

458

168

7.00

6.0

129

4.00

1.30

12.8

092

JAA

-019

81.

4044

545

9410

8-3

.00

-1.0

0-3

.00

-5.0

014

159

155

3.00

2.0

350.

0092

JAA

-019

91.

800

6110

121

6.00

3.00

-3.0

0-5

.00

2732

014

010

.00

2.0

800.

900.

104.

1092

JAA

-022

11.

3015

840

8562

-3.0

0-1

.00

75.0

0-5

.00

1911

511

215

.00

3.0

570.

0092

JAA

-022

91.

5097

5313

169

4.00

-1.0

0-3

.00

-5.0

021

133

141

12.0

02.

046

0.20

0.10

1.90

92JA

A-0

231

0.90

1950

1329

444.

00-1

.00

29.0

07.

007

9850

2.00

2.0

140.

100.

100.

4092

JAA

-023

71.

500

4569

108

4.00

-1.0

0-3

.00

-5.0

07

9815

514

.00

2.0

450.

500.

101.

9092

JAA

-024

81.

4029

9029

1279

-3.0

0-1

.00

-3.0

0-5

.00

1097

149.

002.

031

0.00

92JA

A-0

249

1.30

1510

3937

169

-3.0

0-1

.00

-3.0

0-5

.00

499

898.

002.

052

0.30

0.10

2.50

92JA

A-0

250

1.60

214

3934

624.

00-1

.00

-3.0

0-5

.00

1014

522

48.

002.

066

1.00

0.13

3.70

92JA

A-0

252

0.80

08

435

4.00

-1.0

05.

009.

009

6815

-1.0

02.

05

0.20

0.10

0.30

92JA

A-0

253

1.70

194

4311

998

-3.0

0-1

.00

-3.0

0-5

.00

840

158

19.0

03.

094

1.10

0.10

3.90

92JA

A-0

258

1.20

649

6164

-3.0

0-1

.00

-3.0

0-5

.00

490

189

2.00

8.0

155

2.90

0.80

15.9

092

JAA

-101

71.

3054

307

547

3.00

-1.0

018

.00

7.00

884

121.

002.

07

0.10

0.10

0.20

92JA

A-1

030

1.50

141

231

-3.0

0-1

.00

-3.0

0-5

.00

7568

698

7.00

7.0

614.

401.

2024

.00

92JA

A-1

043

2.40

302

4036

897.

00-1

.00

-3.0

0-5

.00

1413

711

016

.00

3.0

570.

500.

052.

3092

JAA

-105

21.

6026

040

7482

9.00

-1.0

0-3

.00

-5.0

06

9417

812

.00

2.0

571.

400.

103.

6092

JAA

-105

31.

6079

238

7684

-3.0

0-1

.00

-3.0

0-5

.00

519

396

19.0

02.

049

0.50

0.10

2.70

92JA

A-1

073

2.10

343

2126

945.

00-1

.00

-3.0

0-5

.00

4910

0254

626

.00

6.0

164

5.60

1.10

52.7

092

JAA

-109

71.

4029

739

116

77-3

.00

-1.0

0-3

.00

-5.0

019

7211

018

.00

2.0

400.

700.

102.

3092

JAA

-111

61.

4012

12

34-3

.00

-1.0

0-3

.00

-5.0

067

762

416

22.0

04.

058

0.00

92JA

A-1

134

1.50

213

1738

-3.0

0-1

.00

-3.0

0-5

.00

7672

428

817

.00

2.0

101

2.90

0.80

16.2

092

JAA

-114

31.

2020

322

194

-3.0

0-1

.00

-3.0

0-5

.00

6410

4839

814

.00

3.0

145

0.00

92JA

A-1

144

3.00

786

3775

-3.0

0-1

.00

-3.0

0-5

.00

8214

8314

1010

.00

10.0

227

0.00

92JA

A-1

156

1.10

2240

219

674.

00-1

.00

-3.0

014

.00

486

265.

002.

019

0.20

0.10

0.60

92JA

A-1

157

1.50

152

5446

61-3

.00

-1.0

0-3

.00

-5.0

011

9693

8.00

2.0

460.

0092

JAA

-116

21.

1018

612

76-3

.00

-1.0

0-3

.00

-5.0

040

324

340

6.00

7.0

143

2.00

0.40

12.6

092

JAA

-117

01.

4063

5684

163

-3.0

0-1

.00

-3.0

0-5

.00

4048

916

143

.00

3.0

123

1.30

0.10

3.80

92JA

A-1

180

1.70

332

446

-3.0

0-1

.00

-3.0

0-5

.00

8086

582

427

.00

6.0

119

0.00

92JA

A-1

193

1.10

305

426

-3.0

0-1

.00

-3.0

0-5

.00

3031

739

06.

002.

099

0.00

Tabl

e 4.

Con

tinue

d.

Sam

ple

No.

Be

Cr

ScC

uZ

nB

iM

oA

sSb

Rb

Ba

SrL

iN

bZ

rT

hU

La

Met

hod

ICP-

OE

SIC

P-O

ES

ICP-

OE

SIC

P-O

ES

ICP-

OE

SIC

P-O

ES

ICP-

OE

SIC

P-O

ES

ICP-

OE

SX

RF

XR

FX

RF

ICP

XR

FX

RF

XR

FIC

P-M

SIC

P-M

S

36

OGS REPORT 297

92JA

A-0

018

0.90

0.10

0.50

0.20

-0.0

50.

20-0

.10

0.20

-0.0

50.

10-0

.10

0.10

-0.0

592

JAA

-004

510

.50

1.40

7.10

2.30

0.87

3.00

0.40

3.20

0.63

1.80

0.30

1.80

0.25

92JA

A-0

047

9.50

1.30

6.50

2.10

0.71

2.90

0.40

3.20

0.59

1.80

0.30

1.90

0.27

92JA

A-0

066

35.2

03.

7014

.70

2.90

0.97

3.10

0.30

2.20

0.38

1.10

0.10

0.90

0.27

92JA

A-0

109

25.3

02.

509.

301.

900.

521.

700.

201.

000.

170.

500.

100.

800.

1692

JAA

-014

10.

800.

100.

500.

200.

060.

30-0

.10

0.30

0.06

0.20

-0.1

00.

200.

0492

JAA

-014

235

.50

3.50

12.8

02.

600.

942.

400.

301.

700.

290.

800.

100.

800.

1192

JAA

-015

192

JAA

-017

39.

701.

306.

502.

200.

752.

900.

403.

100.

631.

800.

302.

000.

3192

JAA

-019

428

.80

2.80

10.3

02.

000.

401.

600.

201.

000.

170.

500.

100.

600.

1392

JAA

-019

892

JAA

-019

912

.30

1.60

8.00

2.70

1.03

3.40

0.50

3.60

0.72

2.20

0.30

2.50

0.43

92JA

A-0

221

92JA

A-0

229

5.90

0.80

4.50

1.60

0.56

2.30

0.30

2.60

0.56

1.70

0.30

2.00

0.38

92JA

A-0

231

1.10

0.10

0.80

0.30

0.12

0.50

0.10

0.50

0.11

0.30

0.10

0.40

-0.0

592

JAA

-023

76.

000.

904.

501.

600.

502.

300.

302.

400.

491.

400.

201.

500.

2592

JAA

-024

892

JAA

-024

96.

400.

804.

001.

500.

482.

100.

302.

400.

481.

400.

201.

600.

5492

JAA

-025

010

.50

1.40

7.00

2.20

0.77

2.90

0.40

3.00

0.60

1.70

0.30

1.90

0.36

92JA

A-0

252

0.80

0.10

0.40

0.20

0.05

0.30

-0.1

00.

300.

050.

20-0

.10

0.20

-0.0

592

JAA

-025

311

.50

1.60

5.00

2.80

0.90

3.60

0.50

3.90

0.78

2.30

0.30

2.40

0.39

92JA

A-0

258

38.2

03.

8014

.70

3.20

0.87

3.00

0.40

2.20

0.39

1.00

0.20

1.10

0.19

92JA

A-1

017

0.80

0.10

0.50

0.20

0.03

0.20

-0.1

00.

200.

050.

10-0

.10

0.20

-0.0

592

JAA

-103

050

.50

4.90

17.1

03.

200.

612.

700.

301.

300.

180.

500.

100.

800.

1392

JAA

-104

36.

801.

005.

401.

900.

682.

600.

402.

900.

581.

700.

301.

800.

3092

JAA

-105

29.

901.

206.

302.

000.

782.

600.

402.

700.

531.

500.

201.

500.

2092

JAA

-105

37.

601.

005.

001.

700.

592.

200.

302.

300.

451.

200.

201.

300.

2192

JAA

-107

312

0.00

12.7

048

.70

8.50

2.24

7.00

0.70

3.30

0.53

1.40

0.20

1.40

0.20

92JA

A-1

097

6.70

0.90

4.70

1.70

0.61

2.20

0.30

2.50

0.51

1.60

0.20

1.70

0.26

92JA

A-1

116

92JA

A-1

134

34.7

03.

4011

.50

1.90

0.48

1.40

0.10

0.70

0.10

0.30

-0.1

00.

30-0

.05

92JA

A-1

143

92JA

A-1

144

92JA

A-1

156

1.90

0.30

1.40

0.60

0.21

0.90

0.10

1.10

0.22

0.60

0.10

0.70

0.15

92JA

A-1

157

92JA

A-1

162

27.6

02.

9011

.30

2.50

0.67

2.40

0.30

2.00

0.36

1.10

0.10

1.20

0.17

92JA

A-1

170

11.5

01.

708.

903.

301.

234.

500.

705.

001.

053.

100.

503.

500.

4992

JAA

-118

092

JAA

-119

3

Tabl

e 4.

Con

tinue

d.

Sam

ple

No.

Ce

Pr

Nd

SmE

uG

dT

bD

yH

oE

rT

mY

bL

u

Met

hod

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

Neg

ativ

e nu

mbe

rs in

dica

te th

at th

e co

nten

t is

belo

w th

e de

tect

ion

limit

of th

e an

alyt

ical

met

hod

used

.

37


93JA

A-1

001

51.2

915

.44

0.19

6.48

8.59

3.20

0.09

1.25

0.14

9.30

3.20

99.1

6-0

.30

0.04

6720

50.

4153

.80

15.5

4-6

93JA

A-1

005

52.5

612

.53

0.17

4.58

6.03

3.24

0.10

1.52

0.11

14.9

73.

1298

.93

0.58

-0.0

377

00.

3643

.53

-5-6

93JA

A-1

006

44.8

720

.83

0.10

8.92

13.2

91.

170.

100.

09-.

055.

623.

8098

.82

-0.3

0-0

.03

8361

6-0

.234

.95

44.1

8-6

93JA

A-1

008

49.4

813

.91

0.24

7.29

9.53

2.82

0.13

0.78

0.07

11.4

43.

2798

.95

0.68

-0.0

313

417

90.

3358

.77

23.8

0-6

93JA

A-1

014

50.2

012

.14

0.17

10.2

76.

883.

92-.

020.

630.

0810

.51

4.94

99.7

31.

740.

0656

644

-0.2

48.5

914

2.7

-6

93JA

A-1

016

47.8

214

.31

0.20

8.10

5.85

3.09

0.05

1.34

0.10

14.4

13.

9899

.25

-0.3

0-0

.03

7519

60.

4349

.67

167.

2-6

93JA

A-1

020

40.6

55.

410.

1825

.42

8.45

0.15

-.02

0.24

-.05

7.94

10.1

398

.59

2.87

0.03

4219

60-0

.288

.38

19.6

5-6

93JA

A-1

021

56.8

714

.07

0.14

4.75

6.14

2.77

-.02

0.75

0.14

7.79

5.24

98.6

62.

390.

0452

177

0.60

27.6

113

.10

-6

93JA

A-1

027

48.9

414

.77

0.26

3.68

10.9

51.

38-.

020.

720.

0610

.32

7.59

98.6

84.

450.

0643

355

0.28

38.0

010

5.3

-6

93JA

A-1

033

45.0

09.

700.

2211

.31

10.0

12.

57-.

020.

500.

0612

.24

7.16

98.7

83.

750.

0834

2676

-0.2

59.2

290

.65

-6

93JA

A-1

035

45.7

55.

670.

1921

.38

9.18

0.26

-.02

0.29

-.05

10.1

35.

1298

.01

0.71

0.03

1220

80-0

.293

.44

33.1

3-6

93JA

A-1

035D

45.7

75.

680.

1921

.30

9.24

0.26

-.02

0.29

-.05

10.1

25.

4598

.33

0.78

0.03

1222

32-0

.292

.83

33.3

9-6

93JA

A-1

041

47.7

618

.91

0.20

4.29

10.5

42.

620.

810.

810.

087.

276.

1299

.40

4.26

0.15

422

221

0.36

45.1

694

.35

-6

93JA

A-1

042

48.6

914

.15

0.22

6.44

10.1

32.

950.

611.

170.

1113

.69

1.19

99.3

50.

540.

0910

322

60.

4242

.58

109.

6-6

93JA

A-1

043

39.3

64.

650.

1332

.72

1.51

-.01

-.02

0.28

-.05

9.78

10.9

199

.32

0.77

-0.0

314

3599

-0.2

101.

805.

156.

38

93JA

A-1

046

42.8

77.

470.

1622

.22

7.85

0.53

-.02

0.37

-.05

11.6

15.

4798

.60

-0.3

0-0

.03

2626

83-0

.288

.30

71.7

5-6

93JA

A-1

055

67.1

015

.10

0.05

3.04

1.97

5.66

0.45

0.55

0.22

4.16

1.82

100.

09-0

.30

-0.0

310

644

0.62

15.2

2-5

-6

93JA

A-1

059

61.4

115

.73

0.33

1.96

7.47

0.97

1.47

0.59

0.18

6.22

1.99

98.3

20.

320.

0929

514

10.

7021

.10

33.0

5-6

93JA

A-1

062

68.3

916

.53

0.06

1.98

1.99

1.57

2.53

0.64

0.30

3.75

2.79

100.

53-0

.30

1.02

499

700.

7316

.45

19.9

5-6

93JA

A-1

068

50.9

47.

930.

2014

.49

10.9

11.

130.

440.

360.

059.

751.

8998

.09

0.48

-0.0

318

123

77-0

.251

.58

49.0

9-6

93JA

A-1

069

38.2

94.

130.

1535

.15

0.74

-.01

-.02

0.19

-.05

10.7

510

.32

99.6

9-0

.30

0.41

7445

59-0

.212

4.0

129.

86.

95

93JA

A-1

071

67.0

216

.54

0.03

0.93

2.93

4.71

1.43

0.31

0.10

2.24

2.25

98.5

01.

22-0

.03

516

00.

925.

504.

88-6

93JA

A-1

071D

67.6

416

.81

0.03

0.89

2.94

4.67

1.42

0.32

0.10

2.26

2.21

99.2

91.

16-0

.03

515

00.

935.

434.

39-6

93JA

A-1

078

59.7

415

.38

0.11

4.20

6.16

4.07

0.92

0.56

0.23

5.79

2.05

99.2

1-0

.30

0.13

341

114

0.90

21.0

133

.45

-6

93JA

A-1

083

59.3

817

.10

0.09

4.16

4.43

3.54

0.44

0.63

0.21

6.26

2.64

98.8

8-0

.30

-0.0

330

789

0.76

22.6

548

.21

-6

93JA

A-1

085

48.6

815

.26

0.19

8.54

11.3

91.

640.

180.

690.

0711

.50

0.79

98.9

4-0

.30

0.03

7633

00.

2643

.39

72.3

5-6

80.0

3

11.8

1

162.

6

117.

8

152.

7

98.1

2

1444 134.

0

132.

3

758.

6

1335

1321 157.

6

71.7

9

1779

1024 23

.10

51.2

1

41.0

3

203.

2

450.

1

8.26

8.09

79.8

2

85.8

9

99.8

2

Sam

ple

No.

SiO

2A

l 2O3

MnO

MgO

CaO

Na 2

OK

2OT

iO2

P2O

5F

e 2O

3L

OI

TO

TAL

CO

2S

Ba

Cr

Be

Co

Cu

Mo

Met

hod

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

AA

AA

AA

AA

AA

AA

Tabl

e 5.

Who

le-r

ock

geoc

hem

ical

dat

a fr

om R

eeve

s, P

enho

rwoo

d, S

ewel

l and

Ken

ogam

ing

tow

nshi

ps. M

ajor

ele

men

t oxi

de v

alue

s in

wei

ght %

, tra

ce a

nd r

are

eart

h el

emen

t val

ues

in p

pm.

Ni

ICP

-OE

S

38

OGS REPORT 297

93JA

A-1

086

60.0

715

.36

0.09

4.84

6.52

2.72

1.00

0.52

0.13

5.58

1.79

98.6

1-0

.30

-0.0

330

513

40.

6523

.02

53.9

6-6

93JA

A-1

090

47.1

713

.88

0.28

5.37

7.86

1.32

0.06

1.91

0.21

16.9

23.

6398

.60

1.12

0.12

5614

80.

3858

.11

85.1

0-6

93JA

A-1

095

49.0

513

.64

0.18

7.48

9.62

1.45

2.13

0.61

0.06

12.7

41.

7298

.70

-0.3

00.

0322

713

00.

2243

.65

24.9

8-6

93JA

A-1

096

46.2

57.

270.

2019

.25

8.86

0.34

0.02

0.37

-0.0

511

.37

3.95

97.9

1-0

.30

-0.0

330

2611

-0.2

71.6

04.

09-6

93JA

A-1

097

42.2

17.

510.

1423

.50

5.18

0.51

0.82

0.38

-0.0

59.

968.

6098

.85

0.71

0.03

106

1127

-0.2

71.4

013

.93

-6

93JA

A-1

100

53.0

815

.54

0.15

5.02

5.20

4.63

0.30

1.00

0.15

9.45

5.20

99.7

02.

14-0

.03

6210

00.

8133

.13

8.40

-6

93JA

A-1

101

47.1

713

.36

0.20

8.46

8.10

1.52

-0.0

21.

060.

1013

.20

5.65

98.8

13.

750.

0361

114

0.32

48.3

963

.35

-6

93JA

A-1

101D

47.2

113

.34

0.20

8.59

8.10

1.52

-0.0

21.

060.

1013

.21

5.66

99.0

03.

730.

0369

119

0.32

48.8

963

.15

-6

93JA

A-1

102

65.8

615

.27

0.07

1.78

5.35

3.16

0.82

0.48

0.16

4.29

1.62

98.8

7-0

.30

-0.0

319

067

0.73

13.2

020

.56

-6

93JA

A-1

104

48.7

215

.42

0.18

8.28

9.82

2.06

0.13

0.78

0.08

11.6

61.

7698

.88

-0.3

00.

0610

917

80.

2645

.72

146.

8-6

93JA

A-1

106

55.7

715

.71

0.12

4.37

3.88

4.96

0.09

1.13

0.23

8.25

5.27

99.7

82.

33-0

.03

8894

0.62

26.7

684

.94

-6

93JA

A-1

107

46.6

215

.15

0.17

9.22

10.9

31.

190.

040.

590.

0611

.06

3.69

98.7

20.

350.

0676

407

0.24

48.0

211

4.9

-6

93JA

A-1

108

40.1

34.

850.

1133

.28

3.46

0.15

-0.0

20.

24-0

.05

9.15

8.96

100.

36-0

.30

0.03

4318

91-0

.290

.90

9.12

6.27

93JA

A-1

109

38.4

43.

670.

1235

.79

1.64

0.02

-0.0

20.

20-0

.05

8.42

12.2

010

0.51

0.50

0.03

2317

06-0

.294

.36

5.11

6.61

93JA

A-1

111

41.1

65.

310.

1129

.11

3.65

0.06

-0.0

20.

29-0

.05

9.37

9.41

98.5

1-0

.30

0.05

3215

51-0

.290

.77

5.05

-6

93JA

A-1

112

46.3

512

.77

0.23

6.45

8.95

2.15

-0.0

20.

710.

0710

.84

10.5

399

.03

5.95

-0.0

376

124

0.23

26.9

199

.50

-6

93JA

A-1

113

51.3

213

.83

0.20

6.54

9.79

1.78

0.55

0.84

0.09

12.8

41.

3299

.09

-0.3

0-0

.03

106

430.

2643

.40

154.

8-6

93JA

A-1

114

41.8

46.

630.

1625

.64

5.87

0.35

0.05

0.36

-0.0

510

.16

7.52

98.6

2-0

.30

0.03

2924

68-0

.290

.90

7.50

-6

93JA

A-1

114D

41.8

26.

610.

1625

.77

5.85

0.34

0.05

0.36

-0.0

510

.17

7.61

98.7

8-0

.30

0.03

2224

53-0

.289

.82

7.74

-6

93JA

A-1

115

39.7

34.

510.

1432

.06

2.75

0.06

-0.0

20.

25-0

.05

9.75

10.4

499

.72

0.55

0.09

1820

34-0

.293

.07

17.4

4-6

93JA

A-1

117

49.3

915

.16

0.25

4.28

10.5

21.

03-0

.02

0.78

0.07

10.3

96.

5298

.40

2.99

0.10

5941

60.

2756

.68

61.0

9-6

93JA

A-1

118

38.6

21.

320.

1241

.29

0.21

-0.0

1-0

.02

0.04

-0.0

57.

8610

.33

99.7

50.

340.

0642

2488

-0.2

124.

28.

6314

93JA

A-1

119

35.9

11.

600.

0741

.17

0.34

-0.0

1-0

.02

0.02

-0.0

55.

3915

.02

99.4

91.

800.

1230

733

-0.2

101.

613

.76

7.52

93JA

A-1

121

48.3

24.

570.

1521

.20

9.47

-0.0

1-0

.02

0.21

-0.0

58.

614.

9897

.54

-0.3

0-0

.03

1716

74-0

.278

.28

-5-6

93JA

A-1

122

49.3

64.

190.

0725

.72

3.90

-0.0

1-0

.02

0.09

-0.0

58.

635.

9097

.85

-0.3

0-0

.03

1420

43-0

.294

.70

20.3

5-6

93JA

A-1

124

44.2

813

.53

0.11

14.1

115

.28

0.21

0.03

0.16

-0.0

55.

625.

3398

.68

1.42

-0.0

351

1982

0.22

41.0

73.

73-6

127.

6

94.2

4

31.8

8

326.

9

1255 70

.22

179.

4

178.

6

33.1

4

121.

5

72.5

7

185.

7

1767

1985

1707 77

.14

60.3

2

1272

1252

1744 132.

9

2737

2886

1460 582.

8

201.

1

Sam

ple

No.

SiO

2A

l 2O3

MnO

MgO

CaO

Na 2

OK

2OT

iO2

P2O

5F

e 2O

3L

OI

TO

TAL

CO

2S

Ba

Cr

Be

Co

Cu

Mo

Met

hod

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FX

RF

AA

AA

AA

AA

AA

AA

Tabl

e 5.

Con

tinue

d.

Ni

ICP

-OE

S

39


93JA

A-1

001

41.3

626

9.7

25.7

516

4.8

142.

8-3

55.

0914

.40

2.27

10.5

53.

441.

050.

764.

395.

15

93JA

A-1

005

40.8

244

5.9

21.6

672

.11

59.5

3-3

54.

0511

.33

1.74

8.32

2.69

0.66

0.58

3.26

4.02

93JA

A-1

006

19.4

652

.60

2.82

40.8

412

4.7

-35

0.36

0.87

0.15

0.62

0.25

0.21

0.05

0.32

0.36

93JA

A-1

008

38.8

325

7.1

17.0

814

3.1

70.4

9-3

52.

376.

641.

035.

231.

840.

610.

422.

463.

01

93JA

A-1

014

33.3

620

3.5

14.4

472

.38

31.7

7-3

53.

468.

141.

165.

361.

620.

580.

382.

192.

56

93JA

A-1

016

44.9

332

2.4

22.4

113

6.6

50.7

7-3

53.

419.

811.

588.

192.

701.

000.

633.

604.

29

93JA

A-1

020

17.6

011

8.3

6.20

73.5

493

.01

-35

0.46

1.26

0.20

1.20

0.53

0.20

0.14

0.74

1.02

93JA

A-1

021

18.4

213

3.5

13.7

910

4.4

182.

3-3

59.

9922

.72

2.91

12.3

02.

910.

870.

462.

972.

81

93JA

A-1

027

37.8

225

1.5

14.9

381

.26

137.

4-3

52.

025.

900.

994.

971.

680.

680.

372.

222.

68

93JA

A-1

033

30.1

719

9.9

11.4

166

.77

58.3

2-3

52.

876.

640.

914.

221.

340.

480.

321.

702.

14

93JA

A-1

035

20.3

313

5.2

6.90

59.7

229

.01

-35

0.42

1.33

0.25

1.39

0.64

0.16

0.18

0.87

1.22

93JA

A-1

035D

20.3

513

4.5

6.88

59.5

128

.48

-35

0.40

1.31

0.26

1.42

0.65

0.16

0.18

0.93

1.17

93JA

A-1

041

28.0

817

7.6

12.7

675

.26

229.

2-3

52.

707.

471.

226.

141.

890.

830.

382.

302.

50

93JA

A-1

042

41.3

430

8.0

22.6

611

9.8

158.

2-3

54.

1211

.07

1.70

8.16

2.71

0.99

0.58

3.38

4.07

93JA

A-1

043

15.7

911

4.7

3.52

77.1

28.

56-3

50.

230.

730.

120.

750.

330.

140.

080.

460.

62

93JA

A-1

046

23.0

116

7.9

8.13

66.6

119

.67

-35

0.39

1.32

0.24

1.40

0.62

0.33

0.21

1.00

1.47

93JA

A-1

055

7.32

66.0

89.

9744

.72

203.

1-3

517

.29

39.2

44.

8217

.01

3.04

0.83

0.35

2.52

1.85

93JA

A-1

059

15.0

510

9.5

12.8

614

5.3

329.

5-3

517

.64

39.6

54.

8818

.12

3.47

1.13

0.43

3.06

2.41

93JA

A-1

062

12.0

288

.30

13.2

395

.13

234.

4-3

538

.88

85.3

510

.57

37.8

15.

911.

540.

574.

392.

77

93JA

A-1

068

43.3

018

9.2

8.92

85.3

147

.83

-35

1.99

5.20

0.69

3.05

0.95

0.30

0.22

1.27

1.54

93JA

A-1

069

11.9

610

2.8

3.11

85.8

12.

05-3

50.

461.

150.

160.

720.

260.

070.

070.

390.

54

93JA

A-1

071

3.47

31.6

53.

5057

.56

264.

9-3

516

.11

29.5

13.

4511

.86

2.10

0.65

0.20

1.57

0.81

93JA

A-1

071D

3.49

31.2

33.

5158

.34

269.

4-3

516

.15

29.8

13.

4511

.66

2.00

0.66

0.19

1.53

0.84

93JA

A-1

078

14.3

410

3.9

11.3

085

.13

582.

0-3

529

.53

65.0

68.

2730

.62

4.92

1.35

0.49

3.70

2.28

93JA

A-1

083

14.4

411

4.6

11.7

877

.51

428.

2-3

523

.66

53.2

76.

8025

.61

4.48

1.30

0.47

3.62

2.39

93JA

A-1

085

38.7

423

2.5

15.3

186

.82

126.

8-3

52.

626.

851.

085.

071.

710.

640.

402.

262.

74

Sam

ple

No.

ScV

YZ

nSr

WL

aC

eP

rN

dSm

Eu

Tb

Gd

Dy

Met

hod

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

Tabl

e 5.

Con

tinue

d.

40

OGS REPORT 297

93JA

A-1

086

14.2

410

2.0

10.0

772

.35

394.

7-3

516

.16

33.9

74.

1215

.16

2.87

0.87

0.36

2.59

1.96

93JA

A-1

090

34.4

035

0.6

31.2

416

0.2

79.4

0-3

510

.28

26.7

23.

8917

.47

4.93

1.65

0.95

5.94

6.08

93JA

A-1

095

35.1

522

6.7

14.7

713

4.1

193.

6-3

52.

015.

080.

773.

861.

390.

550.

361.

972.

55

93JA

A-1

096

32.6

918

5.6

7.81

100.

112

.24

-35

0.46

1.42

0.25

1.48

0.68

0.24

0.20

1.04

1.45

93JA

A-1

097

21.6

515

4.7

8.02

89.2

688

.24

-35

1.06

2.69

0.41

2.11

0.76

0.29

0.21

1.16

1.44

93JA

A-1

100

23.1

119

3.4

16.1

810

0.9

494.

3-3

513

.36

32.0

44.

1816

.95

3.48

1.11

0.53

3.37

3.18

93JA

A-1

101

30.8

526

3.7

17.4

611

1.3

99.1

2-3

53.

539.

551.

537.

502.

360.

830.

513.

053.

51

93JA

A-1

101D

31.8

425

8.4

17.5

411

0.5

98.6

7-3

53.

419.

301.

497.

252.

390.

840.

512.

903.

68

93JA

A-1

102

10.0

662

.62

13.2

868

.63

204.

1-3

516

.13

34.2

74.

2015

.95

3.26

1.04

0.44

2.99

2.55

93JA

A-1

104

41.1

125

2.6

17.8

693

.64

91.2

1-3

52.

416.

741.

075.

441.

880.

680.

452.

513.

11

93JA

A-1

106

22.4

315

4.2

22.6

211

0.2

137.

7-3

513

.10

31.6

34.

2817

.29

4.20

1.40

0.70

4.30

4.37

93JA

A-1

107

35.3

719

3.5

13.5

593

.51

125.

6-3

51.

984.

570.

794.

081.

370.

550.

321.

852.

30

93JA

A-1

108

9.96

111.

04.

2356

.70

7.10

-35

0.41

1.16

0.21

1.07

0.47

0.17

0.13

0.69

0.93

93JA

A-1

109

7.89

92.5

83.

4967

.40

7.96

-35

0.31

0.93

0.15

0.91

0.36

0.13

0.09

0.52

0.71

93JA

A-1

111

10.3

711

7.0

5.03

56.9

59.

21-3

51.

353.

450.

492.

330.

710.

200.

170.

911.

12

93JA

A-1

112

45.1

626

2.1

16.8

613

0.1

91.6

8-3

51.

805.

220.

884.

471.

600.

640.

402.

322.

95

93JA

A-1

113

45.2

027

3.2

19.6

597

.98

118.

1-3

52.

437.

251.

225.

842.

040.

740.

502.

723.

59

93JA

A-1

114

19.1

516

1.8

7.85

67.9

017

.60

-35

0.53

1.67

0.31

1.73

0.76

0.31

0.21

1.13

1.51

93JA

A-1

114D

19.8

615

9.9

8.08

67.1

617

.31

-35

0.52

1.65

0.31

1.76

0.80

0.32

0.21

1.17

1.60

93JA

A-1

115

13.4

011

5.5

4.93

77.2

015

.17

-35

0.53

1.46

0.24

1.16

0.48

0.17

0.13

0.71

0.98

93JA

A-1

117

41.2

323

8.8

17.1

578

.64

104.

0-3

52.

336.

641.

105.

481.

870.

790.

452.

563.

14

93JA

A-1

118

4.83

49.1

2-2

49.0

12.

83-3

50.

170.

370.

040.

18-0

.07

-0.0

3-0

.02

0.06

0.08

93JA

A-1

119

3.08

41.9

4-2

33.1

11.

50-3

50.

090.

200.

030.

10-0

.07

-0.0

3-0

.02

0.04

0.06

93JA

A-1

121

14.5

310

4.5

6.18

71.5

220

.37

-35

0.53

1.23

0.19

0.97

0.44

0.12

0.12

0.66

0.99

93JA

A-1

122

13.8

779

.62

-247

.65

-1-3

50.

150.

280.

060.

290.

15-0

.03

0.04

0.20

0.31

93JA

A-1

124

28.8

710

3.7

4.97

40.1

184

.57

-35

0.61

1.53

1.15

0.45

0.46

0.12

0.60

0.79

0.19

Sam

ple

No.

ScV

YZ

nSr

WL

aC

eP

rN

dSm

Eu

Tb

Gd

Dy

Met

hod

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-OE

SIC

P-O

ES

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

Tabl

e 5.

Con

tinue

d.

41


93JA

A-1

001

1.11

3.07

0.47

2.94

0.43

2.04

150.

504.

370.

171.

080.

28-1

04

8829

141

6

93JA

A-1

005

0.91

2.54

0.38

2.34

0.35

0.66

67.9

44.

350.

051.

780.

28-1

05

8525

64-5

93JA

A-1

006

0.09

0.24

0.04

0.22

0.04

4.37

129.

55-0

.20

0.08

0.12

-0.0

8-1

0-3

11-5

118

5

93JA

A-1

008

0.68

1.89

0.28

1.77

0.26

3.44

78.1

72.

140.

180.

670.

13-1

03

5422

735

93JA

A-1

014

0.59

1.64

0.25

1.58

0.24

0.24

34.9

02.

180.

161.

370.

15-1

03

5318

34-5

93JA

A-1

016

0.97

2.74

0.41

2.61

0.37

1.61

55.7

73.

620.

250.

540.

22-1

05

7228

52-5

93JA

A-1

020

0.23

0.63

0.10

0.61

0.10

1.25

101.

250.

350.

530.

40-0

.08

-10

-318

888

-5

93JA

A-1

021

0.58

1.57

0.22

1.35

0.21

0.29

190.

475.

820.

081.

470.

36-1

06

108

1717

8-5

93JA

A-1

027

0.61

1.75

0.26

1.63

0.23

0.28

147.

931.

910.

040.

350.

12-1

03

4719

137

-5

93JA

A-1

033

0.47

1.29

0.20

1.16

0.18

0.78

64.3

51.

520.

301.

110.

11-1

03

4314

62-5

93JA

A-1

035

0.26

0.73

0.11

0.69

0.11

0.31

31.3

50.

560.

080.

40-0

.08

-10

-323

930

-5

93JA

A-1

035D

0.28

0.75

0.11

0.66

0.11

0.31

31.2

90.

540.

080.

38-0

.08

-10

-323

829

-5

93JA

A-1

041

0.55

1.39

0.20

1.23

0.19

19.3

024

6.10

2.02

2.91

0.54

0.12

-10

353

1723

218

93JA

A-1

042

0.93

2.63

0.39

2.55

0.40

16.4

916

7.30

3.44

0.27

1.00

0.24

-10

474

2716

018

93JA

A-1

043

0.15

0.42

0.06

0.38

0.06

1.17

8.63

0.33

0.45

0.12

-0.0

8-1

0-3

16-5

9-5

93JA

A-1

046

0.34

0.91

0.14

0.84

0.13

0.28

21.0

00.

420.

030.

37-0

.08

-10

-322

1220

-5

93JA

A-1

055

0.38

0.98

0.15

0.83

0.13

8.30

216.

066.

450.

102.

410.

48-1

06

142

1219

48

93JA

A-1

059

0.50

1.32

0.19

1.23

0.18

35.0

534

9.62

5.43

1.41

2.48

0.37

-10

513

415

319

33

93JA

A-1

062

0.54

1.43

0.21

1.38

0.23

60.3

523

9.32

5.85

0.92

3.91

0.38

-10

716

517

228

57

93JA

A-1

068

0.35

0.92

0.15

0.96

0.15

13.6

552

.09

0.84

2.29

0.76

-0.0

8-1

0-3

3211

4915

93JA

A-1

069

0.12

0.35

0.05

0.32

0.06

0.41

2.00

0.33

0.20

0.10

-0.0

8-1

0-3

16-5

-5-5

93JA

A-1

071

0.14

0.31

0.04

0.24

0.04

42.0

328

5.16

3.79

1.06

2.67

0.28

-10

412

75

257

38

93JA

A-1

071D

0.14

0.31

0.05

0.24

0.04

41.0

528

2.73

3.78

1.07

2.77

0.28

-10

313

0-5

257

36

93JA

A-1

078

0.44

1.10

0.18

1.06

0.17

27.8

059

1.70

4.96

2.85

2.84

0.32

-10

514

213

570

28

93JA

A-1

083

0.46

1.23

0.17

0.97

0.14

11.0

246

0.19

5.84

0.53

1.05

0.36

-10

512

914

420

12

93JA

A-1

085

0.63

1.78

0.26

1.67

0.27

1.98

141.

651.

950.

300.

300.

13-1

04

5319

132

-5

Sam

ple

No.

Ho

Er

Tm

Yb

Lu

Rb

SrN

bC

sH

fTa

Th

Nb

Zr

YSr

Rb

Met

hod

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

ICP

-MS

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FIC

P-M

SIC

P-M

SIC

P-M

SIC

P-M

SIC

P-M

S

Tabl

e 5.

Con

tinue

d.

42

OGS REPORT 297

93JA

A-1

086

0.39

1.04

0.15

0.88

0.13

25.7

640

8.49

3.26

0.73

1.01

0.29

-10

511

012

391

26

93JA

A-1

090

1.31

3.41

0.51

3.12

0.45

1.38

87.1

26.

710.

221.

400.

40-1

07

137

3880

-5

93JA

A-1

095

0.59

1.67

0.25

1.56

0.23

64.5

420

7.88

1.23

1.65

0.52

0.08

-10

345

1819

863

93JA

A-1

096

0.33

0.89

0.14

0.90

0.13

0.47

12.7

20.

440.

110.

39-0

.08

-10

-322

915

-5

93JA

A-1

097

0.33

0.89

0.14

0.87

0.14

28.1

395

.16

0.64

0.60

0.35

-0.0

8-1

0-3

2610

8627

93JA

A-1

100

0.68

1.78

0.27

1.71

0.26

13.0

950

4.77

8.77

4.55

1.46

0.41

-10

890

1946

712

93JA

A-1

101

0.87

2.21

0.33

1.97

0.30

0.70

108.

853.

110.

410.

630.

19-1

03

6722

985

93JA

A-1

101D

0.79

2.04

0.32

2.01

0.29

0.73

107.

563.

040.

410.

600.

19-1

03

6624

98-5

93JA

A-1

102

0.50

1.34

0.18

1.11

0.14

28.1

720

5.67

7.50

2.91

1.22

0.53

-10

714

415

193

26

93JA

A-1

104

0.72

1.96

0.30

1.86

0.28

2.61

96.1

22.

050.

190.

470.

18-1

0-3

5322

915

93JA

A-1

106

0.93

2.46

0.35

2.09

0.27

4.42

138.

164.

390.

111.

650.

29-1

08

158

2813

1-5

93JA

A-1

107

0.51

1.43

0.21

1.38

0.21

0.99

126.

601.

340.

040.

320.

08-1

0-3

3615

120

5

93JA

A-1

108

0.21

0.61

0.09

0.53

0.09

1.14

7.64

0.35

0.39

0.32

-0.0

8-1

0-3

188

9-5

93JA

A-1

109

0.16

0.48

0.07

0.45

0.06

0.68

8.44

0.25

0.27

0.31

-0.0

8-1

0-3

146

10-5

93JA

A-1

111

0.25

0.66

0.10

0.66

0.10

1.92

9.87

0.70

1.64

0.46

-0.0

8-1

0-3

248

11-5

93JA

A-1

112

0.67

1.96

0.31

1.78

0.26

0.14

96.2

1.65

0.03

0.35

0.12

-10

344

1989

-5

93JA

A-1

113

0.83

2.30

0.37

2.35

0.38

19.9

612

32.

20.

220.

940.

13-1

03

5924

120

20

93JA

A-1

114

0.35

0.98

0.15

0.92

0.15

3.05

19.1

90.

550.

700.

52-0

.08

-10

-323

919

-5

93JA

A-1

114D

0.35

0.97

0.15

0.92

0.14

3.06

19.7

00.

550.

710.

55-0

.08

-10

325

1118

5

93JA

A-1

115

0.22

0.63

0.10

0.57

0.09

0.94

15.8

0.37

0.50

0.35

-0.0

8-1

0-3

188

16-5

93JA

A-1

117

0.70

1.93

0.29

1.79

0.27

0.80

111.

632.

080.

090.

410.

13-1

03

5020

104

-5

93JA

A-1

118

0.02

0.05

0.01

0.05

-0.0

20.

152.

99-0

.20

-0.0

2-0

.1-0

.08

-10

-38

-5-5

-5

93JA

A-1

119

0.01

-0.0

50.

01-0

.03

-0.0

2-0

.09

-2.0

0-0

.20

-0.0

2-0

.1-0

.08

-10

-37

-5-5

-5

93JA

A-1

121

0.24

0.74

0.11

0.76

0.13

0.27

21.1

0.39

0.34

0.37

-0.0

8-1

0-3

188

21-5

93JA

A-1

122

0.06

0.19

0.03

0.17

0.03

0.10

-2.0

0-0

.20

0.02

-0.1

-0.0

8-1

0-3

10-5

-5-5

93JA

A-1

124

0.54

0.08

0.47

0.07

0.75

91.8

10.

300.

040.

24-0

.08

-10

-318

684

-5

Sam

ple

No.

Ho

Er

Tm

Yb

Lu

Rb

SrN

bC

sH

fTa

Th

Nb

Zr

YSr

Rb

Met

hod

ICP-

MS

ICP-

MS

ICP-

MS

ICP-

MS

ICP-

MS

XR

FX

RF

XR

FX

RF

XR

FX

RF

XR

FIC

P-M

SIC

P-M

SIC

P-M

SIC

P-M

SIC

P-M

S

Tabl

e 5.

Con

tinue

d.

Neg

ativ

e nu

mbe

rs in

dica

te th

at th

e co

nten

t is

belo

w th

e de

tect

ion

limit

of th

e an

alyt

ical

met

hod

used

.

KAPUSKASING STRUCTURAL ZONE

Eight generations of deformation are recognized in theKapuskasing Structural Zone (Bursnall 1989), and areherein designated D1 through D8. They include early D1 toD4 ductile structures and late D5 to D8 ductile-brittle, fault-related structures. In the KSZ within the map area, D1

gneissosities mainly strike northeast with moderate dips tothe northwest, but are also locally easterly trending, withmoderate northerly dips suggesting folding. Observed out-crop-scale isoclinal folds have shallow plunges to thesouthwest. The map-scale variations in the trend of gneis-sosity from northeast to east are probably the result oflarge-scale D3 folds with shallow westerly or northwesterlyplunges. The variation in the trend of gneissosity may havebeen influenced by the uplift of the KSZ accompanied bysome dextral displacement, rotating gneissosities near thecataclastic zone into Z-shaped asymmetry. Lineations inthe monzonite gneiss of the Ivanhoe Lake cataclastic zonealso suggest dextral offset, as they are oriented obliquelyto the dip of cataclastic foliation, rather than downdip(i.e., plunging west rather than northwest).

Two northwest-trending late faults are associated withthe KSZ in the map area. The western fault lies along theeastern margin of the Shawmere anorthosite complex andwas previously recognized by Riccio (1981). It is charac-terized by numerous “veinlets” of black, aphanitic pseudo-tachylite and mylonite. These cataclastic zones range up toseveral centimetres thick, and are extremely variable inorientation, crosscutting the earlier gneissosity. The east-ern fault has been identified as the Ivanhoe Lake cataclasticzone and is considered to be the boundary between theKSZ and the Abitibi Subprovince (Percival 1990). On aregional scale, it is characterized by a zone of cataclasis upto 1 km wide, marked by positive aeromagnetic anom-alies, paired gravity anomalies with a low centred over thezone, and a broad zone of subsurface reflectors detectedon seismic surveys that dip at about 35° to the northwest(Percival 1990). In the map area, the Ivanhoe Lake cata-clastic zone is characterized by augen-textured monzonitegneiss, exposed along Highway 101 and the old channelof the Ivanhoe River north of Highway 101. The mon-zonite gneiss has shallow, west-plunging stretching lin-eations and gently plunging folds in the plane of foliation,with asymmetry indicating a west-side-up displacementalong the cataclastic zone.

NORTH SWAYZE GREENSTONE BELT ZONE

Five generations of tectonically induced fabric wereobserved within the NSGB, indicating that a number ofdistinct episodes of deformation have affected the belt in acomplex interplay of polyphase folding, transposition and

faulting. Those designated S1, S2 and S3 are interpreted tobe associated with early, regional-scale folding; S4 and S5

are interpreted to be related to late ductile deformation.

The 2 earliest generations of penetrative fabric areroughly parallel to the orientation of the units, and eachother, throughout much of the NSGB. Rarely, early F1 iso-clinal folds and a penetrative, axial-planar S1 cleavagewere observed as refolded folds in tight to isoclinal F2

folds. Because the axial planar S2 foliation is subparallel toS1 (with the rare exception of the fold closures), it is there-fore difficult to distinguish the S1 and S2 fabrics withoutthe presence of overprinting relationships. As the S1 and S2

folds are both isoclinal, it is assumed that the associateddeformation resulted in a large amount of regional short-ening and transposition. It is, therefore, difficult to deter-mine what the original orientations of F1 structures mayhave been because of large-scale transposition into thegenerally easterly trend of F2 structures. The S1 foliation orcleavage is evident in many outcrops as a penetrative flat-tening fabric. The S2 fabric is evident as a variably developed,steeply dipping penetrative foliation to a spaced cleavage,generally subparallel to the S1 fabric. The S3 fabric is asteeply dipping, spaced axial-planar cleavage associatedwith southeast-trending open folds overprinting S1 and S2,and is most evident in the southeastern part of the NSGB.

Lineations within the map area range from steep toshallow in plunge. Lineations which mark the intersectionsof cleavages and/or bedding planes predominate. However,only the stretch lineations which measure the elongation ofclasts or minerals were recorded on Map 2627 (back pocket).The highly variable orientations of minor fold axes and lin-eations is attributed to later refolding episodes.

The S4 and S5 fabrics are only observed in highlyschistose rocks proximal to shear zones and are thus inter-preted to be associated with late ductile deformation. TheS4 fabric consists of a steep, northeasterly trending spacedcleavage, axial planar to open Z-folds and northeast-trendingZ-shaped kink bands. The S5 fabric is a gently dipping,pervasive crenulation or kink cleavage with northwest tonortheast strike orientations that are axial planar to gentlyplunging open folds to locally tight chevron folds. Asoverprinting relationships are uncommon and difficult tointerpret, it is possible that the chronology of S4 and S5

may be reversed.

Folding

A number of fold axes are indicated on Map 2627 (backpocket) with their interpreted generation. The locations arebased on reversals of top indicators or systematic changesin the orientation of primary structures and/or foliations.In the southern part of the Swayze greenstone belt,Heather (1993) was able to differentiate 2 early fabrics

43


Structural Geology

into an Sa schistosity, that is tightly to isoclinally foldedabout a west- to west-southwest striking foliation, des-ignated Sb. It would seem that a similar manifestationand orientation of early folding fabrics in the northernSwayze greenstone belt are likely to have been generatedsynchronously with those in the southern part of the belt.

Although sparsely distributed, top indicators uniformlyindicate a southward younging direction in the northernpart of the NSGB, from the Nat River granitoid complexto the main sedimentary unit. East-plunging minor foldsand a number of reversals in younging direction wereobserved in sedimentary bedding in the vicinity of thesouthern part of Slate Rock Lake, in Keith Township.Coaxially refolded, thinly bedded sedimentary rocks inthis area and other parts of the map area indicate that atleast 2 early regional folding episodes have affected thearea. The interpretation of the pattern of reversals sug-gests an east-trending F2 fold in the southern part ofSlate Rock Lake may have refolded an F1 fold axis,north and south of the F2 axis. Younging reversals, sug-gesting anticlinal and synclinal closures, also occur in aband of predominantly volcanic rocks extending up toseveral kilometres south of the main sedimentary unit innorthern Keith Township. From the Kukatush pluton tothe MacKeith Lake fault, the observed younging direc-tion is consistently to the north. These features suggest thatthe main sedimentary unit in the northern part of Keithand Penhorwood townships lies in the keel of a syncli-norial fold and thus in the uppermost stratigraphic partof the Muskego–Reeves assemblage.

Coaxial refolding of F1 by F2 was also observed inminor folds in the Radio Hill iron formation and is mostlikely the reason for the extensive thickening of the ironformation in the vicinity of Radio Hill, in PenhorwoodTownship. Milne (1972) reports a possible synclinal(F1?) fold that causes the iron formation to bifurcatewest of Leadbeater Lake and end abruptly (close) east ofRadio Hill. He also indicates the iron formation is foldedinto an isoclinal S-shaped fold (F2?), plunging 50° to thenorthwest in the vicinity of Radio Hill.

The Nat River iron formation lies at the boundary ofthe MRA and HNA and delineates a northwest-plunging,east-trending anticlinal structure (see Figure 2). Bothlimbs of the fold dip steeply to the north and thus definean isocline steeply overturned to the south. Top indica-tors uniformly indicate north facings on the north limb,suggesting that the fold is an F1 anticline, but there isinsufficient exposure in the closure area, in the westernpart of the structure, to distinguish it from a possible F2

anticlinal antiform. The map pattern of iron formationrepetition on the north limb in the vicinity of the eastbranch of the Nat River, and south of Crawford Lake,suggests “S” and “Z” drag folds, respectively, that maybe genetically related to the main antiformal (F2) fold.Minor folds in outcrops east of the Crawford River, onthe north limb, indicate that F1 isoclines are refolded by

east-trending F2 isoclinal folds and are overprinted bysoutheast-trending, open F3 folds. In the same area, thelarge-scale “Z” fold in the Nat River iron formation(Map 2627, back pocket) has the wrong vergence to bea drag fold associated with the Nat River anticline, andis thus interpreted to be an F1 isoclinal fold unrelated tothe main structure.

The distribution of the northern ultramafic unit inthe HNA is more continuous and modified by foldingthan was interpreted by Milne (1972). This reinterpretationis based on the field evidence for multiple-foldingevents, the outcrop distribution and the high resolutionaeromagnetic patterns in this area. The new interpretationindicates the unit is isoclinally folded in an easterlytrending F2 (or possibly F1?) antiform and refolded onthe southern limb by southeast-trending F3 folds, north ofChabot Lake.

In the vicinity of the ultramafic to gabbroic unit hostingthe Reeves and Penhorwood mines the trends of S1 and S2

change from predominantly easterly to northerly. The S1

fabric follows the trend of the basal contact of the ultra-mafic cumulate unit around the northern nose of the fold,thus suggesting the ultramafic unit is tightly folded abouta north-trending F2 axis, with the gabbroic unit occupyingthe core of the F2 antiformal syncline (Map 2627, backpocket). Easterly flexures and/or offsets in the F2 fold axisand rock unit contacts are the result of overprinting byearly ductile deformation zones of the D4 to D5 generation(discussed below). The presence of talc-chlorite schistsalong the northwestern margin of the ultramafic unit suggeststhat the contact follows an early (D1 or D2), northeast-trending ductile deformation zone. The presence of thisshear zone may also indicate that the abrupt truncation ofthe clastic sedimentary unit along the western margin ofthe ultramafic body is the result of early faulting.

A southeast-trending F2 antiform and synform areinterpreted in amphibolitic mafic volcanic rocks insoutheastern Ivanhoe Township, based on changes in theorientation of S1 foliations (Ayer 1993).

Faulting

Fault locations are commonly based on the interpreta-tion of geophysical patterns or offset of rock units,because of poor exposure. At least 3 distinct generationsof faulting are evident in the NSGB, but determining thedetailed chronology awaits more detailed structuralwork and high-precision geochronology. The earliestgeneration of faulting is in the widespread ductile defor-mation zones. The early faults are locally truncated byless extensive brittle-ductile faults. Thirdly, the latestgeneration are brittle faults which do not appear to haveany significant ductile deformation but are not wellexposed.

44

OGS REPORT 297

DUCTILE FAULTS

The early deformation zones are generally easterly trending,parallel to the contacts of rock units and are gradationalfrom the moderately foliated and relatively unalteredcountry rock into the highly deformed, carbonatized,sericitized and chloritized schistose rocks whose protolithis often difficult to determine. Intense deformation andalteration commonly occur in zones 10 m to 1 km wide,which anastomose around blocks of less deformed andaltered rock. The most extensive early ductile faulting isassociated with the Slate Rock deformation zone (SRDZ)and is well exposed in southern Muskego and Reevestownships. The SRDZ is an extensive zone of ductiledeformation up to 1.5 km wide, extending eastward acrossthe southern part of Muskego Township. It extends west-ward into Foleyet Township, but poor exposure in this arearesults in a higher degree of uncertainty about its locationand extent. To the east, in Reeves and Sewell townships, itappears to break up into a larger number of parallel zoneswhich are, individually, narrower than the broad zone insouthern Muskego Township.

Three separate fabrics are evident in the schistoserocks throughout much of the SRDZ. The early fabric con-sists of a subvertical, east-trending pervasive schistosity(S1 or S2), which is interpreted to have formed during D1 orD2 deformation. It is overprinted by a northeast-trending,steeply dipping spaced cleavage (S4) which is axial planarto upright Z-folds and a spaced cleavage (S5) with subhor-izontal dips and variable orientations. Small-amplitudecrenulation and chevron folds associated with S5 are sub-horizontal and indicate late north-side-up movement in theSRDZ.

The Deerfoot deformation zone (DDZ) is anotherextensive deformation zone which extends from north ofthe Kukatush pluton in Penhorwood Township to north ofthe HNA in Kenogaming Township. An abrupt changefrom southward younging stratigraphy north of the DDZto northward younging south of the zone suggests the pos-sibility that the younging reversal may be the result ofthrusting along the fault rather than a regional syncline.

The Hardiman deformation zone (HDZ) extends intothe map area from the south, and joins with the DDZ alongthe north boundary of the HNA. The HDZ develops intoseveral parallel faults in southwestern PenhorwoodTownship that dip moderately to the northwest. Thesefaults are the locus of a number of commercially devel-oped veins of quartz and barite that occur along the faultedsoutheastern margins of thin granitic intrusions. In thisvicinity, shear banding indicates late dip-slip movement,with a relative southeast-side-up displacement.

Many of the deformation zones are locally auriferousand have been the focus of gold exploration, such as atthe Joburke Mine in the Joburke deformation zone. Three

separate fabrics are also evident in the shear zones associatedwith the Joburke Mine but, in contrast to the SRDZ, theflat S5 crenulation cleavage is only locally developed,whereas the steeply dipping S4 fabric is a pervasive axial-planar cleavage to northeast trending Z-folds. It has beensuggested (Milne 1972; Jackson and Fyon 1991) that thePorcupine–Destor fault may strike southwest into theNSGB. If this is so, it is probable that these numerous east-northeasterly trending ductile deformation zones representthe extension of this major structure into the map area.

BRITTLE-DUCTILE FAULTS

The MacKeith fault represents a later generation of brittle-ductile faulting. The fault trends east-northeast acrossmuch of Keith Township. Where it is well exposed, in thevicinity of the Joburke Mine, it consists of schistose, brec-ciated and hematitized rock in a zone up to 50 m widewhich clearly truncates a number of east-southeast-trendingrock units and the earlier Joburke deformation zone. Thewestern and eastern extensions of the fault are more spec-ulative, but based on airborne geophysical evidence, thefault appears to be truncated by the Hoodoo Lake pluton inthe east.

The Muskego fault is an east-trending deformationzone along strike with the MacKeith fault, on the west sideof the Hoodoo Lake pluton in Ivanhoe Township. It is onlyexposed in a few small outcrops where it consists of east-trending, foliated, carbonatized and epidotized rocks thatcontain radiating sprays of recrystallized amphibole.Based on aeromagnetic patterns, the fault abruptly truncatesan ultramafic volcanic unit. It is also the locus of an abrupttransition from greenschist-facies rocks north of the faultto amphibolite-facies units south of the fault (Ayer 1993).This transition indicates that higher metamorphic condi-tions were experienced in rocks south of the fault andhence a net south-side-up displacement.

BRITTLE FAULTS

Northerly trending faults are indicated on Map 2627 (backpocket) where they have been interpreted on the basis ofabrupt truncation or offset of rock units. These structuresare most likely high-crustal-level brittle faults which aredelineated by lineaments but are not commonly manifestin outcrop. Although most evident in the eastern part of themap area, they probably occur throughout the region andwere most likely the conduits for the numerousMatachewan diabase dikes. Thus, they are bracketed inmaximum age by the Matachewan diabase dike crystal-lization age of 2454 Ma. The minimum age is given byoffsetting of the east-northeast-trending Abitibi swarmdikes with a crystallization age of 1140 Ma. This suggestsa protracted Proterozoic history.

45


There are records of exploration activity in the area thatdate back to the end of the 19th century (Milne 1972). Thearea has attracted considerable exploration attentionbecause of its apparent continuity with the economicallyprolific Abitibi greenstone belt to the east. Gold, basemetals, iron, and industrial minerals such as asbestos,talc, silica and barite have been the focus of attention;mines have been established and undeveloped depositshave been found containing a number of these commodities.Significant amounts of asbestos and gold have come fromthe Reeves Mine and the Joburke Mine, respectively.Production has also been recorded at the Crydermanbarite, Horwood silica and Roseval silica deposits. ThePenhorwood talc mine is the only actively producingdeposit at the time of writing.

A significant amount of exploration has been con-ducted in the area, the details of which are not coveredhere. For more detailed information on exploration, thereader should consult 1) the assessment files in the ResidentGeologist’s office, Timmins; 2) assessment data in theEarth Resource and Land Information System, in Sudburyand Toronto; 3) previous geological reports of the area(e.g., Prest 1951; Milne 1972; Ayer 1993; Ayer, in press);or a mineral inventory report available in hard copy (Fumer-ton and Houle 1993) and digital copy (Fumerton et al. 1993).

In the following section, localities in which there hasbeen mineral production or notable grades and quantitiesof mineralization are briefly discussed. They are groupedby their principal commodities and discussed in alphabeticorder. The numbers in parentheses in the heading for eachlocality correspond to those appearing on Map 2627 (backpocket). Their names are based on geographic location,name of the discoverer, or the company which conductedthe exploration resulting in the discovery, and are notmeant to reflect current ownership. No formal title searcheshave been conducted as a part of this study.

GOLDGold mineralization occurs in epigenetic vein systems inclose spatial association with ductile deformation zones.It occurs in a wide variety of rock types, but is most com-monly associated with rusty weathering and schistose,iron carbonatized and/or sericitized, mafic volcanic rocks.The mineralization is closely associated with quartz-carbonate veining, commonly with disseminated iron sul-phides, and locally with arsenopyrite, stibnite and basemetal sulphides. Tourmaline and green mica may also bepresent.

Gold was found in sufficient quantities and grade atthe Joburke Mine, in Keith Township, to have supportedthe production of almost 1/2 million tons of ore with anaverage grade of 0.11 ounce Au per ton. The gold miner-alization at the Joburke Mine occurs in 2 structural settings:

1) widespread early mineralization with relatively lowgrades, which occurs in thin quartz-carbonate veins thatparallel the S1 foliation in highly schistose and carbonatizedbasalts within the Joburke deformation zones; and 2) con-centrated in late quartz veins and stringers which crosscutthe S1 foliation. The 4 developed Joburke ore zones occurwhere these late vein systems are thickened by foldinginto steep, easterly plunging, S-shaped fold noses. TheMacKeith Lake fault apparently truncates the Joburkedeformation zones west of the mine and, despite exten-sive diamond drilling, appears to host only minor goldmineralization.

Gold is locally present in other deformation zones,some of them minor and unnamed. Others are of majorextent, such as the Slate Rock Lake deformation zone insouthern Muskego Township, and the Deerfoot deforma-tion zone, which may be the easterly strike extension ofthe Joburke deformation zone.

Arkell (3)Gold mineralization occurs in a north-trending fault inmafic metavolcanic rocks infilled by irregular masses ofquartz, in southwestern Sewell Township. Tanton (1917)reports that the vein material mixed with country rocklocally reaches up to 15 m in width. Three pits were exca-vated on the vein, which was traced for a strike length of800 m. Minerals reportedly associated with the quartz arepyrite, pyrrhotite, chalcopyrite, calcite, tourmaline and“mariposite” (fuchsite?). Tanton (1917) reported assayresults from grab samples of up to 0.7 ounce Au per ton,and chip samples of 0.02 ounce Au per ton across thewidth of the vein.

BHP-Utah Mines Limited (4)From 1985 to 1989, BHP-Utah Mines covered the south-eastern part of Muskego Township with ground magne-tometer, electromagnetic (EM), induced polarization (IP),and geochemical surveys, stripping, trenching and diamond-drilled 20 holes. Surface samples assayed up to 3700 ppbAu southeast of Big Boulder Lake. Slightly auriferouszones were detected in a number of the drill holes, withassay values up to 1030 ppb Au over 0.3 m. Anomalousvalues of zinc in disseminated sulphides within schistosevolcanic rocks were also detected in 2 of the drill holes.

B.P. Resources Limited (5)B.P. Resources Limited explored for gold on a claim groupin south-central Muskego Township and north-central KeithTownship from 1987 to 1989. Work consisted of airborneand ground magnetic, EM and IP surveys, a geologicalsurvey and diamond drilling. Two holes were drilled inKeith Township. One of these drill holes, on the east sideof Slate Rock Lake, encountered a number of auriferous

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OGS REPORT 297

Economic Geology

intersections associated with intrusive porphyry phases.Assay results range from 0.01 to 0.04 ounce Au per tonover 10 to 15 m sections, with gold associated with minorpyrite in thin chloritic fractures. In Muskego Township, 9holes were diamond drilled in the area bounded by KeithLake to the east, Slate Rock Lake to the west and ScorchCreek to the north. One hole, about 1 km west of KeithLake, intersected 4.8 m of auriferous quartz veins in inter-mediate volcanic rocks with assay values of up to 0.011ounce Au per ton over 1.3 m. A second hole, about 500 meast of Slate Rock Lake, intersected 12 m of auriferouscarbonatized wacke. The wacke contains up to 5% dis-seminated pyrite and is cut by quartz-carbonate veins.Assays from this section are slightly anomalous, with valuesof up to 0.027 ounce Au per ton over 1.5 m.

Bromley (6)The Bromley occurrence is located in northwesternPenhorwood Township. Radio Hill Mines CompanyLimited performed a considerable amount of explorationin 1967, including an airborne EM survey, mapping,trenching and diamond drilling. A number of mineralizedquartz veins and stockworks were outlined in pervasivelycarbonatized and sheared mafic volcanic rocks cut bytonalite dikes. Silver-bearing sulphides, including argen-tite and galena, have been reported. Assay values of0.13 ounce Au per ton and 3 ounces Ag per ton over 0.6 m(2 feet) were reported from diamond drilling. Anothershowing, known as the RF zone, occurs north of the mainshowing on the west side of Primer Lake. Samples fromtrenching on this showing returned values of up to 15 ouncesAu per ton and 23 ounces Ag per ton, but typically weremuch lower (Fumerton and Houle 1993).

In 1989, American Barrick Limited intersected anom-alous gold values in a drill hole testing a geophysicalanomaly about 1 km southeast of the main showing. Assayresults reported up to 0.60 g/t Au over 1 m (Fumerton andHoule 1993).

Card Lake Copper Mines Limited (7)In 1971 and 1972, Card Lake Copper Mines Limited carriedout a magnetic and EM survey and diamond drillingfocussed on a stibnite showing in southwestern SewellTownship. The mineralization occurs in a 2 m wide, south-east-trending shear zone within moderately strained, maficpillow lavas immediately east of a northwest-trendingdiabase dike. Quartz veinlets and the schistose mafic rockof the shear zone have variable concentrations of dissemi-nated stibnite, arsenopyrite, pyrrhotite, pyrite and chal-copyrite. Assay values indicated up to 1.8 ounces Au per ton,7.4% Sb and 2.1% As.

Hoodoo-Patricia (10)From 1946 to 1947, Dunvegan Mines Limited (formerlyHoodoo Lake Mines Limited) explored a claim groupsoutheast of the Joburke Mine in Keith Township.

Mineralization similar to that at the Joburke Mine was dis-covered. From 1985 to 1989, G.K. Sanford, GailResources Limited and finally Marshall MineralsCorporation conducted airborne and ground magnetometerand EM surveys, an IP survey, geological mapping, stripping,trenching and diamond drilling. A program of extensiveoverburden removal and limited surface mining for bulksampling was undertaken in the vicinity of the Hoodooand Patricia showings. The stripping uncovered a largearea of outcrop around the showing which was mapped indetail by Siragusa (1990).

Results of work on this claim group by MarshallMinerals Corporation, as summarized from Medd (1990),indicate the gold mineralization occurs in a south-south-east-trending shear zone within carbonatized mafic vol-canic rocks cut by abundant intermediate porphyry dikes.The Patricia zone occurs at the northeast end of the out-crop area exposed by the stripping program. Gold valueshave been intersected in a mineralized zone which pinchesand swells from 3 to 49 m over a strike length of 158 mand to a depth of 184 m. The mineralized zone consists ofquartz-carbonate veining with disseminated pyrite andrarely chalcopyrite and galena. Erratic gold values as highas 0.528 ounce Au per ton over 1.2 m occur over narrowlenses of pyritic quartz-carbonate vein, separated by non-auriferous, less-altered host rock. The Hoodoo west showingis a 0.15 to 1.5 m wide vein extending for a distance ofabout 61 m in the north-central part of the stripped area.The vein system has been sampled every 4.6 m and carriesan average grade of 0.15 ounce Au per ton over a width of1.2 m. The Hoodoo east showing is a quartz-carbonate-pyrite vein hosted in a north-northeasterly trending cross-fracture in the eastern part of the stripped area. This veinreturned values of 0.072 ounce Au per ton over 0.7 m,0.152 ounce Au per ton over 0.6 m and up to 4.03 ouncesAu per ton in grab sample. The drilling in this area onlyintersected low-grade material (0.03 ounce Au per ton over7 m with values of up to 0.18 ounce Au per ton over 0.6 m).

A second area of gold mineralization was outlined bystripping, trenching and diamond drilling, about 1 kmnortheast of the Hoodoo–Patricia prospect. The mineral-ized zones consist of quartz-carbonate veinlets and lenses0.3 to 1.5 m (1 to 5 feet) wide, with pyrite and minor chal-copyrite and galena. The host rocks are felsic volcanicrocks with a pervasive east-northeast-trending high-strainzone consisting of narrow anastomosing zones of sericiticschist surrounding lenticular blocks of more massive felsicrock. Drilling indicated values of up to 0.161 ounce Au perton over 1.8 m (Medd 1990).

Joburke Mine (15)The Joburke Mine property consists of a block of 20patented claims in Keith Township. The property is cur-rently held by Noranda Exploration Company Limited ina joint venture negotiated with Tarzan Gold Incorporatedin 1988. Gold was discovered in 1946 by Joe Burke andMaynard Bromby. Underground work by Joburke MinesLimited was started in July 1947 and continued until

47


August 1948. Approximately 132 diamond-drill holestotalling 39 000 feet were drilled (Neelands 1988). Athree-compartment shaft was sunk on the Main Zone to adepth of 408 feet. Levels were established at the 250- and375-foot levels and 2714 feet of lateral work was com-pleted. This work showed the existence of 2 gold-bearingzones: the Main Zone, on which all the underground workwas focussed at this time, and the North Zone, locatedabout 400 feet northwest of the Main Zone. From thiswork, possible ore reserves in the Main Zone were esti-mated at 130 464 tons averaging 0.268 ounce Au per ton(Neelands 1988).

In 1964, Denison Mines Limited diamond-drilled 6holes totalling about 5000 feet, searching for downdipextensions to the east and west parts of the Main Zonemineralization.

Noranda Exploration Company Limited optioned theproperty in 1973. Mining operations were restricted to the eastand west parts of the Main Zone via a decline extending tothe 250-foot level. From 1973 to 1975, a total of 180 300 tonsgrading 0.105 ounce Au per ton was trucked to the PamourMill in Timmins. Prior to these mining operations,Noranda had estimated a possible reserve of 381400 tonsof 0.21 ounce Au per ton. The resulting low grades mayhave been caused by the erratic nature of the gold miner-alization within a wide alteration zone of quartz-ankerite.In 1979, the decline was extended to its ultimate depthof 489 feet. Total production from 1979 to 1981 was291795 tons grading 0.106 ounce Au per ton. The bulk ofthis was derived from the Main Zone. Near-surface miner-alization was also mined at the North Zone and theNorthwest Pit, a small zone about 1300 feet west of theshaft area. A total of 21374 tons grading 0.082 ounce Auper ton was derived from North Zone and 1209 tons grading0.063 ounce Au per ton from the Northwest Pit.Exploration on the property was reactivated from 1988 to1989 with geological, magnetic, EM and IP surveys, strip-ping, trenching, sampling and diamond drilling.

The property is underlain by compositionally diversevolcanic rocks which include mafic volcanic flows, por-phyritic felsic pyroclastic rocks, flows and/or synvolcanicintrusions and ultramafic flows. Interbedded sedimentaryrocks include magnetite-chert and siderite-chert ironformation, turbidites normally graded from conglomerateor sandstone to siltstone, and graphitic mudstones. Rockunits dip steeply to the north, and strike northeast north ofthe MacKeith Lake fault and southeast south of the fault.All observed top indicators indicate that the stratigraphyfaces consistently to the north. The MacKeith Lake fault(or Joburke fault, Prest 1951) strikes 075° and dips 60° to75° to the north. The fault zone contains brecciated frag-ments of chert, iron formation, lamprophyre dike and talc-chlorite schist. Rocks south of the MacKeith Lake faultgenerally appear to have experienced greater amounts ofductile strain than those north of the fault. A significantamount of dislocation along the fault is suggested by thechange in strike orientation and the abrupt truncation of anumber of rock units. A net sinistral displacement of

greater than 915 m was suggested by Prest (1951) basedon the interpreted dislocation of units. He also suggestedhowever, that this represented the horizontal vector of alarger, but unmeasurable, vertical displacement.

Gold mineralization is mainly confined to zones up toabout 30 m thick, consisting of intense ductile deformationwith accompanying pervasive iron-carbonate alterationand localized quartz veining, within the north and southarms of the Joburke deformation zones. Mineralizationwithin these deformation zones is of 2 distinct styles. Thefirst consists of widespread mineralization with relativelylow grades and occurs in thin quartz-carbonate veinswhich parallel the S1 foliation. These early veins are com-monly folded in conjunction with the S1 foliation intowesterly plunging Z folds with a steeply dipping, north-east-trending axial-planar S2 cleavage. The second con-sists of thicker and higher grade extensional quartz veinsor intricate networks of quartz stringers and veins whichare found in variously silicified, albitized and carbonatizedmafic volcanic rocks. The vein material is largely quartz,albite and carbonate with a minor amount of chalcopyriteand rarely visible gold (Prest 1951). The mined ore zonesare typically confined to locations where these higher gradeveins are thickened by steeply east-plunging S-shapedfolds (Prest 1951).

Johnson Wright (16)

The Johnson Wright occurrence is located in southwesternSewell Township. It has undergone exploration includinggeophysical surveys, stripping, trenching and diamonddrilling. The mineralization occurs in quartz-carbonateveins, with pyrite, tourmaline, and minor chalcopyrite andgalena, in sheared and carbonatized mafic volcanic rocks.The best reported assays of 15 g/t Au and 3.7 g/t Au werefrom trench samples collected by Glen Auden ResourcesLimited in 1987. The mineralization occurs in parallel 2 to25 cm quartz veins spaced 2 to 3 m apart in iron-carbonatized,schistose mafic volcanic rocks exhibiting a southeast-trending schistosity. Individual veins are up to 10 m longand alteration zones are up to 100 m long.

Jonsmith (17)

Mineralization at the Jonsmith occurrence in centralKenogaming Township occurs within schistose felsic vol-canic rocks of the HNA. It consists of pyritic, sericitizedand silicified fragmental rocks with thin sphaleritestringers locally cut by quartz veins containing pyrite andchalcopyrite. Diamond drilling by Falconbridge MinesLimited in 1966 returned assay values of up to 1.21% Zn,0.51 ounce Ag per ton and 0.03 ounce Au per ton over 1.1 m,and 1.03% Zn, 0.55 ounce Ag per ton and 0.01 ounce Auper ton over 4.3 m. It is interesting to conjecture as to theorigin and significance of the mineralization at this occur-rence and it is probably worthy of further study. The dis-seminated nature, associated rock types and alteration

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OGS REPORT 297

might indicate that the mineralization is of a volcanogenicmassive sulphide type modified by later deformation, oralternatively, the mineralization could be epigenetic andrelated to the deformation.

Kalbrook (18)

This gold occurrence in southeastern Reeves Townshiphas undergone a considerable amount of explorationincluding geophysical and soil geochemical surveys, strip-ping, trenching and diamond drilling, dating back toKalbrook Mining in 1946. Late quartz veins with visiblegold and disseminated pyrite crosscut sheared mafic vol-canic rocks with minor interbedded clastic sedimentaryrocks. A number of bands of intense east-trending shearingare separated by relatively undeformed zones. In onelocality, isoclinally folded schistose and altered units arecut by an auriferous quartz vein which is discordant to theearly foliation and is only slightly folded (Fumerton andHoule 1993). The auriferous veins (2 to 20 cm wide) arezoned, with between 2 and 5 cm of grey, coarse-grainedquartz along the walls, and white, very coarse-grainedquartz in the central part of the vein. Pyrite is erraticallydisseminated within the veins and locally is concentratedin the wallrock. Rare chalcopyrite has also been observed.Gold occurs as fine specks along fracture surfaces withinthe white quartz. Chip samples of a quartz vein in a trenchreturned up to 38.89 g/t Au from sampling by Glen AudenResources Limited in 1987. Parallel chip sampling byFumerton and Houle (1993) returned up to 7.68 g/t Au.

Little Long Lac Gold Mines Limited (21)

The mineralization at this location in northern Keno-gaming Township was explored by Little Long Lac GoldMines Limited in 1946, by mapping and 6 diamond-drillholes. The area is underlain by the Nat River iron forma-tion, intermediate to felsic volcanic rocks of the HNA andcumulate ultramafic to mafic complexes. Lenses of mas-sive pyrite and pyrrhotite occur up to 1.4 m wide along theiron formation contacts. The sulphides and small quartzveins carry low gold values of up to 0.04 ounce Au per ton.

Mining Corp (23)

Stripping, trenching and diamond drilling by NorandaExploration Company Limited and Storimin ExplorationLimited have outlined significant gold mineralization atthe Mining Corp deposit in southeastern Sewell Township.At least 2 mineralized quartz veins have been identified indiorite on the western margin of the Kenogamissibatholith, in Sewell Township. The main vein is exposedat the surface for a length of 120 m and is from 0.3 to 2 mthick. The vein occurs in an east-northeast-trending defor-mation zone consisting of highly schistose and carbona-tized diorite up to about 10 m wide. The deformation zone

is parallel in trend, and may be a subsidiary structure to themore extensive Deerfoot deformation zone located severalhundred metres to the south. The main vein consists ofmilky quartz and minor calcite cut by fractures infilledwith pyrite and minor chalcopyrite. Reported assay valuesfrom diamond drilling range up to 0.48 ounce Au per tonover 2.2 m and 0.28 ounce Au per ton over 2.3 m, in 2 sep-arate holes.

Nib Yellowknife (25)

The Nib Yellowknife occurrence, located in north-centralPenhorwood Township, has been explored since the mid1940s. Work done includes stripping, trenching, geophysicalsurveys, and a limited diamond-drilling program bySteetley Industries Limited in 1987. The mineralizationoccurs in quartz veins with disseminated pyrite andarsenopyrite within a gabbroic unit on the western marginof the ultramafic body hosting the Reeves andPenhorwood mines. Reported grab sample assay valuesare up to 0.2 ounce Au per ton.

Tremblay (32)

This showing, in southwestern Sewell Township, has beenexplored by geophysical surveys, a lithogeochemical sur-vey, geological mapping, trenching and diamond drillingsince 1972. American Barrick Resources Limited carriedout a surface sampling program which returned values ofup to 3.14 g/t Au. Fumerton and Houle (1993) indicate thatthe mineralization occurs in a banded altered zone with anaxial quartz vein in schistose mafic volcanic rocks cut bylamprophyre and granitic dikes. The zone strikes west-northwest and is exposed for a length of 50 m. The bandingoccurs on a millimetre to centimetre scale and consists ofiron carbonate-, tourmaline-, sericite- and chlorite-richbands over a width of 1 to 2 m. The axial vein has a highlyirregular shape, is discontinuous and varies between 10and 20 cm thick. The vein is composed of quartz, albiteand tourmaline, pyrite and arsenopyrite.

Unigold Resources Limited (33)

In 1986 and 1987, Unigold Resources Limited exploredthe southeastern part of Muskego Township. Work con-sisted of ground magnetometer, IP and geological surveys,stripping, trenching and 9 diamond-drill holes. One ofthese holes (DDH # UM-2), located about 1 km east ofHighway 101, encountered a 24 m long auriferous inter-section with assay values ranging from 0.01 to 0.1 ounceAu per ton. The intersection is contained within a unit ofquartz-feldspar porphyry with zones of sericitic alterationand 1 to 10% pyrite and arsenopyrite. The highest assayresults of up to 0.1 ounce Au per ton over 1.8 m are cor-related with the higher sulphide content.

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COPPER AND ZINC

The Muskego–Reeves assemblage (MRA) is considered tohave the greatest potential for economic concentrations ofcopper and zinc sulphides in the map area. Two distincttypes are observed, both of which are considered to berelated to exhalative synvolcanic processes: 1) iron forma-tion type and 2) volcanogenic massive sulphide (VMS)type.

The iron formation type of deposits, hosting zinc min-eralization with or without copper, are found scatteredthroughout the map area. These occurrences appear to besimilar to the Shunsby zinc deposit in the southern part ofthe Swayze greenstone belt. The most significant assayresults are from diamond drilling of banded chert-sulphide-facies iron formation and graphitic mudstones, some ofwhich contain highly anomalous base metal values. Forexample, the sulphide iron formation west of theGroundhog River in Keith Township was diamond drilledby Dome Exploration (Canada) Limited. Over a strikelength of about 800 m, 3 diamond-drill holes intersectedchert and graphitic argillite with sulphide-rich sectionscontaining up to 0.74% Zn and 0.03% Cu over 21 m(described in more detail below).

The potential for VMS type deposits appears to begreatest in the northwestern part of the MRA. In thisregion, diamond drilling has indicated the presence ofstratabound massive to disseminated sulphides with minoramounts of sphalerite and chalcopyrite, and associatedzones of volcanogenic hydrothermal alteration includingsilicification and chloritoid-bearing volcanic rocks.Massive sulphides were also observed as clasts in a con-glomerate in Foleyet Township and as inclusions in theIvanhoe Lake pluton, in Ivanhoe Township (Ayer 1993).The sulphides are closely associated with felsic, mafic andultramafic volcanic rocks (Ayer 1993). In the AbitibiSubprovince, VMS deposits are commonly associatedwith this type of compositional diversity (Jackson andFyon 1991).

Hydrothermal alteration is evident in FoleyetTownship by the presence of chloritoid porphyroblasts incarbonatized mafic volcanic rocks that underlie a subeco-nomic, strata-bound massive-sulphide horizon located bya diamond-drill hole in southeastern Foleyet Township.Chloritoid porphyroblasts were also observed in outcropsof carbonatized felsic volcanic rocks along the IvanhoeRiver, about 1.5 km east of the above-mentioned drill hole.It is worthy of note that chloritoid-bearing altered volcanicrocks are associated with a number of Archean vol-canogenic massive-sulphide deposits (Franklin et al. 1975).Another extensive zone of chloritoid alteration occurs inmafic and felsic volcanic rocks within the Slate Rockdeformation zone in south-central Muskego Township. Aschloritoid in greenschist-facies metavolcanic rocks hasbeen documented to be the result of hydrothermal alter-ation (Lockwood 1986) it is assumed that this zone repre-sents conformable hydrothermal alteration, which couldbe associated with sulphide mineralization.

In addition, an extensive zone of volcanogenic silici-fication in northeastern Foleyet Township bears resem-blance to similar alteration associated with a number ofArchean VMS deposits, including the silicification under-lying the Mine Series deposits at Noranda, Quebec(Gibson et al. 1983).

Dome Exploration (9)

From 1972 to 1983, Dome Exploration (Canada) Limitedconducted a number of exploration programs in KeithTownship. The work included an airborne geophysicalsurvey with detailed follow-up work in the northeasternpart of the township. It also including ground magneticand EM surveys and diamond drilling. Anomalous basemetal values were detected in a number of diamond-drillholes, with the most significant results from a hole about1 km south of Slate Rock Lake. This hole intersected a unitof sulphide iron formation within mafic to intermediatefragmental rocks. The iron formation consists of blackgraphitic argillite with alternating bands and disseminationsof pyrite, pyrrhotite, minor sphalerite and chalcopyrite.Reported assay values averaged about 0.6% Zn and 0.05%Cu over 22 m.

Sulphide iron formations were also explored in thenortheastern part of Keith Township. From 1972 to 1973,Dome Exploration (Canada) Limited conducted groundmagnetometer and EM surveys and completed 6 diamond-drill holes. The highest grade of mineralization wasencountered within a base metal-enriched sulphide ironformation striking east-northeast, west of the GroundhogRiver. It was intersected by 3 holes over a strike length ofabout 800 m. The iron formation is intercalated with maficand ultramafic volcanic rocks and consists of bandedrecrystallized chert and graphitic argillite with sulphide-rich sections containing layers of massive to disseminatedsulphides. The sulphides consist mainly of pyrite withminor sphalerite and chalcopyrite. The sulphide ironformation in the easternmost hole is relatively zinc-rich,with an intersection assaying 0.74% Zn and 0.03% Cuover 21 m (including assay values of up to 1.4% Zn over5 m), while the westernmost hole is relatively copper-rich,with assay values of up to 0.3% Cu and 0.25% Zn over 8 m.

From 1972 to 1977, Dome Exploration (Canada)Limited conducted an airborne magnetometer survey withfollow-up ground magnetometer and EM surveys andcompleted 9 diamond-drill holes north of Hoodoo Lake.Two of the holes intersected sulphide-bearing iron forma-tion intercalated with mafic, felsic and ultramafic volcanicrocks. The iron formation reportedly consists of a fine-grained, grey siliceous rock with layers of up to 20%pyrrhotite, minor chalcopyrite and sphalerite. Assayresults from this rock returned values of up to 0.35% Znover 3 m.

From 1972 to 1973, Dome Exploration (Canada)Limited conducted ground magnetometer and EM surveys

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OGS REPORT 297

and diamond-drilled 9 holes on a claim group northwest ofGroundhog Lake. The drilling indicated a wide variety ofvolcanic rocks including ultramafic, mafic, intermediateand felsic volcanic rocks with intercalated iron formation.The iron formation consists of a very fine-grained chertyrock with variable amounts of chlorite-, graphite- andsulphide-rich layers. Sulphides included pyrrhotite, pyrite,chalcopyrite and sphalerite with assay values of up to0.37% Cu over 2 m and 0.25% Zn over 5 m.

Hudbay Mining Limited (12)

From 1980 to 1982, Hudbay Mining Limited conducted anairborne geophysical survey and diamond-drilled 8 holesto follow up on geophysical anomalies in southeasternFoleyet and northeastern Ivanhoe townships. One of theholes in southeastern Foleyet Township intersected a zoneof subeconomic stratabound sulphides. Talc-chloriteschists, assumed to represent deformed ultramafic flows,are found in the uppermost part of the hole. This unit issucceeded by a unit of locally amygdaloidal chlorite-car-bonate schist which represents altered and deformed maficflows containing up to 10% fine- to medium-grained, ran-domly oriented chloritoid porphyroblasts. The schist isabruptly overlain by 8 m of disseminated to massive sul-phides including pyrite, sphalerite and chalcopyrite ingraphitic felsic pyroclastic rock. The highest reported zincassay value from this section was 0.6% Zn over 0.9 m.This mineralized section grades down the hole into unmin-eralized and unaltered felsic pyroclastic rocks that continueto the end of the hole.

Karvinen (19)

From 1982 to 1986, W. Karvinen, Quinterra Resourcesand Utah Mines explored for base metals and gold innortheastern Penhorwood Township by magnetic, EM andIP surveys, geological mapping, trenching and diamond-drilling 1 hole. Sphalerite and chalcopyrite mineralizationare associated with the Nat River iron formation. Values ofup to 0.9% Zn, 0.1% Cu and 11 g/t Ag were reported inselected grab samples. There appears to be some degree ofstructural control to the mineralization, as the iron forma-tion is isoclinally folded and locally brecciated. Highlyschistose and carbonatized mafic and ultramafic volcanicrocks within the Deerfoot deformation zone lie immediatelyto the north of the iron formation.

In 1986, zinc mineralization was identified by strippingand trenching in another showing about 500 m to thenortheast (also known as the Nat River zinc showing).Here, the sulphide mineralization occurs in pillowed tomassive intermediate volcanic rocks of the HNA thatimmediately underlie the Nat River iron formation.Sphalerite mineralization occurs with quartz veins andminor chalcopyrite and pyrite in a narrow (100 cm) anas-tomosing zone with an exposed strike length of about 100 m.Results from grab sampling along the zone indicate up to

10% Zn and may average about 4% Zn over the width ofthe mineralized zone (Fumerton and Houle 1993).

Keevil Mining Group Limited (20)

In 1964 and 1965, Keevil Mining Group Limited conductedground EM and magnetic surveys, geological mappingand diamond drilling in southeastern Foleyet Townshipand northeastern Ivanhoe Township.

A bore hole was drilled west of Highway 101, on theeast side of the old channel of the Ivanhoe River. The holeintersected mainly mafic volcanic rocks with an interbeddedunit of graphitic mudstone with disseminated pyrrhotite,pyrite, sphalerite and chalcopyrite. Assays from this zonereturned values of up to 0.35% Zn and 0.07% Cu over 3.5 m.

Three diamond-drill holes (65-18, 65-19, 65-20) werealso drilled in northeastern Foleyet Township, about 700to 1100 m east of the southeastern margin of the IvanhoeLake pluton. The drill holes intersected mafic flow unitswith interbedded sedimentary units consisting of wacke,siliceous siltstone and graphitic mudstone. Sulphide min-eralization has been reported in all 3 holes associated withthe mudstone units. In 1 hole, disseminated to semi-massivepyrite and pyrrhotite with minor sphalerite and chalcopy-rite constitute up to 30 to 70% of the rock over short sections.Assays from this section returned anomalous values of upto a maximum of 0.28% Zn and 0.05% Cu over 3 m.

Noranda Exploration CompanyLimited (26)

Noranda conducted an exploration program on a claimgroup in the northwestern part of Keith Township from1970 to 1972. The work consisted of ground magnetometerand EM surveys and 2 diamond-drill holes. A unit of brec-ciated intermediate volcanic rocks with thin stringer veinsof pyrrhotite, pyrite and minor chalcopyrite and sphaleritewas intersected in the western hole (DDH K-72-3).Reported assay results range up to 0.12% Zn and 0.02% Cuover 1.7 m.

United MacFie Mines Limited (34)

Exploration at this occurrence has been concentrated on acopper showing in an enclave of sulphide iron formationwithin the Nat River granitic complex, in MuskegoTownship. From 1970 to 1972, United MacFie MinesLimited conducted ground magnetometer and EM sur-veys, and diamond-drilled 3 holes. Sampling of trencheson the mineralized zone returned a weighted average of0.30% Cu over a width of 8.2 m. The diamond-drill holesencountered disseminated sulphides and stringers overvarying widths, consisting of pyrite, pyrrhotite and minorchalcopyrite and sphalerite. Assay results reported in thedrill logs indicate trace amounts of gold and silver, but

51


copper and zinc were not reported. Detailed surface exam-ination of the occurrence reported in Thurston et al. (1977)indicates that the iron formation consists of alternatinglayers of quartz, sulphides, magnetite and amphibole.Locally they contain minor intercalations of what may befine-grained, metamorphosed lithic sandstone. The unithas been intruded by pink, medium-grained porphyriticgranite and blue-grey quartz diorite.

NICKEL AND PLATINUM GROUP ELEMENTS

Nickel occurrences are closely associated with the cumulate-textured ultramafic rocks, mostly within the Hanrahanassemblage (HNA). The presence of large ultramafic bodies,some of which have documented nickel mineralization, isan indication that there may be good potential for komatiite-hosted nickel deposits similar to those found in theTimmins area and the Kambalda area of Australia (Lesher1989). In addition, locally elevated platinum group ele-ment levels in assay results are also of exploration interest.

Akweskwa Lake (1)

There may be some confusion about the location of thisshowing in Kenogaming Township, as the area is under-lain by numerous ultramafic bodies, a number of whichhave associated nickel mineralization. A grab sample takenat this location is reported to have assay values of 1% Cuand 0.9% Ni (Milne 1972). In 1973, Hanna Mining con-ducted a regional survey and sampled ultramafic rocksover much of Kenogaming Township. The highest returnedassay value in this immediate area was only 0.30% Ni.Fumerton and Houle (1993) report a massive, fine- tomedium-grained, highly serpentinized peridotite withabout 2% disseminated sulphides at the indicated area ofmineralization, but could not find any evidence of channelsampling. Grab samples collected by Fumerton and Houle(1993) returned values of up to 0.28% Ni and 0.13% Cu.

Amax Minerals Limited (2)

Amax minerals conducted a magnetic and EM survey in1978 that was followed up by a diamond-drill hole in1979, in northeastern Kenogaming Township. Drill logsreport assay values of up to 0.25% Ni over 3 m within acarbonatized and serpentinized ultramafic unit containingtalc and chlorite bands.

International Norvalie (13)

In 1971, Norvalie Mines Limited optioned the Jonsmithproperty in east-central Kenogaming Township and dia-mond drilled a number of holes in this area, east of theoccurrence. One of the holes returned a value of 0.26% Niover 3 m of serpentinized ultramafic rock containing 1 to 2%disseminated and fracture-filled pyrrhotite and pyrite.

Another hole, located further to the north, intersected an18 m zone with copper mineralization in a unit identifiedas a grey banded tuff. The mineralization consists of chal-copyrite stringers which returned anomalous values of upto 0.32% Cu.

Ireland (14)

The Ireland occurrence is located in northern KenogamingTownship. It was discovered by Timmins NickelIncorporated in 1989 and explored in 1990 by stripping,trenching and diamond drilling. The showing consists ofcumulate-textured dunites differentiating into melagabbro,isoclinally interfolded with magnetite-chert iron formationand felsic tuffs of the underlying HNA. Mineralizationconsists of 1 to 2% disseminated sulphides which locallyform a poorly developed net texture containing up to 10%sulphides. The sulphides consist of pyrrhotite and minoramounts of pentlandite. Late fractures are also mineralizedwith pentlandite. Grab samples returned assay values of upto 0.94% Ni, 0.10% Cu, 0.27 g/t Pt and 0.2 g/t Pd.Geochemical analyses of the ultramafic rocks in the vicin-ity of the mineralization show REE patterns that are dis-tinctively different than those of similar, but unmineral-ized, ultramafic rocks in the same unit to the northeast.The slightly elevated LREE patterns in the rock hostingthe mineralization suggest that contamination of the ultra-mafic magmas may be the mechanism responsible forlocalizing the sulphides and platinum group element min-eralization (see “Geochemistry”).

McIntyre Johnson (22)

The McIntyre Johnson occurrence lies in poorly exposed,amphibolite-facies mafic metavolcanic rocks in the east-central part of Sewell Township. McIntyre PorcupineMines Limited carried out geophysical surveys followedby diamond drilling in 1971. The mineralization is reportedas millerite which occurs in aggregates and along jointsurfaces within a differentiated mafic intrusion. Reportedassay values are up to 0.2% Ni over 2.3 m within peridotite.

Norduna (27)

The Norduna occurrence is located within a cumulate-textured ultramafic body within the HNA, in centralKenogaming Township. There has been considerableexploration work on this occurrence since its discovery in1947. This work has included geophysical surveys, strip-ping, trenching and diamond drilling, with the most recentwork by Falconbridge Limited. The mineralization con-sists of up to 5% disseminated sulphides in serpentinizedultramafic rocks that are in close proximity to the shearedcontact with intermediate fragmental rocks to the south.The best reported intersection was 0.88% Ni and 0.156%Cu over 7.6 m, including a 1.5 m section with 1.25% Niand 0.24% Cu.

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OGS REPORT 297

IRONThere are 2 economically important iron formations in themap area: 1) the Radio Hill iron formation and 2) the NatRiver iron formation. The iron deposits in both of theseiron formations occur where the iron formation appears tothicken by folding and/or faulting.

Nat River (24)Geophysical surveys and 14 diamond-drill holes byKukatush Mining Corporation Limited, from 1959 to1965, outlined a potential iron deposit containing an esti-mated 27 million tons of 29% total iron in northeasternPenhorwood Township. The deposit occurs within the NatRiver iron formation on the northern limb of the HanrahanLake anticline. The continuity of the Nat River iron for-mation has been largely inferred from magnetic surveysand details have not been established. The diamonddrilling clearly indicates the deposit area is underlain by anumber of iron formation intersections (Milne 1972). Apossible interpretation shown on Map 2627 (back pocket)is that of a Z-shaped, isoclinal drag fold on the north limbof an F1 anticline. Alternative interpretations are repetitionby faulting or a number of separate iron formation horizons.

The iron formation consists predominantly of lean,finely banded magnetite- and chert-facies iron formation.In addition, sulphide-, silicate-, carbonate-, and graphite-facies portions are locally present in lesser amounts. Theoxide-facies portions typically consist of thin, lean beds ofblack chert containing magnetite interbedded with whitenonmagnetic chert on a centimetre scale. The sulphide-facies portions occur as beds of disseminated to massivepyrite and minor pyrrhotite up to 20 cm thick interbeddedwith chert and/or graphitic argillite.

Radio Hill (29)Exploration work by Kukatush Mining CorporationLimited from 1958 to 1965, including geophysical sur-veys, mapping, trenching and diamond drilling, has indi-cated an iron deposit with approximately 158 million tonsof magnetic iron ore grading 27.8% acid-soluble iron. Thedeposit occurs near the eastern end of the Radio Hill ironformation in northwestern Penhorwood Township. Theiron deposit has a strike length of 5000 m and a thicknessof up to 500 m. This abnormal thickness is probably theresult of structural modification by at least 2 episodes offolding. It is overlain by komatiite flows to the north andunderlain to the south by thickly bedded wacke. The ironformation is folded into an isoclinal S-shape fold (F2 folding)plunging north-northwest at about 50° (Milne 1972). Theunit consists of magnetite, siderite, sulphide, silicate(minnesotaite), hematite (jasper) and graphite iron formationtypically interbedded with chert.

Milne (1972) has characterized 4 major vertical faciestransitions in the Radio Hill area. They are, from south tonorth (hanging wall to footwall) 1) sulphide, silicate and

carbonate facies (0 to 50 m in thickness); 2) oxide facieswith minor carbonate and silicate facies (30 to 100 m inthickness); 3) carbonate and silicate facies (10 to 80 m inthickness); and 4) sulphide facies (0 to 25 m in thickness).

ASBESTOSThere are numerous asbestos occurrences within the ultra-mafic rocks scattered throughout the map area. However,the only economically significant deposit is that of theReeves Mine, which produced about 146 000 tons ofasbestos. Milne (1972) concluded 1) asbestos mineraliza-tion is always associated with faulting and ductile deforma-tion; 2) the formation of the asbestos veins was a separateevent from the general serpentinization of the ultramaficrocks; and 3) the asbestos veins are later than the mainmetamorphic events affecting the ultramafic rocks.

Reeves Mine (30)The Reeves asbestos mine is located in southeasternReeves Township. Exploration continued over a periodof about 20 years and production was started in 1968by Johns Manville Limited. It produced a total of about146 000 tonnes of asbestos from about 6 million tons ofore. Production was divided between a large western pitand a smaller eastern pit by a north-trending diabase dike.

The ore body is situated within the northern part of adifferentiated ultramafic to gabbroic body 120 to 300 mthick, which also hosts the Penhorwood talc mine to the south.The ore zones occur in serpentinized dunite in the northernclosure of an antiformal structure which plunges about 50°to the northeast. An easterly facing direction, based on thedifferentiation from dunite to gabbro (see “Geochemistry”),and an S1 fabric which wraps around the nose of the fold,indicates that the fold is an F2 antiformal syncline. Thisnorth-trending fold has been cut by northeast-trendingshears. A major northeast-trending shear crosses the north-ern apex of the antiformal syncline. The dip of this fault isapproximately 55° to the northwest at the surface but flattenswith depth. Drag folding suggests that it is a reverse faultin which the north side has moved upwards (Milne 1972).The orebody is enclosed to the west, north and east byabout 30 m of barren serpentinite in contact with maficvolcanic rocks. Thus, the ore zone appears to conformwith the general trend of the antiform and has 3 dominantstructural controls: 1) the apex of a tight fold; 2) drag foldscaused by a steep reverse fault; and 3) major asbestos fibredevelopment is confined to the serpentinized dunitic partof a differentiated ultramafic to gabbroic body (Milne 1972).

The asbestos in the ore zone occurs in a complex net-work of veins of various ages. The average grade of theore ranges from 2.5 to 4%, with fibres ranging in lengthfrom less than 5 mm up to 15 mm. Many of the asbestosfibres are composite in nature, with magnetite occurringeither as a sandwich between 2 parallel veins of asbestosor as a selvage on one wall of the asbestos vein. Ribbonveins, consisting of a central magnetite-asbestos vein bor-

53


dered on both sides by several parallel asbestos veins, alsooccur. Where the diabase dike cuts the orebody, theasbestos fibres have been recrystallized and destroyed forup to 3 m on either side of the dike (Milne 1972).

TALCA number of talc occurrences are associated with theultramafic rocks of the area. The Penhorwood Mine is theonly currently producing deposit in the map area. It is sit-uated near the sheared western margin of a large differen-tiated ultramafic to gabbroic body which also hosts theReeves asbestos mine. The talc mineralization appears to beassociated with early ductile deformation overprinted bylocalized fracturing and pervasive talc-carbonate alteration.

Penhorwood Mine (28)The Penhorwood Mine is currently operated by LuzenacIncorporated, with a milling rate of 450 tons to produce170 to 200 tons of concentrate per day. There is very littledata available on the reserves or dimensions of the deposit.The open pit deposit is located near the western margin ofan extensive north-trending, cumulate-textured serpenti-nite body cut by east-trending deformation zones, in north-eastern Penhorwood Township. The ultramafic unit alsohosts the Reeves asbestos mine further to the north. Thewestern margin of the ultramafic unit is highly deformedand may be the locus of a sheared contact with a unit ofclastic sedimentary rocks to the west.

Fumerton and Houle (1993) indicate that a number ofintense zones of talc-carbonate alteration occur along anortheast line just east of a parallel shear inferred fromgeophysical data. There are several generations of frac-tures that cut the deposit, all of which have varyingamounts of recrystallized magnesite and talc along thefracture plane. The ore consists of about 50% talc. It is amassive, medium-grained, light grey rock consisting ofvitreous talc and translucent carbonate grains togetherwith disseminated grains of ilmenite and/or magnetite.Based on chemical analyses, the CaO content variesbetween 0.3% and 4.5% and FeO varies between 5% and8.5%. The massive rock is cut by a number of recrystal-lized talc and magnesite veins in a number of differentfracture orientations.

BARITEThe Cryderman Mine is the only recorded barite occur-rence in the map area.

Cryderman Mine (8)The Cryderman barite deposit is located in southwesternPenhorwood Township. It was discovered in 1917 and sincethat time has been the focus of a considerable amount ofexploration, including a 450 m decline in 1984 byExtender Minerals Limited. A total of 673 tonnes of barite

were produced from small operations prior to 1940. Reservecalculations indicate a probable reserve of 90 000 tonnesgrading 95% barite. Milne (1972) indicated that thedeposit occurs along the southeastern margin of theKukatush pluton. However, this investigation and high-resolution aeromagnetic patterns suggest the depositoccurs near the southern margin of an elongate body offoliated granodiorite and granite intruded between theKukatush pluton and Kenogamissi batholith. Intense duc-tile deformation associated with the Hardiman deformationzone is focussed along the southeastern margin of thisintrusion and it is in this setting that the Cryderman,Horwood (11) and Roseval (31) veins are situated.

The barite occurs in a northeast-trending vein struc-ture which has been traced over a strike length of 500 m.Individual veins pinch and swell, from stringers to up to 5 mthick, and have been traced for 30 m. The veins are typicallyzoned from quartz and fluorite at the wall rock contact tolaminated barite and calcite in the walls and massive baritein the centre.

SILICASilica, used for decorative stone and smelter flux, has beensporadically produced from a number of open pits on largequartz veins, in the southwestern part of PenhorwoodTownship.

Horwood Mine (11)In 1964, Horwood Mines Limited produced a total of800 tonnes of silica from a quartz vein in southwesternPenhorwood Township. The quartz veins occur along thesoutheastern margins of elongate, foliated granodioriteand granite bodies intruded between the Kukatush plutonand Kenogamissi batholith. The veins occur in highlystrained wall rock within the Hardiman deformation zone.The Horwood deposit is located in the southwestern partof a quartz vein which has been traced for a length ofabout 550 m and is up to 20 m thick. One of the Rosevalquartz deposits is situated on the northeastern part of thesame vein system.

Roseval Mine (31)In 1987 and 1988, Roseval Silica Incorporated producedabout 110 000 tonnes of silica from their number 2 and 3zones. The veins making up these zones occur within paral-lel shears of the Hardiman deformation zone, situated at thehighly deformed southeast margins of elongate foliated gra-nodiorite to granite bodies that have intruded between theKukatush pluton and the Kenogamissi batholith. The num-ber 2 zone is at the north end of the vein system which hoststhe Horwood Mine. The number 3 zone, which occurs on adifferent quartz vein several hundred metres to the north, islocated at the highly strained contact of a granite intrusionwith ultramafic talc-chlorite schists. This vein has beentraced along strike for about 200 m and is up to 50 m thick.

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OGS REPORT 297

Ayer, J.A. 1993. Geology of Foleyet and Ivanhoe townships; OntarioGeological Survey, Open File Report 5851, 42p.

——— in press. Geology of Keith and Muskego townships; OntarioGeological Survey, Open File Report.

Ayer, J.A. and Theriault, R. 1992. Geology of Keith and Muskego town-ships, northern Swayze greenstone belt; in Summary of Field Workand Other Activities 1992, Ontario Geological Survey,Miscellaneous Paper 160, p.196-202.

Barrie, C.T., Ludden, J.N. and Green, T.H. 1993. Geochemistry of vol-canic rocks associated with Cu-Zn and Ni-Cu deposits in theAbitibi Subprovince; Economic Geology, v.88, p.1341-1358.

Bernier, M.A. and Goff, J.R. 1993. Quaternary mapping and surface driftsampling program, western Swayze greenstone belt; in Summary ofField Work and Other Activities 1993, Ontario Geological Survey,Miscellaneous Paper 162, p.250-255.

Bird, D.J. and Coker, W.B. 1987. Quaternary stratigraphy and geochem-istry at the Owl Creek Gold Mine, Timmins, Ontario, Canada;Journal of Geochemical Exploration, v.28, p.267-284.

Breaks F.W. 1978. Geology of the Horwood Lake area, District ofSudbury; Ontario Geological Survey, Report 169, 67p.

Bursnall, J.T. 1989. Structural sequence from the southern part of theKapuskasing structural zone in the vicinity of Ivanhoe Lake,Ontario; in Current Research, Part A, Geological Survey of Canada,Paper 88-1C, p.405-411.

Cattell, A., Krogh, T.E. and Arndt, N. 1984. Conflicting Sm-Nd wholerock and U-Pb ages for Archean lavas from Newton Township,Abitibi belt, Ontario; Earth and Planetary Science Letters, v.70,p.280-290.

Cattell, A. and Arndt, N. 1987. Low- and high-alumina komatiites froma Late Archean sequence, Newton Township, Ontario;Contributions to Mineralogy and Petrology, v.97, p.218-227.

Dendron Resource Surveys Ltd. 1984. Peat and peatland evaluation ofthe Foleyet area; Ontario Geological Survey, Open File Report5492, 244p.

Donaldson C.H. 1982. Spinifex-textured komatiites; in Komatiites,George Allen and Unwin, London, p.213-244.

Franklin, J.M., Kasarda, J. and Poulsen, K.H. 1975. Petrology and chem-istry of the alteration zone of the Mattabi massive sulphide deposit;Economic Geology, v.20, p.63-79.

Frarey, M.J. and Krogh, T.E. 1986. U-Pb zircon ages of the late internalplutons of the Abitibi and eastern Wawa subprovinces, Ontario andQuebec; in Current Research, Part A, Geological Survey of Canada,Paper 86-1A, p.43-48.

Fumerton, S.L. 1992. Western Abitibi mineral deposit study; in Summaryof Field Work and Other Activities 1992, Ontario GeologicalSurvey, Miscellaneous Paper 160, p.207-217.

——— 1993. Swayze greenstone belt mineral deposit study; in Summaryof Field Work and Other Activities 1993, Ontario GeologicalSurvey, Miscellaneous Paper 162. p.248-249.

Fumerton, S.L. and Houle, K. 1993. Mineral showings, occurrences,deposits and mines of the Swayze greenstone belt, interim report;Ontario Geological Survey, Open File Report 5871, 763p.

Fumerton, S.L., Houle, K. and Archibald, G. 1993. Digital data on themineral showings, occurrences, deposits, and mines of the Swayzegreenstone belt, interim report—plus a computer application toupdate and edit the data using FOXPRO; Ontario GeologicalSurvey, Open File Report 5872, 112p.

Gibson, H.L., Watkinson, D.H. and Comba, C.D.A. 1983. Silicification:hydrothermal alteration of an Archean geothermal system withinthe Amulet rhyolite formation, Noranda, Quebec; EconomicGeology, v.78, p.954-971.

Hall G.E.M. and Plant, J.A. 1992a. Analytical errors in the determinationof high field strength elements and their implications in tectonicinterpretation studies; Chemical Geology, v.95, p.141-156.

——— 1992b. Application of geochemical discrimination diagrams for thetectonic interpretation of igneous rocks hosting gold mineralizationin the Canadian Shield; Chemical Geology, v.95, p.157-165.

Harding, W.D. 1937. Geology of the Horwood Lake area; OntarioDepartment of Mines, v.46, pt. 2, 34p.

Harris, J.R., Broome, J. and Heather, K.B. 1994. Swayze greenstone beltGIS project; in NODA Summary Report 1993-1994, OntarioMinistry of Northern Development and Mines, p.115-121.

Heather, K.B. 1993. Regional geology, structure and mineral deposits ofthe Archean Swayze greenstone belt, southern Superior Province,Ontario; in NODA Summary Report 1992-1993, Ontario Ministryof Northern Development and Mines, p.295-305.

Heather, K.B. and van Breemen, O. 1994. An interim report on geologi-cal, structural and geochronological investigations of granitoidrocks in the vicinity of the Swayze greenstone belt; in NODASummary Report 1993-1994, Ontario Ministry of NorthernDevelopment and Mines, p.99-108.

Hill, R.E.T., Barnes, S.J., Gole, M.J. and Dowling, S.E. 1990. Physicalvolcanology of komatiites: a field guide to the komatiites of theNorseman-Wiluna Greenstone Belt, Eastern Goldfields Province,Yilgarn Block, Western Australia; Excursion Guide Book No 1,Geological Society of Australia, 100p.

Jackson, S.L. and Fyon, A.J. 1991. The western Abitibi Subprovince inOntario; in Geology of Ontario, Ontario Geological Survey, SpecialVolume 4, Part 1, p.404-482.

Jackson, S.L., Fyon, A.J. and Corfu, F. 1994. Review of Archeansupracrustal assemblages of the southern Abitibi greenstone belt inOntario, Canada: products of microplate interaction within a large-scale plate-tectonic setting; Precambrian Research, v.65, p.183-205.

Jensen, L.S. 1976. A new cation plot for classifying subalkalic volcanicrocks; Ontario Department of Mines, Miscellaneous Paper 66, 22p.

Kaszycki, C.A. 1992. Quaternary geology of the Foleyet area, northernOntario; in Summary of Field Work and Other Activities 1992,Ontario Geological Survey, Miscellaneous Paper 160, p.203-206.

Kerrich, R. and Fryer, B.T. 1979. Archean precious-metal hydrothermalsystems, Dome Mine, Abitibi greenstone belt. II. REE and oxygenisotope relations; Canadian Journal of Earth Sciences, v.16, p.440-458.

Lesher, C.M. 1989. Komatiite-associated nickel-sulphide deposits; inOre Deposition Associated with Magmas, Reviews in EconomicGeology, v.4, p.45-101.

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References

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Lockwood, M.B. 1986. The petrographic and economic significance ofchloritoid in the Wawa greenstone belt; unpublished MSc thesis,Carleton University, Ottawa, Ontario. 221p.

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Ontario Department of Mines–Geological Survey of Canada 1963a.Carty Lake, Sudbury district; Ontario Department of Mines–Geological Survey of Canada Map 2247G, scale 1:63 360.

——— 1963b. Shenanga Lake, Sudbury, Algoma and Cochrane districts;Ontario Department of Mines–Geological Survey of Canada, Map2248G, scale 1:63 360.

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——— 1963d. Oswald Lake, Sudbury and Cochrane districts; OntarioDepartment of Mines–Geological Survey of Canada, Map 2264G,scale 1:63 360.

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Tanton, T.L. 1917. Reconnaissance along the Canadian Northern Railwaybetween Gogama and Oba, Sudbury and Algoma districts; inGeological Survey of Canada, Summary Report for 1916, p.179-182.

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CONVERSION FACTORS FOR MEASUREMENTS IN ONTARIO GEOLOGICAL SURVEY PUBLICATIONS

Conversion from SI to Imperial Conversion from Imperial to SI

SI Unit Multiplied by Gives Imperial Unit Multiplied by Gives

LENGTH1 mm 0.039 37 inches 1 inch 25.4 mm1 cm 0.393 70 inches 1 inch 2.54 cm1 m 3.280 84 feet 1 foot 0.304 8 m1 m 0.049 709 7 chains 1 chain 20.116 8 m1 km 0.621 371 miles (statute) 1 mile (statute) 1.609 344 km

AREA1 cm2 0.155 square inches 1 square inch 6.451 6 cm2

1 m2 10.763 9 square feet 1 square foot 0.092 903 04 m2

1 km2 0.386 10 square miles 1 square mile 2.589 988 km2

1 ha 2.471 054 acres 1 acre 0.404 658 6 ha

VOLUME1 cm3 0.061 02 cubic inches 1 cubic inch 16.387 064 cm3

1 m3 35.134 7 cubic feet 1 cubic foot 0.028 316 85 m3

1 m3 1.308 0 cubic yards 1 cubic yard 0.764 555 m3

CAPACITY1 L 1.759 755 pints 1 pint 0.568 261 L1 L 0.879 877 quarts 1 quart 1.136 552 L1 L 0.219 969 gallons 1 gallon 4.546 090 L

MASS1 g 0.035 273 96 ounces (avdp) 1 ounce (advp) 28.349 523 g1 g 0.032 150 75 ounces (troy) 1 ounce (troy) 31.103 476 8 g1 kg 2.204 62 pounds (avdp) 1 pound (avdp) 0.453 592 37 kg1 kg 0.001 102 3 tons (short) 1 ton (short) 907.184 74 kg1 t 1.102 311 tons (short) 1 ton (short) 0.907 184 74 t1 kg 0.000 984 21 tons (long) 1 ton (long) 1016.046 908 8 kg1 t 0.984 206 5 tons (long) 1 ton (long) 1.016 046 908 8 t

CONCENTRATION1 g/t 0.029 166 6 ounce(troy)/ 1 ounce(troy)/ 34.285 714 2 g/t

ton(short) ton(short) 1 g/t 0.583 333 33 pennyweights/ 1 pennyweight/ 1.714 285 7 g/t

ton(short) ton(short)

OTHER USEFUL CONVERSION FACTORS

Multiplied by1 ounce(troy) per ton (short) 20.0 pennyweights per ton (short)

1 pennyweight per ton (short) 0.05 ounces (troy) per ton (short)

Note: Conversion factors which are in bold type are exact. The converion factors have been taken from or have been derived from factors given in theMetric Practice Guide for the Canadian Mining and Metallurgical Industries, published by the Mining Association of Canada in co-operation with theCoal Association of Canada.

Metric Conversion Table

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ISSN 0704-2582ISBN 0-7778-3813-3

Documents

Precambrian Geology, Northern Swayze Greenstone Belt