Trace Element Investigation of Spor Mountain, Juab County, Utah

8/14/2019 Trace Element Investigation of Spor Mountain, Juab County, Utah

1/260


2/260


3/260


4/260


5/260


6/260


7/260


8/260


9/260


10/260


11/260


12/260


13/260


14/260


15/260


16/260

15

Plate l.--Panorama of the southern end of Spor.Mountain looking north along the eaat aide.Eagle Rock Ridge ia on right aide of picture.

Plate 2.--Benches cut in a quartz1te h111 a t thesouth end ot the diatr ict by waves ot old LakeBonnev111e.


17/260


18/260


19/260


20/260


21/260


22/260


23/260


24/260


25/260


26/260


27/260

26

Plate 7A.--Garden City formation a t south end ofdis t r ic t . Stratigraphic section in table 2was measured a t this point.

l. '

" ' C . .,.

Plate 7B.--Garden City formation a t south end ofdis t r ic t showing the difference in resistanceto weathering between the massive and thelumpy limestone beds. Base of measured s t ra t -igraphic section i s a t bottom of massive outcrop.


28/260


29/260


30/260

29

I

Plate 8.--Swan Peak formation consisting of theshale member (Oss) and a part of the quartzitemember (Osq) overlying the Garden City forma-tion (Ogc) at the south end of the dis t r Ict

Plate 9.--The shale member of the Swan Peak formation in a small gully.


31/260


32/260


33/260

32

Plate lO.--Foaa1l1ferous dolomite from the shalemember of the Swan Peak formation. The brachiopod is Orthambon1tes m1chael1a.


34/260


35/260


36/260

35

Plate llA.--Fish Haven dolomite (Of) between theFloride dolomite (Sf) and the quartzite memberof the Swan Peak formation (Osq). View looking up northwest side of canyon, which trendssouthwest from the F l ~ o r i n e Queen mine.

,.... - ,,_ ... ,"" ,

i "~ ; ; ~ ~ ~ "":

Plate l lB.--Bell Hill dolomite (Sb) croppiD$ outbetween the overlying Harrisite dolomite lSh)and the underlying Floride dolomite (Sf). Intrusive breccia ( i) pipe in right foreground.


37/260


38/260


39/260


40/260


41/260


42/260


43/260

42

lS30 K \ I I - r t L 6 , U ~ ! t e : e A.t

"

0t ~ ~ \ a ' " U; ~ r ~ a ~ " ' - " - ~ ' ' ' ' ~ I \ " ' " , -: ' ---!, . ' ; L, ' j . . ~ t., . I I t.' _;Plate l2&.--Th1nly laminated ncurlyn beds tromupper part ot the Bell Hill dolom1te.

Plate l2B.--Horn corals from prominent tos .1lbearing bed, 4 to 10 teet above the base otthe Bell Hill dolomite.


44/260


45/260


46/260

45

Plate l3.--Harrisite dolomite cropping out alonga canyon in the aouthern part of Spora Moun-tain. Thia is the type section.


47/260

46

Plate l4A.--Harrlslte dolomite containing numer-ous partly dolomitized Halysites.

Plate l4B.--Cherty member of the Lost Sheepdolomite. Note parallel bands of chert.


48/260


49/260


50/260


51/260


52/260

51

Plate l5A.--Sevy dolomite torming s.. l naturalarch on west side ot Spora Mountain.

Plate l5B.--Sevy doloa1te showing characterist ic grooY1ng along and aeross laa1nations.


53/260


54/260


55/260


56/260


57/260


58/260


59/260


60/260

59

Plate 16A.--Semic1rcular bar or Lake Bonnev111egravels on the northwestern end or SporsMounta1n.

Plate 16B.--Well-conso11dated Lake Bonnev111econglomerate.


61/260


62/260


63/260


64/260


65/260

64

~ ~ , - - - - - - - - ~ Plate l7A.--Large lithophysae in spheruliticrhyolitic glass, from ridge 4.500 feet eastof Lost Sheep pi t .

Plate l7B.--Intrusive breccia from Hilltop no. 1property. Dark specks in matrix and fragmentsare smoky quartz crystals. Light-colored angular rhyolite fragments are set in finegrained reddish matrix.


66/260


67/260


68/260


69/260


70/260


71/260


72/260


73/260


74/260

73

Plate 18A.--Fault pattern Just north of Dellproperty. (Oss-shale member and Osq-quartzite member, Swan Peak formation; Sf-Ploridedolomite; i-intrusive breccia.)

Plate 18B.--Fault traces southwest of Blowoutmine. (De-Sevy dolomite, St-Thursday dolomite, Sl-Lost Sheep dolomite, Sh-Harrisitedolom1te( Sb-Bell Hill dolomite, i-intrusivebreccia.)


75/260


76/260


77/260

Plate 19.--Thru8t fault near the Harri8ite minewith Lost Sheep dolomite (Sl) overlyingThursday dolomite (St) . Fault in backgroundis a normal fault .


78/260

77

Plate 20A.--Repetltlon of Bectlon by northeaBttrendIng faultB In the northern part of SporsMountaIn. (St-ThurBday dolomite, Sl-LoBtSheep dolomIte, Sh-Harrlslte dolomIte, Sb-BellHIll dolomIte, and I-lntrualve breccIa.)

Plate 20B.--Offset of bedB on eaBt-trendlngfault partIally fIl led by travertIne veIn.


79/260


80/260


81/260


82/260


83/260


84/260

33

Plate 2l.--Pluorite in narrow clay-rich layersaround fragments in tuff .


85/260


86/260


87/260

86

Plate 22.--Horn coral completely replaced byfluorite from center of large ore body,Bell Hill property.


88/260

S"',

Plate 23.--Brown boxwork fluorite ore from theOveI'I'J1ght mine.

Plate 24.--Boxwork of pale purple fluor1te fromopen cut, Blowout m1ne.


89/260


90/260

Plate 25.--White dolomite along fractures ingray dolomite country rock.


91/260


92/260


93/260


94/260


95/260


96/260


97/260


98/260


99/260


100/260


101/260


102/260


103/260


104/260


105/260


106/260


107/260


108/260


109/260


110/260

109

Plate 26.--P1t no. 1 on the Bell H1ll propertyshowing the connect1on w1th the undergroundwork1ngs.


111/260


112/260


113/260


114/260


115/260


116/260

115

"'


117/260


118/260


119/260

Plate 28A.--East side of the north end of SporsMountain showing the location of the Blowout,Lost Sheep, Hilltop no. 1 and Oversight mines.

Plate 28B.--Blowout (center) and south ore bodyof Lost Sheep (right). CSt-Thursday dolomite,Sl-Lost Sheep dolomite, Sh-Harrisite dolomite,Sb-Bell Hill dolomite, and i - intrusive brec cia.)


120/260


121/260


122/260


123/260


124/260


125/260


126/260


127/260


128/260


129/260


130/260


131/260


132/260


133/260


134/260

133

Plate 29.--Ma1n p i t on the Lost Sheep property.Back of p it is over 70 feet high.


135/260

134

Plate 30.--Open cut on the ma1n Lost Sheep orebody. Dump ( left background) 1s from ad1tto Blowout ore body.


136/260


137/260


138/260


139/260


140/260


141/260


142/260


143/260


144/260


145/260


146/260


147/260


148/260


149/260

AEC - 728/5

OFFICIAL USE ONLYUNITED STATES

DEPARTMENT OF THE INTERIORGEOLOGICAL SURVEY

WASHINGTON 25. D. C.

Mr. Robert D. Nininger, Assistant DirectorDivision of Raw MaterialsU. S. Atoml,c Energy CommissionWashington 25, D. C.Dear Bob:

IN REPLY REFER TOI

May 31, 1955

Transmitted herewith are three cO;:lies of TEI-252, uGeology ofthe Thomas Range fluorite distr ict , Juab County, Utah," by Mortimer H.Staatz and Frank W. Osterwilld, February 1955.

We are asking Mr. Hosted to approve our plan to publish Part Iof this report as a bulletin.

Sincerely yours,

c ~ * * - . kw. H. BradleyChief Geologist

us G e o t i ~ f SUrveyJAN 2 20m

Denver Ubrli'yWhen separated from enclosures, handle this document as UNCLASSIFIED

OFFICIAL USE ONLY


150/260

' -..-

OFFICIAL USE ONLY

Geology and MineralogyThis document consists of 160 pages,plus 7 figures and 4 plates,Series A

UNITED STATES DEPARTMENT OF THE INTERIORGEOLOGICAL SURVEY

GEOLOGY OF THE THOMAS RANGE FLUORITE DISTRICT,JUAB COUNTY, UTAH

By

Mortimer H, Staatz and Frank W, Osterwald

February 1955

Trace Elements Investigations RepOrt 252

This preliminary report Is distributedwithout editorial and technical reviewfor eonformity with official standardsand nomencl.tur.,. It Is not for publicinspection or quotation.

~ h i s report concerns work done on behalf of the Divisionof Raw Materials of the U. s. Atomic Energy Commission,

When separated from Part.D, handle Part I as UNCLASSIFIED.

OFFICIAL USE ONLY


151/260

1

OFFICIAL USE ONLY2

USGS - TEI-252

GEOLOGY AND MINERALOGY

Distribution (Series A)Argonne National Laboratory .. .. ........ ..Atomic Energy Commission, Washington ..Division of Raw Materials, AlbuquerqueDivision of Raw Materials. Bune ..Division of Raw Materials. CasperDivision of Raw Materials, DenverDivision of Raw Materials. Hot Sp rings ..Division of Raw Materials , IshpemingDiVision of Raw Materials. Phoenix. . .Division of Raw Materials. Salt Lake CityDivision of Raw Materials, WashingtoDo ..

. . .Exploration Division. Grand Junction Operations OfficeGrand Junc tion Operations Office .. .. .. .. ..Technical Information Serv ice . Oak RidgeTennessee Valley Authority. Wilson DamU. S. Geological Survey:Fuels Branch, Washington .. .. .. .. .. " .. Q Q .. .. ..Geochemistty and Petrology Branch. Washington ..Geophysics Branch. WashingtonMineral Deposits Branch, WashingtonE. H. Bailey. Menlo Park . . .A. L. Brokaw. Grand Junction

Denver c. M. Denson.R. K. Hos e, Menlo Park . Klepper. Spokane

Koschmann. Denver

L. R. Page, Washingron .. .. . . ................. . . . .C. B. Read, AlbuquerqueQ. D. Singewald. BeltsvilleR. E. Van Alstine, WashingtonA. E. Weissenborn, Spokane . . .TEPCO. Denver ...... .. .TEPCO, RPS, Washington. (Including master)

OFFICIAL USE ONL Y

No, of coeies1111111111311611113111I131

11112

.......l-46


152/260

I

3CONTENTS

Absuact Introduction ..

Scope of reportLocation and surface featuresHistory and production ....Previous work . . . . . . . . . . . . .. ..Field work and acknowledgments

Geology.. .. .. .. . . . . . . . . . . . . . . . . . . . . ..General features . . . . . . . . .. .. ..Ordovician sedimentary rocks ..

Garden City formation ..Name and distributionLithology Thickness and correlation

Swan Peak formation .. pShale member Distribution

LithologyThickness and corre lation

Quartzite memberDistributionLithologyThickness and correlation

Fish Ha ven dolomite .... 0 ..Name and distributionLithology Thickness and correlation

Silurian sedimentary rocks . . . . . . .Florlde dolomite Name and distributionLithology Thickness and correIa tion

Bell Hill dolomite Name and disulbutlonLithology Thickness and correlation

Harrisite dolomite .. .... .. ..Name and dlsulbutionLithology Thickness and correlationLost Sheep dolomi te Name and distributionLithology Thickness and correlation

Thursday dolomite Name and distributionLithology Thickness and correlation

..

Page101212121618192020212121222228282830303333333434343636383939394041 141 \4143444444444747474849494950


153/260

FageGeology--Contlnued

Devonian sedimentary rocks. 50Sevy dolomite 50. . .Name and distribution 50L i ~ ~ o l o g y 52Thickness and correlation 53Simonson and Gui1lmette fonnallons. undivided. 53Name and distribution 53Lithology" . . .. .... .. . 55Thickness and correlation 55Lake Bonneville sediments 58Volcanic! rocks ... . 58Introducrlon 58Classification. 60Petrography 61Enstarlte-auglte la tl te 61Hypenthene lalite ',Y' o 62Acid IgneoUl. rocks ; . 0 62intrusive breccia 63Pyroclastic rocks o 0 66Agglnmerate . o 68Quartz latitlc tuff 86Rhyolit ic tuff. 66Lapilll tuff , 67Petrology. .. .. .. .. .. " .. .. 67Chemical composition of rhyolites. Petrogenesis 70Suucture

.. " .. .. .. 72Inuoduction . 72Folding 74Faulting 74ThruslJ 75Northeast-trending normal and revene raults. 75Northwest-trending faults . 78North-trending raults 0 0 0 78East-trending faults. 0 o 0 78Joge of faul&lng 79Mechanics of faulting. 79Ore depOIits.. .. .. .. .. .. .. 80Types of depositS 80Pipes ...... .. 80

Veins ...... .. 81Disseminated deposits 82Structural conuol. 84Character of ore . 85Uranium mineralization 90Origin ........ .... .. .. .. 104


154/260

5Page

Structure--ContinuedDescription of individual depos its. 107Bell Hill 0 0 0 10 7Introduction 107

Diamond drilling 110Geology 111Ore deposits 111

Blowout .. ... 117Introduction 117Geology 120Ore deposits 120

Blue Queen No. 1 , . 121Fluorine Queen 123Introduction 123Geology 124Ore deposits 124Fluorine Queen No . 4 125

Harrlsite 0 . 12 7Introduction 127Geology 128Ore deposits 128Hilltop No. 1 131

Lost Sheep 0 132Introduction 132Geology 135

Main pipe 135South pipe. 135Lost Soul No. 1 136

Lucky Louie --137Oversight 138Introduction 138

Geology 140Ore deposits 140Unnamed ad!t 141

Deposits In tuff. 143Introduction 143Deposit No . 1 143Deposit No. 2 144Rainbow No.2. 144

Literature cited . 145Unpublished reports 147

\ ; '\


155/260

Plate 1.

ILLUSTRATIONS

Panorama of the southern end of Spars Mountain looking north along the eastSide. Eagle Rock Ridge is on right sJde of pic ture" " ...... " .... " .. " .... ....

2. Benches cut In a quartzite hill at the south end of the district by waves of oldLakeBonneVille . . . ............ co .. " .... " .. " " " .... "" .. . . . . . . . . . . . . "3, Geologic map of the Thomas Range fluorit e district, Juab County, Utah.

Pageite (Sh)

and the underlying Floride dolomite (Sf), in trusive breccia (i) pipe in rightforeground .... " " " " " " .... " " .. co " " " " " " (I .......... " " . . . . CI

12, A. Thinly laminated CUlly beds from upper part of the Bell Hill dolomiteB. Horn corais from prominent f""lI-bearlng bed, 4 to 10 feet above the base

of the Bell Hill dolomite .. .... " . . . . . . . . " " " . . . . . . . . . . . . . . . . .... ...... ..13. Harrisite dolomite cropping out along a canyon in the southern part of SpOQ

Mountain. This is the type section.. .. " .. .. .. " .. '" .. .. .. .. .. .. .. .. .. .. .. .. ..

..

3542

42

45


156/260

)

7

Plate 14. A. Harrlslte dolomite containing numerous part ly dolomltized Halysites B. Cherty member of the Lost Sheep dolomite . Note parallel bands of chert.

15. A. Sevy dolomite forming small natural arch on west side of Spors MQuntain.B. Sevy dolomite showing character is ti c grooving along and across laminations

16. A. Semicircular bar of Lake Bonneville gravels on northwestern end of sporsMOWltain .... .... " .... " """ .. "" .. .. ,, .. . . . . . .

B. Well-consolidated Lake Bonneville conglomera te ..17, A. Large llthophysae In .pherulltlc rhyolitic glass, from ridge 4, 500 feet east of

Lost Sheep pit " .. " " " .... n " " .. .. .. .. .. .. . . . . . . . . . . .. . . . . . . . . . . . . .. .. ..B, Intrusive breccia from Hilltop No . 1 property. Dark specks In matrix and

fragments are smoky quartz crystals. Light-colored angular rhyolite fragments

Page46465151

5959

64

are set in fine ..grained reddish matrix .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 6418, A. Fault pattern Just north of Dell property. (Oss -shale member and Osq-quartzite

member, Swan Peak fo, mation; Sf-Floride dolomite; I-intrusive breccia,) 73B. Fault Itaces southwest of Blowout mine. (Os-Sevy dolomite, St-Thursday

dolomite; SI-Lost Sheep do lom ite; Sh-Harrlsite dolomite; Sb-Bell HlII dolomite,i -intrwive brecc ian ) " .. " .. " .. .. ...... ..... .. . 0

19. Thrust fault near the Harrls lt. mlDe , with Lost Sheep dolomite (SI) overlying Thurs-73

day dolomite (St). Fault In backgwund Is a normal fault 7620, A. Repetition of section by northeast-trending faults

In the northern part of S!">,, Mountain. (St-Thursday dolomlll '. SI-LostSheep dolomite , Sh-Harrlslte dolomite. Sb-Bell HlII dolomite , and i-intrusivebreccia. ).. .. .. .. .. .. .. .. .. .. .. .. " .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ........ oi

B . Offset of bed. on east-nendlng fault parrially filled by travertine vein21. Fluorite in narrow clay-rich layers around fragments In tuff 22. Horn coral completely replaced by fluorite from center of large ore body, Bell Hili

property . . . . . . . . .. ...... .. .. .. " .... .. ...... .. .. .. .23. Brown boxwork fluorite ore from the Overs ight mine24. Boxwork of pale purple fluo rite from open cu t, Blowout mine25. White dolomite along fractures in gray dolomite country rock

777783

86878789


157/260

8Page

Plate 26. Pit no. 1 on the Bell Hill property showing tbe connection with the undergroundworkings ............. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 109

27, A. Intrusive rhyoli tic tuff band cutting fluorite ore body on 87-foot level of theBell Hill mine ........ .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. 115

B. Irregular band of Intrusive rhyolitic tuff cutting the fluorite ore body on 168-footlevel of the Bell Hill mine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 .. 115

28, A. East side.of the north end of Spors Mountain showing the location of the Blowout,Lost Sheep, Hilltop No. I. and Oversight mine ,. . . . . . . . . . .

B. Blow""t (center) and south ore body of tbe Lost Sheep (right). (St-Thursdaydolomite; Sl-Lost Sheep dolomite; Sh-Harrlslte dolomite; Sb-Bell Hill dolomite;and i-intrusive breccia.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. ..

29. Main pi t on the Lost Sheep property. Back of pi t Is over 70 feet high . . .. .. .. .. ..30. Open cut on tbe main Lost Sheep ore body. Dump (left background) Is from adlt to

Blowout ore body. . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . .. .. . . .. .. .. .. .. .. .. .. .........Figure 1. Index map of the Thomas Range fluorite distr ict , Juab County, showing areas of

Plates 3, 5, and Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

118

118133

134

132. Topographic map of the Thomas Range fluor ite distric t, Juab County, Utah In envelope3. Generalized diagrammatic stratigraphic secrlons of the Fish Haven, Florlde, Bell

Hill, Harrlslte, Lost Sheep, and Thursday dolomites 374. Normative feldspal ratios of rhyolites 715. Graph showing relationships between uranium content and depth in large ore body on

Bell Hil l property co . . . . . . . . . . . .. '. .. .. .. .. 0 .. .. . . . . .. .. . . . . .. .. .. .. .. .. .. 1026. Geologic map of the Bell Hill property, Juab County, Utah. In envelope7. Underground geologic maps of the BeIl Hill mine, Juab County, Utah In envelope8. Geologic sections of the large pipe on the Bell Hill property In envelope9, Block diagram showing the shape of the large pipe on the Bell Hill property 113

10. Geologic map and sections of the Blowout property, Juab County, Utah In envelope11. Underground geologic maps of the Blue Queen No. 1 and Lost Soul No. I, Juab

County. Utah .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . 12212. Geologic map and section of the east pit of the Fluorine Queen, Thomas Range,

Juab County. Utah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. In envelope


158/260

9

Figure 13. Geologic map of the Fluorine Queen No.4. Juab County. Utah Page12614. Diagrammatic vertical section showing the relationship of fluorite bodies to thrust

fault, Harrisite property ... 12915. Geologic maps of the Lost Sheep property. Juab County. Utah In envelope16. Block diagram showing shape of the Lucky Louie pipe 13917. Underground geologic map of ad it southeast of the Thursday prospect. Juab County.

Table 1.2.

3.4.

5.

6.

7.

8.

Utah 142

TABLES

Fluori te production of the Thomas Range district from 1944 through 1952 17Stratigraphic section of the Garden City formation measured at south end of theThomas Range fluorite dlstrict 23Lime and magnesia content of limestones and dolomites from Spon Mountain. 27Stratigraphic section of upper part of shale member of the Swan Peak formation.Locality is approximately one-quarter of a mUe northeast of the Floride mine in theSW 1/ 4 NW 1/4 sec. 2. T. 13 S . R. 12 W. 31Stratigraphic section of the Sevy dolomite. measuring started at a point 5. 540 feetN. 78 W. of the Oversight mine . . . . . . 54Stratigraphic section of the Simonson and Gulllmette formations. undivided.measuring started at a point 11.970 feet S. 770 W. from the Lost Sheep main pit. 56Chemical composition In weight percent and molecular norms of Thomas Rangerocks 68

Analyses of samples from the Thomas Range fluorite district. Juab County. Utah. 92


159/260

) 10GEOLOGY OF TH E THOMAS RANGE FLUORITE DISTRICT,JUAB COUNTY, UTAH

By Mortimer H. Staatz and Frank W. Osterwald

ABSTRACT

The Thomas Range fluorite district includes an area of about 34 square miles surrounding SporsMountain in centtal Juab County, 46 miles northwest of Del ta. Utah. Between the time of its discovery in1943 and the end of 1952. this district produced a total of 75,312 short tons of fluorite ore from 12 properties.Almost al l the fluorite deposits have an abnormally high uranium content. All but one of the seven sampledfluorite veins and pipes that contained over 0.050 percent waniurn are on the southern end of SporsMountain.

The rocks exposed in the district range in age from Lower Ordovician to Pleistocene. The greaterpart of Spors Mountain is made up of a thick series of apparently conformable Paleozoic rocks, which arechiefly carbonates. The Ordovician Garden City formatioD. which is chiefly limestone, is the oldest rockexposed in the disuict. Two other Ordovician formations. the Swan Peak formation c o n s i s ~ 1 n g of a lowershale member and an upper quartzite member and the Fish Haven dolomite overlie the Garden Cityformation. Five newly named Middle Silurian formations: the Floride dolomite. the Bell Hill dolomite.the Harrisite dolomite. the Lost Sheep dolomite. and the Thursday dolomite overlie the Fish Haven. TheDevonian Sevy dolomite and the Simonson and Guillmette formations . undivided (dolomites and limestones).oveJ;'lie the Silurian dolomites and are the youngest Paleozoic rocks in the disuiet. Volcanic rocks. whichinclude latite, quartz latite. rhyolite, agglomerate, lapilli tuff, quartz latitlc tuff. and rhyolitic tuff, ofprobable Tertiary age, surround the Paleozoic sediments. Dikes and plugs of intrusive breccia, rhyolite.and quartz latite inuude the Paleozoic rocks. commonly along faUlts.

All the Paleozoic sediments and the volcanic rocks strike northeast and dip northwest. These con"sistently dipping rocks are cut by about 980 faults belonging to at least five sets of faulting: 1) northeast-, trending thrusts. 2) northeast .trending normal and reverse faults, 3) northwest .trending faults.


160/260

)

114) east-trending faults, and 5) north-nendlng faults, The first three sets were formed prior to theemplacement of the volcanic rocks, but the latter two sets cut both groups of rocks and movement alongthe north-trending set raised Spors Mountain to its present elevation.

During Pleistocene time Lake Bonneville surrounded the Thomas Range. and gravels, conglomerate,and marl were deposited at that time on its flanks and in the surrounding area which is now a desert,

Fluorite deposits are of three types: 1) oval to irregular pipes, 2) veins, and 3) disseminated deposits.The pipes. which show considerable variation in shape and size with depth, have produced more than 99percent of the are. Fluorite deposits are found chiefly In the Silurian dolomites and the underlyingOrdovician Fish Haven dolomite, and show two chief type. of structural control: 1) in or adjacent to faults,and 2) adjacent to ~ n t r u s i v e breccia bodies, The ore consists of 65 to 95 percent fluorite with mommotH .lonite, dolomite, quartz, chert, calcite, and opal as impurities. The fluorite closely resembles a brown,white, or purple clay and forms either soft pulverulent masses or box works. With depth the grade of theore commonly decreases, and masses of montmorillonite. chert. or quartz and dolomite have been foundin increasing abWldance in some deposits.

The ore is be lieved to have been formed from fluorine-r ich fluids which brought in minor amountsof uranium. and which were derived from the magma that formed the topaz-rich rhyolites of the ThomasRange during the last stages of vulcanism. These fluids rose along faults and replaced shattered zones inthe dolomite. Introduced elements other than fluorine and uranium were probably obtained from rocksunderlying the depOSits,

Uranium analyses on 155 fluorite samples ranged from 0.003 to 0.33 percent uranium. The highesturanium samples came from the Bel l Hill , Harrisite. Eagle Rock, Lucky Louie, and two small prospects,D e ~ o s l t s at all of these properties except the Bell Hill are small. The grade of the uranium In the fluoriteare varies considerably even on individual levels of a single mine, Uranium was secondarily enriched,however, near the surface of most depoSits. This is believed to have been caused by slow leaching of theupper part of the are body in an arid climate, in part from material being actively eroded. The uraniumwas redeposited a few inches to 30 feet below the position from which it was leached because the dry u n d e r ~ lying ore absorbed the ground water, The uranium content of the fluorite are from the upper workings maybe as much as twice that found In depth.


161/260

12INTRODUCTION

Scope of report

The fluorite disuier in the western part of the Thomas Range, Juab County. Utah. is one of thenewest mining disaicts in western United States ; since 1950 it has been the largest producer of fluoritewest of the Mississippi River. The present report covers the geology of the entire fluorite producing area,and supplements an earl ier report by Staat z. Wilmarth. and Bauer (1954) on the individual miningproperties.. Additional material is given on al l old operating properties, as well as on those properitesdeveloped between September 1950 and February 1953.

Locat ion aDd surface features

The Thomas Range is on the eastern edge of the Basin and Range province in cen tral Juab County.Utah (fig. 1). The range is about 17 miles long and has a maximum width of 9 miles. It trends northwestand is composed of three distinct topographic un its. The eastern unit is a block approximately 12 mileslong and 3 to 6 miles Wde. composed of Te rt iary (?) rhyolite and tuff. About 2 miles to the west is asecond unit approximately 6 miles long and 1 1 /2 to 2 mile. wide composed chiefly of complexly faultedearly to middle Paleozoic sedimentso The third unit, three and ODe half miles farther northwest, is acircular group of mountains about 4 miles in diameter composed of middle PaleOZOiC sediments.

All the known fluorite deposits are In the second unit called Spors Mountain by Fitch. Quigley. andBarker (1949. p. 63-66). Mining has been limited to an area approximately 5 miles long by 1 mile widealong the eastern side of Spars Mountain. The present report covers, an area of approximately 34 squaremiles. It i ~ c i u d e s aU of SpOts Mountain and extends about 2.4 miles south of its southernmost end. Seefigure 1 and plate Ill.

The mapped area is In Tps. 12 and 13 S R. 12 W Salt Lake principal meridian. The nearesttown is Delta in Millard County, approximately 46 miles southeast from the southern part of the district.,


162/260

13. . . - - - -- _- - --_._ -_._ - - - -- - -

o

TOOELE COUNTYJUAB COUNTY

2 4 MILES

~ O l t Lake City--Ej---'-',,-.JUAB co. :; . .. /DeltaUTAH

l

FIGURE I. INDEX MAP OF THE THOMAS RANGE FLUORITE

TO DELTA

DISTRICT,JUAB COUNTY, SHOWING AREAS OF PLATES m ,"!L ,AND:lZI


163/260

14The area Is reached from Delta, the nearest railhead on the Union Pacific Railroad , by 15.4 miles ofpaved and 30.9 miles of improved dirt road. In the spring of 1952, the Bureau of Public Roads improvedand straightened the road along the east side of Spars Mountain. From this road a second road leadsaround the south end of Spars Mountain and north along its western side (fig. 1). The north part of thissecond road Is passable only by jeep. Several haulage roads lead to the various mines from the main eastside road. During the summer months cloudbursts sometimes wash out the roads.

Spars Mountain rises steeply out of Lake Bonnevil le sediments. which surround It. and fonns a smallrugged range (fig. 2). The base of the mountain Is at an elevat ion of approximately 5,000 feet, and thehighest peak reaches an elevation of 6,584 feet (pl. I), Along the western and southern sides of this smallrange, low hills. as much as several hundred feet h i g h protrude through a cover of Lake Bonneville gravels.Bars of Lake Bonneville gravel as much as 50 feet high are also found across the mouths of valleys, andwa ve cut benches formed by old Lake Bonneville are prominent in the southernmost part of the district(pl. 2). Along the east side of the distr ict, especially the central and northern parts, the topography Issteep and the valleys are V-shapedo

No permanent streams are found in the area , and surface water flows in the water courses only duringand shortlY after occasional summer cloud bursts. Rainfall is scant; during the winter as much as 2 feet ofsnow falls hampering mining operations from late December to early April. The nearest permanent watersupply is east from the northeast corner of the district. There is also a well for watering sheep near theDelta .Callao road approximately 2- 1 / 2 miles south of the district. As the nearest water is either saline orin remote locations, the miners bring their drinking water from Delta.

The area is covered by bushes six Inches to a foot high which Is thickest in the flat area surroundingSpan Mountain. The only trees are twisted junipen, averaging about 7 feet In height, which are mostabundant in the north and central parts of the mountain. These trees are not used as mine timber becausethey are too small.


164/260

15

Plate l.--Panorama of the southern end of Spor.Mountain looking north along the east side.Eagle Rock Ridge is on right side of picture.

Plate 2.--Benches cut in a quartzite hi l l a t thesouth end ot the distr ict by waves ot old LakeBonneville.


165/260

16History and production

All of the mines in this district produce fluor ite. The fluorite ore contains uranium minerals, butup to January 1953, no uranium was recovered from any of the ores. No copper, lead, zinc, silver, gOld.or manganese minerals are known from the district.

The first fluorite was mined from the Floride claim of George Spor and sons in 1943, and was soldthe following year. From 1944 to 1947 there was little other activity in the district, and the Floride con-tinued to be the only shipper. Late in 1947 the Dell No. 1 and No.2 deposits were located, and this wasfollowed in rapid succession by the discovery in 1948 of the Blowout, Dell No,S, Eagle Rock, FluorineQueen, Hilltop. Lost Sheep, Lucky Louie, NODella, Oversight, and Thursday; and in 1949 .by the locationof the BeU Hill and Harrisite. By the end of 1949, almost al l of Spors Mountain was covered by claims.

In 1948, production from the Floride claim was augmented by that from the Dell Nos. 1 and 2, theFluorine Queen, ~ n d the Lost Sheep; in 1952 eight properties were in production. Altogether, by

) December 31, 1952. twenty deposits on 12 different properties had produced a total of 75,312 short tonscontaining 65 to 94 percent fluorite (table 1). All of this was mine run ore and was sold for metallurgicaluse.

From 1944 to 1949 ore was shipped to Geneva Steel Company at Geneva, Utah. Since 1950 theore has been sold to Continental Ore Buyers of Chicago, Ill., brokers. who ship it to various pans of thecountry.

Ore sold for approximately $23. 50 a ton in 1952 delivered in Delta, Utah, based upon a 60 percenteffective grade CaF2._1

_I The effective CaF2 is determined from an analysis of the ore by subtracting 2 1 /2 percent CaF2for each 1 percent of SiOz in the ore. Thus. an ore containing 75 percent CaF2 and 4 percent Si02 wouldbe rated at 65 percent effective.


166/260

17Table 1. --Fluorite production of the Thomas Range district from 1944 through 1952.

Number ofdeposits Production {short tonsproducing Total

Mine fluorite 1944 1945 1946 1947 1948 1949 1950 1951 1 9 5 ~ productionBen Hill 3 0 0 0 0 0 0 ~ 7 . 4 8 0 _ 4,466 11,946Blowout 1 0 0 0 0 0 1,100 2.355 1.313 1,128 5,896Den 3 0 0 0 0 800 3,000 1,300 0 0 5,100De n No. 5 1 0 0 0 0 0 205 0 0 0 205Floride I ( 8,748 ) 0 463 0 0 9,211Fluorine Queen 2 0 0 0 0 ( 9,071 4,321 3,727 17,119Harrisite 2 0 0 0 0 0 0 0 55 0 55Hilltop No. 1 2 0 0 0 0 0 0 0 0 IOn!1 100Lost Sheep 2 0 0 0 o E 11,62511---. . . 5,729 6.241 23, 595Lucky Louie 1 0 0 0 0 0 0 0 0 1,432 1,432Oversight 2 0 0 0 0 0 0 0 0 598 598

Thursday 1 0 0 0 0 0 5511 0 0 0 55TOTAL - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 75, 312

11 Tonnage estimate from size of workings.' ]) From Bauer, H. L Jr,. 1952, Fluorspar deposits north end of Spars Mountain, Thomas

'Range, Juab County, Utah: Univ. Utah, unpublished thesis.


167/260

18Mining in the district is generally begun by open pit methods. The open pit method is continued as

long as walls remain intact, but several mines have had to use underground methods, when their open pitbecame too deep. The small are pipe on the Lost Sheep and the east are pipe on the Fluorine Queen depositshave been mined by driving a short adi t to the are body and raising to the surface. The are In the open pi tis then drawn by slusher to the raise and trammed out underground. The Lucky Louie and Oversight depositswere shaftmined by sinking on the are body and hauling the are out In a bucket. The Bell Hill operatorsdrove an adit 86 feet below the surface and then mined the ore body from a number of stopes both above andbelow the adlt. The large ore pipe on the Dell Nos. 1 and 2 was mined by an adaptation of the block cavingtechnique. The ore was drawn off at the chutes and trammed to the are bins. The wall rocks are sufficientlysolid In al l mines so that litrle tln1ber is necessary.

Previous work

Early work on the Thomas Range was confined to the eastern part, where rhyolite yields the beautifulwine-colored topaz crystals, which have long been a collector's item. The area is the type locality of themineral bixbylte, which was first collected by Maynard Bixby (Penfield and Foote, 1897, p. 105'108).

The topaz area was first reported by Henry Engelmann, geologist for Captain I. H. Simpson'sexpedition across the Great Basin of Utah. in 1859 (Simpson, 1876, P. 325). Since that time, numerousa r t i c l ~ s on topaz and its associated minerals have appeared In print (Kunz, 1885, p. 738; Cross, 1886,p. 436438; Alling, 1887, p. 146147; Kunz, 1893, p. 764; lones, 1895, p. 175177; Penfield and Foote,1897, p. 105'108; Hillebrand, 1905, p. 330331; Patton, 1908, p. 177-192; Palache, 1934, P. 14-15;and Montgomery, 1934, P. 82-87).

The western part of the Thomas Range (Spars Mountain) attracted little geologic attention before1948. No published geologic maps of the Thomas Range are known, though some mapping was done byW. p. Fuller for International Smelting and Refining Company, I. I. Beeson for Geneva Steel Company,and James Quigley for Chief Consolidated Mining Company. The fluorite district is briefly described byFitch, Quigley, and Barker (1949, p. 63-66). The district was visited during August and September of 1950


168/260


169/260


170/260

21Pleistocene Lake Bonneville sediments cover the surrounding desert and the lower elevations of Spars

Mountain o Gravel bars. as much as 60 feet high. are found in the mouths of several canyons.The Paleozoic sediments and the Teritary (?) volcanic rocks strike consistently northeast and dip

northwest. Though the beds have been tUted. no fold axes cross the district.The district is cut by innumerable faults which can be divided on the basis of strike and dip into five

groups.. Three of these. a few small thrusts. a prominent northeast-trending set of faults. and an apparentlylater northwest-trending set, cut the Paleozoic rocks but must have preceded the volcanic rocks becausethey served as conduits for plugs and dikes. Two later sets, trending east-northeast to east. and north. CUtboth the Paleozoic sediments and the volcar.lc :l. The north-trending set shows the largest offset, and along

this set Spors Mountain and the neighboring ridges were raised to their present elevation.

Ordovic ian s e dimentary rocks

Garden City formation

Name and distributiono ..The Garden City formation of Orcovician age WaJ first described byRichardson (1913. p. 408-409) from Garden City Canyon in northeastern Utah . The most comprehensivework at pre,ent is that of Ross (1951) who has studied the stratigraphy and pa leontology in detal.l. At itstype locality the Garden City is 1.225 feet thick (Ro". 1951. p. 3).

The Garden City formation crops out in only two places in the fluorite distr ic t: (1) in hills along theextreme southern margin of the district (pl. 3), and (2) in a small area about 2, 800 feet southeast of theFluorine Queen mine along the ea!it flank of Spors Mountain o At neither place is the entire formationexposed, for in the southern area the base is covered by Quaternary sediments. and in the eastern area itis cut out by faulting. At both localities the Garden City is overlain conformably by the shale member ofthe Swan Peak formation.


171/260


172/260

23

Table 2, --SUatigraphic section of theQ.ardenCity formation measuredat the south end of the Thomas Range fluorite disuicl.

Description

Swan Peak formationQ u a r ~ z i t e member

Shaly memberDolomite. medium-grained. orange to red. limy. interbedded with

layers of fissile green shale, Orthambonites michaelisCovered

Top of Garden City formation on basis of fossil float.CoveredLimestone. light gray. medium-grained. with a few small shale

partingsCoveredLimestone, thin-bedded, light gray. fine-grained, 70 percent

brown chertCoveredLimestone, coarse-grained, dark gray; no chert. Hesperonomiella

sp.CoveredLimestone, fine-to medium-grained, medium gray. 25 to 75

percent brown, irregular chertCoveredLimestone, dark to medium-gray. about 25 percent brown chertCoveredLimestone, medium-grained, medium-gray , about 45 percent

irregular chen

Bedthickness

90.6

102.1

162.8

33.6

83.6

22.0

83.5

9.7

32.7

52.7

21.3

1.5

135.1

14.0

Cumulativethickness

193

102

730

567

534

450

428

345335

302250227226

91


173/260

24Table 2. -Stratigraphic section of the Garden City formation measured at thesouth end of the Thomas Range nuorile district--Continued.

Description

Coquina. dark grayLimestone., massive, medium-grained, medium-gray, numerous

irregular "blebs" of shaleShale, light green, limy; a few gray limestone lensesLimestone, massive, medium-gray; numerous irregular "blebs" of shaleLimestone. light gray. fine-grained. interbedded with light greenish

gray shaleLimestone. medium"grained. dark gray. in part coquina, Tetragraptus sp.Limestone. fine -grained, light gray. interbedded with about 40 percent

light greenish-gray shale, TettagraptUs dissipiensLimestone, coarse-grained, gray. stained r e d d i s h - b ~ o w n on outsideLimestone. light gray, interbedded with 40 percent light gray shale,

Cybelopsis aff . C. speciosa, Lachnostoma latucelsum. Pseudocybele.!!!!!!!!. Klrkella ef. K. declevita. Hesperonomia"'!p Tetragraptus cf.T taraxacum. Teuagraptus cf. T. dissipiens

Limestone, massive , medium-grained . light grayLimestone. light gray. flne-grained. interbedded with light. greenish

gray, non-limy shaleLimestone-coquina. dark gray. Cybelopsis aff. C, speciosa,

Lachnostoma latucelsum. Pseudocybele nasua. Kirkella cf . K, declevita.Hesperonomia sp. I Teuagraptus d, T, taraxacum, Teuagraptus d.T. disslpiens

Limestone. light gray. about 20 percent, greenish-gray shale as flnep ~ r t ; t n ~ s . Contains a few coarse-grained purplish gray coquina lens

Coquina, purplish gray. coarse-grained , lenti cular Cybelopsis aff.C. speciosa, Lachnostoma latucelsum. Pseudocybele nasuta, Kirkella cr,K. 4eclevita, Hesperonomia sp . Tetragraptus cf. T! taraxacum.'Te;tragraptw d, T, dissipiens

Bedthickness

1.3

1.52.3

10.4

1.01.3

2.81.5

4. 96.7

5.9

2.1

5.6

0. 7

Cumulativethickness

77

75

7472

6160

5956

5550

43

37

29


174/260

25

Table 2. --Stratigraphic section of the Garden City formation measured at thesouth end of the Thomas Range fluorite district--Continued.

Description

Shale, light green and gray, limyCoquina, dark purplish grayShale, light greenish gray, limy: a few coquina lensesCoquina, dark purplish grayLimestone, l ight gray, fine-grained, about 25 percent shale as partings,

Cybelopsls aff. C. ' peciosa, Lachnostoma latuceisum, Pse udocybele.!!!!!!. Kirkella cf. K. declevita. Hesperonomia sp Tetragraptus ef ,T. taraxacum, Teuagraptus d , T. dlssipiens

Limestone, light gray. medium-grained small layers of greenish yellowand pinkish shale, Cybelopsis aff. C, speciosa. Lacbnostoma latucelsum.Pseudocybele naSUla, Klrkella cr. K, declevita. Hesperonomia sp. ITettagraptus cf. T. taraxacum. Tetragraptus d , T. dissipiens

Limestone, irregularly bedded, light g r ~ y . fine-grained, comaining greenshale partings

Limestone, light gra y, medium-grainedLake Bonneville gravels

Sedthickness

0.30. 20.60.1

10.9

4.2

2.410.0

Cumulativethickness

292828

28

28

17

1210


175/260

26

Plate 7A.--Garden City formation a t south end ofdis t r ic t . Stratigraphic section in table 2was measured a t this point.

Plate 7B.--Garden City formation a t south end ofdis t r ic t showing the d ~ f f e r e n c e in resistanceto weathering between the massive and thelumpy limestone beds. Base of measured s t ra t -igraphic section i s a t bottom of massive outcrop.


176/260

27Table 3. --Lime and magnesia content of llmestones and dolomites from Spors Mountain

C a D Y Mgo!! Percentcontent contents dolomite inFormation Location (percent) (percent) carbonate Rock name'!:. / Remarks

fraction

Garden City Southern edge ofdistrict 38.13 0.63 4 Limestone Massive beds

Do.


177/260

28Ross states that "the fauna in these collections includes almost the complete faunal assemblage of the "J". ~ . , zone of the Garden City formation of northeast Utah. This same fauna is listed by L. F. Hintze (1951,p. 17) in the lower part of the Wahwah limestone, one of his subdivisions pf the Pogonip fo rma tion . Heprefers to use the name "Pogonip" because the name antedates "Garden City. "and because his measwedsections are closer to the type Pogonip locality (Hansen and Bell, 1941, p. 47). The Ordovician limestonesin the Spars Mountain district resemble in lithology the Garden City formation of nonheastern Utah asdescribed by Ross (1951) more closely than they do the "Pogonip, and because of close faunal similarity,the authors prefer to use the name Garden Cfty fo rmation.

Swan Peak format ion

The Swan Peak formation was named by Richardson (1913, p. 409) in the Rando lph quadrangle ofnortheastern Utah and western Wyoming. As shown by Ross (1951, p. 10-23) in the Rando lph qua drangle ,and Williams (1948, p. 1136) In the Logan quadrangle, the formation consists of three parts : 1) a lower,hale interbedded with silty quartz ite and limestone beds , 2} a middle reddish-brown quartzite interbeddedwith shale, and 3) an upper quartzite.

In the Thomas Range the Swan Peak qua rtz ite consists of two prominent parts : 1) the lower of shaleiOlerbedded at the top with hematitic quartzite beds which grade downward Into a .hale interbedded withhematitic sa ndy dolomite beds, and 2) the upper of massive white quartzlte,(pl. 8). The upper massivequartzite forms prominent cliffs, and the lower shaly forms gentle slopes. These two members have beenmapped separately (pIs. 3, 5, and 6).Shale member

Distribution. --The shale member of the Swan Peak formation conformably oyerlles the Garden Cityformation. The shaly pan is easily weathered and in most places is covered by slope waSh , the bestexposures occurring in little steep-sided gullys (pl . 9) . The shale member crops out most extensively inseveral hills at the exueme southern end of the district , but it is also found along the east side of SporsMountain, chiefly north of the Floride mine and south of the road to the Dell No. 5 mine. The shalemember is not as prevalent as the overlying quartzite member because of faulting.


178/260

29I

Plate 8.--Swan Peak formation consisting of theshale member (Oss) and a part of the quartzitemember (Osq) overlying the Garden City formation (Ogc) at the south end of the distr ict .

Plate 9.--The shale member of the Swan Peak formation in a small gully.


179/260

)

)

30Lithology. --The shale member has not been entuely exposed in any section. The upper 100 feet

are best known and a detailed section made a qua ner of a mile northeast of the Florlde mine is given intable 4. The rock is composed chiefly of dun green shale stained reddish-brown along numerous fractures.The shale contains much fine-grained chert. Most of the shale i5 calcareous and is interbedded with moreresistant beds of quartzite and dolomite , 0,1 to 10 feet thick with the quartzite near the top of the sectiongrading downward through quartzill c dolomite into dolomite. The undersides of some of the quartzite bedsshow fucoids. The quartzi te and dolomite of the shale member are readlly distinguished from lOcks ofsimilar composition in that they are hematitic red in color .

Thlckness and co:relation ...-The shale member was measured completely in two places: two-thirdsof a mlle southeast of tbe Fluorlne Queen mine in sec. 35. T. 12 S. , R. 12 W. (fig. 2), and in tbeextreme ,outhern end of the district In sec . 23, To 13 S . R. 12 w. (fig. 2). At the flIst locallty theshale member is 251 feet thick and at the second locality. approximately 4 miles to the sou th, i t is388 feet thick. Individual beds also vary in thickness , and the quartzite and dolomite beds cannot becorrelated in sections a mile apart.

Two varieties of brachiopods were the only fossils noted : these were scattered throughout both theshale and dolomite from 50 feet below the top of the unit to the bottom, In some small dolomite and shalelayers these f"",iis make up almost the emue layer (pl. 10). Mos t common is Orthambonites michaellsClark (previously caned Orthis michaells Clark). The second brachiopod belongs to the genus Anomalorthis;the species is not certain. These foss ils we re identified by R. J. Ross, Jr ., of the Geological Survey.

The shale member is correlated with the lower Swan Peak formation at the type locality bothstratigraphically and paleontologically. The Swan Peak in northeastern Utah cons ists of an upper massivequartzite and a shaly fossiliferous lower part (Ross, 1951, P. 10; W!l1iarm, 1948, p. 1136- 1137), which issimllar to tbe beds In the Thomas Range. Ro J. Ross, Jr. (written communication) in describlng thebrachiopods from the Thomas Range . states that "these two species are also common in the sh.aly andsilty limestones beneath the qua rtzltic member of the Swan Peak formation in the Logan quadrangle , Utah. "


180/260

31Table 4, --Stratigraphic section of upper part of shale member of the Swan Peak formation, Locality is

approximately one-quarter of a mile northeast of the Floride mine in the SW 1/ 4 NW 1/4sec, 2, T, 13 S . R, 12 W,

Description

Quartzite member

Shaly memberShale, fissile, green, stained red along fractures in lower partand interbedded with brick red, hematitic quartzite, in partmottled, Twelve quartzite beds range in thickness from 0,3to 2 .8 feet. Fucoids are fO\Uld along undersides of quartzitebeds at 95 and 107 feet. Some areas are covered.Shale, fissile, dull green, stained red in part along fracturesand interbedded with brick red, hematitic dolomite. whichis quartzitfc in the upper half. Four dolomite beds range inthickness from 0.1 to 1. 6 feet. About three-quarters of thesection is covered.Shale, fissile, dull green, sta ined red along conchoidal fracturesand interbedded with brick red, hematitic , limy , arenaceousdolomite and limestone l a y e r ~ 3ad lenses . Nine dolomite andlimestone beds range in thickness from 0.1 to 2.7 feet. Numerousbrachiopods with Orthambonites miehaelis being found in .hale at35 feet, in dolomite at 10,B, 17,1, 17,6, 31,0, and 37,0 feet,and in limestone at 21,1 and 24,4 feet ;Anomalorthis sp, beingfound in shale at 35 feet, in dolomite at 16,8 and 31,0 feet, andin limestone at 24. 4 feet.

Slope wash

Bed Cumulativethickness

(feet)

50,7

'29,2

36,7

thickness(feet)

117

66

37


181/260

32

Plate lO.--Foss1l1ferous dolomite from the shalemember of the Swan Peak formation. The brachiopod i s Orthambon1tes michael1s.


182/260

33. iHe further states that "the lithology of the specimen submitted to me is identical to that of part of theSwan Peak in that area." According to Ulrich and Cooper (1938. p. 101) Orthambonites michaelis Clark(listed as Q!!!!!!. michaells Clark) has also been found in the Swan Peak formation in Utah at the followinglocalities: a mile west of Ibex in the Confusion Range. on thewestshore of Bear Lake on Swan Creek. andin Wasatch Canyon. 4-1/2 miles north of Brigham.

Orthambonites michaell s Clark and Anomalorthis sp. have been described from the Pogonip group byHintze (1951, p. 18-19. 57. 62. 64, 68-73, 75-78, 80-81, 83, 85). According to Hintze the faunal zonesof the Pogonip group for the most part correspond with those in the Garden City and Swan Peak formationsof northeastern Utah, Hintze subdivided the Pogonip loto six formations aod the two brachiopod species arefound only in his Kanosh shale. which is probably equivalent in age to the shale member of the Swan Peakformation.Quartzite member

Distribution. - ..The quartzite member of the Swan Peak formation is the most resistant rock toweathering of any formation in the district, and forms prominent reddish-brown cliffs along the eastern sideof Spors Mountain. It is also found in fault blocks near the center part of the range. and crops outextensively in several hills at the extreme southern end of the district,

Lithology. - ..The quartzite member is a remarkably uniform rock that is generally white, though insome places pinkish wh.ere fresh. and reddish-brown to black where weathered. Black coloring is mostcommon along fractwes and appears to be a manganese oxide staining. The greater part of the quartziteis fine-grained and consists chiefly of clear interlocking subrounded quartz grains o Amethyst, orthoclase,and rounded biotite books are present in minor amounts. The chief heavy minerals are well - rounded andpitted olive green tourmaline and well-rounded clear zircons. Most of the beds are well-cemented, butlocally some beds are friable . Cross-bedding was noted throughout the section. Individual beds in thisformatlon:range -from 1 to 10 feet thick but generally langed between 2 to 4 feet thick; .


183/260

34Thickness and.correlation. --The quartzite member is apparently conformable with the overlying Fish

Haven dolomite. It is , however, bounded by faults either on its upper or lower side throughout most of thedistrict. The only area In which both contacts are exposed is along the eastern side of Spors Mountain between the Floride and Fluorine Queen mines. A section measured approximately 800 feet northeast of theFloride mine showed the quartzite to be 592 feet thick at this point.

No fossils were found in the quartzite. The same quartzite overlain by the identical sequence ofdolomites occurs In the northern parI of the Fish Springs Range. 12 miles to the west. In the Gold H!llmining district (Nolan. 1935. p. 16). 28 miles northwest of the Fish Springs Range. an unconformityseparates the Lower Ordovician from the Upper Ordovician Fish Haven dolomite. No Middle Ordovician isfound in the Tintic area (Lovering, T. S. I alaI communication). The quartzite in the Thomas Range iscorrelated with the upper part of the Swan Peak formation, on the basis of its stratigraphy and its positionbetween the lower fossiliferous part of the Swan Peak formation and the Fish Ha ven dolomite.

Fish Haven dolomite

Name and distribution. --The Fish Haven dolomite was named by Richardson (1913. p. 409-410) forits occurrence in the Randolpb quandrangle in northern Utah and western Wyoming. where it was describedas a fine-grained medium-bedded dark gray to biue-black cherty dolomite containing a Richmond fauna .and immediately overlying the Swan Peak formation. Rocks of similar lithology and age are describedas Fish Haven dolomite in the Gold Hill mining district by Nolan (1935. p. 16-17). In the western partof the Thomas Range here described. rocks of similar lithology. lying on top of the Swan Peak formationand containing Upper Ordovician fossi ls, are correlated with the Fish Haven.

The Fish Haven dolomite crops out chiefly along the eaS! side of the southern half of Spors Mountain.Other good sections are found on the northwest side of the canyon that trends southwest from the FluorineQueen property (pl. 11, A), and along the northwest side of the canyon that trends southwest from theDell No. 5 property. In general this formation weathers easily.aDd commonly forms smooth debris-coveredslopes.


184/260

35

Plate llA.--Fish Haven dolomite (Of) between theFloride dolomite (Sf) and the quartzite memberof the Swan Peak formation (Osq). View looking up northwest side of canyon, which trendssouthwest from the F l ~ o r i n e Queen mine.

Plate IlB.--Bell Hill dolomite (Sb) croppins outbetween the overlying Harrisite dolomite lSh)and the underlying Floride dolomite (Sf). Intrusive breccia ( i ) pipe in r ight foreground.


185/260

36Li.tholol!Y. --The Fish Haven dolomite is in general a light-gray to black fine-grained dolomite with

chert In some parts (fig. 3). The lower 30 to 50 feet Is banded. contains small amounts of quartz sand Insome layers, and as much as 10 percent chert, chiefly along f [ ~ ! = t u r e s . Commonly a thin (2 foot) quartz itebed Is found about 20 feet from the base of the section. Above this lower part the dolomite lacks vis iblequartz sand and contains linle chert. About two-fifths of the way up in the formation, a light-gray fine grained calcitic dolomite containing numerow small holes as much as 1 mm in diameter tlat are commonlyfmed with white calcite, forms a distinctive marker bed approximately 30 feet thick, .A light-to dark-graybanded smoothweathering calcitic dolomite overlies this unit in the middle and northern parts of thedistric t. In the southern part, however, the rock is chiefly limestone, (See section 2 , figure 3, )

The Fish Haven formation is distinctive because it is the only carbonate rock containing visiblequartz sand and is the only formation;above the Ordovician Garden City and below the Middle DevonianSimonson-Guillmette formations that contains any l i m ~ s t o n e .

Although the upper part of this unit consists'of calcitic dolomites and limestones, the lower part isdolomite .. A sample collected from the lower part in the vicinity of the Floride mine wa s analyzed(table 3) and wa s found to contain 29.81 CaO. The MgO content of this sample compares favorably wi ththe 21.35 percent MgO found in a sample from near the type section on Fish Haven Creek (Richardson, 1913,p. 410).

Thickness and correlation. - ..The Fish Havendolomite was measwed in two places: half a mile northof the Floride mine in the NE 1/4 NE 1/4 sec . 3, T. 13 S R. 12 W . and 1,700 feet northeast of theDell No. 5 mine in sec. 27, T. 12 S., R. 12 W. The thickness in the two sections (fig. 3) Is 212 feet and180 feet respectively.

The only fossils found came from the limestone in the upper part of the formation in the southern partof Spon Mountain. Thefollowlng fossils, found only in Upper O r d o i c i a n ~ , were Identified byHelen Duncan and Jean Berdan of the Geological Survey:


186/260


187/260

Catazyga ? sp .Hesperorthis sp.Farden ia sp.Favosites sp .

38Hom coral D undeterminedBryozoans o i n e d High -spired gas tropod, undeterminedStromatoporoids

The lithology of the Upp er Ordovician dolomite exposed In the Thomas Range was exa mined by/t. J. Ross, Jr" who states (oral communication) tbat It is almos! Identical with the lithology of the typeFish Haven dolomite. This d o l o m i on the bas is of i ts Late Ordovician age , its stratigraphic pos ition abovethe Swan Peak formation, and the similarity be tween the two lithologies. is correlated with the Fish Havendolomite.

Sil urian sedimentary rocks

Dolomites of Middle Silurian age crop out over most of the western part of the Thomas Range. Inorder to show the structure in the range the Middle SHurf.an rock5 were divide d into five new formations .These are the Floride dolomite D the Bel l Hil l aolomite o the Harr i!iite dolomite Q the Lost Sheep do lomite oand the Thursday dolomite (fig. 3), in order of deereaolng age. The new formations we re also recognizedby the authors in the northern pa rt of the Fish Springs Range, 15 miles nonhwest of the northern end ofSpors Mountain. The lithologic change be tw een these forma tions is as sttiking as the contrast between theFish Haven fo rmation of Ordov ician age and the Midd le Silurian forma tion which overlies it. ,

Fossil collections from these formations were examine d by Helen Duncan and Jean Berdan, who statetbat al1 appear to be Middle Sil ur ian In age. Indications, however, point to two intergrading fa unas, Thelower formations (Florlde and Be l1 Hill) contain a reef with Clrcophyllum, two kinds of Halysltes with smallcorallites, Heliolites, many hom corals, and pentameroid brachiopods, The uppermost formation (Thursday)contains a reef in which stromatoporoids app ear to be much more abundant than in the lower formatioos oThis fauna also contains the coral Zelophyllum in fa ir abundance and a form of Halysites characterized bylarger corallites than the two species common in the lower reefo In additiong many of the species foundin the earlier reef also appear to persist into the la ter ree fo


188/260

39Fossils collected from the five Silurian dolomites such as Favosites sp Halysites sp ... HeUoHres sp

Virgiana sp are similar to those found in the Laketown dolomite in the Logan quadrangle of northeasternUtah (Williams, 1948, p. 1138), the Randolph quadrangle of northern Utah and western Wyoming(Richardson, 1913, p. 410), and the Gold Hill mining district in western Utah (Nolan , 1935, p. 18). Someof the fauna, however, contains elements not observed in the type Laketowno The Silurian rocks of theThomas Range are probably correlative. at least in partt with the Laketown dolomite of northeastern Utah;however, too little is known about tqe exact age of the type Laketown to correlate the Sllwian formations inthe Thomas Range with al l of it .

Flor ide do lomi t e

Name and distribution ... -The Floride dolomite , named fo r i ts occurrence ai the Floride mine o cropsout chiefly along the east !iide of Spors Mo untaL, in the southern half of the range.. In addition prominentoutcrops occur along the lower northwest !:ide :l of three canyons which aend southwest from the FluorineQueen, Dell No. Blowout mines, respectively . Although the section is complete at the Floridemine . type section (5ecd oo 2, fig. 3) Wa.3 measured on a steep hilbide o starting half a mile north ofthe Floride. because of better expocures. Other good sections are located 00 the northwest side of a steepcanyon 1.400 feet southw e:;t of the we.st pipe of the Fluorine Queen, and on a mountain 1,700 feet northeastof the Dell No.5.

Lithology. - -The Floride dolomite is made up of two units which can be easily recognized in thefield and which are shown separately on the detailed regional maps (pis. 5 and 6). The lower two-fifthsis called the black mottled member and the upper three-fifthso the slope maker member.

The black mottled member is a resistant unit, which forms a prominent black band along the mountainSides. This rock is a dark gray to black medium-grained locally cross-bedded detrital dolomite with sandsize grains. Th e most distinctive featwe is a dark mottling. which is most pronounced in the lower half.Small cayities are common and near the base of this member are commonly lined with white dolomite. Asample of this rock (table 3) was analyzed and found to contain 98 percent dolomite in its carbonate fraction .


189/260

40The slopemaker member separates two resistant dolomites and is covered by slope wash in most

places. Several distinct units are found but al l are fine-grained. light to medium gray. and smoothweathering. The lower 39 fee t consists of thin undulating beds. which weather with an irregular bumpysurface. This dolomite is pinkish in a few places and is commonly stained red by iron oxide along bedding-plane surfaces and fractures. The next 20 feet is light gray limy dolomite. followed by 8 feet of mediumgray dolomite containing numerous small cavities as much as 1 mm in diameter, The uppermost unit is alight to medium gray banded dolomite showing a faint mottling in a few places. In general chert is rare inthis member. though locally 1 to 2-inch bands of chert parallel the bedding in the upper part. A sampleof the limy dolomite (table 3) with numerous small cavities was analyzed and found to conta in 81 percentdolomite in its carbonate fract ion. According to Pettijohn (1949. p. 313) this rock would be classifiedas a calcitic dolomite.

Thickness and correlation .. The thickne!ls of the entire Floride formation was measured in twoplaces: at the type section half a mile nouh of the Floride Mine in the NE 1/4 NE 1/4 sec . 3, T. 13 S,.R. 12 W., and 1,700 feet northeast of the Dell No, 5 mine in sec. 27, T. 12 S., R. 12 W. In addit ion,the slopemaker member was also measured 2.750 feet southwest of the Blowout mine in sec. 28 , T. 12 S. 0R. 12 W. The thickness of the black mottled member ranges from 91 to 100 feet, and the slopemakermember from 100 to 135 feet ( f i ~ 3).

The black mottled member contains numerous crinoid stems and a few horn corals includ ingCircophyllum ? sp. identified by Helen Duncan and Jean Berdan. The slopemaker member yielded onlya few unidentified horn corais from the upper part , Although the Floride formation is not very fossiliferous,the few specimens found are similar to those of the overlying Bell Hill formation. and it is , t h e r e f o r e ~ regarded as of probable Middle Silurian age.


190/260

41Bell Hil l dolomite

Name and distribution .. -The Bell Hill dolomite, named from the Bell Hill mine on the southern end

of Spors Mountain. is the thickest Silurian formation In the district. Although named after the Ben Hillmine, numerous faults and poor exposwes make this one of the poorer places to study the formation, therefore. section 2 (fig. 3). on a steep mountain side half a mile north of the F10ride mine is designated the typesection. Other good sections are found on the north side of the canyon southwest of the Fluorine Queenproperty and on the north side of the canyon southwest of the Blowout property (sec. 6. fig. 3). Faultblocks containing the Bell Hill dolomite are scattered throughout Spors Mountain with the exception of its

nonhero tip.The Bell Hill dolomite is a resistant formation and forms steep hills with prominent ou tcrop3

(pl. 11 . B). especially in the central and 50ut!;:ern parts of the rangeoLithology. --The Bel\ Hili dolomite is made up of two members: the lower eight-ninths is a dark

gray coarse-graIned clastic dolomite, and u p p ~ r one"'ninth is a light-gray fine -grained dolomite.. Thecliff-forming lower part is most commonly dark gray but in some places varies to light gray along strike.

with color variations possibly being re lated to the interu:ity of dolomitization. This massive rock ischaracterized by detr ital sand-size grairu of dolomite, local cross-beddingG common banding. and fewdistinctive layers. However. in the northern part of SpOl!!; Moun:ain, a 28-foct thick dolomite bed with ahighly dist inctive contorted. convoluted appearance (thinly laminated "curly beds L pl. 12. A.!) occursapproximately 40 feet from the top of the unit. The upper part is commonly covered. bu, where exposed.is a thin-bedded light-gray balided dolomite. Unllke the sandy lower part, this fine-grained upper part is

a smooth weathering rock, that in places is somewhat limy.. This rock is the ma rker bed between the lowerdark-gray sandy part of the BeU Hill dolomite and the overlying dark-gray sandy Ha rrisite dolomite.

A sample from the lower pa rt of the Bell Hill dolomite (table 3) was analyzed and found to contain98 percent dolomite in the carbonate fraction.


191/260


192/260


193/260

44

The age of tbe Bell Hill dolomite is Middle Silurian. Some of the fossils are similar to thosedescribed in the Laketown dolomite in the Randolph quadrangle (Richardson, 1941, p, 18), the Loganquadrangle (Williams 1948, p. 1138), and the Gold Hill mining district (Nolan, 1935, p. 18) and to theHidden Valley dolomite in the Quartz Spring area, California (McAllister, 1952, p, 15-18),

Harrisite dolomite

Name and disttibution. --The Harrisite dolomite is named for exposures that cap the hill just eastof the Hanisite mine. The section heti is not complete however. and the type section is deSignated asthe steep west side of a cahyon 2, 000 fee t n o r . h ~ . , t of the Harrisire mine (section I, fig. 3/ and pl. 13).Other good sections are fOUi1d on the nOr!hwe3t side of a cznyon 3, 000 feet southwest of the Blowout mineand on the northwest side of a canyon 4,0 00 fee t oouth "'southwest of the Oversight mine. Fault blockscontaining the Harris ite dolomite &re scattered throughoqt Spars Mountain, The Hanisite dolomite is arelatively resistant formation and. with the Bell Hi ll dOlomiteJorms many steep mownain sides and capsnumerous ridges (pl. 13).

A sample from the Harrisite dolomite (,table 3) taken near the Los t Sheep mine was analyzed andfound to contain 98 percent dolomite in its carbonate fraction.

L.lthology. --The Harrisite dolomite Is a mass ive cark gray to black locally banded dolomite, containing as much as 20 percent black chert, chiefly as blebs and discontinuous layers along the bedding.The lower 10 feet of this formation has a mottled appearance and is commonly limy. The Harruite closelyresembles the Bell Hill dolomite in li thology but does not show any variance in color along the strike. Themost distinguishing characteristic of the Harrisite dolomite is faint white squiggly lines (pl. 14, A), mostcommonly preserved in white calcite, which are the remains of Halysites (chain corals).

Thickness and correlation .....The Harrisite dolomite shows considerable variation in thickness. Itwas measured in three places: 1) at the type section in sec. 10, T. 13 S., R. 12 W 2,000 feet northeastof the Harruite mine; 2) 1,000 feet northeast of the Dell No.5 mine in sec. 27, T. 12 S . R. 12 W. ; and3) 2,750 feet southwest of the Blowout mine in sec. 28, T. 12 S. , R. 12 W. The thickness of the Harrlsitedolomite ranged from 110 to 174 feet (fig. 3).


194/260

45

Plate l3.--Harrisite dolomite cropping out alonga canyon in the southern part of Spore Moun-tain. This is the type section.


195/260

46

Plate l4A.--Harrlalte dolomIte contaInIng numer-ous partly dolomitized Halysites.

Plate l4B.--Cherty member of the Loat SheepdolomIte. Note parallel bands of chert.


196/260

47Halysites and crinoid stems are common throughout the format ion but are generally too poorly pre ..

served to identify. Dolomitization has desuoyed the distinguishing characteristics of most of the fossils.The best preserved ones are commonly si licified. One of the best exposures of the Halysites .bearingHarris lte dolomite Is seen on the hill just east of the wo tklngs of the Harrisite mine (pl. 5). The followingfossi ls coUected from this hill were identified by p. E. Cloud, Jr., of the Geolog ical Survey.

Halysiles sp.Pentamerid brachiopod

Gastropod, undeterminedCrinoid stem

According to Mr. Cloud the penta merid brachiopod along with the Halysites . p. indicates that thiso c k is of Silurian age , even without ki'!owledge 01 its $tratigraphic pOS iti on between the Be ll Hill and Lost

Sheep dolomites.

Lo S! Sheep d o l om i te

Name and dizt!' ihuUono - ...The. Los t Sheep dolomite n 1]J. med for its occmrence at the Lost Sheep mine Qis widely distribu ted on the weJ tern ! of Sp:orz Mountain. The type sec tion i'i in the same outcrop stripas that swrounding the Los t Sheep minp. but was measured on the northw est 3 of a steep canyon 2D 000feet southwest of the neighboring Blowo3t mL'I'le (se ctloI! 6, fig . 3) .. Oth er g ood 5ections are fOlmd 550feet and 4 ,000 feet southwest of the Oversight mine.. In addit ion to the mai!l Lost Sheep ore bodyD theBlowout, Oversight, and Lucky Louie ore bodies are found in this formation.

Lithology. --The Lost Sheep dolomite is made up of two membets , mapped separa te ly on the detailedregional maps (pis. 5 and 6). The lower two- thirds is called the gray member and the upper third, thecherty member. The gray member is made up of three light- to medium-gray units and one thin

Documents

Trace Element Investigation of Spor Mountain, Juab County, Utah