Airborne Geophysical Interpretation Hebburn Survey Block

Airborne Geophysical Interpretation

of the

Hebburn Survey Block

Burnaby and Eldridge Townships

Temagami - Temiskaming Area, Ontario

Christopher Campbell, P. Geo. February 16, 2004

Sudbury Mining Division

NTS 031L114 and 031M/03

for

Tres-Or Resources Ltd.

1934 - 131 Street White Rock, BC V4A 7R7

Canada

by

Intrepid Geophysics Ltd.

4505 Cove Cliff Road North Vancouver, BC

Canada V7G 1H7

Project no. 03-085

\'

Summary

A total of 1,812 line-kilometres of helicopter-borne electromagnetic and magnetic data over the 'Hebburn' survey block in the Sudbury Mining Division of northeastern Ontario were reviewed on behalf of Tres-Or Resources Ltd. The data was acquired using traverse lines oriented north-south at a nominal line spacing of 50 metres tied by perpendicular (east-west) control or tie lines every 1,000 metres. Adual ground clearance was approximately 45 metres, mean terrain clearance.

All airborne geophysical data were imported into a database for line-by-line viewing and processing; spreadsheet, profile and grid editing tools facilitated advanced processing and analysis as well as quality control/assurance of the basic data. Filtering transformations yielded secondary products with enhanced information content; this permitted greater information to be extracted from the data. The processed geophysical grids were further subjected to standard image processing techniques to provide increased target quality and higher confidence through integration of all types of data. The final integration of data and information was made using GIS software, where layers of drainage overlay the geophysical images, license permits, etc.

The primary objective of the geophysical interpretation was the identification and ranking of possible kimberlite targets based on their electromagnetic and/or magnetic response. Target selections made on the basis of discrete anomalies identified from these enhanced grid images were crosschecked on a profile-by profile basis. A total of 55 eledromagnetic and/or magnetic targets that fit 'accepted' magnetic criteria for kimbenite intrusions. Of these 55, none are ranked as high priority (rank = 1). However, 1 is ranked as good priority (rank = 2) and 3 are ranked as fair (rank = 3) targets. The remainder are felt to be less likely representative of kimbenite intrusions (on a ranking scale of 1 to 5; 1 being most likely and 5 least likely) although all 'fit' accepted criteria for a kimbenitic, magnetic intrusion with or without a conductive association. All of these anomalies or targets are tabulated in this report, and are further incorporated in the final GIS analysis.

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Table of Contents

Introduction

Location and Access

Survey Technology and Instrumentation

Geophysical Survey Methodology

Data Presentation

Data Description

Interpretation Methodology

Data Interpretation

Conclusions and Recommendations

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8

11

16

10. Certificate of Professional Qualifications 17

11. Appendix A. Aeromagnetic Anomaly Identification - Profile and Map Responses A-1

Table 1

Figure 1

Figure 2.

Figure 3.

Figure 4

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

List of Tables

Aeromagnetic Anomalies - Description and Rank

List of Figures

Project Location, Ontario

Magnetic noise 4th difference

Bird height (bheight)

Bird height <20 m or >40 m for distances of 1 km or greater

Diurnal activity >10 nT over a 2-minute linear chord

Total Magnetic Intensity image, Hebburn Block

Apparent Resistivity, coplanar high-frequency

Apparent Resistivity overiain by M2361 Geology

Idealized geophysical properties of kimberiite pipe

Summary Interpretation; greyscale shaded mag1vd and kimber1ite targets

List of Digital Maps

Map 1 Total Magnetic Intensity (pseudocolour and colourdrape image, 45° declination, 45° inclination), scale 1: 1 0,000

12

3

3

4

4

5

6

7

9

15

Map 2 Horizontal Gradient (colourdrape image, 45° declination, 45° indination), scale 1:10,000

Map 3 Analytic Signal (colourdrape image, 45° declination, 45° inclination), scale 1:10,000

1. Introduction

The Temagami area of Northeastern Ontario is considered prospective for diamond exploration. Tres-Or Resources Ltd.'s Temagami Diamond Claim properties are located 'Nest of the Timiskaming Structural Zone and straddle the Grenville Front, a deep-rooted structure that separates the thick Precambrian Superior Craton from the Grenville Province, a cratonized accreted mobile belt. These deep-seated fault structures may have tapped into the diamond bearing portions of the earth's mantle. The area exhibits many major north to northwest trending faults and lineaments (associated with the Timiskaming Structural Zone) that intersect major east to northeast trending structures. The intersection of these deep-rooted structures may have provided an excellent conduit or "plumbing system" for kimberlite emplacement.

I'

I "OR , ~

•• -t-Figure 1. Project Location, Ontario


2. Location and Access

Tres-Or's Hebburn block lies about mid-way between Temagami and Temiskaming. and is flanked by lake Temiskaming (Ottawa River) on its eastern side. The survey blocks straddles Burnaby and Hebert Townships, and lies within the Sudbury Mining Division. The village of Marten River on the Trans-Canada Highway (Hwy No. 11) lies -40 km to the southwest of the survey block, while Temagami lies some 32 km to the west-northwest. The centre of the survey block is centred roughly at latitude 46°57'N and longitude 79°22W. The property is accessible along several dirt roads from Highway 11, some of which are suitable for snowmobile travel all winter. From these major dirt roads, many small roads and logging trails provide further access. Canoe routes and snowmobile trails provide additional access. Access to some of the larger lakes can be arranged using f10atplane charters from Temagami.

The Temagami - Marten River area of eastern Ontario is characterized by rugged hills separated by lakes and swampy lowlands, with elevation ranging from 350 to 450 m. The area is forested partly with hardwoods, and partly with conifers. Summer field conditions extend from June through September. Winters are cold, but suitable for exploration operations such as drilling and geophysics. Break-up in the spring and freeze-up in the fall limit access to the area.

The climate features intermittently cold winters (-40°C to +10°C) and mild summers, although temperatures can reach +30°C for short periods. Snow commonly reaches 1 to 1.5 m depth in winter. and summer rains average 3 to 5 em per month.

3. Survey Technology and Instrumentation

The airborne survey was flown November 3-12,2003 and was completed with eighteen survey flights by Aeroquest Ltd. using their exclusive "IMPULSE

n six channel frequency time domain helicopter electromagnetic system and high sensitivity cesium vapour magnetometer. Ancillary equipment included a GPS navigation system with GPS base station, radar altimeter, video recorder, and a base station ma~netometer. Complete details of this survey are described in a report by the airborne contractor, previously submitted to Tres-Or Resources Ltd.

A Bell Textron 206L LongRanger helicopter (registration C-GRYS) owned and operated by Gateway Helicopters Ltd., North Bay Airport, OntariO was used as the survey platform. Installation of the geophysical and ancillary equipment was carried out by AeroQuest Ltd. at the Gateway hanger in North Bay; this was also the base of operations. The survey aircraft was flown at a nominal terrain clearance of 200-250 ft (61-76 m).

4. Geophysical Survey Methodology

The survey was flown at 50 metre line spacing in a north-south direction. Total line kilometres flown were 1,812.841 line-kilometres including tie-lines. Data acquisition took place November 3-122003 and was completed with eighteen survey flights.

Navigation was assisted by a GPS receiver and the AG-NAV2 flight path guidance system that reports GPS coordinates as WGS-84latitudellongitude and directs the pilot over a preprogrammed survey grid. The x-y-z position of the aircraft, as reported by the GPS, is recorded at one second intervals. The co-ordinate system employed in the survey design and subsequent data processing/mapping is NAD83, UTM Projection Zone 17.

Fiset, N .. 2003, "Report on a helicopter-borne magnetic and electromagnetic survey: Hepburn and Eldridge Blocks, Temagami Tres-Or Diamond project: Aeroquest Ltd., November 302003.

Intrepid Geophysics Ltd. 2

5. Data Presentation

The airborne geophysical interpretation is based on a profile analysis using Geosoft's Oasis Montaj integrated editors (spreadsheet and flight path). A screen capture of each target is presented at an appropriate, detailed scale for analysis and archival purposes (Appendix A) . All the final data is also presented as a series of digital maps and images generated at scale of 1 :10,000.

The airborne geophysical gridded data was analyzed using the following derived images:

• Total Magnetic Intensity; pseudocolour and colourdrape images

• Vertical derivative (gradient) ; pseudocolour and greyscale shaded-relief images

• Horizontal derivative (gradient); greyscale, shaded-relief and colourdrape images

• Total gradient (analytic signal); greyscale, shaded-relief and colourdrape images

In addition , the final interpretation consisting of kimberlite target identification was prepared in Map/nfo *.tab format and further archived in Section 8 of this report in Word ".doc format.

6. Data Description

Radar altimetry, for the most part, was at the limit or outside contract specifications (30 m); the mean bird height was determined to be 44.64 metres. A histogram of the bird height (birdm) indicates the distribution. An image on the following page (Figure 4) depicts flight lines flown outside specification (30 ± 10 metres) for distances of 1 km or greater.

I . S

1. 0

0. 5

J 7S Ise

~ .. {l'!lJll _ ( ... lC~

~ _."'~7 ~ .!~ ......a:." . ~CIr - ?'Vf'

:: :i~_~ J ~_43"""'J s.wa .. ,.", -.",. !:..r.TJI'I,'II~

125

~.·t.Atfl •• ' ......... :.. i"H:"JI _ ... ~ . ...a«.wl~

-c.OI:<:C'" ~~ "':.010: . :1 ... _n u.. • .;u,~7 ~_:r.a»'9_ JIG ,.".. .. ~!.r.~ ~ -~

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Figure 2. Bird height (birdm) Figure 3. Magnetic noise 4 th difference

The located data provided to the Client from the Contractor is judged to be of good standard, and permitting final processing (Fourier analysis and imaging) of a sirpilar and acceptable standard. The survey's signal-to-noise ratio as determined by 4th difference on the magnetic data indicates a relatively quiet noise background (i.e. , mean of 0.0000 and a standard deviation of 0.010 nT.


Figure 4. Bird height <20 m or >40 m for distances of 1 km or greater

_ ... , .. ...-, , ,-.... ' ... :?!:

~. , .fl · ....

The diurnal activity during flight operations was very quiet and within contract specification (10 nT in a 2-minute linear chord). The followin9 image displays the flight track with no diurnal flagged:

Figure 5. Diurnal activity >2 nT over a 1-minute linear chord


-, ... . -• y

' ,,,. , .. ,-, .....

.......

D l ·_ OWI

4

Figure 6. Total Magnetic Intensity image, Hebburn Block

The Nyquist frequency (fN) for the gridded total field data was determined to be 0.02 cycles/metre with a Fundamental frequency of 0.000082 cydeslmetre; this translates to 50 m and 12.125 km respectively . The Nyquist frequency represents the highest frequency we can determine or resolve in Fourier transform applications (e.g., horizontal gradient and analytic signal). The "Sampling Theorem" states that when a waveform is sampled at an interval t, only those frequencies less than or equal to 1/2t, called the Nyquist frequency, are accurately preserved. Higher frequencies are said to be aliased, i.e., they appear as lower frequencies.

Intrepid Geophysics Ltd . 5

The AEM data is relatively quiet and appears to be within specifications «1 ppm RMS) although this could not be rigorously determined from the data supplied.

Figure 7. Apparent Resistivity, coplanar high-frequency displayed with logarithmic ohm-m

Intrepid Geophysics Ltd . 6

Figure 8. Apparent Resistivity overlain by M2361 Geology

The apparent resistivity does show reasonable correlation with the known geology of the area; major faults and dyke systems all have a resistivity expression. The primary contribution to the resistivity image, however, is coming from the many lakes and streams within the survey area.


7. Interpretation Methodology

The identification of a kimberlite or lamproitic diatreme from geophysics will depend upon the recognition of a characteristic response or signature. Clearly, the! frequency and amplitude of that response will depend on the geophysical contrast between the target diatreme and the surrounding country rocks. Quite simply, if the physical properties are such that the kimberlitellamproite is essentially similar to the country rock, then there will be no gE~ophysical 'anomaly.' Fortunately, the nature of kimberlites and lamproites are such that there are often 'Signature' responses that permit a distinction to be made.

Several workers have reported on the physical parameters of kimberlites and lamproites in particular regions around the world. Gerryts2 provided an excellent overview in 1967, and Macnae3 has provided key facts for several southern African kimberlites. Mwenifumbo has more recently reported" on the geophysical characteristics of Canadian kimberlites in Ontario and Saskatchewan. Data was compiled from multi-parameter boreholie logging on one pipe in Saskatchewan and four pipes in the Kirkland Lake area to obtain in situ physical rock property data on kimberlites and their host rocks. Measurements included natural gamma-ray spectrometry, magnetic susceptibility, resistivity/conductivity, induced polarization. spectral gamma gamma (density and heavy element indicator). temperature, borehole 3-component magnetometer and seismic P-wave velocity. The geophysical data from the kimberlites investigated indicate that the physical properties are variable in a kimberlite pipe and also between different pipes in a single field. Although there is a high degree of variability of the physical properties within the kimberlite, most geophysical measurements show anomalous values that are characteristic of the kimberlites compared to the surrounding sediments.

Kimberlites can contain 5-10% iron oxides consisting predominantly of magnetite, ilmenite and a solid solution of these two constituents5

. Unweathered kimberlites and lamproites typically have a strong magnetic signature. Kimberlitellamproites typically have relatively high porosity and permeability, leading to rapid weathering when exposed to surface and meteoric waters. The uppermost zone may thus break down into a disk-shaped, lower density, highly conductive clay rich horizon depleted in magnetic mineralization. A more modest but still detectable conductivity anomaly in fresh. unweathered kimberlites may be due to serpentinization of olivine during initial diatreme emplacement.

Regardless, it must be stressed that the geophysical responses over kimberlite pipe!; are generally complex, indicating a basic inhomogeneity of the kimberlite and its physical properties. These geophysical responses vary significantly from one geographic area to another, resulting in different workers reaching very different conclusions as to the applicability and reliability of various geophysical techniques. Ideally, a diatreme target in plan view should show a circular to elliptical conductivity response coincident with a strong magnetic anomaly of slightly smaller diatreme (due to the convergent shape of the pipe and the depth of weathering). A similar,

2 Gerryts, E., Diamond prospecting by geophYSical methods-a review of current practice: in Mining and

Groundwater GeophYSics, Proceedings of the Canadian Centennial Conference on Minin9 and Groundwater Geophysics, October 1967, edited by L W. Morely, p.439-446.

3 Macnae, J. C., 1979, Kimberlites and exploration geophysics: GeophYSics, vol. 44, no. 8 (August), p. 1395-1416.

4 Mwenifumbo, C. J., Hunter, J. A M. and Killeen, P. G .• 1996, Geophysical characteristics of Canadian kimberlites: in Searching for Diamonds in Canada. edited by A N. LeCheminant. D. G. Richardson. R N. W. DiLabio and K A Richardson, Geological Survey of Canada, Open File 3228, p. 237-240.

5 Fesq H. W., Kable, E. J. D. and Gurney, J. J., 1975. Aspects of the geochemistry of kimberlites from the Premier mine, and other selected South Africa occurrences with par1icular reference to the, rare earth elements: Physics and Chemistry of the Earth. vol. 9, p.687-707.


matching pattern should be evident on profiles across the pipe. Of course, reality may be very different due to divergence in the geological model from actual geophysical parameters of the target kimber1itellamproite.

Geophysical responses are complicated by tectonism, depth of burial and subsequent erosion, nature of the Quaternary overburden or alluvium as well as the surrounding country rock, permafrost, and lithological/mineralogical variations within the diatreme itself. Figure 6 shows idealized geophysical properties of an altered diatremes. Depth of the weathering profile will influence the size of the conductive cap and depth to 'fresh' kimber1ite. Intensity and relative orientation of the magnetic anomaly are related to the proportion of iron oxides (I.e., magnetite and ilmenite), degree of alteration and remanent magnetization, etc.

Yellow Ground

Blue Ground

Hardebank (fresh)

....

, 'i ' " 1/

" t'

, " '"

..

..

Electrical ~ . .

T

, " , " I J , J

Magnetic " , , ' ' I j

, , , ... , , " If' 'r I , , , , f , I ( , , ,

+

~y/~ Density

T

Figure 9. Idealized geophysical properties of kimberlite pipe.

Hebbum Block

All airborne geophysical data was imported into Geosoft Oasis montaj database for line-by-line viewing and proceSSing. Spreadsheet, Profile and Grid editing tools inherent to the INTREPID

geophysical proceSSing system facilitated advanced processing and analysis as well as quality assurance I quality control of the basic data. Subsequent to the acquisition of airborne magnetic data, corrections were applied to produce located profile. contours and grid versions of the data. Filtering transformations (carried out in Fourier domain) conducted by Intrepid Geophysics yielded secondary products with enhanced information content; this permitted greater information to be extracted from the data. These enhancement techniques included:

• Upward and downward continuations - the effect of shallow anomalies may be suppressed when further detail on contributions from deeper sources is desired, or conversely. shallow. high-frequency anomalies may be 'sharpened' by bringing them 'closer' to surface.

S Urquhart. W. E. S., Exploration geophysics and the search for diamondiferous diatremes: in Diamonds: Exploration, Sampling and Evaluation, Proceedings of a short course presented by the Prospectors and Developers Assodation of Canada, March 27, 1993. p. 251-287.


• Vertical and horizontal derivatives - eliminate long-wavelength regional effects, and resolve adjacent features. Body outlines can also be more precisely identified by the horizontal derivative.

• Analytic signal- (or total gradient) provides a quantity that is independent of the direction of source magnetization and the direction of the Earth's field. Thus all bodies with the same geometry will have the same analytic signal, an obviously useful quality in any interpretation.

The processed geophysical grids were further subjected to standard image processing techniques using ER MAPPER; e.g., aeromagnetics and resistivity grids were 'fused' into a single image using variable bands and colour look-up tables to provide increased target quality and higher confidence through integration of all types of data. The final integration of data and information was made using MAPINFO GIS software, where the gleophysical images were overlain by layers or 'tables' of drainage, license permits, etc.

The primary objective of the geophysical interpretation was the identification and ranking of possible kimberlite targets based on their magnetic response. Target selections made on the basis of discrete anomalies identified from these enhanced grid images were crosschecked on a profile-by profile basis. Essentially, the interpretation was seeking or focusing on presumed geophysical signatures that should occur over intrusive kimberlite pipe-like bodies.

While the significance of basement structural control on kimberlites may be open to discussion, the analysis of lineaments is of fundamental importance to understanding geological structures and the stress regimes in which they are produced. Automatic analysis of lineaments has previously been done with information mapped from remotely sensed data, using either satellitebased imagery or aerial photographs. Potential field data may also be analysed in terms of their lineament content. Edge detection and automatic trend analysis using gradients in such data are methods for producing unbiased estimates of sharp lateral changes in physical properties of rocks. The assumption is made that the position of the maxima in the horizontal graclient of gravity or magnetic data represents the edges of the source bodies, although this should be used with caution. Such maxima can be detected and mapped as points, providing the interpreter with an unbiased estimate of their positions. The process of mapping maxima as points can be extended to many different levels of upward continuation, thus providing sets of points that can be displayed in three dimensions, using the height of upward continuation as the z-dimemsion. There have been recent developments and use of this method for interpretation of potential field data (e.g. Archibald et ai, 19997 and Hornby et ai, 1999B

). Archibald et al refer to this process as "multiscale edge analysis." Milligan9 more recently discusses the spatial and directional analysis of potential field gradients and in particular, new methods to help solve and display threedimensional crustal architecture using a proprietary system of Euler 'worms.'

In multiscale edge analysis the assumption is made that lower levels of upward continuation map near-surface sources while higher levels of continuation map deeper sources. This assumption is generally true but must be treated with caution, due to the non-uniqueness of potential field solutions. The INTREPID software's unique implementation of multiscale edge analysis indudes the use of Euler 'worms' which provide a view of structural geology obtained directly 'from

7 Archibald, N., Gow, P. and Boschetti, F. 1999. Multiscale edge analysis of potential field data: Exploration GeophYSiCS, 30, 3&44.

8 Hornby, P., Boschetti, F. and Horowitz, F.G., 1999, Analysis of potential field data in the wavelet domain: GeophySical Journal International, 137. 175-196.

9 Milligan. P. R., Lyons, P. and Direen, N. G., 2003. Spatial and directional analysis of potential field gradients-new methods to help solve and display three-dimensional crustal architecture: Australian Society of Exploration Geophysicists' 16th Geophysical Conference and Exhibition, February 2003, Adelaide, Extended Abstracts.

Intrepid Geophysics ltd. 10

potential field geophysical data. The method is based on Fourier techniques for continuation, reduction to pole and total horizontal derivatives coupled with automatic edge detection.

8. Data Interpretation

Much reliance in the interpretation process for kimberlite targets is based on an analysis of the horizontal gradient magnetic and analytic signal (total gradient) images. These have proved most beneficial in previous exploration programs and are the primary tools for identifying Idmberlite intrusives directly from gridded aeromagnetic data sets. All anomalies thus identifiecl were crosschecked for their individual profile response and then tabulated. The final edited list of targets identified from the Hebburn airborne geophysical data is tabulated in Table 1 below.

An analysis of the airborne geophysics over the Hebburn property has identified 55 electromagnetic and/or magnetic targets that fit 'accepted' magnetic criteria for kimberlite intrusions. Of these 55, none are ranked as high priority (rank = 1). However, 1 is ranked as good priority (rank = 2) and 3 are ranked as fair (rank = 3) targets. The remainder are felt to be less likely representative of kimberlite intrusions (on a ranking scale of 1 to 5; 1 being most likely and 5 least likely) although all 'fit' accepted criteria for a kimberlitic, magnetic intrusion. It should be pointed out that this geophysical-based interpretation relies on the magnetic susceptibility of the kimberlite being different from the surrounding rock, and/or the electrical conductivity/resistivity being similarly distinguishable. Kimberlite is generally strongly susceptible, having susceptibilities up to 6*10-2 SIlO, which is why the magnetic method is so successful. A diatreme is generally magnetic due to magnetite and ilmenite being present in the unweathered kimberlite; significant weathering can reduce the magnetic susceptibility. The susceptibility values of kimberlites can vary considerably. In some kimbenites, there are multiple phases of intrusions or pyroclastic eruptions and each phase can have a different magnetic susceptibility (Jenke and Cowan, 1994; Jansen and Doyle, 1998). Some phases can appear to be non-magnetic. A number of the kimberlites in the Lac de Gras area (Slave Province, NWT) for instance, show reversed magnetic anomalies, implying that there is strongly remanent magnetic material in the kimbenite.

All anomalies identified in this project comprise relative positives or magnetic highs, a very few were identified from their conductive response alone. None of the anomalies evidenced a negative magnetic character which may have reflected a reversed polarity or the presence or remanent magnetization. Regardless of polarity, particular focus should be paid to targets assigned a rank of 2 to 3; these are believed worthy of ground follow-up using additional geophysics and geological mapping and/or geochemical samplin9.

Experience by the author and the literature confirm that it is often the more fragmented diatreme and crater facies of kimberlites that have the lowest resistivities or highest conductivities. Water (especially when saline or frozen) can also make marked changes to the resistivity v,alues. Resistivities vary strongly with only minor changes in mineralogy such as clay, sulphides, oxide minerals and graphite. The lowest DC resistivities are always recorded in the shallower more weathered kimberlite, and can be as low as 5 ohm-m. A target model for kimberlites sought in this study was felt to be reasonable at 100-1000 ohm-m.

10 Litinskii, VA, 1963, "Measurement of magnetic susceptibility in prospecting for kimberlite pipes," The Mining Magazine, vol. 109, p. 137-146.

Intrepid GeophySiCS Ltd. 11

Table 1. Aeromagnetic Anomalies - Description and Rank

Line fid x y 10 rank comments l60 2329.7 618568.6 5204852.1 HE-1O 5 -250nT mag high originally picked from fixed-wing; weak e.m. due to stream?

~~~~~~~~6~19~2~6~8~.5~~5~19~8~6=4~3.=2~~B~U~-6=2~ __ 4~~_-~17~5~n~T~m~a~gi~so~la~t~ed~hi~glh~(plr~ev~io~u~s~ily~p~iic~k=ed~j)~o~~==ur~ri~ng~o~n~la~n~d~;n~o~d~ir~e~ct~A~E=M~ __________ -4 . ~~~~~6=1~93~2~0~~.7~~5=20~3~9~7~0~.5~~H~E~-09~ __ ~3 __ ~-~3~00~n~T~m~ag~hi~g!h,~IY~lin~lg~in~s~w~a~m~p;;p~lo~s~it~iv~e~A~E~M~c~o~rr~e=la~tio~n~ ______________________ ~

l201 5486.0

~ .. 4110.0

l270 3618.0 619620.2 5199800.0 BU-64 2 strong AEM response across 2-3 lines (double-peaked CX?); coincides with 1000nT mag high l280 3408.3 619671.1 5199228.0 BU-65 5 -580nT mag high offset from magnetically anomalous zone; negative in-phase suggested

~g 2978.9 619716.1 5199873.1 BU-66 3 strong AEM response across 2-3 lines; flanking 1000nT mag high (see anomaly BU-67) l320 1993.5 619864.6 5198819,4 BU-67 .. _. 4 isolated -200nT mag high lying across river (small lake?); weak CP response

+600nT mag high coinciding with small hill, previously picked from fixed-wing survey. Negative in-.~~~~~~~~~~~~=-~~~~+-~5_~a~s~e __________________________________________________________ ~

-370nT mag high offset from magnetically anomalous zone; negative in-phase. Previously picked 5 from fixed-wing survey

Ll?70 .... 348.8 620125.3 5201758.9 BU-08

l~390 . I

5132.0 620219.8 5200808.9 BU-05

+800nT mag high lying at end of mafic trend; previously picked form fixed-wing survey. Negative ~~~~~~~~~~~==~~~~~~ __ ~5 __ ~in-pha~s~e ________________________________________________________ ~

5 i. -250nT double-peaked mag high lying at S end of NNW trend; negative in-phase suggested

l450 3032.6 620519.3 5202883.9 BU-12 l470 2365.9 620617.8 5203844.5 HE-08

i-=-=~i---'-'=-:.::~~=:...::::::'-'-'-+~..:.=.:::.:.....:~~.=:....::.:,-+--.::.5- -110nT mag high on lake shore, lying across 2-3 lines; no sionificant AEM correlation

4 '1-,onT mag h;gh lying In lake; broad e.m. '"ooesls lake bottom 'eds, -650nT mag high, somewhat isolated (previously picked) albeit lying off NW-trend. No supporting

~~+-_5 e.m. __________________________________________________________ ~

I

-150nT mag high, previously picked from fixed-wing; no supporting e.m. Coincides with break in 5 tono

L500 i 1313.9 620752.1 5196741.0 . BU-68 L520 799.9 620866,4 5204006.3 HE-39

L590 14640.9 HE-

621223,4 5205741.5 02106

I I . L~1352IA I 621422.4 5206307.3 I HE-15

~O 2211.0 621605.8 5207179.2 HE-22 =~:"=':":=-+-==-==-jL-..::5L- -250nT mag hJgh originally picked from fixed-wing; no supportino e.m.

. I +100nT mag high on south flank of NW-trending dyke; no supporting e.m. Coincides with small

~~-4~~=4-=~~~~~~~~H=E-~1~~5--~hj~II------------------------------------------------__________ ~ HE-07 I 5 -750nT mag high; intense negative in-phase on AEM

l700 1532.2 621765.9 5206315.8

~ ... 394.9 621918.6 5203863.0 L740 2818.6 621965.8 5206489.5 -==:..::.::..;,.;;:.c:.:..c-+-H-,E:::c-_4,.:-0-+--=5,---+---=6:.;:5..=.0.:..cnT.:....:...rT1ag high offset from NW-trending dyke; no supporting e.m. L780 1719.1 622167.5 5203952.1 HE-41 3 moderate-strong e.m. response lying in swamp, lake edge; flanking -35nT mag high

L890 7250.5 622724.5 5201595.0

i

L890 7286.3 622724.5 5200492.2

L.~950 5238.8 623018.9 15199032.0

I -700nT mag high occurring on N-S linear (line bust?) at intersection with NNE linear; no II

BBuu

-_o0

731 '5 - significant AEM correlation .

-700nT mag high across 6-7 lines at lake edge, previously picked; weak CP response may be :~==c.:::..-~= associated with lake bottom seds.

.. I'" weak AEM response; correlates to break in magnetic gradient Occurs in swamp/NE-trending ~~~~~~~=-:.::~~~~~~=B~U~-6~9~ __ 4~ .. ~~in~a~gle~ ________________________________________________________ ~

Intrepid Geophysics lid. 12

.. -----, .... Line fid x y 10 rank comments ....

-170nT mag high across 3-4 lines, previously picked from fixed-wing sUivey; negative in-phase L960 4713,0 623068,3 5200717,2 BU-04 5 suggested L980 3901,9 623169,9 5198357,0 BU-70 5 isolated -1 OOnT mag high beside stream; no AEM correlation

-950nT mag high occurring on lake shore (previously picked from fixed-wing survey); negative in-L1030 2094,2 623419,1 5199114,7 BU-02 ... -~~ .. 5 phase suggested

L1150 1467,3 624018,5 5201988,2 BU-10 I 5 -500nT mag high, picked form previous fixed-wing survey, Coincides with hill, no AEM correlation L1200 4932.4 624270,8 5199422,1 BU-71 5 -250nT mag high, isolated, Negative in-phase suggested,

~tL:~,6 624316,3 5199850,0_ BU-72 ,

5 -130nT mag high, appears to lie on tfIN linear. No supporting AEM .....

-180nT mag high previously picked from fixed-wing; lies on edge of hill, no direct AEM correlation L1210 4573,5 624322.2 5203880,5 HE-01 ... ~.

5 (top of hill coincides with CX in-phase response)

-400nT mag high originally picked from fixed-wing survey; not supported by current heli-borne ~q-~:8 624321,9 5207016,8 HE-16 ~~ ....,<lIl1fmag

-880nT mag high, originally picked from fixed-wing survey, somewhat isolated, Negative in-phase L1220 4204,1 624367.4 5202430,6 BU-11 5 AEM

, -200nT mag high lying across 3 lines; negative in-phase suggested, Occurs very near small lake, L1320 442,3 624863,1 5199881.4 BU-73 4 swamp,

-380nT mag high; no e,m, Previously picked from fixed-wing,,, likely due to mafic units (?), not L1330 987,6 624912,5 5205815,2 HE-13 5 kimberlite signature L1350 2322,3 625021,7 5205397,5 HE-12 5 -250nT mag high originally picked from fixed-wing; negative in-phase CP indicated on AEM L1390 1081,0 625216.4 5205118.8 HE-11 5 -=-300nT mag high originally picked from fixed-wing; negative in-phase CP on AEM ,-

L1390 11236.4 625221,5 I 5200062.2 I -320nT mag high across 2-3 lines; very weak CX response, Occurs on NE end of small lake,

BU-74 5 swamp L1390 1317,0 625213,5 5197333,9 BU-75 5 isolated -180nT mag high across 3-4 lines (see also BU-76); no correlative AEM L1420 2186,0 625371.5 5197533,8 . BU-76 5 isolated -65nT mag high across 2-3 lines (see also BU-75); no correlative AEM L1510 5265,0 625803,8 5196963,3 BU-77 5 isolated -65nT mag high; no correlative AEM ~O 5516.4 625867,9 5201163,6 BU-78 5 -260nT mag high (double-peaked?), elongated N-S '" -300m, No significant AEM correlation

L1530 5701,5 625915,7 5198597,2 BU-79 5 isolated 40nT mag high, on land, No supporting AEM L1590 1267,9 626212.8 I 5197504,8 BU-80 5 -90nT mag high across 2-3 lines; negative in-phase indicated on CP

I L 1610 1670,9 626321.4 5199034.5 ell Q~ 5 isolated 170nT mag high on flank of smali hill. No supporting AEM 1..IU-V I

I L1610 1733,1 626331,1 i 5196664.1 BU-82 5 -60nT mag high, occurs on land and flanks NE-SW lineament. No significant AEM L1660 631.4 626566,8 5198171.4 BU-83 5 ... ~I mag high coinciding with small hill; negative in-phase suggested on CP L1670 835,7 626612,0 5199131.8 BU-84 5 isolated 170nT mag high on land, Negative AEM suggested L1730 1890.3 626923,5 5197570.2 BU-85 5 -130nT mag high across 4 lines (see BU-86);weak CP response. Occurs on NE-trending hill

?107,21 626969,2 -140nT mag high across 4 lines (see BU-85); negative in-phase on Cp, Occurs on NE-trending

L1740 5197671.9 BU-86 5 hill

Intrepid Geophysics Ltd, 13

x comments 627074.7 ative AEM. Occurs on land 627165.5 627320.5 627667.1 621944.9 624007.1 5199502.0


Figure 10. Summary Interpretation; greyscale shaded mag1vd and kimberlite targets.

Intrepid Geophysics LId. 15

9. Conclusions and Recommendations

The objective of this geophysical interpretation was the identification and priority ranking of kimber1ite targets derived from an airborne geophysical survey flown over the Hebburn Block in November 2003. Results of this interpretation effort are listed in Table 1 and further noted in Appendix A; anomalies are further identified and posted in a Map/nro GIS table, and are included in the digital archive attached to this report.

Follow-up testing of the geophysical anomalies ranked 2-3 is recommended by further geochemical indicator mineral sampling, where applicable, and ground geophysics such as electromagnetics, gravity and magnetics, as well as by, ultimately, by auger or drill testing where those results warrant. The always ambiguous geophysical character of the anomali€!s tabulated by this interpretation dictates that additional information, such as positive indicator results, be confirmed before drill testing on anyone target be undertaken. Regardless, in the event that any of the above-listed priority targets are indeed drilled as kimberlite, then all airborne targets should be further reviewed in light of that success.

Ground follow-up geophysics should consist of electromagnetic profiling (either frequency-domain such as the MaxMin II horizontal-loop system or time-domain such as the Geonics Protem 57 system) as well as confirmatory magnetics. Gravity readings might also be utilized in selected traverses across the 2-3 ranked targets.

The success of electromagnetic methods in detecting kimber1ite depends on a distinct contrast in conductivity of the kimberlite as compared with the surrounding material. Kimber1ites in the NWT have (although not in every instance of course) exhibit a moderately conductive (about 100 to 1000 ohm-m) response. Fortunately, this is significantly more conductive than the surrounding country rock in the NWT. which is typically greater than 10,000 ohm-m. Initial grouncl electromagnetics carried out to date in the general region of the Hebburn property indicates (personal communication) distinct EM anomalies over the known kimberlite pipes tested to date, and thus an electromagnetic method should reasonably be expected to aid in exploration.


10. Certificate of Professional Qualifications

I, Christopher J. Campbell, with business address of 4505 Cove Cliff Road, North Vancouver British Columbia V7G 1 H7, hereby certify that:

• I am a graduate (1972) of the University of British Columbia, with a Bachelor of Science degree in Geophysics.

• I am a graduate (1986) of the University of Denver, with a Miilsters of Business Administration.

• t am a registered member in good standing of the Association of Professional Engineers and Geoscientists of British Columbia.

• I am a registered member in good standing of the Association of Professional Engineers, Geologists and Geophysicists of Alberta.

• I have practiced my profession for approximately thirty years in Canada (British Columbia, Alberta, Manitoba, Ontario and Quebec, Yukon and Northwest Territories I NunElvut), United States of America, Australia, Lesotho and Botswana.

• I have no interest, direct or indirect, in the properties or securities of Tres-Or Resources Ltd., or in any of their related companies or joint venture partners anywhere in Canada.

Dated this day February 16, 2005 in North Vancouver, British Columbia.

Christopher J. Campbell, P. Geo.


Appendix A. Aeromagnetic Anomaly Identification - Prlofile and Map ReslPonses

Intrepid Geophysics Ltd. A-1

BU-64: ---,------... _- .

HE-OS:


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HE-41:

Intro~pid Geophysics Ltd . A-3

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intrepid Geophysics Ltd _ A·5

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BU-89:


BU-90:

HE-10:

-Intrepid Geophysics Ltd. A-7

BU-65:

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, ..


BU-05:

BU-1 2:


HE-08:

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HE-02~/OO~: ~~~~~~~~~;!~~~ .......................... ~~

HE-15:


HE-22:

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BU-03:

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BU-04:

BU-70:


BU-02:

BU-10:

Intrepid Geophysics Ltd . A-16

BU-71:

BU-72: .-'" ......... --_ . .-.. ' ._ .... "".


HE-01:

HE-16:

Intrepid Geophysics Ltd_ A-18

BU-11:

HE-13:


HE-12:

'HE-1 1:

Intrepid Geophysics ltd. A-20

BU-74:

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BU-76:

BU-77:


BU-78: "6 _ ..... "" p,.,.TI.·· •••• ....-_._ ••• ~ ..... ' ••

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Intre . pld Geophysics Ltd.

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Intrepid Geophysics Ltd .

7

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BU-86:

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Intrepid Geophysics ltd_ A-28

BU-91 :

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Documents

Airborne Geophysical Interpretation Hebburn Survey Block