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TRANSCRIPT
Ontario Geological SurveyOpen File Report 5967
Kimberlite, Base Metal andGold Exploration TargetsBased upon Heavy MineralData Derived from SurfaceMaterials, Kapuskasing,Northeastern Ontario
1998
ONTARIO GEOLOGICAL SURVEY
Open File Report 5967
Kimberlite, Base Metal and Gold Exploration TargetsBased upon Heavy Mineral Data Derived from Surface Materials,Kapuskasing, Northeastern Ontario
by
T.F. Morris, D.C. Crabtree and S.A. Averill
1998
Parts of this publication may be quoted if credit is given. It is recommended thatreference to this publication be made in the following form:
Morris, T.F., Crabtree, D.C. and Averill, S.A. 1998. Kimberlite, base metal and goldexploration targets based upon heavy mineral data derived from surface materials,Kapuskasing, Northeastern Ontario; Ontario Geological Survey, Open File Report5967, 41p.
e Queen’s Printer for Ontario, 1998
iii
e Queen’s Printer for Ontario, 1998.
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This report has not received a technical edit. Discrepanciesmay occur for which the OntarioMinistry ofNorthernDevel-opment andMines does not assume any liability. Source references are included in the report andusers are urged to verifycritical information. Recommendations and statements of opinions expressed are those of the author or authors and arenot to be construed as statements of government policy.
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Parts of this report may be quoted if credit is given. It is recommended that reference be made in the following form:
Morris, T.F., Crabtree, D.C. and Averill, S.A. 1998. Kimberlite, base metal and gold exploration targets basedupon heavy mineral data derived from surface materials, Kapuskasing, northeastern Ontario; OntarioGeological Survey, Open File Report 5967, 41p.
v
Contents
Abstract ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Project History and Purpose 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Study Location 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Physiography 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Regional Geology 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bedrock Geology 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Quarternary Geology 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Methods 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Material Sampling 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Pebble Lithology 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Heavy Mineral Recovery and Identification 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Kimberlite Indicator Minerals 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Garnet 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chromite 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Mg--Ilmenite 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cr--Diopside 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Metamorphosed Magmatic Sulfide Indicator Minerals 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cr--Diopside 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chromite 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Gahnite 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Statistics 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Results 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Pebbles 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Kimberlite Indicator Minerals 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cr--pyrope Garnet 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chromite 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Mg--Ilmenite 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cr--Diopside 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Recommendations for kimberlite exploration 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Metamorphosed Massive Sulfide Indicator Minerals 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Gahnite 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Recommendations for massive sulfide exploration 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gold Grains 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acknowledgements 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendixes MRD 34*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Metric Conversion Table 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIGURES1. Study area location 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Bedrock geology 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Pebble lithology of modern alluvium sample 577--Ma--97 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Pebble lithology of till sample 145--Tp--97 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. Percentage of metavolcanic clasts recovered from till over metavolcanic terrane 14. . . . . . . . . . . . . . . . . . .
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6. “G10” and “G9” Cr--pyrope garnets 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7. Regionald distribution of Cr--pyrope garnets 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Plot of chromite Cr2O3 vs. MgO (wt%) 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9. Plot of chromite Cr2O3 vs. TiO2 (wt%) 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10. Regional distribution of chromite grains 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11. Plot of Mg--Ilmenite Cr2O3 vs. MgO (wt%) 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12. Regional distribution of Mg--Ilmenite 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13. Regional distribution of Cr--diopside 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14. Regional distribution of total KIMs 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15. Regional distribution of gahnite 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16. Ternary plot of gahnite geochemistry 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17. Regional distribution of Group 1 vs. Group 2 gahnite 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18. Regional distribution of total MMSIMs 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19. Regional distribution of gold grains 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TABLES
1. Comparison of local vs. exotic pebbles in different sampling media 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Summary of statistics for KIMs 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Summary of reduced vs. oxidized environments for Mg--Ilmenite grains 22. . . . . . . . . . . . . . . . . . . . . . . . .
4. Recommended areas for kimberlite exploration 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5. Summary of statistics for MMSIMs 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6. Recommended areas for massive sulfide exploration 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7. Summary of statistics for gold grains 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8. Recommended areas for kimberlite exploration 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
*Miscellaneous Release—Data 34Heavy mineral indicator database derived from overburden, for kimberlite,massive magmatic sulfides and gold, Kapuskasing area, northeastern Ontario; by T.F. Morris.This release consists of data related to kimberlite indicator minerals, massive magmatic sulfide indicator minerals andgold grains recovered from modern alluvium, till, glaciofluvial and glaciolacustrine samples collected in an area southof Kapuskasing, northeastern Ontario. This data release consists of 10 sets of data stored as both tab delimited, ASCII(.txt) and Microsoft Excel (.xls) files. Data sets consist of: 1) definitions of abbreviations used in each of the data files(KAPINTRO); 2) sample site locations (KAPAPPA); 3) pebble data summary (KAPAPPB); 4) sample processing data(KAPPAPPC); 5)detailed gold grain summary (KAPAPPD); 6) summary of kimberlite indicator mineral (KIMs) counts(KAPAPPE); 7) summary of massive magmatic sulfide indicator mineral (MMSIMs) counts (KAPAPPF); 8) summaryofmicroprobe data for KIMs (KAPAPPG); 9) summary ofmicroprobe data for gahnite (KAPAPPH); and 10) heavymin-eral picking remarks (KAPAPPI). These files are on one 3.5 inch MS--DOS diskette in a self--extracting, compressedformat. Extracting instructions are included.
This diskette is available separately from the report.
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Abstract
This report provides data and preliminary interpretations on the types and distribution of kimberlite heavymineral indicators, metamorphosed magmatic sulfide indicator minerals and gold grains recovered frommodern alluvium, till, glaciofluvial and glaciolacustrine samples collected in an area south of Kapuskas-ing. This data can be used to focus exploration efforts for kimberlite, base metal and gold deposits. A totalof 201 modern alluvium, 97 till and 15 glaciofluvial and glaciolacustrine samples were collected fromacross the area.
From these samples, 4 “G10” Cr--pyrope garnets were recovered. The recovery of these grains is sig-nificant, as they are rare and commonly associated with diamond--bearing kimberlite. Six potential areasand 5 individual sites for kimberlite exploration were identified. One hundred and seventy five gahnitegrains were recovered. These grains are also rare and important indicators of massive sulfide deposits.Seven potential areas and 2 individual sites for base metal exploration were identified. Very few goldgrains were recovered, however, 2 areas for gold exploration were identified.
1
Introduction
PROJECT HISTORY AND PURPOSEAQuaternary geology mapping and modern alluvium sampling program conducted by the Ontario Geo-logical Survey (Morris 1990, 1991, 1992a, 1992b, 1994, 1995, 1996a, 1997; Morris et al. 1997; Morris etal. 1994) in theWawa area, northeastern Ontario, was successful in defining kimberlite indicatorminerals(KIMs) and their distribution. KIMs are a suite of heavy minerals (Cr--pyrope garnet, chromite, Mg--richilmenite, Cr--diopside and olivine) related to kimberlite; a rock often associatedwith diamonds. Thisworkestablished a link between the distribution of KIMs and regional faults associated with the KapuskasingStructural Zone (KSZ). The KSZ is a broad belt of rock thought suitable for hosting kimberlite (Bolandand Ellis 1989).
The KSZ and associated faults extend northeast from Wawa through the Kapuskasing area into theJamesBayLowland (Figure 1). Given the success of theWawaproject a need existed to determinewhetherother areas along the KSZ were suitable for kimberlite exploration.
During the course of aQuaternary geologymapping and overburden sampling program in the Separa-tion Lake area, northwestern Ontario (Morris 1996b), metamorphosed/magmatic sulfide indicatorminer-als (MMSIMsTM)* were recovered from till samples. These stable minerals are useful indicators of mas-sive sulfide deposits hosted by high grade metamorphic terrane. Themassive sulfides are difficult targetsto detect by conventional geochemistry because sulfide minerals dispersed into the near surface environ-ment are unstable and are quickly destroyed by weathering. Chalcopyrite is marginally more stable thanother sulfides but too few grains survive to be detected geochemically. High--grade metamorphism, how-ever, creates other Al, Mg, Mn and Cr silicate and oxide indicator mineral species, which are heavy,coarse--grained, visually distinctive and chemically stable. These heavy minerals include staurolite, silli-minite, anthophyllite, hypersthene, olivine, spessartine, red epidote, sapphirine and Cr or Zn oxide andsilicate minerals such as chromite, red rutile, ruby corundum, Cr--diopside and gahnite.
The primary objective of the current program is to enhance the regional information base on the typesand distribution ofKIMs found inmodern alluvium, till and coarse--grained glaciofluvial and glaciolacus-trine sediments. Heavy mineral assemblages were also examined for gold grains andMMSIMs; the latteras high grade metamorphic terrane occurs in the study area. This study provides a general assessment ofthe potential for kimberlite exploration along a portion of theKSZ, and a specific assessment of the poten-tial for kimberlite, basemetals and gold for theWomanFalls--WakusimiRiver area, south ofKapuskasing.
Secondary objectives include: 1) determining the geochemical properties of local till to aid in basemetal, gold and rare--element pegmatite exploration; and 2) surficial geologymapping to provide a frame-work in which to interpret heavy mineral or geochemical anomalies. This mapping and till geochemistryalso provide useful information for environmental and land--use planning exercises.
This report summarizes the types, concentrations and distribution ofKIMs,MMSIMs and gold grainsrecovered from the different surficial materials. Recommendations for kimberlite, base metal and goldexploration are proposed. The data is summarized in digital format (Morris 1998) and consists of the fol-lowing ASCII (.txt) and Microsoft Excel (.xls) files:
1) KAPINTRO: Definitions of abbreviations used in the appendices2) KAPAPPA: Sample site locations.3) KAPAPPB: Pebble data summary.4) KAPAPPC: Sample processing data.5) KAPAPPD: Detailed gold grain summary.6) KAPAPPE: Summary of kimberlite indicator counts.7) KAPAPPF: Summary of massive magmatic sulfide indicator mineral counts.
* Registered trademark of Overburden Drilling Management Limited, Nepean, Ontario
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3
8) KAPAPPG: Summary of microprobe data for KIMs.9) KAPAPPH: Summary of microprobe data for gahnite.10) KAPAPPI: Heavy mineral picking remarks.
STUDY LOCATIONTheWoman Falls--Wakusimi River area south of Kapuskasing (Figure 1) was chosen for this study as: 1)the area has several fault controlled structures associated with the KSZ; 2) access from Kapuskasing isrelatively easy; and 3) overburden cover is relatively less than that found nearKapuskasing and the area tothe northeast.
The Woman Falls--Wakusimi River area is covered by the National Topographic Series (NTS) andincludes the 1:50 000 scaleWomanFalls (42G/2) andWakusimi Rivermap sheets (NTS 42G/1). The areais bounded by longitudes 82o00’W and 83o00’W and latitudes 49o00’N and 49o15’N.
PHYSIOGRAPHYThe study area is located north of theGreat Lakes--HudsonBay drainagedivide. All surface drainage flowsnorth into James Bay. Flow from the 2 local major drainage basins is through the Kapuskasing andGroundhog rivers.
The study area is part of the Abitibi Uplands subregion of the James physiographic region (Bostock1976). This region, and much of the study area, is underlain by crystalline Archean rocks and exhibits abroad rolling surface that rises gently from the Hudson Bay Lowland.
Much of the study area’s topography is subtle with total relief of only 85 m. Bedrock outcrops in thewestern and eastern parts of the study area and along parts of the Kapuskasing,Wakusimi andGroundhogrivers.
4
Regional Geology
BEDROCK GEOLOGYThe area includes 5 bedrock domains (Berger 1986,OntarioGeological Survey 1991; Figure2). Theseare:1) ametasedimentary suite consisting ofwacke, arkose, argillite, slate, marble, chert, iron formation and aminor component of metavolcanic rocks; 2) a gneissic tonalite suite consisting of tonolite to granodioritewithminor supracrustal inclusions; 3) a granodiorite to granitic suite consisting ofmassive to foliated gra-nodiorite to granite; 4) the Casselman greenstone belt consisting of mafic to intermediate metavolcanicrocks; and 5) a migmatized suite consisting of supracrustal, metavolcanic and minor metasedimentaryrocks, and mafic and granitic gneisses.
TheKSZ strikes southwest across the study area. A series of northeast--trending faults associatedwiththe KSZ controls the orientation of several rivers in the area including the Kapuskasing River. The Rufusfault (Berger 1986) cuts through the northwestern part of themap sheet and stands--out clearly on airbornemagnetic surveys (Geological Survey of Canada 1963). The orientations of several other streams andlakes, perpendicular to theKSZ structural trend, are also likely controlled by faults. TheKSZ is significantas it consists of fractured, deep crustal material that may host kimberlite rock (Boland and Ellis 1989, R.P.Sage, Ontario Geological Survey, personal communication 1998).
QUATERNARY GEOLOGYPrior to this study, surficial geologymappingwas completed at a regional scale (1:506 880) byBoissoneau(1968). The majority of surficial materials were deposited during the Wisconsinan glaciation. Ice flowdirection is defined by scattered striae and drumlinoid features. In the study area 3 sets of glacial striaewere noted. Theyoungest, orientated 120o, occurs primarily on outcrops in thewest and southwest parts ofthe region. Older striae orientated 160--180owere observed at only 2 sites; northwest of the study area andin the extreme southwest--central part of the study area. The 120o ice flow eradicated such striae on out-crops in the northeast except on an unexposed lee--side face, whichwas protected from glacial abrasion. Athird set of striae orientated 220o was observed on many outcrops in the east and southeast. This set ofstriae is also truncated and eroded by striae orientated 120o on one outcrop. The relative age relationshipbetween the 160--180o and 220o events is not clear.
Two sets of drumlinoid features were observed. The first set is restricted to the northeast part of theregion and aligned at 220o. The second set is restricted to the northwest andwest portions of the study areaand is aligned at 120o. These features are cored primarily with till although several are cored by stream-lined bedrock and at least one is cored by sand and gravel.
Three different types of till were identified within the study area. A till consisting of a pebbly, sandymatrix, exhibiting thinwavy bedswas observed in one section. This section is interpreted as consisting ofaseries of subglacial flows. This till has similar properties to that of theMathesonTill described by others tothe east (McClenaghan 1992, Paulen and McClenaghan 1997). Regional ice flow associated with the de-position of theMatheson Till was originally southwest with a subsequent shift in flow to the south--south-east. The striae record and drumlinoid features in the study areamay have been formed during the ice flowevents that deposited the Matheson Till. The stony, sandy material associated with the Matheson Tillwould be capable of forming the striae.
The second till type, a deformation till, was observed in 2 sections and was noted to directly overliefine--grained glaciolacustrinematerials. This flowmaybe related to theCochrane ice advance. Till associ-ated with this advance is commonly fine--grained due to the incorporation of glaciolacustrine material de-posited within a glacial lake that existed following the retreat of the ice that deposited the Matheson Till.The direction of ice flow that deposited this till was south. The fine--grained nature of this material is notlikely capable of striating bedrock surfaces. Therefore the striae and the drumlinoids were not likely de-posited by this ice flow event.
A third till type, a flow till, was observed in several sections (4 to 6m thick) and encountered through-out the study area in test pits and soil probes. This till, the likely stratigraphic equivalent of the Cochrane
5
6
Till, makes--up much of the till plain covering the central part of the study area and was likely depositedinto Glacial LakeBarlow--Ojibway. These tills may have covered the drumlinoid features associatedwiththe Matheson advance.
Landforms associated with deglaciation include; a till plain, recessional moraines and eskers. The tillplain is composed of primarily the flow till. Recessional moraines are subtle features, rarely extendinghigher than 4 to 5 m above the till plain. They are sinuous, up to 1 km long, trend westerly and consistmainly of till. The majority are concentrated in the north--central part of the study area.
Two major eskers occur within the study area along with a number of smaller ones less than 1 km inlength. TheRemiLake esker extends south fromRemi Lake into the north--central part of the study area. Asecond prominent esker trends east across theKapuskasing River aboveWoman Falls then southeast, par-alleling the surrounding drumlinoid ridges.
Theoldest observed glaciolacustrinematerial consists of sand and gravel underlying fine--grainedgla-ciolacustrine silts and clays. This sequence was observed at one site, a gravel pit, located west of theGroundhogRiver. The fine--grained glaciolacustrine silts and clays were observed in section at 2 sites andoccasionally along the banks of the Groundhog and Kapuskasing rivers. Within the 2 sections, this fine--grained unit exhibited alternating beds of silt and clay--rich materials. Arguably, they may be varves, butthis was difficult to ascertain as many beds were badly disturbed by loading.
Anupper fine--grained glaciolacustrine unit, observed in theKapuskasing River section and occasion-ally in soil probes and pits in thewestern half of the study area, overlies flow tills. Thismaterial consists ofvarved silts and clays and is, on average, 2 m thick.
Several small pockets of sand and gravel are scattered throughout the central part of the study area.These deposits may represent proglacial subaquatic fans that were deposited in associationwith the reces-sional moraines. The deposits are covered by flow tills.
7
Methods
MATERIAL SAMPLINGIn this study, modern alluvium, till and coarse--grained glaciofluvial and glaciolacustrine materials weresampled. Sample numbers, sample types and locations (byU.T.M.) are summarized inMorris (1998, Ap-pendixA). Thebenefits and limitations of using each of thesematerials are discussed inMorris (1995) andMorris and Kaszycki (1997).
Modern alluvium was chosen as the primary sampling media as it is used commonly as a means ofgaining a fast, relatively inexpensive heavy mineral signature for individual drainage basins. The heavymineral signature derived frommodern alluvium is a product of erosion of both bedrock and overburden,and the subsequent transportation and depositional history of the eroded material. Of particular impor-tance, however, is the recognition that lakes within drainage basins act as sediment traps, restricting thedown drainage transport of heavy minerals. Therefore, when modern alluvium sample sites were chosenfor this study, an attempt wasmade tomaximize the length of stream section between the sample site and alake. This maximizes the area of drainage basin sampled by the stream.
The only till in the region consistently accessible for sampling was flow till. This till is composed ofdebris derived from different areas within the ice sheet and its matrix consists primarily of material trans-ported into the study area from elsewhere. This is an important fact to consider when assessing heavymin-eral signatures derived from the till as well as modern alluvium signatures as many drainage basins withinthe study area consist of flow till. The sameconsiderationsmust bemade for the glaciofluvial and glaciola-custrine materials.
Modern alluvium was collected from bars or sediment traps within streams where heavy minerals areconcentrated.Material was sifted through a 7mmmesh, steel sieve to exclude the coarse fraction. Amini-mum of 15 kg of less than the 7mm sizedmaterial was collected at each site. A sample of the greater than 1cm sized fractionwas collected for determination of pebble lithology (Morris 1998,Appendix B).Modernalluvium was also panned at each site and the concentrate was stored for future reference.
For till sampling, a hypothetical 5 km2 gridwas placed over themap area and asmany of the grid areasas possiblewere sampled. At each site, approximately 200 g of humus and till “B” and “C” horizonmateri-al, a 15 kg till “C” horizon bulk sample and apebble samplewere collected. Due to the fine--grained natureof the flow till, field sieving was not necessary. The 200 g samples of humus and till “B” and “C” horizonmaterial were submitted for instrumental neutron activation analysis (INNA) and inductively coupledplasma (ICP) geochemical analysis. This data will be released at a later date. The 15 kg till “C” horizonbulk sample was submitted for heavy mineral concentration and subsequent analysis. Determination ofpebble lithology was made on the pebble sample (Morris 1998, Appendix B).
Glaciofluvial and glaciolacustrine materials were sampled from all accessible sand and gravel pits.Materialwas sifted through a7mmmesh, steel sieve to exclude the coarse fraction. Aminimumof10 kgofless than 7 mm sized material was collected at each site. A sample of the greater than 7 mm sized fractionwas collected for determination of pebble lithology determination (Morris 1998, Appendix B).
Sample site observations of the types summarized in Morris and Kaszyki (1997) and Morris et al.(1997)were recorded. In total, 201modern alluvium, 97 till and 15 glaciofluvial and glaciolacustrine sam-ples were collected.
PEBBLE LITHOLOGYPebble lithology was determined by comparing the physical properties of pebbles to representative sam-ples of local bedrock. Pebbles lithologies identified include: a) granite; b) gneiss; c) metasedimentary; d)mafic metavolcanic; e) ultramafic phaneritic; f) carbonate; g) quartz; h) sandstone; and i) ironstone.
HEAVY MINERAL RECOVERY AND IDENTIFICATIONHeavy minerals (greater than 3.2 specific gravity) were isolated from the modern alluvium, till, glaciola-custrine and glaciofluvial samples prior to further processing byOverburdenDrillingManagement Limit-
8
ed in Nepean, Ontario. The procedure is summarized in Morris et al (1994) and Morris and Kaszycki(1997). Sample processing data, includingweight of table feed andweight of bothnon--magnetic andmag-netic fractions, are summarized in Morris (1998, Appendix C).
The lab procedure that is used is designed to recover a range of heavy minerals including gold grains.A detailed gold grain summary is provided in Morris (1998, Appendix D). The physical appearance ofeach gold grain is evaluated and classified as being pristine,modified or reshaped. Due to gold’smalleabil-ity, grain shape is transformed during transport by glacial ice (DiLabio 1990). Therefore, a reshaped grainhas been transported farther from source than has a pristine one.
The lab procedure used also recovered 6 types ofKIMs: 1) Cr--pyrope garnet; 2) Cr--poormegacrysticpyrope garnet; 3) eclogitic pyrope--almandine garnet; 4) Cr--diopside; 5) Mg--rich ilmenite; and 6) chro-mite. Forsteritic olivine, a mineral commonly associatedwith kimberlite, was also picked when observedin the heavy mineral concentrate (Morris 1998, Appendix E).
This lab procedure also recovers 13 main types of MMSIMs: 1) anthophyllite; 2) chalcopyrite; 3)chromite; 4)Cr--diopside; 5) gahnite; 6) hypersthene; 7) olivine; 8) ruby corundum; 9) red epidote; 10) redrutile; 11) sapphirine; 12) spessartine; and 13) staurolite (Morris 1998, Appendix F). OtherMMSIM spe-cies are also reported where present.
Precise geochemistry is required to properly identify KIMs. Suspected KIM grains were mounted onepoxy plugs and sent to the Ontario Geosciences Centre (OGC) for microprobe analysis (Morris 1998,Appendix G). Gahnite (an MMSIM) geochemistry was also determined by microprobe analysis (Morris1998,AppendixH). Gahnite geochemistrymay be useful in identifying not only polymetallic deposits butalso rare--element pegmatite (Morris 1996b). The calibration routine and operating conditions for the mi-croprobe are summarized in Morris et al. (1997).
The parameters used to define KIMs are presented in Morris et al. (1994) and Morris et al. (1997).Parameters used to define rare--element pegmatite gahnite and polymetallic gahnite are defined inMorris(1996b), however, they are presented here again due to their importance.
Kimberlite Indicator Minerals
GARNET
Garnet grains analyzed in this study includeCr--pyrope, pyrope, almandine, andradite and grossular. Gar-nets of peridotite origin are typically Cr--rich pyropes. This mineral may originate from many differenttypes of peridotite, themost important of which are harzburgite and lherzolite. Eighty--five percent of Cr--pyropes that occur as inclusions in diamonds are Ca--depleted, Cr--enriched and harzburgitic in origin(Gurney 1984). These types of garnet have been termed “G10” (Dawson and Stephens 1975) and are con-sidered to be important KIMs. The recovery of “G10” garnets from surficial material is important since itsuggests that theseminerals originated from harzburgitic peridotite, and aremore strongly associatedwithdiamond than are garnets of lherzolitic (“G9”) origin (Dawson and Stephens 1975).
Other pyrope garnets associated with kimberlites are the megacrystic suite, which are not directly as-sociatedwith diamond. These, when foundwith other KIMs, can also be useful indicators. Thesemineralsmay range from Cr--poor to moderate levels (2 to 3%) of Cr2O3.
The geochemistry of mantle derived eclogitic garnet is complex and overlap may exist between gar-nets of peridotitic and deep crustal origin (Dawson and Stephens 1975). However, eclogitic garnets aretypically Cr--poor and range from pyrope to almandine--pyrope in composition. Eclogitic garnet inclu-sions in diamond have been found to have elevated Na concentrations (Na2O greater than 0.09%) and,therefore, like the “G10” garnet, are considered a valuable KIM. Low--Na eclogitic garnets may also beuseful indicators if found in conjunction with other KIMs. Almandine, spessartine--almandine, grossularand andradite garnets, such as those recovered in this study, are not likely associated with kimberlite andare, therefore, of little interest to kimberlite exploration.
CHROMITE
Chromites found in diamond inclusions differ from most other chromites by their high Cr2O3 content,generally greater than 61weight percent (Gurney 1984). In addition, they also have aMgO content greater
9
than 10weight percent (Fipke et al. 1995). Finding such a chromite in surficial material or a rock sample isjust as significant as finding a “G10” Cr--pyrope garnet.
Chromite Cr2O3--TiO2 plots are useful in differentiating chromite unique to lamproites and kimber-lites from those that are non--lamproitic or kimberlitic in origin (Fipke et al. 1995). Those chromites thatplotted in the non--lamproite/kimberlite field were excluded from the KIM data base, while those thatplotted in the overlap field were included.
MG--ILMENITE
Ilmenite found within kimberlite is generally Mg--rich, with MgO values that range between 4 and 15weight percent (McCallum and Vos 1993). In this study, such ilmenites recovered from overburden areregarded as useful KIM indicators.
CR--DIOPSIDE
Alone, Cr--diopside is not a definitive kimberlite indicator as it occurs in both kimberlite and other basicand ultrabasic rocks. Cr--diopside associated with lherzolitic rock commonly has high chrome values(greater than 1 weight percent). For this reason, Cr--diopsides with Cr2O3 values greater than 1 weightpercent were chosen as KIMs for this study.
Metamorphosed Magmatic Sulfide Indicator Minerals
CR--DIOPSIDE
Those Cr--diopsides with Cr2O3 values less than 1 weight percent were chosen as MMSIMs. Such Cr--diopsides are associated with nickel deposits in Finland (Stu Averill, Overburden Drilling ManagementLtd, personal communication 1998) andwith the Thompson nickel belt inManitoba (Matile andThorlief-son 1997).
CHROMITE
Those chromites that plot in the non--lamproitic/kimberlitic field and overlap field of Fipke (1995)Cr2O3--TiO2 diagram were included in the MMSIM data base.
GAHNITE
This mineral is useful in searching for polymetallic deposits in high grade metamorphic terrane due to itshardness (8) and stability in metamorphic rocks (Parr 1992). Although rare, it is reported in a number ofpolymetallic deposits (Chew 1977, Plimer 1977, Spry 1982, 1987a, 1987b, Williams 1983, Sheridan andRaymond1984, andSpry andScott 1986). Gahnitewas also successfully evaluated as an indicatormineralin glacial dispersal plumes from the Montauban polymetallic deposit in Quebec (Lalonde et al. 1994).
Gahnite, however, is not unique to polymetallic depositswithin high grademetamorphic terranes. It isalso found in pegmatite (Cerny et al. 1981, Cerny and Hawthorne 1982).
Little work has been done using mineral geochemistry to differentiate gahnite found within differentsource rocks (Batchelor and Kinnaird 1984). Although still preliminary, data from gahnite geochemistryfrom known source rocks, as derived from the literature and analytical work carried out in conjunctionwith the Separation Lake andKinniwabi Lake projects (Morris 1996b,Morris 1997), indicate that gahnitefrompolymetallic deposits hasMgOvalues greater than 2weight percent. Gahnite from rare--element peg-matite has MgO values less than 2 weight percent. Gahnite recovered from samples in this study weresimilarly classified.
STATISTICSTo identify areas or sites favorable for kimberlite, basemetal or gold exploration, it is important to identifythe location of important KIMs (“G10”Cr--pyrope garnets, “inclusion--field” chromites), MMSIMs (gah-nites, lowCr--diopsides) and gold grains (pristine) and their relative abundance. The proportional dot dia-grams presented in this section illustrate the relative abundanceof heavy indicatorminerals throughout the
10
study area. These diagrams are based on statistics that involve calculating percentiles. The largest dotsrepresent sites with heavy mineral concentrations with values greater than the 95th percentile. Sites withthese values are considered anomalous and are significant.
Databases for theKIMs andMMSIMshavebeen normalized in 2 differentways. First, someestimatesrather than precise counts of the number of heavymineral indicators in a concentrate, were presented in thepicking notes (Morris 1998, Appendix I). For example, the heavy mineral concentrate of sample620--TM--97 contained an estimated 10 600+ low Cr--diopsides. However, only 45 representative grainswere picked due to the impracticality of picking and analyzing all grains. The geochemistry of the 45picked grains was then used to determine the number of low Cr--diopside grains from the high within theestimated population of 10 600+ Cr--diopsides. Secondly, the data for KIMs, MMSIMs and gold grainswere normalized by table feedweight against 15 kg, the estimated averageweight of all collected samples.
11
Results
PEBBLESDetermining pebble lithology was difficult due to the complex composition of some rock domains. Forexample, themetasedimentary terrane consists ofmany rock types, someofwhich are notmetasediments.Therefore, the composition of a pebble sample collected over, or down ice from such a terrane may reflectmany different bedrock types, as opposed to just “metasedimentary” pebbles. Similarly, a pebble samplecollected over a gneissic terrane may consist primarily of metavolcanics derived from a local inlier in thegneisses rather than from a more distal metavolcanic belt (Figure 3).
Alternatively, there are certain pebbles that are not derived from local sources and their presencewith-in a samplemay beused as an indicator of the degree of distalmaterialwithin that sample. For example, thepresence of a large percentage of carbonate or sandstone clasts may indicate that much of that samplewasderived from distal, not local, sources (Figure 4).
In general terms, pebble lithology data derived from flow till samples indicates a greater proportion ofpebbles derived from distal sources than for modern alluvium, glaciofluvial and glaciolacustrine samples(Table 1). Nonetheless, given the significant percentage of distally derived pebbles within each sampletype, it is important to consider the pebble lithology of each sample individually. This will help evaluatethe proximity of a heavymineral signature to its source. This point is emphasized if the distribution and therelative concentration of the till’s mafic metavolcanic clasts are considered. There is a poor relationshipbetween the distribution of the sample sites with high maficmetavolcanic clasts and the local maficmeta-volcanic terrane (Figure 5).
KIMBERLITE INDICATOR MINERALS
Cr--Pyrope GarnetOne hundred and twenty five garnets were submitted to the OGC for microprobe geochemical analysis.Four “G10” Cr--pyrope garnets and 64 “G9” Cr--pyrope garnets were identified (Figure 6). Other garnetsidentified include almandine, pyrope, andradite and grossular (Morris 1998, AppendixG). Summary sta-tistics for the normalized Cr--pyrope data is summarized in Table 2.
There are 3 areas where concentrations of these “G10” and “G9” Cr--pyrope occur (Figure 7). Theseareas are: 1) The Kapuskasing River valley (552--Ma--97, 554--Ma--97, 607--Ma--97, 608--Ma--97,569--Gf--97); 2) theOscarLake area (660--Ma--97, 570--Ma--97); 3) the south--central part of the study area(683--Tm--97, 695--Ma--97); and 4) the lower Swanson Road (008--Ma--97, 084--Gf--97; 541--Gf--97).
ChromiteOne hundred and forty four chromite grains were submitted to the OGC for microprobe anlaysis (Morris1998, Appendix G). None of these grains plot in the inclusion field of Fipke et al. (1995) (Figure 8) andonly one chromite grain (623--Ma--97) plots in the field unique to kimberlite and lamproite on their TiO2vs. Cr2O3 (wt %) chromite plot (Figure 9). Twenty--eight grains plot in the non--lamproitic/kimberliticfield and thesewere excluded from theKIMdata set. The remaining 115 grains plot in the overlap field andwere included in the KIM data set.
There are 3 areas where anomalous concentrations of chromite occur (Figure 10). These areas are: 1)the south--central part of the study area (007--Ma--97, 507--Ma--97); 2) part of the Wakusimi River valley114--Ma--97, 003--Ma--97, 124--Ma--97); and 3) the southeast part of the study area 025--Ma--97,020--Ma--97, 014--Ma--97).
Mg--IlmeniteFifty--five ilmenites were submitted to the OGC for microprobe analysis. Of these, 33 are Mg--ilmenites(Morris 1998,AppendixG). Of these, 16 fall in the reducing part ofGurney andMoore’s (1991)Mg--ilme-
12
13
nite parabolic plot suggesting favorable conditions for diamond preservation within the magma. Ninegrains fall outside of the plot and only 8 fall in the oxidizing component of the plot, an environment wherediamonds are reabsorbed into themagma (Figure 11, Table 3). A reducing trend from the core to rim is alsofavorable for diamond preservation. Of the 33 grains, 21 have a reducing trend from core to rim, 6 have anoxidizing trend and 6 have no trend.
There are 2 areas where anomalous concentrations ofMg--ilmenite occur (Figure 12). These areas in-clude: 1) the Kapuskasing River valley (542--Ma--97, 598--Ma--97, 553--Tm--97); and 2) the east side ofSaganash Lake (693--Tm--97, 694--Ma--97).
Cr--DiopsideTwo thousand onehundred and fifty--two chromediopsideswere submitted to OGC formicroprobe analy-sis (Morris 1998, AppendixG). Of these, 577 are chrome diopsides with greater than 1wt%Cr2O3. Thereare 4 areas where anomalous concentrations of these chrome diopside occur (Figure 13). These areas in-clude: 1) the upper part of Graveyard Creek (590--Ma--97, 592--Ma--97); 2) the Oscar Lake area(660--Ma--97, 618--Ma--97, 617--Ma--97, 621--Ma--97, 620--Ma--97); 3) the Kapuskasing River valley(546--Ma--97, 598--Ma--97, 552--Ma--97); and 4) the south central part of the study area (541--Gf--97,511--Tm--97).
Recommendations for Kimberlite ExplorationIn examining the distribution and geochemical properties of individual KIMs, several sites and relatedareas were identified as favorable for kimberlite exploration. However, by considering the total number ofKIMs for each site fewer exploration targets of higher quality could be recommended (Figure 14). Thismay bemore desirable in that the recommended exploration areaswould bebased on sample sites contain-ing significant KIMs (e.g., a “G10”) or a variety ofKIMs (e.g., “G10”, Mg--ilmenite and chromite) (Table4).
Estimating proximity ofKIMsignature to source is difficult given the glacial history of the area. How-ever, the pebble data may be useful. A sample site with a predominantly local mix of pebbles (granite,gneiss, metavolcanics, metasediments), as opposed to pebbles derived from more distal sources (carbon-ates, sandstones), may suggest a relatively close proximity to source (Table 4).
14
15
16
Aeromagnetic datamay also beuseful (Geological Survey ofCanada 1963). Samples with anomalousvalues of KIMs close to a circular--ellipsoid magnetic signature (Morris and Kaszycki 1997) suggestsproximity to a potential source. Sample 552--Ma--97, for example, has ellipsoid magnetic depressionsnearby. In addition, structural datamay be useful. The same samplewas taken froma section of theKapus-kasing River, the orientation of which is fault controlled.
Close proximity to source is also suggested by the presence of perovskite or perovskite/ilmenite rinds(014--Ma--97, 116--Ma--97, 694--Ma--97) or kelyphitic rinds on Cr--pyrope grains (568--Ma--97,569--Ma--97, 608--Ma--97) (Morris 1998, Appendix I). These rinds are regarded as soft and break downeasily in the surface environment (Morris and Kaszycki 1997). In addition, the presence of olivine(015--Ma--97, 056--Ma--97, 086--Ma--97, 591--Tm--97, 629--Ma--97) also suggests that KIMs are close tosource, as olivine breaks down very easily in the surface environment.
17
Figure7.RegionaldistributionofCr--pyropegarnets.Num
beredareassummarizedintext.Thenumberinbracketsbesidethesamplenumberrepresentsthe
numberofCr--pyrope
garnetsrecoveredfrom
thatsite.N
otethatthisdatahasbeen
normalized.The
suffix“97”
hasbeen
droppedfrom
samplenumbers.
18
19
20
Figure10.Regionaldistributionofchromite
grains.Num
beredareassummarizedinthetext.Thenumberinbracketsnexttothesamplenumberrepresentsthe
numberofchrom
itesrecoveredfrom
thatsite.Notethatthisdatahasbeennormalized.*Onegrainfrom
623--M
aplotsinthefielduniquetolamproiteandkimber-
liteon
Fipkeetal.(1995)Cr 20 3v.s.Ti02(wt.%)plot.
21
22
23
Figure12.RegionaldistributionofMg--Ilmenite.Num
beredareassum
marizedintext.Thenumberinbracketsbesidethesamplenumberrepresentsthenumberof
Mg--Ilmenitesrecoveredfrom
thatsite.N
otethatthisdatahasbeen
normalized.
24
Figure13.Regionaldistributionofchromediopsidesw
ithgreaterthan1wt%
Cr 20 3.Num
beredareassum
marizedintext.Thenumberinbracketsbesidethe
samplenumberrepresentsthenumberofchromediopsidesrecoveredfrom
thatsite.N
otethatthisdatahasbeen
normalized.
25
Figure14.RegionaldistributionoftotalK
IMs.Num
beredareasaresummarized
inTable4alongwith
anom
alousindividualsites.
26
27
METAMORPHOSED MASSIVE SULFIDE INDICATOR MINERALSThe distribution and the relative abundance of many of the individual MMSIMs are very similar to thetotal MMSIMs distribution and will therefore not be presented here. Actual number of grains picked aresummarized in Morris (1998, Appendix E). The normalized data and summary statistics are presented inTable 5. Geochemistry ofMMSIMCr--diopside and chromite is presented in Morris (1998, Appendix G)(as low--chrome chromite, chromite and low Cr--diopside). Gahnite geochemistry is presented in Morris(1998, Appendix H).
GahniteOne hundred and ninety--five gahnite--like grains were submitted to theOGC formicroprobe analysis. Ofthese, 175were identified as gahnite (Morris 1998, AppendixH). There are 6 areas where anomalous con-centrations of gahnite grains occur (Figure 15). These areas are: 1) the southwest corner of the study area(001--Tm--97, 523--Tm--97); 2) the south central part of the study area (519--Ma--97, 541--Gf--97; and theeastern portion of the area 3) 069--Ma--97, 098--Ma--97; 4) 011--Ma--97, 014--Ma--97; 5) 029--Ma--97,056--Ma--97; and 6) 033--Ma--97, 041--Ma--97. It is worth noting that: 1) most of these target areas areassociated with modern alluvium in the eastern part of the study area; and 2) a very high number of gah-nites, 102, recovered from sample 541--Gf--97 The gahnite is also accompanied by 22 red rutile grains, 5ruby corundum grains and 22 chalcopyrite grains.
The geochemistry of gahnites is plotted in Figure 16. Two distinct groups are evident:Group 1: Consists of 6 grains with normalized 0 to 2 wt %MgO, normalized 75 to 90 wt % ZnO and
normalized 10 to 45 wt % FeO. This group corresponds well with the geochemistry ofgahnite recovered from pegmatite in the Separation Lake area and to similar geochemicalfields of gahnite recovered from till samples collected in the Separation Lake area and frommodern alluvium samples collected in the Kinniwabi Lake area (Morris 1996a, Morris1997).
Group 2: Normalized 3 to 20 wt % MgO, normalized 55 to 90 wt % ZnO and normalized 10 to 45weight percent FeO. This group corresponds well with the geochemistry of gahniterecovered from various polymetallic deposits in Ontario (Geco, Mattabi, HurdmanTownship) in addition to similar gahnite grain geochemical fields recovered from tillsamples collected in the Separation Lake area and frommodern alluvium samples collectedin the Kinniwabi Lake area (Morris 1996a, Morris 1997).
The distribution of these 2 different groups is illustrated in Figure 17. Note that most of the group 1gahnites plot in the eastern part of the study area.
Recommendations for Massive Sulfide ExplorationLike the KIM data, examination of the distribution of individual MMSIMs identified several sites andrelated areas favorable for massive sulfide exploration. However, by considering the total number ofMMSIMs for each site fewer exploration targets of higher quality could be recommended (Figure 18).This may be more desirable in that the recommended exploration areas would be based on sample sitescontaining significantMMSIMs (e.g., a gahnite) or a variety ofMMSIMs (e.g., gahnite, chalcopyrite, Cr--diopside) (Table 6).
Like the KIM data, estimating proximity of anMMSIM signature to source is difficult given the gla-cial history of the area; using pebble data, however, may be useful (see KIM discussion) in locating asource. In addition, the presence of olivine (015--Ma--97, 056--Ma--97, 086--Ma--97, 591--Tm--97,629--Ma--97) also suggests close sample site proximity to source, as olivine breaks down easily in the sur-face environment.
Aeromagnetic data may also be useful in determining site proximity to source. Samples with anoma-lous values of MMSIMs close to a positive magnetic signature may suggest proximity to a potentialsource. Sample 590--Ma--97, with the very anomalous concentration of Cr--diopside grains (1056), occursjust down--ice from the Rufus fault, easily recognized by a linear positive magnetic anomaly. Similarly,sample site 541--Gf--97, with the anomalously high concentration of gahnite (102 picked grains) occursjust down--ice from a second, larger, northeast trending magnetic anomaly.
28
29
Figure15.Regionaldistributionofgahnite.Num
beredareassum
marizedintext.Thenumberinbracketsbesidethesamplenumberrepresentsthenumber
ofgahnite
grainsrecoveredfrom
thatsite.N
otethatthisdatahasbeen
normalized.
30
31
Figure17.RegionaldistributionofGroup
1vs.Group2gahnite.NotethatmostoftheGroup1gahnite
plotsintheeasternpartofthestudyarea.
32
Figure18.RegionaldistributionoftotalM
MISMs.Num
beredareasaresummarizedinTable4alongwith
anom
alousindividualsites.
33
34
GOLD GRAINSThe number of gold grains recovered in this study is small relative to other studies (Bajc 1994, Bernier1994). This is reflected by the percentile data where values defining anomalous concentrations of goldgrains are very low (Table 7). Most gold grains were recovered from modern alluvium and these grainswere primarily reshaped suggesting some distance of transport (Table 7). One till sample (553--TM--97),however, had a relatively high number of gold grains andwas the only sample to have pristine grains, sug-gesting close proximity to source. Very few gold grains were recovered from the glaciofluvial and glacio-lacustrine sediments (Table 7).
Despite the low number, there are 2 areas where gold grains are concentrated (Figure 19). These areasand individual sample sites are summarized in Table 8.
35
Figure19.Regionaldistributionofgoldgrains.Num
beredareassum
marizedinTable8alongwith
anom
alousindividualsites.Samplesite553--Tmisthe
onlysitewith
pristinegoldgrains.
36
37
Acknowledgements
Steve Dunlop, Chris Hartle and Rory Osborne provided excellent field assistance. Roxanne Shank pro-vided excellent work drafting figures on short notice. Dan Scholtz and Jennifer Stewart mounted and pol-ished all heavyminerals onto the epoxy plugs formicrprobe analysis. SylvieHandley (NorthernDevelop-ment Officer, Ministry NorthernDevelopment andMines), Danny Haines and Brian Cassidy (Ministry ofNatural Resources), Ken Durst and Don Stratton (Spruce Falls Inc.) and local individuals such as GerryDespres and Lorraine Brunet provided invaluable information regarding local logistics, communicationsand geoscientific information. AndyBajc andRichardDyer provided helpful discussion regarding the sta-tistics. Cam Baker and Ross Kelly provided excellent reviews of the manuscript.
38
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41
Metric Conversion Table
Conversion from SI to Imperial Conversion from Imperial to SI
SI Unit Multiplied by Gives Imperial Unit Multiplied by Gives
LENGTH1 mm 0.039 37 inches 1 inch 25.4 mm1 cm 0.393 70 inches 1 inch 2.54 cm1 m 3.280 84 feet 1 foot 0.304 8 m1 m 0.049 709 chains 1 chain 20.116 8 m1 km 0.621 371 miles (statute) 1 mile (statute) 1.609 344 km
AREA1 cm@ 0.155 0 square inches 1 square inch 6.451 6 cm@1 m@ 10.763 9 square feet 1 square foot 0.092 903 04 m@1 km@ 0.386 10 square miles 1 square mile 2.589 988 km@1 ha 2.471 054 acres 1 acre 0.404 685 6 ha
VOLUME1 cm# 0.061 023 cubic inches 1 cubic inch 16.387 064 cm#1 m# 35.314 7 cubic feet 1 cubic foot 0.028 316 85 m#1 m# 1.307 951 cubic yards 1 cubic yard 0.764 554 86 m#
CAPACITY1 L 1.759 755 pints 1 pint 0.568 261 L1 L 0.879 877 quarts 1 quart 1.136 522 L1 L 0.219 969 gallons 1 gallon 4.546 090 L
MASS1 g 0.035 273 962 ounces (avdp) 1 ounce (avdp) 28.349 523 g1 g 0.032 150 747 ounces (troy) 1 ounce (troy) 31.103 476 8 g1 kg 2.204 622 6 pounds (avdp) 1 pound (avdp) 0.453 592 37 kg1 kg 0.001 102 3 tons (short) 1 ton (short) 907.184 74 kg1 t 1.102 311 3 tons (short) 1 ton (short) 0.907 184 74 t1 kg 0.000 984 21 tons (long) 1 ton (long) 1016.046 908 8 kg1 t 0.984 206 5 tons (long) 1 ton (long) 1.016 046 90 t
CONCENTRATION1 g/t 0.029 166 6 ounce (troy)/ 1 ounce (troy)/ 34.285 714 2 g/t
ton (short) ton (short)1 g/t 0.583 333 33 pennyweights/ 1 pennyweight/ 1.714 285 7 g/t
ton (short) ton (short)
OTHER USEFUL CONVERSION FACTORS
Multiplied by1 ounce (troy) per ton (short) 31.103 477 grams per ton (short)1 gram per ton (short) 0.032 151 ounces (troy) per ton (short)1 ounce (troy) per ton (short) 20.0 pennyweights per ton (short)1 pennyweight per ton (short) 0.05 ounces (troy) per ton (short)
Note:Conversion factorswhich are in boldtype areexact. Theconversion factorshave been taken fromor havebeenderived from factors given in theMetric PracticeGuide for the CanadianMining andMetallurgical Industries, pub-lished by the Mining Association of Canada in co-operation with the Coal Association of Canada.
ISSN 0826-9580ISBN 0-7778-7169-6