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Ontario Geological Survey Report 191
Geology of McNish and Janes Townships
District of Sudbury
By
Burkhard O. Dressler
1979
Ministry of Hon- ^ames A. c. Auld Minister Natural . .,. D Dr. J. K. Reynolds ReSOUrCeS Deputy Minister Ontario pMNR-OGS 1979 Printed in Canada
Every possible effort is made to ensure the accuracy of the information contained in this report, but the Ministry of Natural Resources does not assume any liability for errors that may occur. Source references are included in the report and users may wish to verify critical information.
Publications of the Ontario Ministry of Natural Resources and price list are obtainable through the Map Unit, Public Service Centre, Queen©s Park, Toronto, and the Ontario Government Bookstore, 880 Bay Street, Toronto. Orders for publications should be accompanied by cheque or money order, payable to the Treasurer of Ontario ISSN 0704-2582 ISBN 0-7743-3803-2
Parts of this publication may be quoted if credit is given. It is recommended that reference to this re port be made in the following form:
Dressler, Burkhard O. 1979: Geology of McNish and Janes Townships, District of Sudbury; Ontario Geological Sur vey, Report 191, 91 p. Accompanied by Map 2425, scale 1:31 680 (l inch to ©/2 mile).
1000-300-79-TP CONTENTS PAGE Abstract ...... ix Introduction ...... l Access ...... l Topography ...... l Previous Geological Work ...... 2 Present Geological Survey ,...... ,...... 3 Acknowledgments ...... 3
General Geology ...... 3 Table of Lithologic Units ...... 4 Precambrian ...... 5 Southern Structural Province ...... 5 Early Precambrian ...... 5 Metavolcanics and Metasediments ...... 6 Mafic Metavolcanics ...... 6 Metasediments ...... 6 Felsic Intrusive Rocks ...... 7 Granitic Rocks ...... 7 Mafic Intrusive Rocks ...... 8 Diabase ...... 8 Middle Precambrian ...... 10 Huronian Supergroup ....,...... 10 Hough Lake Group ...... 10 Mississagi Formation ...... 10 Cobalt Group ...... 12 Gowganda Formation ...... 12 Lorrain Formation ...... 17 Nipissing Intrusive Rocks ...... 21 Gabbro ...... 21 Quartz Monzonite ...... 24 Granitic Dike Rocks Intruding the Gabbro ...... 32 Sudbury-Type Breccia and Pseudotachylite ...... 34 Grenville Structural Province ...... 35 Middle Precambrian ...... 35 Metasediments ...... 35 Biotite-Plagioclase and Biotite-Hornblende Plagioclase Gneiss ..... 36 Feldspathic Gneiss ...... 38 Migmatites ...... 39 Mafic Intrusive Rocks ...... 40 Late Precambrian ...... 40 Anorthosite Suite Intrusive Rocks ...... 40 Southern Structural Province and Grenville Structural Province ...... 48 Late Precambrian ...... 48 Mafic Intrusive Rocks ...... 48 Olivine Diabase ...... 48 Ultramafic Intrusive Rocks ...... 49 Phanerozoic ...... 53 Cenozoic ...... 53 Quaternary ...... 53 Pleistocene and Recent ...... 53
Structural Geology ...... 54 Structures not associated with the Grenville Front Tectonic Zone ...... 57 Joints ...... 57 Faults and Lineaments ...... 61 Structures in the Grenville Front Tectonic Zone ...... 61 Cleavage ...... 61 Schistosity ...... 62 Gneissosity ...... 62
Hi Lineations ...... 63 Grenville Front Boundary Fault ...... 63 Metamorphism ...... 65 Correlation between Geology and Aeromagnetic Data ...... 68 Economic Geology ...... 68 Copper and Nickel Associated with the Nipissing-Type gabbro ...... 68 Kennco Explorations (Canada) Limited [1970] (4) ...... 70 Kirkland Townsite Occurrence (5) ...... 70 Ossington Explorations Limited and Triller Explorations Limited[1960] (6)...... 71 Pan Central Explorations Limited (7)...... 71 Copper-Lead-Zinc Mineralization in Northwestern McNish Township ...... 72 Disseminated Sulphides in Early Precambrian Rocks ...... 72 Synsedimentary Detrital Mineralization in Rocks of the Gowganda Formation ...... 73 Mineralized Hydrothermal Quartz Veins and Silicified Zones within Early Precambrian and Huronian Supergroup Rocks ...... 75 Exploration for Copper, Lead, and Zinc in Northwestern McNish Township ...... 76 Jerome, A.E. (1) ...... 76 Waltenbury Occurrence (3) [Palston Mining and Development Company] ...... 77 Sulphide Mineralization in Quartz Veins and Dikes ...... 81 Wiemer Occurrence (8) ...... 81 Uranium-Bearing, Pyritiferous Conglomerate of the Mississagi Formation ...... 81 Saville, Th. D.(2) ...... 81 Garnet ...... 82 Sand and Gravel ...... 82 Suggestions for Future Exploration ...... 82 References ...... 85 Index ...... 89
TABLES 1-Table of Lithologic Units ...... 4 2-Modal analyses of Early Precambrian metasediments ...... 8 3-Modal analyses of Early Precambrian granitic rocks ...... 9 4-Modal analysis of Early Precambrian mafic intrusive rocks ...... 9 5-Huronian sedimentary rocks in south-central McNish Township ...... 13 6-Modal analyses of rocks of the Gowganda Formation ...... 16 7-Modal analyses of rocks of the Lorrain Formation ...... 19 8-Stratigraphic section through part of the Lorrain Formation ...... 20 9-Chemical analyses of Nipissing gabbro ...... 25 10-Modal analyses of Nipissing gabbro ...... 26 11-Modal and chemical analyses of Nipissing gabbro; diamond-drill cores; Janes Township ..... 27 12-Chemical analysis and norms of quartz monzonite ...... 33 13-Modal and chemical analyses of a granitic dike intruding the Nipissing gabbro ...... 34 14-Modal analyses of metasediments south of the Grenville Front Boundary Fault ...... 37 15-Modal and chemical analyses of Anorthosite Suite Intrusive Rocks ...... 42 16-Modal analyses of olivine diabase ...... 50 17-Chemical analyses of olivine diabase ...... 52
iv 18-Modal analyses of ultramafic rocks ...... 53 19-Description of the showings on Waltenbury Occurrence (3) ...... 78
FIGURES 1-Key map showing the location of McNish and Janes Townships ...... ix 2-Surface distribution and thicknesses of Nipissing gabbro ...... 22 3-Variation of modal and chemical composition of Nipissing gabbro. Diamond-drill hole, Janes Township ...... 29 4-Titanomagnetite rimmed by biotite. Olivine diabase ...... 51 5-Pleistocene and Recent geology ...... 55 6-Structural geology of McNish and Janes Townships ...... 58 7-Stereogram for joints in the rocks of the Gowganda Formation and in Nipissing gabbro ...... 59 8-Stereogram for fracture cleavages Southeastern McNish Township and northern and central Janes Township ...... 59 9-Stereogram for schistosity. Southern and east-central Janes Township, north and northwest of the Grenville Front Boundary Fault ...... 60 10-Stereogram for gneissosity. South of the Grenville Front Boundary Fault ...... 60 11-Plunge of lineations north and south of the Grenville Front Boundary Fault ...... 64 12-Zones of regional metamorphism in McNish and Janes Townships ...... 66 13-Diamond drill-hole location plan. P.C.E. Explorations Limited ...... 72 14-Geological sketch-map by Palston Mining and Development Company ...... 80
PHOTOGRAPHS 1-Biotite - muscovite schist, Early Precambrian metasediments ...... 7 2-Laminated silty greywacke, Gowganda Formation ...... 17 3-Soft sediment deformation, Gowganda Formation ...... 18 4-Rafted clast in greywacke, Gowganda Formation ...... 18 5-Talc and magnetite replacing pyroxene, Nipissing gabbro ...... 24 6-Granophyre in quartz monzonite ...... 31 7-Strongly deformed quartz monzonite ...... 32 8-Migmatitic biotite-plagioclase gneiss ...... 36 9-Poikiloblastic garnet wrapped around by biotite and muscovite. Biotite-muscovite-hornblende gneiss ...... 38 10-Amoeboid garnet ...... 39 11-Faulted Nipissing gabbro ...... 41 12-Layered anorthosite gabbro ...... 44 13-Augen texture in gneissic anorthositic gabbro ...... 45 14-Transition from massive to gneissic gabbroic anorthosite ...... 45
V 15-Twinned and somewhat saussuritized plagioclase in a granoblastic mosaic of commonly untwinned recrystallized plagioclase ...... 47 16-Exsolution lamellae of plagioclase in plagioclase ...... 47 17-Part of a corona, anorthosite suite rock ...... 48 18-Subophitic texture, olivine diabase ...... 50 19-Crossbedded Pleistocene deposits ...... 54 20-Strongly cataclastic arkose of the Lorrain Formation ...... 56 21-Strongly folded quartzite ...... 57 22-Altered pyrrhotite in Nipissing gabbro ...... 69 23-Flame-like exsolution body of pentlandite in pyrrhotite, Early Precambrian metavolcanics ... 73 24-Ore clast in conglomerate of the Gowganda Formation ...... 74 25-Sulphide mineralization in quartz veins ...... 75
GEOLOGICAL MAP (Back Pocket) Map 2425 (coloured)-McNish and Janes Townships, District of Sudbury. Scale 1:31 680 (l inch to ©/2 mile)
VI CONVERSION FACTORS FOR MEASUREMENTS IN ONTARIO GEOLOGICAL SURVEY PUBLICATIONS
If the reader wishes to convert imperial units to SI (metric) units or SI units to imperial units the fol lowing multipliers should be used:
CONVERSION FROM SI TO IMPERIAL CONVERSION FROM IMPERIAL TO SI SI Unit Multiplied by Gives Imperial Unit Multiplied by Gives
LENGTH 1 mm 0.039 37 inches 1 inch 25.4 mm 1 cm 0.393 70 inches 1 inch 2.54 cm 1m 3.280 84 feet Ifoot 0.304 8 m 1m 0.049 709 7 chains 1 chain 20.1168 m 1km 0.621 371 miles (statute) 1 mile (statute) 1.609 344 km AREA 1 cm2 0.155 0 square inches 1 square inch 6.451 6 cirr 1 m2 10.763 9 square feet 1 square foot 0.092 903 04 m2 1km2 0.386 10 square miles 1 square mile 2.589 988 km2 lha 2.471 054 acres 1 acre 0.404 685 6 ha VOLUME 1 cm3 0.061 02 cubic inches 1 cubic inch 16.387 064 cnr 1m3 35.314 7 cubic feet 1 cubic foot 0.028 316 85 m3 1m3 1.308 0 cubic yards 1 cubic yard 0.764 555 CAPACITY 1L 1.759 755 pints 1 pint 0.568 261 1L 0.879 877 quarts 1 quart 1.136522 1L 0.219 969 gallons 1 gallon 4.546 090 MASS lg 0.035 273 96 ounces (avdp) 1 ounce (avdp) 28.349 523 lg 0.032 150 75 ounces (troy) 1 ounce (troy) 31.103 476 8 1kg 2.204 62 pounds (avdp) 1 pound (avdp) 0.453 592 37 kg 1kg 0.001 102 3 tons (short) 1 ton (short) 907.184 74 kg It 1.102311 tons (short) 1 ton (short) 0.907 184 74 t 1kg 0.00098421 tons (long) 1 ton (long) 1016.046 908 8 kg It 0.984 206 5 tons (long) 1 ton (long) 1.016 046 908 8 t CONCENTRATION Ig/t 0.029 166 6 ounce (troy)/ l ounce (troy)/ 34.285 714 2 g/t ton (short) ton (short) Ig/t 0.583 333 33 pennyweights/ l pennyweight/ 1.7142857 g/t ton (short) ton (short)
OTHER USEFUL CONVERSION FACTORS l ounce (troyVton (short) 20.0 pennyweights/ton (short) l pennyweight/ton (short) 0.05 ounce (troy)/ton (short)
NOTE-Conversion factors which are in bold type are exact. The conversion factors have been taken from or have been derived from factors given in the Metric Practice Guide for the Canadian Mining and Metallurgical Industries published by The Mining Association of Canada in co operation with the Coal Association of Canada.
VII
ABSTRACT
McNish and Janes Townships are located approximately 55 km northeast of Sudbury and 11 km northwest of River Valley. Mapping at a scale of 1:15 840 (final map scale 1:31 680) shows that the area is underlain by Pre cambrian metamorphic, igneous, and sedimentary rocks. The Grenville Front Boundary Fault crosses Janes Township near the southern boundary of the map-area. Rocks of Middle Precambrian age, namely the Huronian Supergroup and Nipissing Intrusive Rocks predominate north of the fault. The oldest rocks, the Early Precambrian metasediments, metavolcanics, granitic rocks, and
Figure 1-Key map showing location of McNish and Janes Townships. Scale 1:3 168 000 (1 inch to 50 miles).
mafic intrusive rocks underlie only small sectors of northern McNish Township. Breccias, pseudota- chylites, and Late Precambrian olivine diabase dikes also occur north of the Grenville Front Bound ary Fault. South of the fault, the rocks consist of biotite-plagioclase gneiss, amphibolite, anorthosite gabbro, gabbroic anorthosite, migmatite, minor olivine diabase, and ultramafic rocks of the Grenville Tectonic Province. Thick deposits of Pleistocene sand and gravel blanket the Precambrian bedrock over most of the map-area. The Grenville Front Tectonic Zone is the major tectonic feature in the area. Far north of it, in McNish Township and northwestern Janes Township, the rocks were not subjected to the Grenvil- lian deformation. Nearer to the Grenville Front Boundary Fault, fracture cleavage is widely devel oped in the rocks, and still closer to the Grenville Front Boundary Fault, the rocks are schistose. South of the Grenville Front Boundary Fault, the rocks are gneissic. There are no producing mines in the region. However, the area has a certain economic interest and exploration has been carried out for copper, nickel, lead, zinc, gold, silver, and uranium during the last forty years. Syngenetic copper and nickel mineralization occurs in the Nipissing gabbro. Copper, lead, zinc, gold, and silver occur in hydrothermal deposits within Early Precambrian met asediments and metavolcanics and within the Huronian sedimentary rocks. Uranium occurs in con glomerates of the Mississagi Formation of the Huronian Supergroup.
ix
Geology of McNish and Janes Townships District of Sudbury
By Burkhard O. Dressler1
INTRODUCTION
Janes and McNish Townships comprise approximately 186 km2. The centre of the area is located about 55 km northeast of the City of Sudbury (Figure 1). During the 1976 field season these two townships were mapped by a geological field party under the direction of the author. The purpose of the project was the mapping of Huronian sedimentary rocks and Nipissing Intrusive Rocks to aid in determining the mineral potential of the area and to provide guides to mineral exploration.
Access
The area is bounded by Latitudes 46037©30" and 46048©N and Longitudes 800 17© and 80025©W. Access is provided by Highways 539A and 805 from River Valley, by a gravel road from Riviere Veuve, and by a network of lumber roads. Janes Township and the eastern half of McNish Township can be reached by ca noe via the Sturgeon River. Ozhway Lake, located in this sector of the area, is accessible by float-equipped aircraft. The Canadian National Railway line be tween North Bay and Capreol crosses the southern part of Janes Township.
Topography
McNish and Janes Townships are located on the Precambrian Shield of northeastern Ontario. The average elevation above sea level is about 270 m. Local topographic relief is only about 90 m, but the country is nevertheless rug-
geologist, Precambrian Geology Section, Ontario Geological Survey, Toronto. Manuscript ap proved for publication by the Chief Geologist, April 5th, 1978. This report is published with the per mission of E.G. Pye, Director, Ontario Geological Survey. 1 McNish and Janes Townships ged. The highest elevation in the area is 350 m above sea level in northern McNish Township, the lowest is 240 m above sea level in the Sturgeon River Valley in southeastern Janes Township. The topography is strongly controlled by bedrock lithology and by structure. Nipissing gabbro is resistant to erosion and forms hills and ridges. The Gow ganda Formation greywacke underlies large parts of the area and in general oc curs at lower elevations than other rocks. However, the Gowganda Formation forms high hills in eastern Janes Township and in many places in McNish Township, for instance just north of Silver Creek. Olivine diabase weathers eas ily and is expressed as long topographic depressions. Some faults, such as the Floodwood Chutes Fault and the Grenville Front Boundary Fault are expressed by river and stream valleys or by topographic li neaments. Glaciation has rounded the hills and ridges and partly filled the topographic depressions and valleys with glacial deposits. All the area drains to the south via the Sturgeon River. The Sturgeon River is the only major river in the area, and it flows through it from northern McNish Township to southern Janes Township meandering in a wide, commonly sand covered valley. In southern Janes Township, at "The Elbow" it abruptly changes its direction towards the east.
Previous Geological Work
The first geological reconnaissance in the area was carried out by Alexander Murray (1853-56) who in 1856 ascended the Sturgeon River for about 83 km dur ing his historical surveys to Lake Huron and Georgian Bay. In 1892, the Ontario Bureau of Mines published a map entitled "Map of parts of the districts of Nip issing and Algoma" that had been compiled from plans of surveys by the De partment of Crown Lands, Toronto, and plans of the Geological Survey Depart ment, Ottawa. This map is at the scale of 1:253 440 (l inch to 4 miles) and includes McNish and Janes Townships. In 1897, A.E. Barlow (1899) mapped the Nipissing and Timiskaming map-sheets. The eastern halves of Janes and McNish Townships are part of Barlow©s map. In 1932, E.L. Bruce mapped Janes, McNish, Pardo, and Dana Townships at a scale of 1:31 680 and in 1973 a preliminary map of the River Valley Area (Lumbers 1973) was published by the Ontario Division of Mines. This map was published at a scale of 1:63 360 and in cludes the map-area. Prior to the publication of Lumbers© map, a preliminary ge ological compilation map, the Capreol Sheet, was issued by the Ontario Division of Mines in 1966. It had been compiled by H.D. Meyn (1966), is at a scale of 1:126 720, and includes McNish and Janes Townships. Kelly and Davis Town ships, west of McNish and Janes Townships, were mapped by Jas. E. Thomson and K.D. Card (1963) at a scale of 1:15 840 and Afton, Scholes, Macbeth, and Clement Townships north of McNish Township by Meyn (1977) at the same scale. The area is also covered by aeromagnetic maps of the Geological Survey of Canada (GSC 1965a and b). Preliminary geological maps of the map-area were published in 1977 (Dres sler 1977a and b).
Present Geological Survey
The field work for this report was carried out during the summer of 1976. Transport within the area was by means of a four-wheel-drive vehicle, by canoe, and on foot. Pace and compass traverses were run at approximately 0.4 km inter vals between topographic points such as roads, lakes, and rivers. Outcrops along roads, rivers, and along lakeshores were also examined. In the field, outcrop data were plotted on acetate overlays on air photo graphs at a scale of 1:15 840. These data were subsequently transferred to base maps of the same scale which were supplied by the Forest Resources Inventory, Division of Forests, Ontario Ministry of Natural Resources. All chemical analyses presented in this report were performed by the Geosci ence Laboratories, Ontario Geological Survey. F.J. Pettijohn©s (1975) classification of sedimentary rocks was used by the author throughout the report. The modal compositions presented in this report were obtained using a Rathenow Eltinor 4 point counter. Eastings and northings of sample locations are from 1:50 000 topographic maps produced by the Federal Surveys and Map ping Branch, Department of Energy, Mines, and Resources, Ottawa (Maps 41- 1/9 and 41-1/16,1975).
Acknowledgments
The author was ably assisted in the field by A. Andrews, G. Finn, and R. Wagner. Andrews was responsible for mapping about 20 percent of the area. The author is indebted to Dr. S.B. Lumbers, Royal Ontario Museum, for fruitful dis cussions in the field and during laboratory investigations.
GENERAL GEOLOGY
The area is underlain by Precambrian rocks. Pleistocene and Recent uncon solidated sediments cover the bedrock in many places. Early Precambrian metavolcanics, metasediments, granitic rocks, and mafic intrusive rocks are the oldest rocks in the map-area. The metavolcanics and met asediments were intruded by granitic rocks which were emplaced approximately 2500 m.y. ago (Van Schmus 1965; Fairbairn et al. 1960). Early Precambrian mafic dikes intruded the metasediments and are believed to be younger than the granitic intrusions because they are known to be intrusive into the Early Pre cambrian granitic rocks in regions to the north of the map-area. Middle Precambrian rocks of the Huronian Supergroup unconformably McNish and Janes Townships
TABLE 1 TABLE OF LITHOLOGIC UNITS FOR McNISH AND JANES TOWNSHIPS.
PHANEROZOIC CENOZOIC QUATERNARY PLEISTOCENE AND RECENT Fluvial and glacial sand, gravel and boulders; swamp deposits
Unconformity PRECAMBRIAN SOUTHERN STRUCTURAL PROVINCE AND GRENVILLE STRUCTURAL PROVINCE LATE PRECAMBRIAN MAFIC INTRUSIVE ROCKS Olivine diabase and ultramafic rocks Intrusive Contact GRENVILLE STRUCTURAL PROVINCE LATE PRECAMBRIAN ANORTHOSITE SUITE INTRUSIVE ROCKS Anorthositic gabbro, gabbroic anorthosite, massive and gneissic Intrusive Contact MIDDLE TO LATE PRECAMBRIAN MAFIC INTRUSIVE ROCKS Amphibolite Intrusive Contact MIDDLE PRECAMBRIAN METASEDIMENTS Biotite-(homblende)-plagioclase gneiss; feldspathic gneiss; migmatites SOUTHERN STRUCTURAL PROVINCE MIDDLE PRECAMBRIAN SUDBURY-TYPE BRECCIA AND PSEUDOTACHYLITE NIPISSING INTRUSIVE ROCKS Gabbro, quartz monzonite and granitic dike rock, schistose, cataclastic, and gneissic rocks equivalents Intrusive Contact HURONIAN SUPERGROUP COBALT GROUP LORRAIN FORMATION Quartz arenite, arkose, minor silty greywacke GOWGANDA FORMATION Conglomerate, greywacke, quartz arenite, arkose HOUGH LAKE GROUP MISSISSAGI FORMATION Conglomerate, arkose, quartz arenite, greywacke, argillite, metamorphosed equivalents
continued . . . Table l continued Unconformity EARLY PRECAMBRIAN MAFIC INTRUSIVE ROCKS Diabase
Intrusive Contact FELSIC INTRUSIVE ROCKS Granitic Rocks
Intrusive Contact METAVOLCANICS AND METASEDIMENTS METASEDIMENTS Greywacke MAFIC METAVOLANICS Amphibolite overlie the older rocks. They were deposited 2150 to 2400 m.y. ago (Van Schmus 1976), an age bracket which corresponds to the Aphebian of C.H. Stockwell (1964). Rocks of the Mississagi Formation, the Gowganda Formation, and the Lorrain Formation occur in the area. The Mississagi Formation consists of con glomerate, sandstone, greywacke, and argillite; the Gowganda Formation of greywacke, conglomerate, arkosic wacke and subarkose; and the Lorrain Forma tion of sandstone, and minor silty greywacke. Nipissing Intrusive Rocks, mostly gabbros, intrude all the older formations. These rocks are about 2150 m.y. old (Van Schmus 1965, 1976; Fairbairn et al. 1969). A Late Precambrian olivine dia base dike outcrops in northwestern Janes Township. All these rocks occur north of the Grenville Front Boundary Fault, and are in the Southern Structural Prov ince of the Canadian Shield. South of the Grenville Front Boundary Fault, in the Grenville Structural Province, the rocks consist of biotite-plagioclase gneiss, biotite-hornblende-pla- gioclase gneiss, feldspathic gneiss, amphibolite, gabbro, anorthositic gabbro, gab broic anorthosite, migmatite, olivine diabase, and ultramafic rocks. The rock units of the area are shown in the Table of Lithologic Units (Table D.
Precambrian
SOUTHERN STRUCTURAL PROVINCE
Early Precambrian
Early Precambrian metavolcanics, metasediments, felsic, and mafic intru sive rocks occur in northern McNish Township where they form three small inli- ers within the younger rocks of the Huronian Supergroup. McNish and Janes Townships
METAVOLCANICS AND METASEDIMENTS
Mafic Metavolcanics
Mafic metavolcanics are minor in the map-area. Only four small outcrops were observed, in northwestern McNish Township. Contacts with other Early Precambrian rocks were not observed. The rocks are fine grained, black or dark grey on the fresh surface, and weather dark greenish grey to greenish grey. Primary textures and structures were destroyed by deformation and metamorphism. The origin of the metavol canics is therefore unknown, and the rocks in the area are best classified as "am- phibolites of unknown origin". In the area to the north of McNish Township, Meyn (1977) described massive and pillowed basaltic flows, porphyritic flows, gabbroic intrusions, and pyroclastic rocks. In thin section, the rocks exhibit the common greenschist facies mineralogy of mafic metavolcanics. Plagioclase is altered to albite-oligoclase and to minerals of the epidote group. Pyroxene was replaced by actinolitic amphibole and chlor ite. Secondary biotite was also noted. Pyrite and iron oxide minerals are com monly present in minor amounts.
Metasediments
The metasediments make up the bulk of the Early Precambrian rocks in the map-area. They are fine grained, dark grey or greenish grey biotite-muscovite schist originally deposited as mudstone and greywacke. Sedimentary features such as bedding, graded bedding, and crossbedding were not observed and the only possible primary sedimentary texture is a fine lamination in some of the rocks. Shearing has obliterated the original textures and structures. Meyn (1977) described the mineral foliation to be commonly parallel to the bedding planes in Early Precambrian metasediments of Afton, Scholes, Macbeth, and Clement Townships north of the area. However, in the area, the relationship of these structures could not be determined. In thin section, the rocks are revealed to be composed of a granoblastic, ine quigranular mosaic of quartz and feldspar. Biotite and muscovite form an open or a closed (Photo 1) fabric depending on the amount of micas present. In places, the recrystallized micas wrap around possibly primary detrital clasts of subangu lar to subrounded quartz or plagioclase. Plagioclase and quartz show more or less straight grain boundaries with each other. Plagioclase is commonly strongly saussuritized, but clear and untwinned unaltered albite-oligoclase was also ob served. Microcline was noted in only one thin section. Biotite flakes are brown to dark brown and measure 0.04 by 0.15 mm, and rarely are as much as 0.15 by 0.3 mm. Muscovite is somewhat greenish and commonly exhibits a smaller grain size than biotite. Chlorite is diaphthorite and has partly replaced biotite. Pri mary metamorphic chlorite was also observed, forming fresh, big sheets. These occur together with and parallel to unaltered biotite. OGS 10,024
Photo 1-Biotite - muscovite schist, Early Precambrian metasediments. Crossed polarizers. Scale 0.07 mm, thin section 63C34. Location: Northwestern Janes Township, easting 546380, northing 5182330.
Table 2 presents four modal analyses of Early Precambrian metasediments. The rocks may be somewhat arbitrarily classified as arkosic greywacke, and mudstone.
FELSIC INTRUSIVE ROCKS
Granitic Rocks
Granitic rocks underlie a very small sector of northeastern McNish Town ship. These rocks are commonly non-foliated and therefore are believed to be in trusive into the foliated Early Precambrian metasediments. They are overlain by rocks of the Huronian Supergroup. The granitic rocks are medium grained, non-foliated, or very weakly foliated, light grey or pink. In thin section, these rocks are seen to be composed of plagioc lase, quartz, a small amount of microcline, biotite, muscovite, and accessory apa tite, zircon, and opaque minerals. Plagioclase is hypidiomorphic, and microcline McNish and Janes Townships
TABLE 2 MODAL ANALYSES OF EARLY PRECAMBRIAN METASEDIMENTS, MCNISH TOWNSHIP. Modal Analyses in Volume Percent
Specimen Number 49C1A 49C2 52C4 63C34 Quartz 28.8 22.8 37.6 26.4 Plagioclase 25.3 48.0 21.2 8.2 Microcline 3.8 Biotite 37.2 0.2 37.0 32.4 Muscovite 1.7 2.4 1.6 30.8 Chlorite 3.3 21.6 1.4 0.2 Epidote 3.3 0.6 0.4 1.2 Opaque minerals 0.4 0.6 0.8 0.8 Grain size (quartz and feldspar) in mm 0.02-0.06-0.10 0.05-0.15-0.30 0.02-0.05-0.25 0.05-0.10-0.20
Location: Easting 553960 553950 547780 546380 Northing 5181000 5180750 5182500 5182330
is xenomorphic. The micas are partly chloritized and plagioclase is commonly saussuritized. Almost unaltered plagioclase is scarce and has been optically de termined as andesine (An35 5). Table 3 presents three modal analyses. In the classification of granitic rocks (Ayres 1972) the rocks are quartz diorites, in the IUGS classification (Streckeisen 1974,1976), tonalite to granodiorite.
MAFIC INTRUSIVE ROCKS
Diabase
At a few localities, the Early Precambrian metasediments and metavolcanics are intruded by diabase dikes. Most dikes have a near vertical dip and com monly strike northwesterly. In general, they range in thickness from a few deci metres to about 3 m. Thicker dikes were not observed, but are reported from many locations in the Superior Province not far north of the map-area. Diabase is a dark greenish, greenish grey weathering, fine- to medium- grained, subophitic rock. Most primary minerals are almost completely altered. Plagioclase is altered to saussurite, consisting of clinozoisite, chlorite, albite, and minor quartz. Pyroxene, light greenish to brownish augite, is almost completely replaced by actinolite. Biotite has replaced some of the actinolite. Leucoxene, once titanomagnetite, makes up almost four percent of the rock; xenomorphic, opaque minerals about one percent. A modal analysis is given in Table 4. 8 TABLE 3 MODAL ANALYSES OF EARLY PRECAMBRIAN GRANITIC ROCKS, McNISH AND JANES TOWNSHIPS.
Specimen Number 49L13 49L14 49C15
Quartz 29.0 30.7 23.1 Plagioclase 54.0 56.3 59.8 Microcline 9.0 2.6 5.8 Biotite 5.8 7.2 1.7 Muscovite 1.4 7.9 Chlorite 0,4 3.0 0.7 Apatite 0.2 0.2 0.2 Opaque minerals 0.2 0.8
Location: Easting 553960 553950 553900 Northing 5179720 5179810 5179850
TABLE 4 MODAL ANALYSIS OF EARLY PRECAMBRIAN MAFIC INTRUSIVE ROCK, McNISH TOWNSHIP.
Modal Analysis in Volume Percent
Specimen Number 64C4
Albite 35.2 Epidote 24.1 66.1 "Plagioclase" Chlorite 5.7 Quartz 1.1
Pyroxene 0.4 Actinolite 26.1 29.1 "Pyroxene" Biotite 2.6
Leucoxene 3.9 3.9 "Titanomagnetite" Opaque minerals 0.9 0.9 Opaque minerals
Location: easting 546250, northing 5181650 McNish and Janes Townships
Middle Precambrian
HURONIAN SUPERGROUP
The classification of the rocks of the Huronian Supergroup as Mississagi, Gowganda, and Lorrain Formations is based on lithologic evidence, field evi dence, and on the comparison of these rocks with descriptions given by Thomson and Card (1963) and Meyn (1977). In places, the classification adopted by the author differs from the one made by S.B. Lumbers (1973) on his preliminary map of the River Valley Area. The reasons for that are discussed in the chapter on the Lorrain Formation. Bruce (1932) classified the rocks that outcrop south and just north of the Grenville Front Boundary Fault as "Sudbury Series". Coleman (1913) and Thomson and Card (1963) designated them as "Sudbury Group" in Davis Town ship west of Janes Township. Thomson and Card (1963, p.4) stated:
This sedimentary group [the Sudbury Group] has been traced eastward into the map-area from Maclennan and Scadding Townships where field relationships indicate that it lies stratigraphically below the Huronian System and is separated from it by a great unconformity (Thomson 1961). The sedimentary group also extends eastward into Janes and Pardo Townships where the Huronian rocks again lie with great unconformity upon it (Bruce 1932, p.13; Thomson 1960). Lumbers (1973) classified the rocks as Huronian that were mapped as "Sud bury Series" by Bruce (1932). Field evidence in the map-area appears to sub stantiate Lumbers© stratigraphic correlation. In eastern Janes Township little or non-metamorphosed Huronian sedimentary rocks appear to grade into higher rank metasediments near the Grenville Front Boundary Fault. In southwestern Janes Township, the change in metamorphic grade is very abrupt because of faulting along an east-striking fault, the Ess Creek Fault, North Branch (Thom son and Card 1963).
Hough Lake Group
Mississagi Formation
Rocks of the Mississagi Formation outcrop in an area just north of the Gren ville Front Boundary Fault in Janes Township and in northeastern McNish Township where they unconformably overlie Early Precambrian granitic rocks and metasediments. The Mississagi Formation is overlain by sedimentary rocks of the Gowganda Formation. The rocks of the Mississagi Formation consist of conglomerate, arkosic aren ite, greywacke, and argillite. Large outcrops of these rocks are not present in the area, and near the Grenville Front Boundary Fault, the rocks are strongly de formed. In Janes Township, just north of the Grenville Front Boundary Fault, the 10 thickness and the stratigraphy of the formation are not known. In northeastern McNish Township, the Mississagi Formation is thin. In south-central McNish Township, about 3.2 km west-northwest of Silver Creek, Newmont Mining Cor poration of Canada Limited, diamond drilled a 1203 m deep hole through the sedimentary rocks of the Gowganda Formation and underlying Huronian rocks. Table 5, courtesy of Newmont Mining Corporation of Canada Limited, presents the stratigraphy of the drill hole as described by them which classified the rocks from about O to 550 m as Gowganda Formation, from 550 m to about 790 m as Middle Huronian, and from 790 m to the Early Precambrian basement at 1184.9 m depth as Mississagi Formation. The author discussed the company©s dia mond-drill records with K.D. Card (Geologist, Ontario Geological Survey, per sonal communication, January 1977) and tentatively subdivided the drill hole li thologic column as follows: 0-800 m: Gowganda Formation; 800-1061.3 m: Mississagi Formation; 1061.3-1093 m: Pecors Formation (Hough Lake Group); 1093-1171 m: Ramsay Lake Formation (Hough Lake Group); 1171-1184 m: Matinenda Formation (Elliot Lake Group). If this stratigraphic interpretation is correct, the Pecors, Ramsay Lake, and Matinenda Formations possibly also outcrop within the map-area, and have been mapped by the author as the Mississagi Formation. In northeastern McNish Township, the exposed conglomerate is pyritiferous and radioactive (Lumbers 1973). The clasts are up to 10 cm in diameter, com monly rounded, and consist of quartzite, quartz, and siltstone. The conglomerate is clast-supported. The matrix consists of more than 90 percent greenish muscov ite and a little quartz, feldspar, and opaque minerals. No radioactive minerals were found in the one thin section of the conglomerate studied. Arkosic arenite and a silty greywacke overlie the conglomerate. The arkosic arenite is coarse grained, grey and is overlain by a darker grey, silty greywacke. No thin sections have been made from these rocks and their classification as arkosic arenite and greywacke is based on field observations only. Just north of the Grenville Front Boundary Fault in Janes Township, the rocks of the Mississagi Formation mainly consist of grey to greenish grey, fine grained greywacke and dark grey to black argillite. Both rock types are lami nated in places and grade into biotite-chlorite and biotite-chlorite garnet schist from the north towards the Boundary Fault. A conglomerate occurs near "The Elbow", on the south side of the Sturgeon River, at the mouth of the Kabikotit- wia River. Bruce (1932, p. 10) presented a photograph of this conglomerate and described the clasts that are included in the rock as quartzite. A white quartzite bed has been observed in southwestern Janes Township at the Canadian Na tional Railway tracks (see Photo 21).
11 McNish and Janes Townships
Cobalt Group
Gowganda Formation
Rocks of the Gowganda Formation occur in large sectors of the map-area. The contact between the Gowganda Formation and Early Precambrian rocks is a sharp unconformity. Contacts with the underlying Mississagi Formation are not exposed in the area. Just north of the map-area, in Afton, Scholes, Macbeth, and Clement Townships, Meyn (1977) described the Gowganda Formation as conformably overlying the sedimentary sequence of the Mississagi Formation. In the Maple Mountain Area, about 30 km north of McNish Township, how ever, the contact between the Gowganda Formation and the older Huronian rocks is an angular unconformity "as evidenced by onlap of the Gowganda over successively older formations, local strike and dip discordance as noted in out crops, and angular dip discordance as shown by diamond drilling" (Card et al. 1973, p.24). In McNish and Janes Townships, the rocks of the Gowganda Formation are for the most part flat-lying or gently dipping. Therefore no reliable estimate of the thickness of the formation can be made from exposures. In the very eastern part of central McNish Township, the formation is about 150 m thick and is in tercalated between the rocks of the Mississagi and the Lorrain Formations. In western and central McNish and Janes Townships, some sections exposed across flat-dipping parts of the formation are about 100 m thick. In this sector of the area the rocks are very monotonous in appearance, no marker horizons are pres ent, and it is therefore not possible to determine the relative stratigraphic posi tion of several separate exposures to form a complete section across the Gow ganda Formation. In south-central McNish Township, the Gowganda Formation is about 800 m thick; this includes a 16.7 m thick Nipissing gabbro sill (Table 5). In the Maple Mountain Area (Card et al. 1973), north of the map-area, the Gowganda Formation ranges from no recorded thickness to 1500 m and averages about 900 m in thickness. The variations in thickness are caused by a strong basement topographic relief in excess of 900 m. The rocks of the Gowganda Formation consist of conglomerate, greywacke, quartz arenite, arkose, and lithic greywacke. The formation in general is divisi ble into a lower conglomerate unit and an upper greywacke unit. The lower conglomerate unit is exposed mainly in northwestern McNish Township. Polymictic paraconglomerate and orthoconglomerate are present. They are composed of angular to rounded boulders, cobbles and pebbles set in a fine- to medium-grained lithic wacke or arkosic wacke matrix. In a few places the matrix is weakly stratified. Rock fragments make up between 15 and 90 percent of the rock and consist of metasediments, metavolcanics, and granitic rocks. In places, fine- to medium-grained greywacke is interbedded with the conglomer ate. These rocks form grey or pinkish grey, in places laminated or crossbedded beds that are 30 cm to l m thick. Commonly they are coarser grained than the greywacke of the upper greywacke unit. Petrographic studies show that the greywacke interbeds and the matrix of 12 TABLE 5 HURONIAN SEDIMENTARY ROCKS IN SOUTH-CENTRAL McNISH TOWNSHIP. DIAMOND DRILLED SECTION (NEWMONT MINING CORPORATION OF CANADA LIMITED, 1967). DESCRIPTION FROM DIAMOND-DRILL RECORDS OF THE COMPANY, ASSESSMENT FILES RESEARCH OFFICE, ONTARIO GEOLOGICAL SURVEY, TORONTO.
0-481.2 m Greywacke (Gowganda Formation): fine grained, greenish grey; scat tered cobbles and boulders, rounded, mainly granitic. No visible bed ding. 14.3-14.8 m: fine grained arkose, containing disseminated pyrrhotite (boulder or bed?). 149 m: 7.5 cm thick quartz vein. Around 183 m there is a gradational change to less quartzitic, darker greywacke. 238.3-238.6 m: small "zebra" bedding; "varves" 300 to hole axis. 261-261.3 m: small "zebra" bedding; "varves" 250 to hole axis. 275.2-275.3 m: small "zebra" bedding; "varves" 300 to hole axis. 438-446.8 m: Conglomerate with greywacke matrix. Abundant angular clasts of pebble size, some cobbles. The pebbles appear to be greywacke, grey quartzite or grey granite. 481.2-545 m Argillite-quartzite, varved: Dark bands predominate. Quartzite with micro-crossbedding, becomes cleaner, thicker and greenish towards bottom of section. Bedding thickness ranges from 0.3 to 5 cm. Occa sional thicker greywacke bed, unbedded, up to 1.8 m thick. Occasional rafted clasts. 531.9-532.2 m: greenish grey quartzite. 545-561.7 m Diabase: Fine to medium grained, gradational contacts with Huronian rocks. 561.7-619 m Quartzite: Impure, grey, in places pinkish, medium grained, with zones of quartzitic greywacke. 576-577 m: Diabase or lamprophyre dike. 619-663.5 m Greywacke, argillite, quartzite: Interbedded, varves abundant in argil lite. Rafted pebbles abundant at bottom. 663.5-708.7 m Conglomerate: Grades into overlying rocks; matrix is bedded grey wacke. Pebbles are greenstone, granite, and quartz. 677.6-678.5 m: quartzitic greywacke. 708.7-781.5 m Quartzite, argillite, greywacke unit: interbedded and commonly varved. 781.5-800.1 m Conglomerate: Clast rich, polymictic, pebbles and cobbles with a greenish greywacke matrix, a microconglomerate itself. The clasts are better packed than in the conglomerate above. Clasts are quartzo- feldspathic, greywacke, granite, amphibolite, greenstone, and make up 30 percent, locally 50 percent of the rock. 800.1-956.1 m Quartzite: Black speckled. Very uniform, medium grained. Contains rare scattered siliceous pebbles or pebble beds. 956.1-963.1 m Argillite: black-green. 963.1-1034.5 m Quartzite: Black, paler towards bottom of this section. Disseminated pyrite throughout. Rare siliceous pebbles. 1034.5-1051.9 m Quartzite: Grey, coarse grained. 1051.9-1061.3 m Quartzite: Impure, containing perhaps 15 percent greenish argillite debris. Table 5 continued on next page Table 5 continued
1061.3-1064.7 m Intraformational conglomerate: Displays numerous scales, plates, and chunks of argillite in impure quartzite. 1064.7-1078.4 m Argillite: Massive, pale greenish grey; soft. 1078.8-1092.4 m Greywacke: Argillaceous, greenish grey. 1092.4-1093 m Quartzite: Fine grained, mottled. 1093-1095.1 m Greywacke: Gritty, greenish grey, medium grained. 1095.1-1105.8 m Grit (Microconglomerate): Coarse grained, angular debris of shale, quartz, chert. 1105.8-1108.9 m Conglomerate: Fine grained, Terrazzo-like debris. Clast size l to 7 mm. Clasts consist of argillite, quartz, chert, and other lithologies. 1108.9-1121.3 m Argillite: With coarser gritty sections. 1121.3-1169.8 m Conglomerate: With gritty sections. Unsorted, well packed. Polymict. Angular clasts that consist of argillite, quartzite, quartz and jet-quartz. Sizes l to 50 mm, but 7 to 15 mm dominant. Matrix is dolomitic, sugary. At bottom less greenish, with more sulphides and less carbon ate. 1159.4-1169.8 m: Coarse cobble and pebble conglomerate similar to beds above. 1169.8-1171 m Grit: Some clasts. 1171-1171.6 m Transitional layer: between upper grit and Lower Mississagi quartzite. 1171.6-1172.4 m Quartzite: Conglomeratic; pebbles or quartz (white or black), quart zite or chert, angular. 1172.4-1172.6 m Quartzite: Impure, medium grained. 1172.6-1172.9 m Conglomerate: Angular pebbles and cobbles, loosely packed, grey quartzite matrix, some pyrite. 1172.9-1175.6 m Quartzite: Medium grained, grey, with arkosic zone. 1175.6-1175.9 m Conglomerate: Angular quartz and fine grey siliceous rock clasts of pebble size; medium to well packed; dark quartzite matrix with 10 percent pyrite. 1175.9-1176.5 m Quartzite: Coarse grained, white to grey, arkosic; pyrite. 1176.5-1177.4 m Quartzite: Medium grained, white. 1177.4-1178.3 m Quartzite: Coarse, arkosic; pyrite seams. 1178.3-1181.4 m Quartzite: Medium grained, impure, rare pyrite, some siliceous clasts. 1181.4-1181.7 m Quartzite: Coarse grained, arkosic. 1181.7-1181.8 m Pebble layer: Rounded quartz pebbles in yellow quartz sericite matrix. 1181.8-1183.5 m Quartzite: White to grey, some arkosic layers. 1183.5-1194.9 m Quartzite: Coarse grained, dark, impure; dark rounded quartz grains. 1184.9-1187.8 m Transition Zone (Possibly lithified paleosol): Irregular banding and streakiness in several directions, with irregular fragments and "dykes" of Mississagi-like quartzite. 1187.8-1203 m Greywacke: Fine to medium grained. Bedding absent, but some band ing and also streakiness throughout. Slightly sheared. Fine feldspar and calcite veins criss-cross the rock, that is more cracked and dis turbed and finer grained than otherwise similar greywacke of the Mississagi Formation. Therefore: Basement.
1203 m: end of hole. 14 the conglomerate consist of angular to subrounded quartz, feldspar, and rock fragments set in a matrix of chlorite, epidote-group minerals, and, in places, car bonate, biotite, and muscovite. In Table 6, the specimen 50C4 is from a lithic wacke bed in the lower conglomerate unit. The upper greywacke unit consists of grey or dark grey, greenish grey weathering commonly fine-grained greywacke. Conglomerate beds and fine- to medium-grained, pinkish grey arkosic beds are common in the greywacke, and make up about five percent of the upper greywacke unit. The greywacke is commonly a very homogeneous, massive looking rock. A thin laminated bedding (Photo 2) is a characteristic feature of part of the grey wacke unit. Ball and pillow structures, convolute lamination, and intraforma tional breccias were observed. Photo 3 shows an example of such a soft sediment slumping feature. "Rafted" rock fragments are very common throughout the greywacke (Photo 4) and range in size from a few millimetres to about 2 m. These fragments are commonly subangular, but all shapes from angular to rounded were observed. Most fragments are granitic in composition, but gab broic, metasedimentary, and metavolcanic fragments also occur. Paraconglomer ate and, less commonly, orthoconglomerate occasionally form beds within the greywacke that are 0.5 m to several metres thick. A thick unit of paraconglomer- ates forms the top of the formation in northeastern Janes Township. Both types of conglomerate in the greywacke, namely the matrix-supported and the clast- supported varieties, show a wide range of clast size, clast shape, and clast compo sition, and are very similar to the conglomerate of the lower conglomerate unit of the Gowganda Formation in the map-area. The matrix of these conglomerates is commonly unstratified. In thin section, the greywacke and the greywacke matrix of the conglomer ate are seen to be composed of angular to subrounded grains of quartz and felds par ranging from less than 0.03 mm to 0.5 mm in size set in a very fine grained matrix of chlorite, epidote, opaque minerals, and, in places, of carbonate. Biotite and a light greenish muscovite were also noted in the matrix. The fine lamina tion of some greywackes is caused by a fine interlayering of commonly disconti nuous silty, quartz, and feldspar-rich beds and finer grained chlorite and mica rich laminae (see Photo 2). Petrographic data and paleocurrent measurements by D.A. Lindsey (1969) and K.D. Card et al. (1973) indicate that the source of the Gowganda sedimen tary rocks is the greenstone and granite terrain north of the Cobalt region. Col lins (1917), Lindsey (1969), and many other authors have described the rocks of the Gowganda Formation as glacial sediments. Card et al. (1973, p.31) postulate that not all sedimentary features can be explained by glaciation and state the following:
Rocks of the Gowganda Formation were derived under vigorous climatic conditions from older Archean rocks and deposited by south-flowing depositional media in a basin formed initially by faulting. Glaciation was the main process of transportation and deposition, whereas turbidity cur rents, slumping, and erosion along fault scarps were of lesser, though wide spread, importance. There was possibly a transition from continental to marine conditions in the area southwest of Lady Eve lyn Lake during the time of deposition of the Gowganda Formation.
15 quartz- LO LO O5 rH 9 in rounded, eformed. chlorite 1 andstone 553400 5172710 27C8B rH 0 CD O rH CN d J2 0 barkuose C-- CM d t* CO rt q 0 d 3 ^2 T3 J- U3 ua V co ^ oi ^! wea 05 00 CD CO CM 0 ^ epidote secoar- y 550270 ^ d O rt subrounded muscovite, letavolcanics, 5182230 TOWNSHIPS O t rt c- O5 d 0 0 chlorite tite, carbonate oup-minerals etasediments greywacke 0 rH rH CO (M CM 3 raniticrocks, arkoserained LO q bc co q rt d V U y bc bc B S bc Z -C 0 "0 O5 rH lO C.O LO LO 00 d o i -o 0) 0) 0) c/f to" -2 at y 0) o o -3 rt CD O O CM rH LO rt biotil medium-1 LO CO L rH CM carbonal y etavolcanic greywacl lith greywacli O5 CD Q O5 (N rH r d "3 graineoarse CM d bc subrounde O CM (M Z co etasedimen LO C- rt y LO rH q 1 LO K d I-Hcc V rt Z bc y y s s z"
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Photo 2-Laminated silty greywacke, Gowganda Formation. Plane polarized light, scale = 0.5 cm, large thin section 19C16. Location: Northwestern Janes Township, easting 546260, northing 5168240.
Lorrain Formation
Sandstones, namely quartz arenite and arkose of the Lorrain Formation, un derlie southeastern McNish Township and sectors of east-central Janes Town ship. Minor silty greywacke occurs in a few places. The sandstones are medium grained, grey, light grey, in places pinkish weathering quartz arenite and arkose. Rounded quartzite pebbles up to about 10 cm in size have been observed in a few places. Thin pebble beds and a thin cream-coloured argillite bed have been found in a diamond-drill hole (Assess ment Files Research Office, Ontario Geological Survey, Toronto). 17 McNish and Janes Townships
OGS10.026
Photo 3-Soft sediment deformation, greywacke, Gowganda Formation. Plane polarized light, scale = 0.5 cm, large thin section 15C4. Location : Southwestern McNish Township, easting 54720, northing 5175250.
OGS 10,027
Photo 4-Rafted clasts in greywacke, Gowganda Formation. Western Janes Township.
18 TABLE 7 MODAL ANALYSES OF ROCKS OF THE LORRAIN FORMATION, JANES AND McNISH TOWNSHIPS.
Modal Analyses in Volume Percent
Specimen Number 6C14B 27C1 29C16
Quartz 65.9 52.1 60.8 Microcline 4.9 1.6 4.1 Plagioclase 11.1 13.2 12.6 Muscovite 2.9 15.7 8.6 Chlorite 0.1 Biotite 1.0 0.3 tr. Matrix 14.1 17.1 13.9
Grain size (mm) 0.2-0.7 0.4 0.2-0.7 Grain shape deformed deformed deformed
Location: Easting: 549610 554250 552240 Northing: 5168300 5172450 5171550
Three dark grey, silty greywacke beds up to 14 m in total thickness have been observed in central Janes Township, about 1.5 km west-southwest of southern Sargesson Lake (easting 549190, northing 5167720) where the Gow ganda Formation seems to grade into the Lorrain Formation. In thin section, the sandstones are seen to consist of quartz, plagioclase, mi crocline (see Photo 20), chlorite, greenish muscovite, and, in Janes Township, also a little biotite. In Table 7, three modal analyses are presented. A reliable classification of the modally analysed rocks was not possible because all three samples appeared to be strongly cataclastic. The rocks mapped as Lorrain sandstone (Map 2425, back pocket) were clas sified as Lorrain Formation by Jas. E. Thomson (1960, Chart H) and as Missis- sagi Formation by Lumbers (1973). The author of this report supports Thom son©s classification, because the sandstone appears to overlie the Gowganda Formation in many places, although no contacts of Gowganda Formation sedi mentary rocks with overlying Lorrain sandstone have been observed. Strike and dip measurements of bedding planes in both formations in many places indicate that the sandstones overlie the rocks of the Gowganda Formation; evidence of faulting was not observed. In January 1977, Hollinger Mines Limited(Mander- strom-Saville option) diamond drilled a 291.7 m deep hole through the quartz sandstone that is herein classified as Lorrain Formation in Pardo Township east of McNish Township and north of Pud Lake to evaluate the uranium poten-
19 McNish and Janes Townships
TABLE 8 STRATIGRAPHIC SECTION THROUGH PART OF THE LORRAIN FORMATION FROM DIAMOND-DRILL HOLE LOG, HOLLINGER MINES LIMITED, PARDO TOWNSHIP, ASSESSMENT FILES RE SEARCH OFFICE, ONTARIO GEOLOGICAL SURVEY, TORONTO.
Depth (m) Description of rocks (as in the diamond-drill report).
0-3.8 Overburden 3.8-176.8 Dark grey to blue grey quartzite, local quartz pebble beds, in places sericitic, in places minor pyrite. 13.1-13.7 m: Two 7.5 cm thick quartz pebble beds. 13.7-14.3 m: Scattered pebbles. 17.1-17.2 m: Pebble bed, locally chloritic. 18.2-83.8 m: Scarce scattered pebbles in quartzite. At 68.6 m bedding at 850 to cone axis. At 82.3 m a 10 cm thick bed of cream coloured argillite. 176.8-188 Light grey, coarser-grained quartzite with scattered quartz pebbles, minor quartzite. Sericitic bands in places. 188.1-201 Bleached massive quartzite, grading to grey green coloured quartzite. No pebbles. 201.3-205 Dark finer-grained quartzite grading into coarser grained grey green quart zite with local pebbles. Bedding at 900 to core axis. 205.7-291 Continuing from 205.7 m onward the rock is a grey to grey green quart zite with occasional very fine pebbly horizons. 210.3-212.1 m: Gradation to fine pebble zone. Occasional pyrite. 212.1-221.0 m: Greenish quartzite. Only one clast observed. 221.0-222.9 m: Gradual increase of alteration. Near the lower part of this horizon occasional clasts and bleach ing and sericitization. 222.9-229.2 m: The quartzite becomes more "granular" in appear ance. Minor feldspar content. 229.2-233.6 m: Coarser-grained granular quartzite. Beginning at 284.4 m, the rock grades less "granular" and acquires the more normal characteristic of a quartzite at 285.6 m. At this depth the quartzite is relatively fine grained, greyish to grey green in colour and moderately altered with sericite. Minor pyrite and feldspar.
tial of the rocks. No anomalous radioactivity has been measured and the se quence encountered in the diamond-drill hole is not typical either for the Missis- sagi Formation or the Lorrain Formation (Table 8). Disseminated pyrite is com mon in the diamond-drill cores and this possibly supports the classification of the rocks as being part of the Mississagi Formation. This evidence, however, is not conclusive, and the author favours the classifi cation of the sandstones as being part of the Lorrain Formation because of the above-mentioned structural evidence.
20 NIPISSING INTRUSIVE ROCKS
Gabbro
Nipissing gabbro intrusions occur throughout the area as irregularly shaped or sill-like bodies. The original shape of the intrusions is not known due to strong faulting, folding, and erosion during the geological evolution of the rocks. Figure 2 is a sketch-map showing the distribution of the gabbros within the map-area, the thicknesses (Assessment Files Research Office, Ontario Geological Survey, Toronto) of some of the igneous bodies, and the strike and dip of some contacts observed in the field. Most contacts are assumed to be intrusive. However, fault contacts also occur. Near the contacts, sedimentary fragments that are several centimetres to several metres in size may be found in the gabbros. The varia tions in the preserved thicknesses of the large gabbro body in eastern Janes Township might be explained by folding of a tabular gabbro sill or by the as sumption of a primary oblong lopolith-like intrusion with thick central parts and thin rims. The most common rock type of the Nipissing intrusions is a medium- grained, dark greenish grey, grey-olive weathering subophitic gabbro. Near its contacts, the rock is finer grained and exhibits a diabase-like texture. Pegmatitic gabbros occur in small pods within the medium-grained gabbro and are com monly found in association with small, light coloured and white pinkish weath ering felsic schlieren. These pegmatitic pods and felsic schlieren are commonly only 0.5 m to a few metres in size, and exhibit gradational contacts with the gab broic host rock. Mineralogically, there are no differences between the finer grained diabase of the contact zones and the medium-grained, subophitic gabbro. Primary min erals are quartz, plagioclase, pyroxene, biotite, apatite, sphene, and opaque min erals. Secondary, namely metamorphic and alteration minerals are actinolite, talc, epidote, scapolite, chlorite, leucoxene, and carbonate. Primary quartz makes up two to eight percent of the gabbro. In one thin section, a granophyric intergrowth of quartz and sodic plagioclase was noted. The plagioclase content ranges from about 38 to 65 percent. The plagioclase forms idiomorphic to hypidiomorphic laths that are about 0.2 to 2.5 mm long. The anorthite content varies from An55 to An65 in little altered rocks. However, in many places, the plagioclase is strongly saussuritized and completely replaced by clinozoisite, albite, and little sericite. The "filled plagioclase" was counted as plagioclase in the modal analyses (see Table 10). Pyroxenes are commonly hypidiomorphic to xenomorphic. Orthopyroxene and clinopyroxene occur and fill the space between plagioclase crystals; however, both minerals may contain idiomorphic plagioclase laths up to 0.5 mm long. The orthopyroxene is a somewhat brownish, weakly pleochroic hyper- sthene-bronzite that in places forms the cores of clinopyroxene, which is an al most colourless augite. Exsolution lamellae of augite in the orthopyroxene are spindle-like, in places myrmekite like, discontinuous over the width of the host, and up to 0.01 mm thick. Where the orthopyroxene is an inclusion in a neigh bour to an augite crystal, the augite exsolution lamellae show the same extinc- 21 McNish and Janes Townships
Strike and dip of contact of Nipissing gabbro. Vertical drill hole, with thickness of Nipissing gabbro, in metres.
Figure 2-Surface distribution and thicknesses of Nipissing gabbro. 22 tion as the host or neighbouring augite. Some orthopyroxenes show exsolution lamellae only in their inner parts. The exsolution lamellae are commonly parallel to the (100) crystallographic plane of the host orthopyroxene. The augite is almost colourless, commonly twinned, and shows herring bone-like exsolution lamellae of orthopyroxene parallel to the augite (100) crys tallographic plane. In a few places, clinopyroxene is enclosed by a common green hornblende. Biotite was not noted in every thin section of the metagabbro. It is dark brown to brown, pleochroic, and is believed to be of primary origin. Biotite is hy pidiomorphic, commonly concentrated around titanomagnetite crystals, and did not grow to replace other ferromagnesian minerals. Other primary minerals in medium-grained gabbro are hypidiomorphic apa tite, weakly pleochroic sphene, and opaque minerals. The average content of opaque minerals is about l percent. In mineralized samples up to 10.4 percent opaque minerals were observed. The ore minerals, as determined under the ore microscope, are chalcopyrite, pyrrhotite, minor pyrite, and magnetite, and are present in this order of abundance. Secondary minerals in the gabbro are actinolite, talc, epidote, scapolite, chlorite, leucoxene, and carbonate. In places, these minerals have replaced all or almost all the primary minerals. Actinolite replaces pyroxene and forms weakly pleochroic hypidiomorphic laths up to 1.2 by 2.1 mm in size or fine fibrous uralite. Talc replacing pyroxene was also observed. Photo 5 shows talc pseudomorphous after pyroxene. The iron of pyroxene, not absorbed by the talc,is precipitated along fractures of the for mer pyroxene. Tremolite-actinolite, not visible in the photo, has started to re place talc. In one place, 0.8 km south of Wawiashkashi Lake, medium-grained gabbro exposed as a small isolated outcrop, is almost completely replaced by carbonate. This carbonatization is not accompanied by any mineralization. Pegmatitic gabbro consists of long actinolitic hornblende needles generally 0.3 by 2.0 cm, in places 0.8 by 7.0 cm in size, set in a medium-grained matrix con sisting of plagioclase, quartz, muscovite, and biotite. The felsic differentiates are composed of about 20 percent quartz, plagioclase (An 15+5), minor potassic felds par, light greenish muscovite, and light brown to greenish brown biotite. Chemical analyses of mineralized Nipissing gabbro are presented in Table 9. The analyzed samples are grab samples from mineralized showings in Janes Township. Table 10 presents nine modal analyses. Table 11 shows an additional 21 modal and chemical analyses obtained from diamond-drill cores from central Janes Township. In Figure 3, these analyses are illustrated graphically showing the chemical and mineralogical variations of the gabbro with the length along the diamond-drill hole. It is to be noted that epi dote minerals are present in minor amounts in all the thin sections examined, but they form larger recrystallized grains from a length of about 7 m to 15 m and further on in the drill core. The scapolitization of plagioclase is strongest at about a length of 35 m. At about a length of 38 m, the gabbro is strongly silicified and almost all plagioclase is replaced by quartz and chlorite. The unconformity of related diagram pairs in Figure 3, for instance quartz - Si02 and opaque miner als - Cu, Cr, Ni, is believed to be caused by the inevitably unsatisfactory sam pling method. A modal analysis of a thin section of a randomly picked core speci-
23 McNish and Janes Townships
OGS 10,028
Photo 5-Talc (T) and magnetite (black) replacing pyroxene, Nipissing gabbro. Plane polarized light, scale 0.05 mm, thin section 19C9. Location: Western Janes Township, easting 547350, northing 5169990.
men is shown vis-a-vis a chemical analysis of a composite specimen of about 30 percent of a 1.5 m long diamond-drill core section. The nickel and copper content of the diamond-drill cores in general appears to decrease, but chromium, as well as the total iron tend to increase with depth. No evident magmatic differentition trends can be recognized for ti e other plots on Figure 3.
Quartz Monzonite
Quartz monzonite occurs mainly in eastern Janes Township where the best exposures are along Highway 805. Another readily accessible body of this rock type is located in central Janes Township about 0.7 km west of Sargesson Lake. The rocks intrude the Nipissing gabbro and are believed to represent late di fferentiates of a "Nipissing magma". In central Janes Township they include large rafts of Huronian metasediments that are up to about 15 m in size. The quartz monzonite is very fine grained to aphanitic, in places porphyritic, showing a few small (maximum 0.5 mm by 1.0 mm) feldspar phenocrysts. At a 24 TABLE 9 CHEMICAL ANALYSES OF NIPISSING-TYPE GABBRO, McNISH AND JANES TOWNSHIPS.
Major Components in Weight Percent Specimen Number 18C10 23C5 23C7 20C3B* Si0 2 51.30 48.80 41.70 55.40 A1 203 13.70 13.70 11.10 20.20 Fe 20 3 3.03 3.78 14.20 3.27 FeO 8.70 6.59 5.20 6.42 MgO 8.99 8.91 4.17 3.30 CaO 9.99 11.70 7.97 0.56 Na 2 O 1.66 1.24 1.67 1.03 K 20 0.42 0.35 0.10 3.87 Ti02 0.52 0.45 0.56 0.80 MnO 0.19 0.15 0.10 0.12 0.08 0.07 0.08 0.20 0.60 1.24 2.23 4.07 H 20- 0.24 0.30 1.18 0.46 C0 2 0.16 0.28 0.15 0.08 S 0.73 1.77 9.48 0.03 TOTAL 100.31 99.33 99.89 99.81 Trace Elements in ppm Cu 1740 6200 2.30 85 Ni 640 2320 1.36 131 Zn 86 92 36 54 Co 72 97 480 36 Pb 14 20 50 10 Cr 77 840 252 206 Ba 80 60 30 190 Li 8 14 8 52
* Border facies Note: Chemical Analyses by Geoscience Laboratories, Ontario Geological Survey.
few localities, for instance in central Janes Township, the rocks are fine to me dium grained. The aphanitic varieties are dark grey or almost black; the coarser grained ones are pinkish grey. On the weathered surface all types are pinkish. In thin section, the rock is seen to be composed of an inequigranular, pan-xe- nomorphic matrix of plagioclase, microcline, quartz, hornblende, and/or mica. Chlorite, xenomorphic sphene, and opaque minerals, hypidiomorphic apatite, and minor epidote make up the rest of the rock. Microcline and/or plagioclase phenocryst^ are hypidiomorphic. Feldspar in the matrix is commonly strongly altered and stained by a very fine iron oxide dust that causes the common pink ish colour of the rocks. The plagioclase composition is An 30 5. A green to very
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—" ^ ?- 23j.ia, o CD C S .E. II .i^x ^ -ll||.a| a |.g a l S |cS .2 O S E S. l I|llfl|i|Mli||l4 3 g ^15 S O'o.a.•<•*:: SoSwtnM'J 28 '.CQ. W O •d CO 2ra .5E. yen -i o w o C g) o ui O S 8 EM-s ® If E! *-2 cra o ra .o "ra d o S| l5 •a? 5 2 o E 3 c x o o S o. E S o ^t- os T- CO ,- r .E o oo c c CO .26" o^-cMro^fmcor^oocna l S H^CM i-^co ^t- i-in1 "S.S CDi-i- i i -5 -^ ^ "^ ** "^ Is ra co 0) 29 McNish and Janes Townships ra jo o. x Ul JD .O CO O) - ra T3 05 o c CO •— CO T- . o H S 8 i 30 ../•^ . ./'V^mi** -, - TL©Aa&L*. OGS 10,029 Photo 6-Granophyre in quartz monzonite, crossed polarizers, scale = 0.15 mm, thin section 7C1B. Location: Central Janes Township, easting 550910; northing 5169400. dark green to almost black hornblende (ZAc = 15-170 ) is present in some thin sections. In other thin sections, commonly in strongly deformed specimens taken along Highway 805, mica was observed. Some specimens show very dark brown to brown biotite and hornblende, some biotite or muscovite alone. The coarser grained varieties in central Janes Township are strongly granophyric (Photo 6). Close to the Grenville Front Boundary Fault, at the railroad cuts near Glen Afton, the rocks are weakly recrystallized and are schistose to gneissic. The rocks were not modally analyzed because of the fine grain size, the com mon strong alteration, and the deformation (Photo 7). The classification of the rocks as quartz monzonite is therefore based on chemical analyses that are pre sented in Table 12. This table also shows the CIPW norms. There is no clear evidence for classifying all the quartz monzonite as intru sive. The possibility that the very fine grained and aphanitic varieties are extru sive cannot be disregarded. The strong deformation and alteration that obliterated practically all primary textures, though, make a reliable decision im possible. Extrusive contacts, such as quartz monzonite flowing over older rocks, were not observed. Quartz monzonite intruding other quartz monzonites was noted. This relationship supports neither mechanisms of emplacement. 31 McNish and Janes Townships OGS 10,030 Photo 7-Strongly deformed quartz monzonite. Scale, 1 cm, specimen 9C4B. Location: Southeast ern Janes Township, easting 554060, northing 5166170. Bruce (1932) described quartz monzonite as feldspar porphyry and noted that the rock is cut by a diabase dike about 3 m in width "at the ridge east of Theriault Lake". He assumed that the diabase belongs to the Nipissing gabbro southwest of Theriault Lake. Granitic Dike Rocks Intruding the Gabbro A granitic dike about 60 cm thick, occurs in the Nipissing gabbro 2.1 km northwest of the mouth of the Chiniguchi River where it meets the Sturgeon River. The dike strikes N400E and dips 500 to the southeast. Ossington Explora tions Limited (Assessment Files Research Office, Ontario Geological Survey, To ronto) diamond drilled through a non-outcropping possibly similar, granitic dike about 58 m thick near the eastern bank of the Sturgeon River about 0.4 km north of the mouth of the Chiniguchi River. The dike rock northwest of the mouth of the Chiniguchi River is fine to me dium grained, pinkish grey, and weathers pinkish. The contacts with the host rock are sharp and a small and short apophysis from the dike into the gabbro was observed. In thin section, the rock appears to consist of plagioclase (An 25+5)* quartz, and microcline. Grain sizes of these minerals vary from 0.1 to 0.5 mm. Chlori- 32 TABLE 12 CHEMICAL ANALYSIS AND CIPW NORMS OF QUARTZ MONZON ITE, McNISH AND JANES TOWNSHIPS. Specimen Number 9C12A Major Components in Trace Elements Weight Percent in ppm SiO 2 69.50 Cu 49 Al 2Os 12.90 Ni 16 Fe2O3 3.65 Zn 66 FeO 2.11 Co 7 MgO 0.75 Ph 14 CaO 1.22 Cr 10 Na 2O 3.64 Ba 600 K 2O 3.95 Li 6 TiO 2 0.57 MnO 0.06 P2C-5 0.18 H 2O* 0.67 H 2O- 0.20 CO2 0.12 S 0.02 TOTAL 99.54 CIPW Norms in Weight Percent Q 28.70 OR 24.16 AB 33.79 AN 5.04 DI 0.00 FO 0.00 FA 0.00 NE 0.00 C 0.96 AP 0.39 PO 0.07 IL 0.82 MT 3.88 HM 0.05 EN 2.14 FS 0.00 33 McNish and Janes Townships TABLE 13 MODAL AND CHEMICAL ANALYSES OF A GRANITIC DIKE INTRU DING NIPISSING-TYPE GABBRO, McNISH AND JANES TOWNSHIPS. Modal Analyses Major Components Trace Ele in Volume Percent in Weight Percent ments in ppm Specimen Number 19C3 Quartz 46.5 Si0 2 75.90 Cu 11 Plagioclase 31.1 A1 203 12.10 Ni 15 Microcline 11.8 Fe 20 3 0.76 Zn 12 Myrmekite 1.3 FeO 0.65 Co 5 Chloritized biotite 0.7 MgO 1.00 Pb 10 Actinolite 1.9 CaO 1.07 Cr 17 Epidote 6.1 Na 2O 6.14 Ba 20 Opaque minerals 0.6 K 2 0 0.14 Li 3 Ti0 2 0.33 Location MnO 0.02 Easting: 546010 0.08 Northing: 5170420 0.53 H 2 0- 0.28 C02 0.10 S 0.01 TOTAL 99.11 Notes: Chemical analyses by Geoscience Laboratories, Ontario Geological Survey, Toronto. tized biotite, actinolite, epidote, and opaque minerals make up 9 percent of the rock. Plagioclase is hypidiomorphic. All other minerals are xenomorphic. Tiny actinolite needles, about 0.003 by 0.1 mm in size, occur as small sheaf-like bun dles. The texture of the rock is non-oriented and more or less equigranular. A modal analysis and a chemical analysis of the rock are presented in Table 13. The rock is a granodiorite in the IUGS classification of plutonic rocks (Streckeisen 1974, 1976) and a quartz monzonite in the Ontario Division of Mines classification of granitic rocks (Ayres 1972). SUDBURY-TYPE BRECCIA AND PSEUDO!ACHYLITE Sudbury-type breccia and pseudotachylite have been found at a few places in the map-area. The breccias occur at two localities in Janes Township, namely 0.6 km northwest of Sargesson Lake and 0.4 km south of Floodwood Chutes just west of the Sturgeon River. Northwest of Sargesson Lake, the breccia consists of big, subrounded clasts of quartz sandstone of the Lorrain Formation set in a fine-grained matrix. This matrix consists of a quartz-rich rock flour and small angular to rounded quartz 34 sandstone fragments. The big clasts are up to 80 cm in diameter. The breccia outcrops in an area underlain by quartz sandstone of the Lorrain Formation. The breccia near the Floodwood Chute contains fragments ranging from a few millimetres to 10 m in size. The fragments consist of medium-grained grani tic rocks, Nipissing gabbro, fine-grained diabase, and Gowganda Formation grey wacke. The matrix is very fine grained and is composed of a rock powder derived from wall rocks and fragments by tectonic abrasion. Pseudotachylites are aphanitic, black or grey ultramylonite rocks that pene trate, like igneous injections, the host rocks in a very irregular pattern. In the map-area, these rocks have been found at only three locations in McNish Town ship, and appear to be associated with major faults. They form veinlets and dis continuous dikes that are up to 25 cm wide. Pseudotachylites and the host rock in the map-area, whether Nipissing gabbro, or Gowganda Formation sandstone, are of the same chemical composition. The pseudotachylite originated from the host rock by strong and abrupt tectonic forces. Pseudotachylites are known from major tectonic faults and from meteorite impact craters. Pseudotachylites and Sudbury-type breccias are found around the Sudbury Basin and are believed to be related to the Sudbury Event, which is due to either a volcanic explosion or an impact of a meteorite. The reader is referred to B. Dressler (1977c) where he will find a more detailed discussion of these rock types and where additional references are presented. There is no clear evidence that the pseudotachylites and the breccias in McNish and Janes Townships are re lated to the Sudbury Event or if they originated through conventional tectonic forces. The rocks are younger than the deposition of the Huronian sediments and the intrusion of the Nipissing gabbro. No geological data are known that would allow to draw an upper time limit for the breccia and pseudotachylite- forming event. GRENVILLE STRUCTURAL PROVINCE Middle Precambrian METASEDIMENTS Most of the terrain south of the Grenville Front Boundary Fault is underlain by metasediments. The rock type varies in colour and quantitative mineralogical composition. For mapping purposes two units were differentiated, a biotite and biotite hornblende plagioclase gneiss unit and a unit of feldspathic gneiss. The first unit is believed to represent metagreywacke, the second, meta-arkose. All these rocks were metamorphosed during the Grenville orogeny. The age of sedi mentation of the original rocks is unknown. The rocks are intruded by amphi- bolites that are believed by the author to be equivalents of the Nipissing gab- bros. Therefore, the rocks are somewhat arbitrarily classified as Middle Precambrian. 35 McNish and Janes Townships OGS 10,031 Photo 8-Migmatitic biotite-plagioclase gneiss, southwestern Janes Township. In places the gneisses are migmatitic (Photo 8). Where the rocks contain 50 percent or more of granitic neosome they were mapped as migmatites. Biotite Plagioclase and Biotite-Hornblende Plagioclase Gneiss These metasediments are well foliated, gneissic, and in a few places schis tose. They are grey to dark grey and fine to medium grained. A compositional layering that looks like bedding is common. In thin section, the gneiss is seen to be composed of quartz, plagioclase, biot ite, and hornblende. Garnet and a little microcline may be present. Accessory minerals are opaque minerals, apatite, sphene, zircon, and in places, allanite. Quartz is weakly strained or unstrained and shows straight grain boundaries against quartz and plagioclase. The latter mineral is unaltered, and xenomorph ic, forms 15 to 30 percent of the rock, and is an oligoclase-andesine (An 3015). The hornblende is a common green hornblende and lies with its long crystal lographic axis in the foliation plane. It is hypidiomorphic to xenomorphic, and commonly poikiloblastic including such minerals as quartz, plagioclase, zircon, and magnetite. Its optical properties are given in Table 14. The biotite is dark brown, and in places is almost opaque to brown. It is re- crystallized as are the other major minerals and includes magnetite and zircon. 36 TABLE 14 MODAL ANALYSES OF METASEDIMENTS SOUTH OF THE GREN VILLE FRONT BOUNDARY FAULT, McNISH AND JANES TOWN SHIPS. Specimen Number 76C7 11D17A 13D4 13D14 76C1 Quartz 33.0 43.0 34.0 27.4 41.4 Plagioclase 28.0 19.0 32.2 14.2 Microcline 20.4 24.2 11.2 — Hornblende 7.6 — 10.4 29.2 Biotite 7.2 12.8 11.4 10.4 0.4 Garnet — — — 15.6 55.2 Sphene 1.6 0.8 0.4 2.2 Apatite 0.2 Tr. 0.2 0.2 Allanite — 0.2 0.2 0.2 Opaque minerals 2.0 — — 0.6 3.0 Plagioclase composition An25±5 An25±5 An26±5 An30±5 — Location Easting: 545250 552350 551000 550560 544400 Northing : 5164320 5164650 5164930 5165190 5165160 Notes: Hornblende (specimen 13D14), optical properties: X - yellowish green 2VX = 810 ± 50 y = green ZAc = 200 ± 20 Z z green Field Names: 76C7: Meta-arkose 11D17A: Meta-arkose 13D4: Meta-arkose 13D14: Garnetiferous biotite-hornblende gneiss "Metagreywacke". 76C1: "Garnet nodule" in garnetiferous biotite plagioclase gneiss (see text). Its (001) crystallographic plane commonly lies in the foliation plane, but biotites showing their (001) plane normal to the foliation were also observed. In garneti ferous gneiss, biotite curves around garnet (Photo 9). Garnet is a common mineral in gneiss, but was not observed everywhere. In places, for instance in southwestern Janes Township, near the Canadian Na tional Railway tracks, garnet constitutes more than forty percent of the rock. The garnet is brownish red and commonly l mm to about 5 mm in diameter. In a few places, however, for instance southeast of Chudleigh and south of the Ka- bikotitwia River (Bruce 1932, p.7), garnet reaches diameters of over 2.5 cm. The 37 McNish and Janes Townships OGS 10,032 Photo 9-Poikiloblastic garnet wrapped around by biotite and muscovite, biotite-muscovite-horn- blende gneiss. Plane polarized light, scale ^ 0.5 mm, thin section 13D14. Location: south-central Janes Township, easting: 550560, northing 5165190. garnet is commonly poikiloblastic, hypidiomorphic, and grew replacing biotite. In a garnet-rich rock, a biotite-chlorite schist in southwestern Janes Township near the Canadian National Railway tracks and just south of the Kabikotitwia River, big garnet-quartz ball-like or lensoid bodies were observed that are up to 15 cm in diameter. Up to about 15 to 20 "balls" may be found on a l m2 outcrop surface and give the rock a conglomerate-like appearance. Photo 10 is of a thin section of such a ball-like structure showing amoeboid, poikiloblastic garnet, and quartz. Garnet constitutes about 55 percent, and quartz about 40 percent of the rock (Table 14). The origin of these garnet quartz "balls" is unknown. The compositional layering that is commonly seen on an outcrop surface can also be noted on a smaller scale in thin section. Feldspathic Gneiss Feldspathic gneiss is fine to medium grained, pinkish grey, and weathers pink. A compositional layering that is some millimetres to some centimetres thick and that looks like bedding on weathered surfaces can be seen in many 38 OGS 10,033 Photo 10-Amoeboid garnet. Garnet, quartz, and opaque minerals. Plane light, scale 0.2 mm, thin section 76C1. Location: Southwestern Janes Township, easting 544400, northing 5165160. places. In the rock, feldspar constitutes 35 to 50 percent and quartz as much as 45 percent (Table 14). Dark coloured minerals are biotite and hornblende, and in a few places, subordinate garnet, sphene, apatite, allanite, and opaque minerals also occur. In thin section, feldspathic gneiss shows textures and structures similar to those of biotitic gneiss. Dark brown biotite and green hornblende form an open fabric in a granoblastic mosaic of plagioclase, microcline, and quartz. All these minerals are recrystallized; feldspars are commonly clear and unaltered, and quartz is only weakly strained. The pinkish colour of the feldspathic gneiss is caused by a fine iron oxide dust within the feldspars. Garnet is pink to pinkish brown, xenomorphic, and less than l mm to about 2 mm in diameter. Allanite is brown, strongly altered, and rimmed by epidote. These allanite-epidote grains are up to 0.2 mm in size. Sphene and opaque minerals, mostly magnetite, are xe nomorphic. Migmatites The rocks mapped as migmatites contain about 50 percent or more medi um-grained, and in places, pegmatitic mobilizate. Metamorphism accentuated 39 McNish and Janes Townships the original bedding or destroyed it. "Lit par lit" mineral segregations subparal- lel to gneissic layering are a few millimetres to some centimetres wide and are commonly discontinuous. Granitic neosome that cuts across the gneissosity forms veinlets and irregularly shaped bodies. These metatectic textures, the "lit par lit" segregations and the cross-cutting neosome, are more common than dia- tectic (Mehnert 1972) nebulites in which schlieren-like relicts of almost com pletely granitized gneiss swim in a medium- to coarse-grained neosome. The granitic neosome consists mainly of quartz, microcline, and minor plagioclase with accessory biotite, magnetite, and in a few places, muscovite. The diatectic mobilizate appears to contain more biotite than the neosome of the metatexites. * In a few places, the anatexis produced coarse-grained, microcline-rich peg matitic, granitic rocks that do not show any relicts or inclusions of metasedi- ments. These pegmatites are included in map-unit 9c of the geological map (Map 2425, back pocket). MAFIC INTRUSIVE ROCKS Fine- to medium-grained amphibolite occurs in several places along the Grenville Front Boundary Fault. Just north of the Boundary Fault these rocks can easily be recognized as equivalents of the Nipissing gabbro. Also at the Boundary Fault itself, amphibolite can be recognized as Nipissing gabbro de spite a strong deformation. The rocks show relicts of undeformed gabbro in an otherwise strongly faulted rock (Photo 11). Therefore they, and the "amphibol ite schist" just north of the Boundary Fault were mapped as Nipissing gabbro. South of the Boundary Fault amphibolite occurs that is believed to be equiv alent to the Nipissing gabbro, because at two localities the Grenville Front Boundary Fault appears to cut across an intrusion of Nipissing gabbro (see Map 2425, back pocket). At the Boundary Fault, or just north of it, the rocks are dark greenish grey; south of it, they are recrystallized and almost black. Further south of the Boundary Fault, amphibolite is very similar in appearance to the rocks just south of it, and is therefore somewhat arbitrarily classified as Middle Precambrian. Amphibolite is fine to medium grained, and in thin section is seen to be com posed of granular plagioclase (An35±5), hypidiomorphic common green horn- blende,a little quartz, and accessory minerals such as biotite, apatite, and opa que minerals. Plagioclase makes up an estimated 50 percent of the rock, hornblende about 40 percent, and quartz l to 5 percent. Late Precambrian ANORTHOSITE SUITE INTRUSIVE ROCKS Anorthosite Suite Intrusive Rocks are widespread in the northwestern part of the Grenville Structural Province of Ontario (Ayres et al. 1971 a and b; Lum- 40 OGS 10,034 Photo 11-Faulted Nipissing gabbro showing little deformed relicts in strongly sheared rock, Grenville Front Boundary Fault, southwestern Janes Township, at Canadian National Railway tracks. bers 1973,1975). Lumbers (1975) stated: ...that the Anorthosite Suite Intrusive Rocks are less deformed and less recrystallized than Mid dle Precambrian granitic rocks which they locally intrude and that these relationships along with preliminary geochronologic studies suggest that the Anorthosite Suite Intrusive Rocks are Late Pre cambrian in age. In the map-area, intrusive contacts of anorthosites with Middle Precam brian metasediments and inclusions of metasediments in the anorthosites have been observed. In the map-area, an anorthosite - anorthositic gabbro - quartz gabbro (Table 15) suite of rocks occurs in the southeastern and southwestern parts of Janes Township and north of the Grenville Front Boundary Fault on Highway 805 in east-central Janes Township. At the latter locality, anorthosite appears to in trude the Middle Precambrian Nipissing gabbro. The anorthositic rocks at all three occurrences in Janes Township belong to the same intrusive as shown on Lumbers' (1973) preliminary map of the River Valley Area. Anorthosite and related mafic rocks are commonly medium- to coarse- grained gneissic rocks. Massive anorthosite occurs only in a few places in south western Janes Township. A primary, igneous compositional layering is present in many places (Photo 12). Near the border of the anorthositic complex, the 41 0) LO ^^"^ O^ ^D GO rH O"5 CO O"5 ^^ CD 'O ^ lac W d "* rn cd CM d r4 in od SSc'3 Si ^ ^ Tt 05 g o tt O in co o :g X 05 c ^ i-* 'g J- 0) C .2 "S c c OH M w 0 c .2 -rj ffi •"* Q -u in coo CM (M ,j co T}* rt ^ Tt Ji *c oo -o . w o TOWNS continue 0 d Tt co d - ^ ^ d " k " 1 S 1 ||| oi | in CD ^ .g Si 00 10 -oo in PM c rH z rt "-a CM 3 oo" U CMCNCM s-.'^ tO —J OOWUO) rt 1^2" "" Se |o |1| H O ~t Tt CD C ^3 -S O in rH lac rt t- in MO F^H C W rt ,—i, 0) ^ 'y oo CM 'C mocNTtcM Ttco Oin oowcjo QJ OH S? co Tt Tt c-: do in +I 2 3 'S S .S U3 H ^ " -t w -N ^g ^S'SS-c oT i—l c o ^ ^ 5 x S •^* a J in rH bC -g ~ o ^ g HHI 0) C u P (^ rt 00 O) -., ttT (N 0 W S COCOrHCOrH CNCO CMrtm OOWNQ "H H -Sgcc'ddd dc^ rt tJ +I ^S'i^ 'a 00 K^m Tt Tt in a; 3 "2 0) 0 •^ t- in CD c o- S c in rH ac oT ffi •- lO ea EH "u 0) tf EA O .2 Z "rt co de ^* coo Ttoo CM oo,..'iJj-iTtTt cMinm oo uoo "tt ^g rHO CO 0---dcO Tt+l+1 gg ||| 01 o ea T3 C^ in CD C jC So 00 O in rH lac -w "^ JS"o 00 S ^o i rt JS"tt d CO in CQ COO5 O COiJ liJCMCO 00 in OO 0)UO) 0) z -1-1 (4-1 gdrHTtd- -cod 2 g li all rt a ^ ^ c^ at J-J X 2 Tt CD g ^ -C ea in rH C rt t- o in MO tt c O wi S ffi •a0 - o 00 Q cot~-oocM cor~ coo—j oooijjo M rt rtoomo coco OCM —' ^? ;5 "* *H j tt^ Z .. ^o to rt CD 2 o* S, (A 2* rt JS *sj in •y tt Q . o; CT .2 -o O SJ SG J2 .S S ^ J2 ^ 4) g a) 2 o c ^ ^ "rt z g * S 'S 1 8 Si S rt ^i o)^-a^ 'S -s at -w D '-3 -S '^3 IM in C cflOr-iO) H Q. ea "* -4-9 oj ** ii S y * — ^. S ^ ^ ^0)0)3, ^^So!c o -z * •- 0) UJ -i •5 Z .2. o c g -S S '-S o cr.2 'S "C c 2 .2 g o "w '3 ea CO o) SSfCfeSo-SsyS — 2. -cSSMgc S "g tt '5,.5^ o >-.;:Q, Q< •i3 o•tt.Co)W•2.2o< o ^S 1 i 1- oo Cyex.UffiEHCQoo^NOWOooOcHO, O- J O Z rH (M 42 c O) CJ V. O) PH -*j 3 03 c J2 c O) c o o. S o o SH o 11 l is ^ OOOOLOOOOCDCOIMtDC^INCO o c^ Q9'~! r1 T~! cvl cc! a! c1'~! c! 10. C^! c? N -2 — •- 4) 73 31"Sea* c f 80 2 o "S c a, t M McNish and Janes Townships OGS 10,035 Photo 12-Layered anorthosite gabbro, southeastern Janes Township. rocks are commonly richer in mafic minerals and in gabbroic and ultramafic lay ers than towards the centre of the intrusive which is located south and southeast off the map-area (Lumbers 1973). The compositional layers are contorted, but in general are continuous over the size of a normal outcrop (Photo 12). In the gneissic varieties, discontinuous layers, lenses, and streaks of mafic minerals produce the gneissosity. Plagioclase is fine to medium grained, and ex hibits a typical sugary texture on the weathered outcrop surface. Larger plagioc lase clasts and augen were observed in less deformed rocks (Photo 13). Layers rich in hornblende tend to be also rich in garnet and the garnet grains and blebs are in places concentrated near the contacts of the melanocratic layers with leu cocratic layers. The massive anorthosite in southwestern Janes Township contains aggre gates of hornblende, and in many places, garnet set in a fine- to medium-grained sugary matrix of recrystallized plagioclase. Larger plagioclase porphyroclasts up to l cm in diameter were occasionally noted imbedded in the finer recrystallized plagioclase "mortar" like groundmass. Coronitic textures are defined by cores of black hornblende surrounded by red garnet. Transitions from massive to gneissic anorthosite occur over the size of an outcrop (Photo 14). 44 OGS 10,036 Photo 13-Augen texture in gneissic anorthositic gabbro. Scale 1 cm, hand specimen 75C23, Lo cation: Southeastern Janes Township, easting 554090, northing 5164550. OGS 10,037 Photo 14-Transition from massive to gneissic gabbroic anorthosite, southwestern Janes Town ship. 45 McNish and Janes Townships In thin section, most plagioclase is revealed to be granular and recrystallized forming a polygonal mosaic. The recrystallized grains are unaltered, clear, and twinned or untwinned. The recrystallization is younger than a strong saussuriti zation of primary plagioclase because the recrystallized plagioclase in many places includes epidote of the same microscopic appearance as the saussurite epi dote in porphyroclasts of the saussuritized, primary, magmatic plagioclase. Photo 15 shows an altered porphyroclast imbedded in granoblastic, recrystal lized plagioclase. North of the Grenville Front Boundary Fault at Highway 805, no recrystallization of the almost completely saussuritized feldspar took place. The plagioclase ranges in composition from An 0.10 in highly altered and non-re- crystallized plagioclase, to An 50.60 in granoblastic recrystallized plagioclase and to An 78 in the porphyroclasts. In porphyroclastic plagioclase, exsolution lamellae of plagioclase were occasionally noted that are steeply inclined to the (010) cleav age traces (Photo 16). Similar exsolution lamellae in calcic plagioclase are known to occur in gabbroic rocks of the Ivrea-Zone in northern Italy (Jager and Hut- tenlocher 1955) and in the anorthosites of eastern Quebec (Franconi, Quebec De partment of Natural Resources, oral communication, 1972). E. Jager and H. Huttenlocher reported the lamellae to be parallel to the (061) - crystallographic plane of the host crystal and the host plagioclase to be bytownite (An 76). Clinopyroxene was observed in only one thin section, i.e. in the highly al tered, non-recrystallized anorthosite of east-central Janes Township. It forms small, highly fractured, and cleaved relicts in tremolite. Orthopyroxene was not observed. The most abundant mafic mineral in the Anorthosite Suite Intrusive Rocks is a green, strongly pleochroic hornblende. It ranges in size from under 0.05 mm to about l mm, and is xenomorphic to hypidiomorphic. Its optical properties are as follows: X = light green Y = green Z = (olive) green 2V = 84±50 ZAc = 19-220 Primary accessory minerals are opaque minerals, sphene, apatite, and zir con. Quartz is not present in all thin sections, and commonly makes up less than three percent of the rocks. Secondary and metamorphic minerals are biotite, tremolite, epidote, chlor ite, sericite, and garnet. Only garnet and epidote are of special interest. Garnet in places forms aggregates up to 5 cm in diameter in gabbroic layers of the anor thosite complex and is also found forming the outermost zone of coronitic tex tures. These coronitic textures are shown and described in Photo 17. Epidote (clinozoisite) is found in altered plagioclase, but also forms hypidiomorphic to idiomorphic crystals in recrystallized anorthositic rocks that are up to 0.5 cm by 4.0 cm in size. These big crystals are believed by the author to have grown by a kind of accretive recrystallization consuming up all or part of the smaller epidote grains that had been left over from saussuritized primary plagioclase during pla gioclase recrystallization. The recrystallized plagioclase is Ca-poor compared with little altered magmatic plagioclase. The Ca balance is now found in the epi dote. Table 15 shows eight modal analyses of Anorthosite Suite Intrusive Rocks 46 OGS 10,038 Photo 15-Twinned and somewhat saussuritized plagioclase (P) in a granoblastic mosaic of com monly untwinned recrystallized plagioclase, gneissic anorthositic gabbro. Crossed po larizers, Scale 0.2 mm, thin section 75C23. Location: Southeastern Janes Township, easting 554090; northing 5164550. OGS 10,039 Photo 16-Exsolution lamellae of plagioclase in plagioclase, gabbroic anorthosite. Crossed polar izers, scale 0.02 mm, thin section 10D3B. Location: South of Grenville Front Boundary Fault in northern Henry Township, easting 545920; northing 5163010. 47 McNish and Janes Townships OGS 10,040 Photo 17-Part of a corona (left two thirds of photo). Garnet (black) and hornblende (H) around a fine-grained granoblastic mosaic (M) of hornblende and quartz. P is saussuritized pla gioclase. Anorthosite Suite rock. Crossed polarizers, scale is 0.15 mm, thin section 67C18. Location: Southwestern Janes Township, easting 544480, northing 563360. and also presents the classification of the analysed samples according to A.F. Buddington's (1939) scheme for the Adirondack anorthosites. For a detailed de scription of Anorthosite Suite Intrusive Rocks of the northwestern part of the Grenville Structural Province of northeastern Ontario, the reader is referred to Lumbers (1975) where additional references can also be found. SOUTHERN STRUCTURAL PROVINCE AND GRENVILLE STRUCTURAL PROVINCE Late Precambrian MAFIC INTRUSIVE ROCKS Olivine Diabase In northwestern Janes Township, an olivine diabase forms an elongate northwest-trending dike. It is part of the "Sudbury Swarm" and according to 48 W.H. Fahrig and D.L. Jones (1969), belongs to the "Mackenzie Igneous Event", that produced north-northwesterly striking diabase dikes in large areas of the western part of the Canadian Shield. Most of the Sudbury dikes are about 1250 ± 50 m.y. old (Fahrig and Wanless 1963; Van Schmus 1965), but T.M. Gates and P.M. Hurley (1973) obtained a radiometric age of 1460 ± 130 m.y. on dikes in the Sudbury area. In northwestern Janes Township, the long olivine diabase dike probably oc cupies a pre-existing fault, and is offset by a later movement along the north- northeast-striking Floodwood Chutes Fault. The dike has a maximum thickness of 240 m in the northwestern corner of Janes Township, and becomes thinner to wards the Floodwood Chutes Fault and thins out completely about 1.5 km east of the Sturgeon River. The dike is steeply or vertically dipping and produces a linear magnetic anomaly. Two outcrops of olivine diabase were found 1.5 km and 2.2 km east of Floodwood Chutes. The strike, width, and length of an olivine dia base in southern Janes Township south of the Grenville Front Boundary Fault is unknown and the mapping of this dike is somewhat arbitrary (Map 2425, back pocket). Olivine diabase in the map-area is a medium to very coarse grained, dark grey, brown weathering rock. The rock weathers easily, and therefore its occur rence is commonly marked by a topographic lineament. All olivine diabase dikes in the area, including the one south of the Grenville Front Boundary Fault are undeformed. In thin section, olivine diabase is seen to be composed of plagioclase, olivine, pyroxene, biotite, and opaque ore minerals. The texture commonly observed is subophitic (Photo 18). Plagioclase is calcic, in places zoned, and forms idiom orphic laths, and is not or is only very weakly saussuritized. Olivine is xeno morphic, and makes up to 33 volume percent of the rock. Xenomorphic pyrox ene is a pinkish to purplish titaniferous augite, and replaces and includes olivine. Biotite is dark brown to reddish brown, and is believed to be of primary origin. In places, it seems to be concentrated around titanomagnetite (Figure 4). Apa tite makes up 0.3 to almost 2 volume percent of the rock. In the very coarse grained diabase, some apatite is as much as 0.25 by 2.8 mm in size. The opaque mineral present is mainly titanomagnetite and very little pyrrhotite and chalco pyrite occurs. Table 16 shows four modal analyses. All minerals listed are prima ry. The only noticeable alteration is a very weak saussuritization of plagioclase. Two samples(23C12 and 24C17) that were modally analysed were also chemi cally analysed and the analyses are shown in Table 17. The diabases are of alkali basaltic composition and are remarkably high in Ti (3.78 percent Ti02) reflecting 5 to 11 volume percent of titanomagnetite, and 2 to 10 volume percent of titani ferous augite. Ultramafic Intrusive Rocks Two small bodies of ultramafic rocks occur south of the Grenville Front Boundary Fault. Contacts between the intrusions and the surrounding gneisses are not exposed, and the shape of the bodies is not known because they are mostly covered by glacial drift. 49 McNish and Janes Townships y OGS 10,041 Photo 18-Subophitic texture in olivine diabase. P = pyroxene; PI = plagioclase, O = olivine. Crossed polarizers, scale is 0.22 mm, thin section 23C12. Location: Northwestern Janes Township, easting 545710; northing 5171280. TABLE 16 MODAL ANALYSES OF OLIVINE DIABASE, McNISH AND JANES TOWNSHIPS. Specimen Number 20C7 23C12 24C17 32C7 12D7 Plagioclase 50.3 52.4 68.0 67.5 42.4 Olivine 33.1 22.0 20.5 11.3 22.7 Pyroxene 3.9 9.9 1.9 7.9 16.6 Biotite 3.5 4.4 3.1 2.9 8.7 Apatite 0.3 0.5 1.8 0.5 1.5 Opaque minerals 8.9 10.8 4.7 9.9 8.1 Plagioclase composition An60±5 An60±5 An58±5 An60±5 An60±5 Location Easting: 548560 545710 546610 550560 547800 Northing: 5169850 5171280 5170750 7169590 5164390 Olivine (Fa 51-25): 2Vx = 182 ± 50 Pyroxene (Ti - augite): 2Vx - 580 ± 5 0 ; X a = 180 ± 20 ; Z c = 420 ± 50 Specimen 12D7 from south of Grenville Front Boundary Fault, all others north of it. 50 McNish and Janes Townships TABLE 17 CHEMICAL ANALYSES OF OLIVINE DIABASE, JANES TOWNSHIP. Specimen Number 23C12 24C17 Major Components in Weight Percent 41.60 45.60 A12O3 13.30 18.20 1.70 2.00 FeO 18.40 11.70 MgO 9.05 6.14 CaO 6.11 7.76 2.85 3.53 K 2O 0.93 0.84 3.78 2.35 MnO 0.25 0.16 0.42 0.34 H2O+ 1.25 1.63 H2O- 0.23 0.24 CO2 0.17 0.16 S 0.05 0.03 TOTAL 100.09 101.68 Trace Elements in ppm Cu 44 32 Zn 185 124 Ni 154 105 Co 82 54 Pb 10 10 Cr 140 63 Ba 380 330 Li 8 6 Notes: Chemical analyses by Geoscience Laboratories, Ontario Geological Survey. The rocks are probably younger than the intrusion of the Anorthosite Suite Intrusive Rocks. Lumbers (1975) described similar rocks southwest of the Gren ville Front Boundary Fault in the Burwash area that he classifies as younger than the Anorthosite Suite Intrusive Rocks. In the map-area, the rocks are com monly strongly altered, however, they do not exhibit signs of a strong tectonic deformation as do the surrounding gneisses and anorthositic rocks. In places the ultramafic rocks are almost completely replaced by a medium-grained, dense, ol ive-green felt of actinolite-tremolite. In other places they are porphyroblastic, dark greenish grey, and exhibit a somewhat rusty weathering. A relict, possibly igneous layering has been observed in one place, namely near the very southern boundary of Janes Township, almost south of "The Elbow". 52 TABLE 18 MODAL ANALYSES OF ULTRAMAFIC ROCKS, McNISH AND JANES TOWNSHIPS. Specimen Number 76C4 14D11 Olivine 2.3 tr. Clinopyroxene 9.7 12.4 Chlorite 18.3 25.2 Iddingsite 19.5 1.2 Actinolite tremolite 42.7 50.0 Carbonate tr. 5.6 Opaque minerals 7.5 5.6 Location: Easting: 545200 549030 Northing: 5164550 5163550 In thin section, the ultramafic rocks exhibit relict primary mineralogy. Oli vine is almost completely replaced by iddingsite and magnetite. Colourless clino pyroxene makes up about 10 to 15 percent of the rock and forms hypidiomorphic crystals up to 4.5 mm by 7.0 mm in size. Secondary minerals are actinolite-tre- molite, a colourless, polysynthetically twinned chlorite, carbonate, and possibly traces of talc. Amphibole makes up 40 percent to almost 100 percent of the rock, and in places, forms big hypidiomorphic porphyroblasts up to l cm by 2 cm in size. Two modal analyses are presented in Table 18. Phanerozoic CENOZOIC Quaternary PLEISTOCENE AND RECENT The map-area was subjected to glaciation during the Pleistocene Epoch. Glacial striae show that the direction of ice movement was about ISO0 to 2200. At a few locations, two sets of striations were observed, the older striking 1800 to 2100 , the younger 2150 to 2400 . A discontinuous blanket of ground moraine and glaciofluvial deposits covers large parts of the area. The ground moraine consists of unsorted boulder till, and 53 McNish and Janes Townships OGS 10,042 Photo 19-Crossbedded Pleistocene deposits, Davis Township, approximately 0.4 km west of southern Janes Township. in general is thin. Locally, however, it reaches more than 15 m in thickness. Photo 19 shows a bedded and crossbedded glaciofluvial deposit just outside Janes Township in southeastern Davis Township. Recent deposits of sand, gravel, and boulders occur in the Sturgeon River and Kabikotitwia River valleys. Peat accumulations are common along streams and in swamps. Figure 5 is a sketch-map showing the Pleistocene and Recent features of the map-area. STRUCTURAL GEOLOGY The map-area is located at the boundary of the Grenville Structural Prov ince and the Southern Structural Province of the Canadian Shield (Stockwell 1964). The Grenville Front Tectonic Zone, a zone up to 30 km across, which is superimposed upon earlier structures in the Grenville, Southern, and Superior Provinces (Lumbers 1975), runs through the southern and eastern parts of Janes Township. The Grenville Front Boundary Fault (Lumbers 1973) crosses Janes Township near the southern boundary of the township. From the southeastern corner of Janes Township, the Boundary Fault passes in a northeasterly direc tion through Dana Township. Stockwell (1961) included the map-area north of the Grenville Front Bound ary Fault in the Cobalt Plain which is characterized by flat-lying rocks of the 54 LEGEND Outcrop area. Pleistocene cover, O-10 percent outcrop. Recent swamp. Fluvial sand. SYMBOLS Glacial striae. Esker. Figure 5-Pleistocene and Recent geology of McNish and Janes Townships. 55 OGS 10,043 Photo 20-Strongly cataclastic arkose, Lorrain Formation. Crossed polarizers, scale is 0.1 mm, thin section 8C5. Location: Central Janes Township, easting 550940, northing 5170230. Huronian Supergroup which overlie the Early Precambrian rocks of the Superior Province. Early Precambrian rocks are exposed in three inliers in northern McNish Township. They exhibit a west-northwesterly striking and steeply dipping schis tosity. The rocks of the Huronian Supergroup and younger rocks are weakly de formed in McNish Township. The degree of deformation increases from south ern McNish and northern Janes Township towards southern Janes Township. In McNish Township, joints are the most prominent structures. In southeastern McNish and in northern and central Janes Township, the rocks commonly exhi bit narrowly spaced cleavages. Near the Grenville Front Boundary Fault, in southern and eastern Janes Township, the rocks are strongly cataclastic (Photo 20), schistose, and commonly folded (Photo 21). South of the Boundary Fault, the rocks are gneissic (Figure 6). 56 OGS 10,044 Photo 21-Strongly folded quartzite, southwestern Janes Township at Canadian National Railway tracks. Structures Not Associated With The Grenville Front Tectonic Zone JOINTS In McNish and northern Janes Townships, joints are well developed in the rocks of the Huronian Supergroup and the Nipissing gabbro. The attitudes of about 200 joints were plotted on a Schmidt equal area net and are shown in Fig ure 7. A prominent maximum exists for northeasterly striking and steeply to vertically dipping joints, and another, a weaker maximum exists for north-nor thwesterly striking and steeply to vertically dipping joints. These joint direc tions are the same as north of McNish Township in Afton, Scholes, Macbeth, and Clement Townships from where Meyn (1977) reported the most prominent joint directions to be N300E to N500 E vertical and N400W to N300W vertical. These two joint directions are parallel to faults and lineaments in the map-area and in the area mapped by Meyn (1977). This indicates that faulting was active after deposition of the rocks of the Huronian Supergroup and after intrusion of the Nipissing gabbro. These features do not appear to be related to the Grenvil- lian deformation because similar faulting and jointing extends to areas far north 57 McNish and Janes Townships SMC 14257 SYMBOLS ^g^^ Jointing (see figure 7) ^H^^^H Early Precambrian (Schistosity}. mj| Cleavage fractures (see figure 8) -———j Geological boundary. v^v.-V.I Schistosity (see figure 9) and .'.•/.f.'.j strong cataclasis. ~^^- | Tiend of foliations. Gneissosity (see figure W). .^r Lineations. Figure 6-Structural geology of McNish and Janes Townships showing the general trend of foliations and linea- 58 tions. 0.5 percent. 211 points Figure 7-Stereogram for joints in the rocks of the Gowganda Formation and in Nipissing gabbro, McNish and northwestern Janes Townships. CONTOURS AT ^H 10.00 percent. ^H 5.00percent. ^^1 2.50 percent. 1.25 percent. 80 points Figure 8-Stereogram for fracture cleavages, Southeastern McNish Township and northern and central Janes Township. 59 McNish and Janes Townships CONTOURS AT 8.3 percent. O. 7 percent. 144 points Figure 9-Stereogram for schistosity, southern and east-central Janes Townships, north and northwest of the Grenville Front Boundary Fault. CONTOURS AT 6.0 percent. 0.5 percent. 198 points Figure 10-Stereogram for gneissosity, south of the Grenville Front Boundary Fault. 60 of the Grenville Front not affected by the Grenville Orogeny,and because the de formation and structural trends of the rocks within the Grenville Front Tectonic Zone (Figures 8, 9, and 10) are different from the ones north of this zone, for ex ample those in McNish Township. FAULTS AND LINEAMENTS Numerous faults and lineaments can be recognized on airphotos and in the field. They strike northeasterly, or less commonly northerly or northwesterly. The Floodwood Chutes Fault offsets an olivine diabase dike for about 0.5 km. In southwestern McNish Township, just east of Namasang Lake, two parallel northwesterly-striking faults border a 0.4 km wide valley between two plateau composed of greywacke of the Gowganda Formation, and suggest the presence of a graben structure. A long northeasterly-striking fault that occurs from about "The Elbow" in south-central Janes Township to Theriault Lake in eastern Janes Township and across this lake, is possibly related to Grenvillian deforma tion as it is more or less parallel to the general trend of the Grenville Front Tec tonic Zone in Janes and Dana Townships. Shearing and brecciation are com monly associated with all the faults in the area. Structures in the Grenville Front Tectonic Zone Figure 6 shows the approximate width of the Grenville Front Tectonic Zone in Janes Township. From the northern boundary of the map-area, to the Gren ville Boundary Fault, a gradual transition is evident from cleaved and weakly cataclastic rocks in the north to strongly cataclastic and schistose rocks in the south. The Grenville Front Boundary Fault separates the schistose greenschist facies rocks of the Southern Structural Province in the north from higher meta morphic grade gneisses of the Grenville Structural Province in the south. The Grenville Front Tectonic Zone is characterized by (Lumbers 1975, p.125): northeasterly [Janes Township easterly and northeasterly] trending cataclastic foliation and by a prominent southeasterly-plunging rodding lineation. The Tectonic Zone formed as a result of major deformation that apparently culminated after the climax of the Late Precambrian high rank regional metamorphism in the Grenville Province between 1,400 and 1,200 million years ago and before the emplacement of late pegmatite dikes, about 1,000 million years ago. CLEAVAGE Cleavages are closely spaced, parallel planes along which a rock has a tend ency to split. They may or may not be accompanied by some recrystallization on the cleavage planes and thus are intermediate structures between joints and schistosity. 61 McNish and Janes Townships Not all rocks underlying the northern part of the Grenville Front Tectonic Zone are visibly cleaved and cataclastic, and a characteristic feature of this "subzone" is that some of its rocks are strongly cleaved, whereas others nearby and of the same formation are not at all. This indicates that in places, the defor mation occurred along distinct zones of less competent rocks. In places, these zones are thin, only a few tens of centimetres wide, and half of a small rock expo sure may be visibly deformed, whereas the other half may not be deformed. In Figure 8, cleavage planes of northern and central Janes Township are plotted and the prominent direction of steeply southward-dipping planes ap pears to be N800 E to N800W, and with an east-west strike parallel to the Gren ville Front Boundary Fault. This fault bends to the northeast in Dana Township just east of Janes Township (Lumbers 1973). This change of direction is also in dicated in the stereogram of Figure 8. SCHISTOSITY Schistosity is a variety of foliation that is the result of the parallel arrange ment of micaceous minerals such as chlorite, muscovite, and biotite. Mica-rich schist splits up in plates parallel to the schistosity. Schistose rocks underlie a 0.7 to 3.8 km wide zone just north and northwest of the Grenville Front Boundary Fault. One hundred and forty-four measure ments are plotted in the stereogram of Figure 9 and this stereogram is almost identical to Figure 8, the "cleavage" stereogram. In a similar manner, it shows a prominent maximum at N800 E to N800W, a steep dip to the south, and the change in direction of strike to the northeast of the Grenville Front Boundary Fault in Dana Township. GNEISSOSITY Gneissosity is the foliation typical of gneisses, rocks in which granular min erals alternate with layers in which schistose minerals predominate, or in which the schistose minerals are oriented parallel to one another and are homogene ously or inhomogeneously dispersed in a more or less granular rock. In the map-area, gneissic rocks occur south of the Grenville Front Boundary Fault. About 200 measurements are plotted in the stereogram of Figure 10. Most foliations strike about east, parallel to the Grenville Front Boundary Fault, and dip to the south. In the very southeastern part of Janes Township, foliations turn away from the Boundary Fault and strike N300W due north and dip verti cally or steeply to the northeast or southwest indicating intense folding. This change of direction can also be seen just north of the Boundary Fault. 62 LINEATIONS Gneissic and schistose rocks within the Grenville Front Tectonic Zone are li- neated in many places. Rodding lineations and more commonly mineral linea- tions are present in them. The rodding structures consist of parallel "rods" on the foliation plane, and are about l to 5 cm thick and 0.5 m to 2 m long. Mineral lineation is marked by the arrangement of mafic minerals in the foliation planes, and by the elongation of flattened quartz crystals. In amphibolite, hornblende commonly delineates the lineation with its crystallographic c-axis. Most lineations plunge between 400 and 550 southeasterly. In his report on the geology of the Burwash Area, Lumbers (1975, p. 119) stated that within the Grenville Front Tectonic Zone: the lineation steepens (like the dip of the foliation) in plunge toward the Boundary Fault from an average of about 40 degrees near the eastern margin of the Tectonic Zone to about 60 to 70 degrees at the Boundary Fault. Plunge measurements (Figure 11) in the map-area seem to be inconsistent with Lumbers' observations. The map-area, however, includes only part of a sec tion across the Grenville Front Tectonic Zone and a complete section and more measurements may show a different picture. A more detailed tectonic study of the rocks north and south of the Grenville Front Boundary Fault may also re veal that the plunge of the lineations is strongly affected by other faults, for in stance, the Ess Creek Fault (North Branch) or the faults in southeastern Janes Township. GRENVILLE FRONT BOUNDARY FAULT While the mapping of the boundaries of the Grenville Front Tectonic Zone is somewhat arbitrary, the Grenville Front Boundary Fault is a distinct mappable feature (Lumbers 1975, p. 122). In the map-area, the Grenville Front Boundary Fault crosses Janes Township in the Kabikotitwia River-Sturgeon River valley. The Grenville Front Boundary Fault separates recrystallized gneissic rocks of the Grenville Structural Province from weakly recrystallized rocks of the Southern Structural Province. Rocks within the Grenville Front Boundary Fault are strongly cataclastic and in places tightly folded (see Photo 11 and Photo 21). Outcrops in the fault, along the Canadian National Railway tracks, commonly show strongly brecciated and rusty-stained rocks. Quartz veins and dikes were observed at a few places within and near the Grenville Front Boundary Fault. Lumbers (1975, p.122-125) presented a hypothetical cross-section of the Grenville Front Tectonic Zone; a simplified model showing a theoretical repre sentation of the relative degree of strain in rocks of the Superior Province block to the northwest and the Grenville Province block to the southeast. Lumbers postulated from his model: ...that rocks of the Grenville Province moved upward with respect to rocks of the Southern and Superior Provinces, but because rocks of the Southern and Superior Provinces underwent considera ble strain near the Boundary Fault, the magnitude of vertical slip on the Fault is relatively small. 63 McNish and Janes Townships siKNiMUji {o a6uny 8 S 8 S k S (O T3 D O li lo •ol c (O C : |DBj i jepun tg iui jj am uiaig O (A C O -CM* 64 Moreover the amount of vertical slip decreases with depth, and eventually a point is reached where there is a zero vertical slip due to load pressure. METAMORPHISM The Early Precambrian rocks in northern McNish Township were meta morphosed under greenschist facies conditions. Biotite is abundant, and is partly replaced by diaphthoritic chlorite. No higher rank metamorphic minerals or ana tectic remobilisations have been observed in the Early Precambrian rocks. The greenschist facies metamorphism is Early Precambrian in age. The diaphthore sis is probably younger than 2,150 m.y., namely younger than the emplacement of the Nipissing-type gabbros, and is possibly related to the Hudsonian Orogeny (about 1700 m.y.). The rocks of the Huronian Supergroup and the Nipissing gabbro north of the Grenville Front Boundary Fault were metamorphosed under conditions ranging from very low greenschist facies to upper greenschist facies of regional metamorphism. In most of McNish Township and in northwestern and west-central Janes Township, the rocks are of low greenschist facies metamorphic rank ("chlorite subfacies"). Towards the Grenville Front Boundary Fault, the grade of meta morphism increases through the biotite-chlorite subfacies to the biotite-(chlor- ite)-garnet subfacies (Figure 12) near the Grenville Front Boundary Fault. The biotite-chlorite zone is very wide in northern Janes Township and very thin near the Grenville Front Boundary Fault in southwestern Janes Township. The boundary between the biotite-chlorite zone and the biotite-(chlorite)-gamet zone is parallel to the Boundary Fault in western Janes Township. In eastern Janes Township it swings northeastward reflecting the north-northeastward trend of the Grenville Front Boundary Fault in Dana Township (Lumbers 1973). The boundary between the chlorite and the chlorite-biotite zones swings ab ruptly towards the north-northeast in southwestern Janes Township, and in northern Janes and southern McNish Township, is subparallel to the Grenville Front Boundary Fault in Dana Township. South of the Grenville Front Boundary Fault, the gneisses of the Grenville Province were metamorphosed under amphibolite facies conditions. In this zone, index minerals are garnet, biotite, and plagioclase OAn20). The rocks are com monly somewhat migmatitic. Concordant neosomes are folded, thus the meta morphism was initiated prior to the last folding events. Zone Ib in the biotite- plagioclase-garnet zone in Figure 12 represents a zone of high anatectic remobili- zation showing 50 percent or more granitic neosome. The paleosome is biotite- and hornblende-rich, and in many places garnetiferous. Diatectic rocks also oc cur in this zone. Index minerals of higher rank regional metamorphism, such as staurolite, kyanite, and sillimanite were not observed in the area. The diaphthoresis of the Early Precambrian rocks and the low grade meta morphism (chlorite zone) of the Huronian rocks and the Nipissing-type gabbros are probably of the same age, i.e. probably Hudsonian. Further north in the Southern Structural Province, the rocks were also subjected to low greenschist facies metamorphism. The higher rank metamorphism in the map-area, the 65 McNish and Janes Townships Figure 12-Zones of regional metamorphism in McNish and 66 Janes Townships. LEGEND AMPHIBOLITE FACIES Biotite-plagioclase-garnet. Migmatites (> 50percent granitic neosome). Biotite, diaphthorite chlorite (Early Precambrian Rocks). SYMBOLS Chlorite. Biotite. Garnet. Chlorite* biotite. Chlorite 4- biotite 4- garnet. Biotite* garnet. Plagioclase composition An 25 4.5. Metamorphic zone boundary, assumed. Metamorphic zone boundary, approximate. 67 McNish and Janes Townships biotite chlorite zone to biotite-plagioclase-garnet zone, would appear to be re lated to the Grenvillian metamorphic events (950 ± 150 m.y.). CORRELATION BETWEEN GEOLOGY AND AEROMAGNETIC DATA Geological Survey of Canada Aeromagnetic Maps 1501 G, Glen Afton and 1502 G, Lake Timagami (GSC 1965a and b) include the map-area. A number of magnetic features can be related to bedrock geology. The magnetic contrast of the terrain underlain by rocks of the Huronian Su pergroup and by Nipissing gabbro commonly is low, and gamma values are about 2100 to 2300. The isomagnetic lines are commonly widely spaced over these rocks, and only in northern McNish Township, just west of Wawiashkashi Lake, a Nipissing Intrusion causes a north-south trending magnetic high. In Janes Township, the major magnetic feature is caused by a northwesterly trend ing, titanomagnetite-rich olivine diabase dike. The dike and the anomaly (2300 to 2475 gammas) are offset by the Floodwood Chutes Fault. Near the Grenville Front Boundary Fault, the isomagnetic lines run approximately parallel to the Boundary Fault, and the uniform trend of the lines is disturbed only over the terrain underlain by the Anorthosite Suite Intrusive Rocks. No explanation is known for a small circular anomaly just west of Floodwood Chutes and for a lin ear, westerly striking anomaly east of the falls. ECONOMIC GEOLOGY The following descriptions of mineral occurrences and of properties and the general statements on the economic geology of the area are based on personal in vestigations and on information drawn from the assessment files in the Assess ment Files Research Office, Ontario Geological Survey, Toronto, and the Resi dent Geologist's Files, Ontario Ministry of Natural Resources, Sudbury. Not all the information available from the assessment files can be reproduced in the re port and for a complete file the reader is referred to the aforementioned sources. McNish and Janes Townships contain some interesting mineral occurrences and several companies and individuals have explored the area for copper, nickel, lead, zinc, uranium, and gold. Garnet for possible industrial use occurs in south western Janes Township. Sand and gravel were observed by the field party over most of the map-area, but the quality and dimensions of these deposits were not examined in detail. Copper and Nickel Associated with the Nipissing-Type Gabbro Syngenetic nickel and copper sulphide minerals have been found in several places in the Nipissing gabbro. Disseminated sulphides consist of chalcopyrite, 68 OQS 10.045 Photo 22-Altered pyrrhotite (P), and chalcopyrite (C), Nipissing gabbro. Polished section 23C7B. Scale is 0.04 mm. Location: Northwestern Janes Township, easting 547300, northing 5171210. pyrrhotite, pyrite, and magnetite. The host Nipissing gabbro does not show any alteration which the surrounding, non-mineralized Nipissing gabbro does not also show. In a few places, however, mineralization appears to be associated with a weak carbonatization of the gabbro. The mineralization appears to occur near contacts with sedimentary rocks of the Huronian Supergroup (Pan Central Explorations Limited (7)1 ) or form irreg ularly-shaped, schlieren-like bodies within the Nipissing gabbro intrusions themselves (Kirkland Townsite Occurrence (5), Kennco Explorations (Canada) Limited (4), and Ossington Explorations Limited and Triller Explorations Lim ited (6) [I960]). Five polished thin sections of mineralized grab samples were examined using an ore microscope. The thin sections were also modally analyzed (see Table 10) and some of the samples chemically analyzed (see Table 9). The ore minerals of the mineralized specimens compose 1.9 percent to 10.4 percent of the rocks. In all specimens, chalcopyrite appears to be more abundant than pyrrhotite. Pyrite and magnetite are present only in very minor amounts. The grain sizes of the xe nomorphic opaque minerals range from 0.03 mm to 0.6 mm, and rarely are as large as 2.0 mm. In places, pyrrhotite includes a little chalcopyrite, and is com monly somewhat altered showing in thin section very thin worm-like features (Photo 22) occurring through the pyrrhotite in almost every direction. Under 'Number in parentheses refers to property number on Map 2425, back pocket. 69 McNish and Janes Townships very high magnification, these worm-like features appear to consist of pyrite and/or marcasite. The grab samples from mineralized showings in northwestern Janes Town ship (Kennco Explorations (Canada) Limited (4)) that were analyzed for major components (see Table 9) were also analyzed for copper and nickel. Copper com prises 0.17 percent to 2.3 percent, and nickel 0.06 percent to 1.36 percent. Considerable exploration has been carried out to evaluate the economic po tential of the mineralization in the Nipissing gabbro. In the following accounts the history of some of these exploration efforts are described under the heading of the companies involved. The listing is in alphabetic order. KENNCO EXPLORATIONS (CANADA) LIMITED [1970] (4)1 In 1968, Questor International Surveys Limited performed a combined air borne magnetic and electromagnetic survey for Kennco Explorations (Canada) Limited over an area of approximately 673 km2 including Janes, McNish, and neighbouring townships with the object of investigating occurrences of base metal mineralization within the area. As a result of this work and a geological survey, efforts were concentrated on an area west of Chiniguchi River in Janes Township. In 1969 and 1970, Kennco Explorations (Canada) Limited diamond drilled 11 holes totalling 3070 m and put down several packsack drill holes on claims registered under the name of E.J. Rivers. The diamond drilling was per formed near exposed mineralized gabbro and up to 778 m of gabbro per hole were intersected. In its diamond-drill records, the company described very minor sulphide mineralization consisting of disseminations of chalcopyrite and pyrrho tite and minor amounts of these minerals on fractures and shears. Only in one diamond-drill hole were promising concentrations of up to 60 percent sulphides observed. This concentration of sulphide minerals occurs at lengths from 172.8 m to 177.6 m in a diamond drill hole 2.4 km west of Floodwood Chutes, and con sists of chalcopyrite, pentlandite, and pyrrhotite. Below this mineralized zone lie 1.5 m of 40 percent sulphide-bearing gabbro that is cut by 5 cm to 25 cm wide calcite veins. The mineralized zones near the diamond-drill sites are commonly small, only about 5 to 50 m2 in size and irregular in form. Grab samples were taken from these zones by the author. They were chemically analyzed and yielded up to 2.3 percent copper and up to 1.36 percent nickel (see Table 9). No further work was reported and the claims were allowed to lapse. KIRKLAND TOWNSITE OCCURRENCE (5) In 1968, G.H.D. Consultants Limited conducted a magnetometer survey and some electromagnetic test work for Kirkland Townsite Gold Mines Limited in an area in west-central Janes Township on claims recorded under the names of 'The number in parentheses refers to the property list on Map 2425, back pocket. 70 H.V. Barry and E.J. Rivers. The original showing has been stripped for a width of 54 m and the easterly trending mineralization traced for a distance of about 105 m. Preliminary assays of grab samples containing up to 0.39 percent copper and up to 0.06 percent nickel were reported (Assessment Files Research Office, Ontario Geological Survey, Toronto). No further work has been reported for assessment work credit and the claims were allowed to lapse. In 1970, the original showing was tested by dia mond drilling (Kennco Explorations (Canada) Limited, see section on Kennco Explorations (Canada) Limited [1970] (4)). In 1968 and 1969, Ossington Explorations Limited and Triller Explorations Limited, two closely associated companies, conducted electromagnetic and mag netometer surveys in an area west and northwest of Sargesson Lake in Janes Township. A 9 m deep shaft was excavated north of this lake, but no values were reported from this shaft. Nor was the exact location of the shaft reported. Nine holes were diamond drilled in the gabbro by Ossington Explorations Limited for a total length of 615 m near the mouth of the Chiniguchi River where it meets the Sturgeon River. Five of the diamond-drill holes were drilled to test east- trending electromagnetic anomalies and four others to test a mineralized show ing in the gabbro 0.4 km north of the mouth of the Chiniguchi River, just east of the Sturgeon River. The company reported 2.45 percent copper and 0.13 percent nickel from this surface mineralization. Assays obtained from a diamond-drill core from the same location yielded 0.09 percent copper and 0.19 percent nickel (Assessment Files Research Office, Ontario Geological Survey, Toronto). No fur ther work has been reported, and the claims were allowed to lapse. PAN CENTRAL EXPLORATIONS LIMITED (7) In the fall of 1964, H. Barry discovered several occurrences of chalcopyrite and pyrrhotite north of Sargesson Lake in Janes Township. In 1965 and 1968, Pan Central Explorations Limited conducted a magnetometer survey and dia mond-drilled eight holes totalling 527 m in length in this region where the com pany still holds a group of 11 claims. Traces of disseminated copper and iron sulphides are present in many places in a steeply southeast dipping Nipissing gabbro sheet within the claim group. However, they appear to be most abundant on claims numbered S127142, S127143, and S126334 in a zone paralleling the contact and within 30 m of the quartz sandstone contact on the northwest side. It is in this zone that Pan Cen tral Explorations Limited drilled the eight diamond-drill holes (Figure 13). This company reported assays for copper which ranged from 0.08 percent to 0.80 per cent with an average of 0.36 percent, and for nickel which ranged from 0.07 per cent to 0.74 percent with an average of 0.19 percent (Assessment Files Research 71 McNish and Janes Townships Figure 13-Diamond drill-hole location plan, Pan Central Explorations Limited. Office, Ontario Geological Survey, Toronto). The best combined percentage re ported by the company was 1.08 percent. A strongly carbonatized zone in hole 8 carried 0.18 ounce of gold per ton. The Nipissing gabbro of hole 2 was chemically and mineralogically studied in some detail. The results are presented in Table 11. Copper-Lead-Zinc Mineralization in Northwestern McNish Township Numerous showings of sulphide mineralization occur in a 1.6 by 2.4 km area in the northwestern part of McNish Township. Three genetically different types of mineralization have been observed by the author: 1) Disseminated sulphides in Early Precambrian rocks. 2) Synsedimentary, detrital mineralization in rocks of the Gowganda Formation. 3) Mineralized hydrothermal quartz veins and silicified zones within the rocks of the Huronian Supergroup and Early Precambrian metasedi- ments and metavolcanics. Disseminated Sulphides in Early Precambrian Rocks Minor, fine-grained sulphide disseminations are common in all Early Pre cambrian rocks in northwestern McNish Township. They do not appear to be of economic importance, although in places they make up almost three percent of the rocks. 72 OGS 10,046 Photo 23-Flame-like exsolution body of pentlandite (P) in pyrrhotite (Py); chalcopyrite (C). Mafic metavolcanic (Early Precambrian), polished section 66C10. Scale is 0.01 mm, (contrast exaggerated by development on very high contrast photographic paper). Location: Northwestern McNish Township, easting 547060; northing 5182330. In the Early Precambrian metasediments, only traces of pyrite have been observed. In the mafic metavolcanics, up to 3 percent sulphides occur. An esti mated 90 percent of these sulphides are pyrrhotite, 8 percent chalcopyrite, and about 2 percent pyrite. All these ore minerals are xenomorphic. Pyrrhotite is up to 0.56 mm in size and rarely contains minute flame-like exsolution bodies of pentlandite (Photo 23). Chalcopyrite is rarely up to about 0.2 mm and pyrite is 0.1 mm in maximum diameter. In the Early Precambrian mafic intrusive rocks, sulphides make up about l percent of the rocks and consist of an estimated 80 to 90 percent of xenomorphic pyrrhotite and 10 to 20 sulphide percent of chalcopyrite. Pyrrhotite is 0.003 mm to 0.16 mm in size, chalcopyrite 0.003 mm to 0.1 mm. Synsedimentary Detrital Mineralization in Rocks of the Gowganda Formation Conglomerate and arkosic greywacke of the Gowganda Formation in north western McNish Township contain detrital sulphides and sulphide-bearing 73 McNish and Janes Townships OGS 10,047 Photo 24-Angular ore clast in conglomerate, Gowganda Formation. Plane polarized light. Scale 0.44 mm, thin section 63C10. Location: Northwestern Janes Township, easting 545850, northing 5182550. clasts. Detrital pyrite and pyrrhotite are up to l mm in size. Pyrrhotite detritus with intergrown chalcopyrite has been observed. The mineralized clasts are su bangular to rounded and consist of felsic to intermediate, recrystallized metavol canics. The sulphide minerals in the metavolcanics are pyrrhotite and chalcopy rite and combined make up almost 60 percent of the clasts (Photo 24). About 20 percent of the sulphide minerals consist of chalcopyrite. These detrital sulphides do not comprise deposits of economic importance in themselves, and the origin of the detrital sulphides and mineralized pebbles is not known. However, the detrital pyrrhotite grains and the pyrrhotite in the ore pebbles are unaltered. This probably indicates that they had not been trans ported too long a distance and were not exposed to atmospheric conditions over too long a period of time before deposition. If this is correct, a search for the source area of the ore pebbles should be made not far north of McNish Township in Macbeth Township. Mineralized Early Precambrian rocks are abundant in southern Macbeth Township (H.D. Meyn, Geologist, Ontario Geological Survey, oral communication, 1977). 74 OGS 10,048 Photo 25-Sulphide mineralization (S) in quartz veins. Specimen 66C8. Location: Northwestern McNish Township, easting 547080, northing 5182310. Mineralized Hydrothermal Quartz Veins and Silicified Zones Within Early Precambrian and Huronian Supergroup Rocks Hydrothermal quartz-sulphide mineralization within Early Precambrian and Huronian Supergroup rocks occurs mainly just west of the banks of the Sturgeon River and near the small lake that is nearest to the northwestern cor ner of the McNish map-sheet. The mineralization consists predominantly of py rite, sphalerite, chalcopyrite, and galena in approximately this order of abun dance. Galena and sphalerite were not observed everywhere. The ore minerals form stringers, blebs, and fine disseminations within quartz veins and silicified rocks. They also occur in shear zones. Photo 25 shows a mineralized hand speci men taken from an outcrop near the west bank of the Sturgeon River (A.E. Je rome (1)). The source of the mineralization in the quartz veins was probably the sul phide disseminations in the Early Precambrian rocks and the detrital sulphides in the Huronian rocks. The age of the hydrothermal remobilization is not known. 75 McNish and Janes Townships Exploration for Copper, Lead, and Zinc in Northwestern McNish Township The copper, lead, and zinc mineralization in northwestern McNish Town ship has attracted the interest of prospectors and exploration companies several times during the last forty years. The history of these exploration activities is de scribed on the following pages. A.E. JEROME (1) In 1971, prospector A.E. Jerome discovered copper mineralization in sili cified conglomerate on the west bank of the Sturgeon River and subsequently discovered two more showings nearby. Twenty-four claims were staked, and in December 1971, Jerome Explorations Limited was incorporated. In 1972, geolog ical mapping, trenching, sampling, and electromagnetic and magnetic surveys were carried out. The magnetic survey revealed the existence of several signifi cant anomalies. Diamond drilling and field examinations have shown that nearly all of the magnetic features are caused by pyrrhotite associated with quartz veining, silicification, and shearing of the Early Precambrian and Gow ganda Formation host rocks. The electromagnetic surveys indicated the exist ence of a number of conductors that are due to bands and disseminations of py rite, chalcopyrite, and pyrrhotite within quartz-veined or silicified rocks. In 1972 and 1973, 24 short holes totalling 646 m in length were diamond drilled to test the geophysical anomalies and the surface mineralization. The approximate lo cations of the diamond-drill holes are indicated on the accompanying map (Map 2425, back pocket). For a detailed description of the diamond-drill holes and for their exact locations the reader is referred to the File No. 63.3062B, Assessment Files Research Office, Ontario Geological Survey, Toronto. In this assessment file report, the reader also will find a description of the 24 mineralized showings examined by the company. Most of these showings were already known to the Palston Mining and Development Company and a repetition of the descriptions therefore is superfluous (see section on "Waltenbury Occurrence (3)"). The min eralization occurs within quartz veins or is associated with fracturing, shearing and/or hydrothermal silicification of host rocks. The quartz veins and shear zones commonly strike northeast (Waltenbury Occurrence (3)). Quartz veins also are stockwork-like. Palston Mining and Development Company, and Jerome Explorations Limited have separately reported assays from mineralized expo sures that are commonly low. The best results are from a showing 460 m west of the Sturgeon River and 600 m north of Ozhway Lake in greywacke near a con tact with a gabbro dike (showing A of Jerome Explorations Limited copper 2.98 percent; zinc 0.53 percent; gold 0.02 ounce per ton; silver 1.88 ounces per ton) and from the Palston Mining and Development Company showing Number 8 (see Table 19). The best assays from diamond-drill cores obtained by Jerome Ex plorations Limited were 0.69 percent copper, 0.58 ounce of silver per ton and 0.02 ounce of gold per ton over a 1.25 m long section. The extent of the mineralization along strike and at depth is not known. No further work has been reported for 76 assessment work credit, and most of the 24 claims were allowed to lapse. A.E. Je rome presently (on December 31st, 1976) holds three claims (S 323356-58 inclu sive) just west of the Sturgeon River. WALTENBURY OCCURRENCE (3) [PALSTON MINING AND DEVELOPMENT COMPANY] In the 1930s, prospector George Waltenbury staked 42 claims and erected a small mining camp near "Beaver Pond", the small lake that is nearest to the northwestern corner of McNish Township. From a shaft, which went down ap proximately 5 m, he removed considerable amounts of mineralized rock. In 1935, George Waltenbury sent test samples to the Timiskaming Testing Laboratories. The results of the analyses are not known. In 1938-1939 George Waltenbury dis covered sphalerite-bearing float immediately to the northwest of Ozhway Lake (Figure 14). Nearby he then located lead-zinc mineralization in place and exca vated a 3.3 m deep trench. It was found that the mineralization occurred within a silicified Gowganda Formation conglomerate. About the end of 1939, financial difficulties forced Waltenbury to abandon all further exploration efforts, and in 1944 the area was restaked by his son. However, the claims were allowed to lapse. In 1956, prospecting by local prospectors renewed interest in the area. The same year, Palston Mining and Development Company conducted an electro magnetic and a gravity survey. Fifteen separate showings were examined and several pits and trenches were blasted. Figure 14 is a sketch-map by the com pany showing the 15 examined mineralized occurrences. A short description of each showing is presented in Table 19. In general, the sulphide mineralizations are associated with quartz veins, minor fracture planes, and minor shear zones in the rocks of the Huronian Supergroup and within the silicified parts of the host rocks. The best assays were obtained from showing Number 8 (Table 19), the showing immediately to the northwest of Ozhway Lake and first discovered by George Waltenbury in 1938-1939. Palston Mining and Development Company reported six assays (Showing Number 8) obtained from random grab samples that averaged 0.75 percent copper, 6.79 percent lead, 13.53 percent zinc, and 1.37 ounces of silver per ton. The best values were 3.88 percent for copper, 14.25 per cent for lead, 22.04 percent for zinc, and 2.50 ounces of silver per ton. The host rock, a silicified conglomerate overlain by greywacke ("argillite") strikes N100 to 300 E. The ore is massive in character, and the ore zone is about 15 cm thick as reported by the company. Four attempts were made to test the zone with a packsack drill. Heavy overburden, however, made these attempts futile. The quartz veins and mineralized zones strike commonly northeast as re ported by the Palston Mining and Development Company. Their extension is not known due to heavy glacial overburden in the area. No further work was re ported by the company and the company became inactive through lack of funds and the titles to the company's claims subsequently lapsed. 77 of 03 00 op 03 , m XI •3 •0 Q N o O •a co c 22 c ^^ cd 0) S OD c g 03 *P to ® OD M C C .C *J ^ oi i— i OD OD 0 6 6 •^ N C 3 * td 0 *bC OH o .g o x: 'N Z *"™c z:CJ 0) l*-*r— M W OD X] •2 -2 X] X x: "S C C "cd k \ OD Q "cd 'h' 01 U cd .2 c 0) C 3 l * J 0) O" "B 01 Scd *oj .2 ^ 01 Cr, •S vi "** 0 •P o SSMENT1 Nominera wacke;pos U CO Evidencec Sphalerite- M Similarto mineraliza 3 placement thediscto 3 Remarks shearing i! 1 OD OD Trench EC 03 01 0 03 O (N O •H 'S CO CO CO a CO CO CO •z I-H 00 S HjJ o co ^ 0H 6? to i r-( JS (N q O ' O •* d is o -~- u o -. .. (N f* SS EH 01 S 2 s ^ t- "a— Ift Q J3 i Z co'(N 3 w di O 1*"I d "1 .. c 6? 01 03 c5** oo 03 1OH ea r^ N" XI 0 3 .~ in ^1 O X! T! o OH it 02 x: td 2 ^0 •- N d Is* o u 3 W s-i fe g (N 8 o 8 g c "^ ^ o Ift ^ r\ Cd t^ 03 eg cd cN -* O CO ^ w " Ul i 2 i d i 2 TH yj d o CO " tf W S 3 OD 3 oi) 3 OC tp is -o 3 3 ^ ^ 2" ^ ^ ^^ — •t; si o 0 O 0) OO 01 01 01 u So T3 •rg a TJ OD C SHOWINGSAFTERPALSTONMIN 'C Mineralizationinveinsquartzgreyw; 0quartzitestriking50-50NW;15wicm 0N105E-striking,shear30widecmzon mineralizedveinswithinshearquartzz Mineralizationwithindiabasecuttinga NEmineralizationwidestriking1.2m Sulphidesassociatedwith2-5arecmw whichstockwork-veinsinquartzoccur SEARCHOFFICE,ONTARIOGEOLO NE-striking15wide,veinquartzcm withinGowgandaconglomerate.zone Mineralizationfractureplanesin chertyMineralizationpebblewithin Z 0conglomeratestrikethatN10Eto N300overlainE;slatyargilliteby mineraliscarbonatezone;gangue 2 0) fashionlikeconglomeratein !H 060"veinsNWstrike20to Hostrockgreywackeis Attitude,hostrock u throughgreywacke Ift U9 T4 -S f" N 0) ** isIs cr W K ,. 01 X K ,, f 0 E" co -2 O) V a" O! TJ '-3.2 'J"? fTj W t^ C •^ o "C Jjr i~3 a 09 ^ X! * 0 0 O ^ 0) a t . 0) a X! x; ASSESSMENTI Minorchalcopyrit Galena,pyrrhotite chalcopyrite,pyrii DESCRIPTION Galena,sphalerite Pyrrhotite,chalco Galena,pyrite,py Pyrrhotite,chalco Sphalerite,galena, chalcopyrite,pyrr Chalcopyrite,pyn Chalcopyrite,pyrr Mineralization galena,pyrite chalcopyrite Chalcopyrite sphalerite pyrite pyrite pyrite pyrite O) OD t* ui c oi j i— i (N eo * U3 to ^ 00 o o rH CO O | i— i t- w2 CO S •H M s g o 41 Si o l f. ^ 3^ o g JO --H c g S H II o ES CO T ift 6S 0 CO CO V ••t CJ 4* o Tf d g d d •3 O Z 3 y *s; O T3 a- C ea o 01 N -* L- 0) E CB •o •5 -4J to a. 'i Cj" JS i 'IC > QC E J2 'C C CJ ea N •5 ^ 12 Ift L4 CO ^ CO CO 3 CJ cd c a- CO C Ol a S c C le CO Js S o O) ea ic Oi 'i ! L. 0) 'i V CU Z .Q x i c O) c C o o ^o "eiO o 0 0 w ea N CO c M N CJ S 0 N in C .S CJ "cO V ineral inera 2 C Z JO !g S K XI •5 'i •o ea * S 60 (0 S is i OJ 'k*.2 "o ax x 8 x "ea a i" CJ *J* s ^ a a^ o 0 0 .c ^"3 "eojy 1 U U McNish and Janes Townships l o o"c (D O. o d) •o CO D) 'E l o w (O Q. l CO Q. (O E ea o 80 Sulphide Mineralization in Quartz Veins and Dikes Sulphide mineralization in silicified rocks and quartz veins occurs mainly in northwestern McNish Township. During the field investigation, minor sulphide mineralization in quartz veins was noted in a few places in other parts of the map-area. Some of the veins are up to l m or more thick and attracted the interest of prospectors probably searching for gold mineralization. For instance, about 350 m west of southern Theriault Lake, a dike l m wide, vertically dipping, and striking N1000 E was pitted. In places, the quartz is somewhat rusty stained. However, no sulphide mineralization was observed by the author. The host rock is Nipissing gabbro and the dike could be traced by the author only over the width of a 5 by 5 m large outcrop. WIEMER OCCURRENCE (8) In 1962, in southwestern Janes Township, Mr. H.F. Wiemer diamond drilled three holes totalling 98 m in length through massive quartz near the Grenville Front Boundary Fault. The quartz forms an outcrop of about 10 m2 in an area underlain by schistose Nipissing gabbro. The exposed quartz shows traces of dis seminated pyrite and chalcopyrite. Also in the diamond-drill records (Assess ment File Research Office, Ontario Geological Survey, Toronto), only traces of these sulphide minerals and no gold mineralization were mentioned. Uranium-Bearing, Pyritiferous Conglomerates of the Mississagi Formation TH.D. SAVILLE(2) Uranium occurs in a pyritiferous quartz-pebble conglomerate of the Missis sagi Formation in northeastern McNish Township (Lumbers 1973). The con glomerate is very similar to the uraniferous conglomerate east of McNish Town ship in Pardo Township in the vicinity of Tee and Silver Lakes. The conglomerates in Pardo and McNish Townships in turn are similar in appear ance to the uraniferous conglomerates of the Blind River Area. In McNish Township, the conglomerate is at the base of the Huronian Su pergroup and overlies Early Precambrian metasediments and granitic rocks. It is commonly matrix-supported, in places a clast-supported conglomerate. The clasts are some millimetres to about 10 cm in size, subangular to rounded, and consist of quartzite and mudstone. The matrix is very fine grained and is com posed of greenish sericite, a little quartz, and pyrite. No assessment file information is available about this occurrence of radioac tive conglomerate, and the only sign of any exploration activity in the field is an 81 McNish and Janes Townships almost completely overgrown, 3 to 6 m long trench. No uranium assays were re ported and the land (December 31st, 1976) was held by Th.D. Saville. The radioactive conglomerate in northeastern McNish Township is continu ous with uraniferous conglomerate in Pardo Township to the east as shown by Jas.E. Thomson (1960).In Pardo Township, the conglomerate ranges from 0.6 to 12 m in thickness. It has a low uranium content. The highest averaged assay re ported by Pickle Crow Gold Mines Limited (1956-57) is 0.017 percent U308 over a 0.6 m long drill section. In most of the 16 holes (total length 2282 m) diamond drilled by this company, assays are between 0.002 and 0.009 percent U308 (As sessment Files Research Office, Ontario Geological Survey, Toronto). Just east of McNish Township, in Pardo Township a weakly radioactive ar kose (2-times background, 150-200 c.p.m.) was found by the author (Dressler 1977b) that has been classified as Lorrain Formation in this report. The rusty weathered outcrop is a few m2 in size. No abnormal radioactivity was measured from similar rocks in the map-area. Garnet Garnet for possible industrial use has been observed by the author in south western Janes Township. It is in fine-grained biotite gneiss and biotite-chlorite schist that strike northwest and dip steeply to the southwest. Garnet occurs in garnet-quartz nodules that are up to 10 cm in size and makes up more than 30 percent of the rock. The most promising exposure just south of the Kabikotitwia River, 0.4 km east of the western township boundary, is about 4 by 10 m in size. The outcrop surface is more or less parallel to the strike of the gneiss, and there fore the thickness of the garnet-rich unit is not known. In the section on met- asediments, the garnetiferous nodules are described and Photo 10, a thin section, shows the typical garnet-quartz intergrowth of the nodules. Quartz envelopes garnet, that in turn surrounds quartz and minor iron oxide. Sand and Gravel Thick deposits of sand and gravel occur along the Sturgeon River, the Chini- guchi River, and the Kabikotitwia River valleys, and in many other places throughout the map-area. Some small gravel pits exist in the region where the gravel and sand deposits have been used in the construction of Highway 805 and logging roads. SUGGESTIONS FOR FUTURE EXPLORATION Much of the prospecting to date has been restricted to surface and near sur face exploration. Detailed exploration could be rewarding in particular in areas underlain by the Nipissing gabbros and in northwestern McNish Township 82 where rich hydrothermal copper, lead, and zinc mineralization is known to oc cur. In the conglomerates of the Gowganda Formation of this same area base- metal sulphide-rich pebbles occasionally occur. Efforts should be undertaken to find the "mother lode". This would require determination of the sediment trans port direction. The uranium potential of the area is indicated by a surface show ing and detailed radiometric surveys followed by diamond drilling could be re warding. During the 1976 field season, a weakly radioactive (2-times background, 150-200 c.p.m.) pyrite-bearing and rusty-weathering quartz sand stone was found by the author in Pardo Township just east of McNish Town ship (Dressler 1977b). This occurrence and the surrounding terrain in Pardo and McNish Townships should be examined in detail. 83 REFERENCES Ayres, L. D. 1972: Guide to Granitic Rock Nomenclature Used in Reports of the Ontario Division of Mines; Ontario Division of Mines, Miscellaneous Publication 52,14p. Ayres, L.D., Lumbers, S.B., Milne, V.G., and Robeson, D.W. 1971a: Ontario Geological Map, East Central Sheet; Ontario Department of Mines and North ern Affairs, Map 2198, scale l inch to 16 miles. Compilation 1970. 1971b: Ontario Geological Map Southern Sheet; Ontario Department of Mines and Northern Affairs, Map 2197, scale l inch to 16 miles. Compilation 1970. Barlow, A.E. 1899: Report on the Geology and Natural Resources of the Area Included by the Nipissing and Timiskaming Map-Sheets; Geological Survey of Canada, Annual Report 1897, Volume 10, Report I, p.51-3021. 1907: Second Edition of a Report on the Geology and Natural Resources of the Area Included by the Nipissing and Timiskaming Map-Sheets; p. 139-140 in Geological Survey of Canada, Report Number 962, (spine date 1908). Bruce, E.L. 1932: Geology of the Townships of Janes, McNish, Pardo, and Dana; Ontario Department of Mines, Volume 41, Part 4, p. l-28. Accompanied by Map 41f, scale l inch to Vi mile. Buddington, A.F. 1939: Adirondack Igneous Rocks and Their Metamorphism; Geological Society of America, Memoir 7, 354p. Card, K.D., Mcilwaine, W.H., Meyn, H.D. 1973: Geology of the Maple Mountain Area, Operation Maple Mountain, Districts of Timis kaming, Nipissing and Sudbury; Ontario Division of Mines, Geological Report 106, 160p. Accompanied by Maps 2256; 2257; 2258; 2259, scale l inch to l mile, and Map 2260, scale l inch to Vz mile. Coleman, A.P. 1913: The Nickel Industry: with Special References to the Sudbury Region, Ontario; Canada Department of Mines and Technical Surveys, Mines Branch, Report 170. Collins, W.H. 1917: Onaping map-area; Geological Survey of Canada, Memoir 95, 157p., accompanied by 2 maps. Dressler, B. 1977a: Janes Township, District of Sudbury; Ontario Geological Survey, Preliminary Geologi cal Map P.1231, Geological Series, scale 1:15 840 or l inch to Vi mile. Geology 1976. 1977b: McNish Township, District of Sudbury; Ontario Geological Survey, Preliminary Geo logical Map P. 1230, Geological Series, scale 1:15 840 or l inch to Vi mile. Geology 1976. 1977c: Geology of Emo, Rhodes, and Botha Townships, District of Sudbury; Ontario Geologi cal Survey, Open File Report 5224, 53p., 8 Tables, 12 Photos, (xerox copies) 11 Fig ures, and 3 Maps. Fahrig, W.H., and Jones, D.L. 1969: Paleomagnetic Evidence for the Extent of Mackenzie Igneous Events; Canadian Jour nal of Earth Sciences, Volume 6, p.679-688. Fahrig, W.H. and Wanless, R.K. 1963: Age and Significance of Diabase Dike Swarms of the Canadian Shield; Nature, Volume 200, p.934-937. 85 McNish and Janes Townships Fairbairn, H.W., Hurley, P.M., and Pinson, W.H. 1960: Mineral and Rock Ages at Sudbury - Blind River, Ontario; Proceedings of the Geological Association of Canada, Volume 12, p.41-66. Fairbairn, H.W., Hurley, P.M., Card, K.D., and Knight, C.J. 1969: Correlation of Radiometric Ages of Nipissing Diabase and Huronian Metasediments with Proterozoic Orogenic Events in Ontario; Canadian Journal of Earth Sciences, Volume 6, Number 3, p.489-497. Gates, T.M., and Hurley, P.M. 1973: Evaluation of Rb-Sr Dating Method Applied to the Matachewan, Abitibi, Mackenzie, and Sudbury Dike Swarms in Canada; Canadian Journal of Earth Sciences, Volume 10, p.900-919. Geological Survey of Canada 1965a: Glen Afton, Ontario; Geological Survey of Canada, Geophysical Paper 1501, Aeromag netic Series, Map 1501G, scale l inch to l mile. Survey 1959-1960. 1965b: Lake Timagami Sheet, Ontario; Geological Survey of Canada, Geophysical Paper 1502, Aeromagnetic Series, Map 1502G, scale l inch to l mile. Survey 1959-1960. Jager, E. and Huttenlocher, H. ' 1955: Beobachtungen an basischen Plagioklasen der Ivrea-Zone; Schweiz. Min. Petr. Mitt. Band 35, Heft l, p. 199-207. Lindsey, D.A. 1969: Glacial Sedimentology of the Precambrian Gowganda Formation, Ontario, Canada; Bul letin of the Geological Society of America, Volume 80, Number 9, p.1685-1701. Lumbers, S.B. 1973: River Valley Area, Districts of Nipissing and Sudbury; Ontario Division of Mines, Pre liminary Map P.844, Geological Series, scale l inch to l mile. Geology 1971, 1972. 1975: Geology of the Burwash Area, Districts of Nipissing, Parry Sound, and Sudbury; On tario Division of Mines, Geological Report 116, 160p. Accompanied by Map 2271, scale l inch to 2 miles. Meyn, H.D. 1966: Capreol Sheet, Districts of Sudbury and Nipissing; Ontario Department of Mines, Pre liminary Map P.367, Geological Compilation Series, scale l inch to 2 miles. 1977: Geology of Afton, Scholes, Macbeth, and Clement Townships, Districts of Sudbury and Nipissing; Ontario Geological Survey Report 170, 77p. Accompanied by Maps 2385 and 2386. Murray, A. 1853-56: Report of Progress; Geological Survey of Canada, 1853-56, p. 101. Pettijohn, F.J. 1975: Sedimentary Rocks, Third Edition; Harper and Row, Publishers, New York Evanston, San Francisco, and London. Stockwell, C.H. 1961: Structural Provinces, Orogenies and Time Classification of Rocks of the Canadian Pre cambrian Shield; p.108-118 in Age determinations by the Geological Survey of Can ada, Paper 61-17. 1964: Fourth Report on Structural Provinces, Orogenies, and Time-Classification of the Cana dian Precambrian Shield; p.l-21 in Age Determinations and Geological Studies, Part II, Geological Studies, Geological Survey of Canada, Paper 64-17 (p.II), 29p. Accompanied by Sketch Map and Chart. 86 Streckeisen, A. 1974: Classification and Nomenclature of Plutonic Rocks - Recommendations of the IUGS Subcommission on the Systematics of Igneous Rocks. Geologische Rundschau, Band 63, Heft 2, p.773-786. 1976: To Each Plutonic Rock its Proper Name; Earth-Science Review, Volume 12, p.1-33. Thomson, Jas. E. 1960: Uranium and Thorium Deposits at the Base of the Huronian System in the District of Sudbury; Ontario Department of Mines, Geological Report l, 40p. Accompanied by 10 Maps and Plans. 1961: Maclennan and Scadding Townships; Ontario Department of Mines, Geological Report 2, 34p. Accompanied by Map 2009, scale l inch to Vfe mile and 3 Charts. Thomson, Jas. E. and Card, K.D. 1963: Geology of Kelly and Davis Townships; Ontario Department of Mines, Geological Re port 15, 20p. Accompanied by Map 2037, scale l inch to Vz mile. Van Schmus, W.R. 1965: The Geochronology of the Blind River - Bruce Mines Area, Ontario, Canada; Journal of Geology, Volume 73, Number 5, p.755-780. 1976: Early and Middle Proterozoic History of the Great Lakes Area, North America; Philo sophical Transactions of the Royal Society London, A.280, p.605-628. 87 INDEX Page Page Age dates...... 3,49 Conglomerate, radioactive...... 81 Aggregate Contacts: See: Sand; Gravel. Anorthosites-Middle Precambrian Allanite ...... 36,39 metasediments ...... 41 Amphibolite 40 Gowganda Formation-Early Pre Amphibolite facies conditions ...... 65 cambrian rocks ...... 12 Analyses: Gowganda Formation-Mississagi Chemical. . . .25,27-28,33,34,42-43,52 Formation ...... 12 Modal ...... 8,9,16,19,26,27-28, Greywacke-gabbro...... 76 34,37,42-43,50,53 Contacts, nature of; Nipissing Discussion ...... 23 gabbro intrusions...... 21 Anatexis ...... 40 Copper ...... 68,70 Anorthosite ...... 41,44 Mineralization...... 76,83 Anorthosites-Middle Precambrian See also: Assays. metasediments, contacts . . 41 Anorthosite Suite Intrusive Rocks . .52,68 Detrital sulphides, origin...... 74 Anorthosite Suite Intrusive Rocks, Diabase ...... 8,21 modal and chemical Diamond-drill hole log, Lorrain analyses...... 42-43 Formation ...... 20 Apatite ...... 23 Diamond-drill section in Huronian Arkose ...... 17 (Gowganda) sedimentary Arkose, radioactive ...... 82 rocks...... 13-14 Arkosic arenite ...... 11 Diaphthoresis ...... 65 Arkosic greywacke...... 7 Dikes ...... 81 Assays: Gabbro ...... 76 Cadmium...... 78 Granitic...... 32 Copper ...... 70,71,76,77,78,79 Olivine-diabase ...... 49,68 Gold...... 72,76,78,79 Lead...... 77,78 Early Precambrian inliers ...... 56 Nickel...... 70,71,78,79 Early Precambrian rocks-Gowganda Silver ...... 77,78 Formation, contact . . . . . 12 U3 08 ...... 82 Epidote ...... 46 Zinc ...... 76,77,78 Epidote, theory of growth...... 46 See also: Analyses; Mineralization. Ess Creek Fault (North Branch) . . . .10,63 Exsolution lamellae ...... 21 Barry, H...... 71 Exsolution lamellae in plagioclase. . . . . 46 Barry, H.V...... 71 Photo ...... 47 Beaver Pond ...... 77 Biotite-chlorite subfacies...... 65 Feldspathic gneiss ...... 39 Biotite-( chlorite )-garnet subfacies. . . . . 65 Floodwood Chutes ...... 34,35 Biotite-chlorite zone ...... 68 Floodwood Chutes Fault ...... 49 Biotite-plagioclase-garnet zone ...... 68 Boulders ...... 54 G.H.D. Consultants Ltd...... 70 Breccia ...... 35 Gabbro ...... 21,33 Nipissing ...... 40 Calcite veins ...... 70 Pegmatitic ...... 23 Chalcopyrite...... 23,49,68-81 passim Galena...... 75,78 Chemical analyses ...... 25,27-28,33,34, Garnet. . . . .36-39 passim, 44,46,65,68,82 42-43,52 Photos...... 38,39 See also: Modal analyses. Garnet-quartz 'balls'...... 38 Chemical analyses, discussion...... 23-24 Garnet-quartz nodules ...... 82 Chiniguchi River ...... 32,70,71,82 Glacial striae...... 53 Chudleigh ...... 37 Glen Afton...... 31 CIPW Norms, quartz monzonite ...... 33 Gneiss ...... 36 Cleavage, defined...... 61 Gneiss, feldspathic...... 39 Cobalt Plain ...... 54 Gneissosity, defined...... 62 Conglomerate ...... 11 Gold ...... 68 Conglomerate, pyritiferous See also: Assays. quartz-pebble ...... 81 89 McNish and Janes Townships Page Page Gowganda Formation, modal Mackenzie Igneous Event ...... 49 analyses...... 16 Mafic intrusive rock, modal Gowganda Formation-Early Precam analyses of...... 9 brian rocks, contact .....12 Magnetic contrast ...... 68 Gowganda Formation-Mississagi Magnetic survey ...... 76 Formation, contacts. . . . .12 Magnetite...... 23,39,53,69 Granitic dike ...... 32 Manderstrom-Saville option...... 19 Granitic dike, modal and chemical Marcasite ...... 70 analyses...... 34 Meta-arkose ...... 35 Granitic rocks, modal analyses of ...... 9 Metagreywacke ...... 35 Granodiorite...... 8 Metamorphic grade ...... 10 Gravel...... 54,68,82 Metasediments, modal analyses . . . . .8,37 See also: Sand. Metatectic textures ...... 40 Greenschist facies ...... 4 Middle Precambrian metasediments- Conditions...... 65 anorthosites, contacts. . . .41 Low ...... 65 Migmatites ...... 36 Upper ...... 65 Mineralization: Grenville Front...... 61 Copper, Lead, Zinc ...... 83 Grenville Front Boundary Fault. . . 10,11, Mississagi-Gowganda Formations, 31,35,40,41,46,49, contacts...... 12 56,61,62,65,68,81 Mobilizate, pegmatitic ...... 39 Grenville Front Tectonic Zone. . . . 54,61, Modal analyses . . . . . 8,9,16,19,26,27-28, 62,63 34,37,42-43,50,53 Grenville Orogeny ...... 35,61 See also: Chemical analyses. Grenville Structural Province . . . 40,48,54, Modal analyses, discussion...... 23-24 61,63 "mother lode" ...... 83 Greywacke...... 12,15 Mudstone...... 7 Silty ...... 11 Greywacke-gabbro dike contact ...... 76 Namasang Lake...... 61 Newmont Mining Corp...... 11 Hollinger Mines Ltd...... 20 Nickel...... 68,70 Hollinger Mines Ltd. (Manderstrom- See also: Assays. Saville option) ...... 19 Nipissing gabbro ...... 40,68,69 Hudsonian Orogeny ...... 65 Nipissing-type gabbro: Huronian sedimentary rocks: Chemical analyses ...... 25,27-28 Table ...... 13-14 Modal analyses ...... 26,27-28 Huronian Supergroup...... 68 Olivine ...... 49,53 Iddingsite...... 53 Olivine diabase: Inliers, Early Precambrian ...... 56 Chemical analyses ...... 52 IUGS classification of plutonic Modal analyses ...... 50 rocks...... 34 Olivine diabase, subophitic texture in: Jerome, A.E...... 75 Photo ...... 50 Jerome Expl. Ltd...... 76 Olivine diabase dikes ...... 49,68 Origins, quartz monzonite...... 31 Kabikotitwia River ...... 11,37,38, Orthoconglomerate ...... 12 54,63,82 Ossington Expl. Ltd...... 32,69 Kennco Expl. (Canada) Ltd. . . . .69,70,71 Ozhway Lake ...... 76,77 Kirkland Townsite Gold Mines Ltd. . . . 70 Kirkland Townsite Occurrence...... 69 Paleosome ...... 65 Kyanite ...... 65 Palston Mining and Dev. Co. Ltd. . . .76,77 Pan Central Expl. Ltd...... 69,71 Lamellae, exsolution ...... 21 Peat ...... 54 Lead...... 68,83 Pegmatitic gabbro ...... 23 See also: Assays. Pegmatitic mobilizate...... 39 Lithologic units...... 4-5 Pentlandite...... 70,73 Lorrain Formation, modal Pickle Crow Gold Mines Ltd...... 82 analyses...... 19 Pleistocene Epoch ...... 53 Lorrain Formation stratigraphic Plutonic rocks, IUGS classification section ...... 20 of...... 34 90 Page Page Polymictic paraconglomerate ...... 12 Formation: Pseudotachylites ...... 35 Table ...... 20 Pud Lake...... 19 Striae, glacial ...... 53 Pyrite ...... 23,69,70,73-78 passim, 81 Sturgeon River ...... 11,32,34,49,54,63, Pyritiferous quartz-pebble 71,75,76,77,82 conglomerate ...... 81 Sudbury Event ...... 35 Pyroxene, exsolution lamellae ...... 21 Sudbury Group...... 10 Pyrrhotite ...... 23,49,69-79 passim Sudbury Series ...... 10 Sudbury Swarm ...... 48 Quartz arenite...... 17 Superior Province ...... 56 Quartz diorite...... 8 Survey, magnetic...... 76 Quartzite ...... 11 Quartz monzonite, chemical Texture: analyses...... 33 Metasediments ...... 6 Origins of...... 31 Granitic rocks...... 7 Quartz sandstone, radioactive ...... 83 Textures, metatectic ...... 40 Quartz veins...... 75,76,77,81 Texture, subophitic in olivine Questor Int. Survey Ltd...... 70 diabase: Photo ...... 50 Radioactive arkose...... 82 "The Elbow" ...... 11,61 Radioactive conglomerate ...... 81 Theriault Lake ...... 32,61,81 Radioactive quartz sandstone...... 83 Thickness: Rivers, E.J...... 70,71 Gowganda Formation...... 11,12 Rodding structures ...... 63 Tonalite...... 8 Trace elements in: Sand...... 54,68,82 Granitic dike ...... 34 See also: Gravel. Nipissing-type gabbro...... 25 Sandstones...... 19 Olivine diabase ...... 52 Sargesson Lake ...... 19,24,34,71 Quartz monzonite ...... 33 Scapolite ...... 21,23 See also: Analyses. Schistosity, defined ...... 62 Triller Expl. Ltd...... 69 Schmidt equal area net...... 57 Sedimentary environment...... 15 Ultramafic rocks, modal analyses . . . . . 53 Sedimentary features ...... 6 Uranium ...... 68,81 Sedimentary structures...... 15 Sillimanite ...... 65 Veins: Silty greywacke...... 11 Calcite...... 70 Silver Creek ...... 11 Quartz...... 75,76,77,81 Southern Structural Province. . . . . 54,61, 63,65 Waltenbury Occurrence ...... 76 Sphalerite ...... 75,77,78 Wawiashkashi Lake ...... 68 Sphene ...... 23,25,36,39,46 Wiemer, H.F...... 81 Staurolite...... 65 Stratigraphic interpretation: Zinc ...... 68,83 Gowganda Formation...... 11 See also: Assays. Stratigraphic section in Lorrain Zircon...... 7,36,46 91 . -- -- '-"Vt v4x'-''Vi ' t'i ':~ ' - p c Ministry of Hon. James A. C. Auld Minister Ontario Geological Survey Natural Map 2425 Dr. J. K. Reynolds McNish and Janes Townships Resources Deputy Minister Ontario MACBETH TOWNSHIP Scale, l inch to 50 miles N.T.S. Reference 41 1/9,41 1/16 SYMBOLS Glacial striae. LEGEND Esker. PHANEROZOIC Small bedrock outcrop. CENOZOIC* QUATERNARY PLEISTOCENE AND RECENT Area of bedrock outcrop. Fluvial and glacial sand, gravel and boulders, swamp deposits. Bedding, horizontal. UNCONFORMITY Bedding, top unknown; (inclined, PRECAMBRIAN6 vertical). SOUTHERN AND GRENVILLE Schistosity; (horizontal, inclined, STRUCTURAL PROVINCES vertical). LATE PRECAMBRIAN Gneissosity, (horizontal, inclined, vertical). MAFIC INTRUSIVE ROCKS Cleavage fractures; (horizontal, 12a Olivine Diabase. inclined, vertical). fesiisJ 12b Ultramafic Rocks. INTRUSIVE CONTACT Lineation with plunge. GRENVILLE STRUCTURAL PROVINCE Geological boundary, observed. ANORTHOSITE SUITE INTRUSIVE ROCKS Geological boundary, position 11a Gneissic gabbro, anorthosite . interpreted. bro. 11b Massive gabbroic anorthosite. Fault; (observed, assumed). Spot 11c Gneissic gabbroic anorthosite. indicates down throw side, arrows indicate horizontal movement. INTRUSIVE CONTACT Lineament. MIDDLE TO LATE PRECAMBRIAN l. MAFIC INTRUSIVE ROCKS Jointing; (horizontal, inclined, vertical). 10 Amphibolite. Anticline, syncline, with plunge. INTRUSIVE CONTACT MIDDLE PRECAMBRIAN Drill hole; (vertical, inclined). METASEDIMENTS 9a Biotite-h or n blende -plagioclase Swamp. gneissjn places garnetiferous meta- greywacke. 9b Biotite-plagioclase-potassic feldspar Motor road, provincial highway gneiss meta-arkose, number encircled where applicable. 9c Migmatitic 9a and 9b. Other road. SOUTHERN STRUCTURAL PROVINCE NIPISSING INTRUSIVE ROCKS Trail, portage, winter road. 8a Medium-grained gabbro. 8b Pegmatitic gabbro. Building. 8c Metamorphosed and cataclastic 8a and 8b. 8d Aphanitic to fine-grained, porphy District boundary; approximate ritic, quartz monzonite commonly position only. cataclastic. 8e Fine-grained granitic dikes. 8f Metamorphosed and cataclastic Township boundary; approximate schistose to gneissic 8d. position only. INTRUSIVE CONTACT Surveyed line; approximate HURONIAN SUPERGROUP position only. COBALT GROUP LORRAIN FORMATION Mining property, surveyed; approximate position only. i©:..t.^ f Quartz arenite, arkose, minor silty greywacke. Mineral deposit, mining property, unsurveyed. GOWGANDA FORMATION 6a Greywacke. 6b Quartz arenite, arkose. 6c Polymictic paraconglomerate. 6d Polymictic orthoconglomerate. HOUGH LAKE GROUP MISSISSAGI FORMATION 5a Argillite, minor interbedded grey PROPERTIES, MINERAL DEPOSITS wacke. 5b Greywacke, MCNISH TOWNSHIP 5c Arkosic arenite. 5d Conglomerate. 1. Jerome A. E. 5e Metamorphosed and deformed 5a 2. Savi/le Th.D. and 5d. 3. Waltenbury occurrence. UNCONFORMITY JANES TOWNSHIP EARLY PRECAMBRIAN 4. Kennco Explorations (Canada) Ltd. [1970]. MAFIC INTRUSIVE ROCKS 5. Kirkland Townsite occurrence. 6. Ossington Explorations Ltd. and 4 Diabase. Triller Explorations Ltd. [I960]. 7. Pan Central Explorations Ltd. ' INTRUSIVE CONTACT 8. Wiemer occurrence. FELSIC INTRUSIVE ROCKS Information current to December 31st, 1976. Former properties on ground now open for staking are only shown where exploration information is available. A 3 Granitic rocks. date in square brackets indicates last year of explora.- tion activity. For further information see report. INTRUSIVE CONTACT METAVOL.CAN1CS AND METASED1MENTS ———~*— METASEDIMENTS Greywacke, mudstone. M ETA VOLCANICS SOURCES OF INFORMATION Geology by B. Dressler and assistants, Geological Mafic metavolcanics (amphibol- Branch, 1976. Geology is not tied to surveyed lines. ites). Assessment files research office, Ontario Division of Mines, Ministry of Natural Resources, Toronto. Res ident geologist©s files, Ontario Ministry of Natural Breccia. Resources, Sudbury. Aeromagnetic maps, 1501G, 15Q2G, Geological Sur vey of Canada. Silicified rock. Ministry of Natural Resources, O.D.M. Map 41 f, Janes, McNish, Pardo and Dana Townships, scale 1 inch to Y, mile; Vol. XL!, pt IV, issued 1933. Carbonate. Preliminary maps O.D.M. P 844 River Valley Area, Copper. scale J inch to 1 mile, issued 1973 and P 387 Capreol Garnet. - Sheet, scale 1 inch to 2 miles, issued 1966. Nickel. Cartography by D. Laroche and assistants, Surveys and Mapping Branch, 1978. Lead. Base maps derived from maps of the Forest Resources Quartz. Inventory, Surveys and Mapping Branch, with addi tional information by B. Dressler. Sulphide mineralization. Magnetic declination in the area was approximately Uranium. 9" 14© W. 1976. Zinc. Parts of this publication may be quoted if credit is given. It is recommended that reference to this map a Unconsolidated deposits. Cenozoic deposits are be made in the following form: represented by the lighter coloured and uncoloured parts of the map. Dressler, B. 1978: McNish and Janes Township; Ontario Geolog ^Bedrock geology. Outcrops and inferred extensions ical Survey Map 2425, Precambrian Geology of each rock map unit are shown respectively in deep Series, scale 1 inch to J4 mils. Geology 1976. and light tones of the same colour. Published 1979 Ontario Geological Survey Map 2425 McNISH and JANES TOWNSHIPS SUDBURY DISTRICT Scale 1:31,680 or l Inch to V2 Mile Chains 80 2 Miles Metres 1000 3 Kilometres Feet 1000 O 5,000 10,000 Feet