RG 137(A) GEOLOGY AND SULFIDE DEPOSITS OF THE MATAGAMI AREA, ABITIBI-EAST COUNTY QUEBEC DEPARTMENT OF NATURAL RESOURCES Honorable Paul-E. Allard, Minister MINES BRANCH GEOLOGICAL REPORT 137 GEOLOGY AND SULFIDE DEPOSITS of the MATAGAMI AREA Abitibi-East County by John I. Sharpe QUEBEC 1968 MINERAL DEPOSITS SERVICE TABLE OF CONTENTS Paoe INTRODUCTION 1 Summary statement 1 Location and topography of the area 2 Field work 2 Previous work 3 Acknowledgements 3 REGIONAL GEOLOGIC SETTING 5 GENERAL GEOLOGY 5 Table of Formations 6 Volcanic rocks 7 Distribution, subdivision and nomenclature 7 Lac Watson Group 9 Lithologic units 10 Porphyritic rhyolite 10 Spherulitic rhyolite and rhyodacite 10 Tuff and agglomerate 11 Brecciated and silicified rhyolite 13 Chloritic rhyolite 14 Chloritized intermediate volcanic rock 14 Mafic lavas 16 Wabassee Group 17 Lithologic units 17 Dacitic lavas 17 Andesite-basalt 18 Tuff and agglomerate 19 Tuffite 20 Intrusions related to volcanism 23 Correlation of volcanic sequences 24 Alteration and metamorphism of volcanic rocks 24 Silicified rocks 27 Environments of extrusion 27 Intrusive rocks 29 Older intrusions 29 Bell River complex 29 Marginal zones 30 Core zone 32 Apophyses and subsidiary intrusions 32 Structure of the northwest part of the complex 34 Possible consanguinity of gabbros and mafic lavas 36 Peridotite 37 Quartz diabase 37 Younger intrusions 37 Granite, granodiorite, quartz diorite, siliceous, feldspathic and mafic dikes 37 Pane Late gabbro dikes 38 STRUCTURAL GEOLOGY 38 Folds 39 Faults and schist zones 39 Schist zones 39 Transverse faults 40. Foliation and joints 40 ECONOMIC GEOLOGY 41 DESCRIPTIONS OF DEPOSITS 41 INTRODUCTION 41 Copper-zinc deposits 42 Mattagami Lake Mines Ltd 42 General geology 43 Volcanic rocks 44 Intrusive rocks 45 Structure 46 Orebodies 47 Form of deposits and relations to structures, host rocks and dikes 47 Ore types and distribution 50 Tuffite ore 50 Banded, layered, foliate and massive sphalerite-pyrite ores 51 Magnetite-pyrite-pyrrhotite ore 52 Metallized schist and breccia 53 Alteration 53 Summary 56 Orchan Mines Ltd. 56 General geology 56 STRUCTURE 57 Orebodies 57 Form and relations to host rocks and structure 57 The ores 58 Alteration 61 Summary 61 Bell Allard Mines Ltd. 61 General geology 62 Sulfide deposit 62 Consolidated Mining and Smelting Co. of Canada 63 New Hosco Mines 65 General geology 65 Structure 67 Orebodies 67 Form and relations to host rocks, structure and intrusive rocks 68 — Iv — Page The ores 69 Summary 71 Radiore Uranium Mines "A" Deposit 71 General geology 72 Sulfide deposit 73 Alteration 75 Structural relations 75 Summary 75 Bell Channel Mines Ltd. (No. 1 Deposit) 76 General geology 76 Sulfide deposit 77 Form and relation to host and wall rocks 77 The sulfides 77 Alteration 78 Summary 78 Bell Channel Mines Ltd. (No. 4 Zone) 78 Radiore Uranium Mines Ltd. "East Deposit" 79 General geology 79 Sulfide deposit 80 Form and relations to host rocks, structure and intrusive rocks 80 The sulfides 81 Alteration and metamorphism 82 Caron Lake Mines 82 General geology 82 The sulfide zone 83 Alteration and metamorphism 84 Daniel Mining Co. Ltd. 84 New Calumet Mines Ltd. 85 Near Matagami townsite 85 South of Chenal rapids 85 Galinée-Mattagami Mines 85 Bracemac Mines Ltd 85 Gold and silver 85 Northern Quebec Explorers Ltd 87 Dearing Explorers Corp. 87 Magado Mines Ltd. 87 Molybdenite 87 COMPARISON OF THE SULFIDE MASSES 88 Gross mineral and metal compositions of deposits 88 Ore types and distribution 90 Tuffite sulfides 90 Metallized schist, breccia and coarse pyroclastic rocks 91 Pyrite-magnetite-pyrrhotite mixtures 91 Pyrite-sphalerit.e ore type 92 Chalcopyrite ores 93 -v - Page Paragenetic relations 93 Zonation of ore-types 94 Temperatures of crystallization 94 Sphalerite geothermometer 94 Pyrrhotitegeothermometer 98 Significance of results 98 Disposition of sulfides in volcanic rocks 98 Stratigraphic and lithologic relations 98 Host rocks 100 Relations to intrusive rocks 101 Structural environments of deposits 103 Schist zones and fractured zones 103 Folds and warps 105 Transverse faults 106 SUMMARY AND CONCLUSIONS 106 General field relations 106 Characteristics of the deposits 107 Environment of metallization 109 APPENDICES 110 Appendix A 110 Prospecting 110 Appendix, B 110 Analyses of rocks 112 BIBLIOGRAPHY OF MATAGAMI AREA 114 REFERENCES CITED 116 ALPHABETICAL INDEX 119 TABLES Table 1 - Volcanic. Sequences and Correlation 25 Table 2 - Results from Sphalerite Geothermometer 95 Table 3 - Results from Pyrrhotite Geothermometer 99 Table 4 - Chemical Analyses of Rocks 113 - VI - ILLUSTRATIONS A1212k Page One inch equals 1,000 ft. scale: No. 1631 - S.E. Part Daniel; (in pocket) No. 1632 - S.W. Part Isle-Dieu; (in pocket) No. 1633 - S.E. Part Isle-Dieu; (in pocket) No. 1634 - N.W. Galinée; (in pocket) No. 1635 - N.E. Galinée (in pocket) Figures Fig. 1 - Regional Setting of Matagami Area 4 Fig. 2 - General Geology - Matagami Area (in pocket) Fig. 3 - Generalized Graphic of Holes through Tuffite 21 Fig. 4 - Northwest Part of Bell River Igneous Complex (in pocket) Fig. 5 - Plans and Sections of Sulfide Deposits (in pocket) Fig. 6 - Fault System, Crchan Mines Ltd. 60 Fig. 7a - Relative Proportions Metallic Minerals 96 Fig. 7b - Metal Ratios 97 Plates Plate I - Lac Watson Group Rocks 12 Plate II - Wabassee Group Rocks 15 Plate III - Bell River Complex Rocks 35 Plate IV - "Key Tuffite", Mattagami Lake Mines 48 Plate V - Sulfides in "Key Tuffite", Mattagami Lake Mines 54 Plate VI - Sulfide Fabrics 64 Plate VII - Microscopic Nature of Ores 86 Plates VIII- Microscopic Nature of Ores 89 GEOLOGY AND SULFIDE DEPOSIT Q MATAGAMI AREA Abitibi-East County by John I. Sharpe INTRODUCTION Summary statement A group of Early Precambrian rhyolitic rocks and a younger group of lavas and pyroclastic rocks are intruded by a layered gabbro- anorthosite pluton. Both the pluton and the volcanic rocks are folded and intruded by granite. Thirteen deposits of chalcopyrite and sphalerite have been found; mining of three of these began in 1963. The deposits are restricted to a stratigraphic zone near the contact between the volcanic groups. The upper limits of metallization are concordant against lava or chert units of the younger group, whereas the lower extremities of some deposits follow transverse structures. Mineral and fabric relations indicate that, except for some layers of sulfides in chert, the ores are epigenetic. Geothermometric data from sphalerite and pyrrhotite indicate temperatures of crystallization above 425°C. The sulfide masses are deformed and appear to be intruded by pre-orogenic dikes. Close relations between metallization and volcanic lithology and stratigraphy, and the preliminary investigation of the fabrics and crystallization temperatures of the ores, suggest that they were formed by replacement, at high temperatures, in the volcanic environment. - 2 -- Gold-bearing veins, small amounts of bismuth, molybdenite and disseminated chalcopyrite also occur within the map-area. Location and topography of the area The Matagami area, as described in this report, is consid- ered to be an area of 155 square miles, near latitude 49°45' and longitude 77°45'. It comprises ranges I to VII in Isle-Dieu township, the east halves of ranges I to VII in Daniel township, and the north half of Galinée township. The Matagami townsite, at the Bell river, is 112 miles by road from the town of Amos and hydroelectric and railway lines have been extended into the area. The main rivers are navigable except for the rapids in the Bell river near the townsite and Inlet rapids at Matagami lake. Inlet rapids can be run except at times of low water. The land surface is level, the few hills and irregularities being subdued by lacustrine deposits of glacial-lake Barlow-Ojibway. Out- crops are scarce except in the northeast, where the Mount Laurier hills extend west into the area, and along the main waterways, the Bell and Allard rivers, and Matagami lake. The rivers flow north into the lake and thence into Nottaway river and northward to James Bay. Field work The extensive exploration activity, precipitated by the discovery of a major base metal deposit in 1957, made it desirable to compile and integrate the rapidly accumulating geologic data. The field work was done in 1961, 1962, and 1963 and included geologic mapping, at scales from 100 feet to the inch to 1,000 feet to the inch, according to the complexity of the geology. In many areas, such as in northwest Galinée township, information on bedrock is derived principally from drill-hole data. Detailed geophysical surveys performed by mining companies over much of the area were useful in outlining certain rock units. Networks of cut lines over the area provided survey controls. Most of the laboratory work was done at McGill University. A comprehensive, though preliminary,study has been made of the sulfide deposits, large and small. The main aims have been to: present a description of each deposit; study each in relation to the general geol- ogy; and to compare and contrast the deposits and their environs in hope of determining the disposition of the metallization in space and time. * The official spelling is now "Matagami" (previously "Mattagami"). - 3 - Previous work The earliest recorded geological observations are those by Robert Bell (1895, 1900), who crossed Matagami lake on his trip down the Nottaway river. Bancroft's (1912) survey for the Quebec Bureau of Mines included descriptions of some outcrops in the area and the recogni- tion of a large mafic igneous complex. By 1936, Freeman and other workers of the Geological Survey of Canada had outlined the basic features of the geology. Systematic mapping was undertaken by the Quebec Bureau of Mines in 1938 and resulted in the publication of 1 inch to 1 mile maps, by Longley (1943), Freeman and Black (1944) and Béland (1953), which encompass the Matagami area.