DV 98-04 GEOLOGY AND METALLOGENY OF THE CHAPAIS-CHIBOUGAMAU MINING DISTRICT GEOLOGY AND METALLOGENY OF THE CHAPAIS-CHIBOUGAMAU MINING DISTRICT Geology and Metallogeny of the Chapais-Chibougamau Mining District : a New Vision of the Discovery Potential Proceedings of the Chapais-Chibougamau 1998 Symposium Editor : Pierre Pilote With the contributions from : G.O. Allard, Y. Bellavance, A. Biais, B. Boily, H. Brisson, E.H. Chown, R. Daigneault, H. de Corta, C. Dion, D. Gervais, P.A. Girard, R. Girard, J. Guha, R.V. Kirkham, V. Larouche, G. Lavallière, G. Maltais, R. Morin, W. Mueller, P. Pilote, F. Robert, L. Schmitt, M. Simard, W.D. Sinclair 1- Gouvernement du Québec C M ' Institut Canadien des Mines ~e ~ Ministère des Ressources Chapais - Chibougamau naturelles Association des Prospecteurs du Québec A New Vision of the Discovery Potential DIRECTION DE LA GÉOLOGIE Director : J.-L. Caty SERVICE GÉOLOGIQUE DU NORD-OUEST Chief : R. Marquis Manuscript submitted: from avril 1st to august 15th, 1998 Prepared by the Service Géologique du Nord-Ouest Cover page : 1 - Intermineral dyke crosscutting a pyritic bearing 1 2 stockwork, Clark Lake section, Doré Lake Complex; 2 - Volcaniclastic rocks showing a selective substratiform 4 sericitization and chloritization propagating along 3 bedding, Blondeau Formation, Bourbeau hill; 3 - Layered Zone of the Doré Lake Complex (South limb), mineralized in vanadiferous magnetite; 4 - Hydrothermal breccia mineralized in cp-py-Au, Troilus mine, Frotet-Évans greenstone belt. Dépôt légal - Bibliothèque nationale du Québec, 1998 ISBN : 2-551-19027-4 © Gouvernement du Québec ii Geology and Metallogeny of the Chapais-Chibougamau Mining District FOREWORD Two contrasting depositional settings, a southern basalt plain and a northern volcanic arc, occur and This volume will focus on both the Chibougamau affect syngenetic deposits in the two domains, segment and the Southern Caopatina segment of whereas the entire region is united by a common the Northern Abitibi Belt, an area which has been deformation and intrusion pattern. Porphyry actively explored over the past 15 years. copper-type mineralization occurs mainly in the arc The objective of this volume is to present a environment. However, mesothermal, or "orogenic", summary of the talks and field excursions given for lode-type gold mineralization occur in both the "Symposium Chapais-Chibougamau 1998", domains, without apparent discrimination. The organized by the Chibougamau-Chapais section of geology of the Frotet-Evans greenstone belt is also the Canadian Institute of Mining (CIM) for the described, with an exhaustive description of the centenary celebrations (1898-1998) of this Troilus mine, which is operated by Inmet Minimg organization. This volume will tend to show a new Corp. The area was marked by geological processes vision of the discovery potential of this region. This throughout the Proterozoic and culminating in the meeting is organized to help to promote investments Late Proterozoic Grenvillian Orogeny. and exploration in this high potential, but This volume has been structured to present an inadequately explored area. updated version of the geology of the area, This guidebook, which is inspired by Chown et according to the most recent published or ongoing al. (1990) contribution, presents an overall view of work in this region, followed by stop or deposit the volcanic stratigraphy (from deep water to descriptions. The latter section presents, in some subaerial environments), mafic to ultramafic sills cases, new views and ideas concerning the origin and plutonic intrusions (tonalite to carbonatite), of some deposits in the Chibougamau mining camp. structures (Archean synvolcanic to late tectonic We hope this excursion will generate stimulating Grenvillian) and their various controls on ore discussions between participants, authors and formation. This leads to an examination of the exploration geologists involved in this symposium. exploration significance of various types of deposit with respect to their regional setting. ACKNOWLEDGMENTS Previous guidebooks (Allard et al., 1972; Allard et al., 1979; Guha and Gobeil, 1984) focused mainly Preparation for this excursion has involved the on the Chibougamau region. In their guidebooks, efforts of numerous organizations and companies. Chown et al. (1990) and Pilote et al. (1995d and We would like to thank SOQUEM, Meston Lake 1998c) attempted to consider the regional geology Resources, MSV Resources, Inmet Mining Corp., in the light of possible global tectonic settings, both GéoNova, the Université du Québec à Chicoutimi, at the time of formation of the supracrustal and and the Ministère des Ressources naturelles du intrusive rocks, and during regional deformation. Québec. This approach is conserved in this volume. The editor : Pierre Pilote iii A New Vision of the Discovery Potential TABLE OF CONTENTS FOREWORD iii ACKNOWLEDGMENTS iii TABLE OF CONTENTS iv PART A - GEOLOGICAL SETTING OF THE EASTERN EXTREMITY OF THE ABITIBI BELT 1 INTRODUCTION 1 HISTORY OF THE CHIBOUGAMAU CAMP 2 VOLCANO-SEDIMENTARY SUPRACRUSTAL SEQUENCE - GENERAL ASPECTS 3 CHIBOUGAMAU-CAOPATINA REGION (CCR) 5 STRUCTURAL GEOLOGY 16 PLUTONIC ROCKS 19 TECTONIC MODELS 23 PROTEROZOIC 25 GRENVILLIAN OROGENY 26 PART B - METALLOGENY OF THE EASTERN EXTREMITY OF THE ABITIBI BELT 29 INTRODUCTION 29 I - MINERALIZATION RELATED TO THE EMPLACEMENT OF MAFIC INTRUSIONS (OXIDES AND SULPHIDES OF MAGMATIC ORIGIN) 29 II - SULPHIDE DEPOSITS RELATED TO THE SYNVOLCANIC PERIOD 30 III - MINERALIZATION RELATED TO HIGH LEVEL PLUTONIC ACTIVITY AND ASSOCIATED VOLCANIC LAND FORMS 31 Porphyry type and associated mineralization - the Cu-Au veins of the Doré Lake mining camp 31 Epithermal precious metal veins 38 IV - ARCHEAN MESOTHERMAL GOLD DEPOSITS SPANNING MAJOR DEFORMATION AND PLUTONIC ACTIVITY 38 V - DEPOSIT OF UNCERTAIN AGE - OPEMISKA TYPE VEINS 40 CONCLUDING REMARKS 41 iv Geology and Metallogeny of the Chapais-Chibougamau Mining District PART C - REGIONAL GEOLOGY 43 GOLD MINERALIZATION AND MINING POTENTIAL OF THE SHORTT LAKE REGION 43 GEOLOGICAL AND METALLOGENIC COMPILATION OF THE CAOPATINA SEGMENT 51 GEOLOGICAL SYNTHESIS OF THE FROTET-TROILUS REGION 53 PART D - ECONOMIC GEOLOGY 61 PORPHYRY TYPE MINERALIZATION IN THE DORÉ LAKE COMPLEX - CLARK LAKE AND MERRILL ISLAND AREAS 61 THE BERRIGAN LAKE SHOWING - A POSSIBLE EXAMPLE OF AN ARCHEAN EPITHERMAL-TYPE Au-Ag-Cu-Pb-Zn-As MINERALIZATION 79 MERRILL ISLAND Cu-Au VEINS AND CLARK LAKE Cu-(Mo) PORPHYRY DEPOSIT, DORé LAKE MINING CAMP, CHIBOUGAMAU 85 THE "CORNER BAY" COPPER DEPOSIT 93 THE LAC DORÉ VANADIUM DEPOSIT, CHIBOUGAMAU 99 THE CHEVRIER ZONE, AN IMPORTANT MINERAL RESOURCE FOR THE CHIBOUGAMAU REGION 103 GEOLOGY OF THE JOE MANN MINE 109 THE JOE MANN AURIFEROUS DEFORMATION ZONE 115 THE TROILUS Cu-Au DEPOSIT 119 EPITHERMAL GOLD DEPOSITS : STYLES AND POTENTIAL FOR DISCOVERY IN ANCIENT TERRANES 129 SOQUEM'S VISION 131 MSV RESOURCES CORPORATIVE VISION 137 CHIBOUGAMAU: SPEARHEAD OF NORTHERN MINING 143 REFERENCES 145 V A New Vision of the Discovery Potential vi Geology and Metallogeny of the Chapais-Chibougamau District PART A - GEOLOGICAL SETTING OF THE EASTERN EXTREMITY OF THE ABITIBI BELT E. H. Chown, Réal Daigneault, Wulf Mueller Sciences de la Terre, Centre d'Études sur les Ressources Minérales, Université du Québec à Chicoutimi, 555 boul. Université, Chicoutimi, Québec, G7H 2B1; and Pierre Pilote Ministère des Ressources naturelles du Québec, 400 bouI. Lamaque, Val-d'Or, Québec, 19P 3L4. (modified from Chown et al., 1990) INTRODUCTION volcanic rocks in the southern part of the CCR (Sharma et al., 1988). The detailed mapping The Chibougamau-Caopatina region (CCR) is programme of the Québec Ministère des Ressources located in the northeastern corner of the Abitibi belt naturelles (formerly Ministère de l'Énergie et des (Figure Al). Differences in lithology, such as Ressources) has shown a need to reevaluate the presence of komatiites in the south, and the greater stratigraphy in specific areas of the CCR. Recently abundance of plutons and extensive mafic to ultramafic sills in the north, as well as a difference in stratigraphic thickness prompted Dimroth et al. Superior Province (1982, 1984) to divide the Abitibi belt into a northern, Plutonic Province Internal Zone and southern, External Zone. In the Volcano-plutonic Province \Minto same manner, Ludden et al. (1986) have made a Metasedimentary Province distinction between the two segments, and called Metamorphic Province them the Northern Volcanic Zone and the Southern Volcanic Zone. The (CCR) forms part of the Hudson Bay Northern or Internal Zone which is limited on the Pikwitonei + °(12 sr- SOpinaca James north by the Opatica belt, and on the east by the Bay Grenville Province (Figure A2). The contact zone atica between the two provinces, the Grenville Front English (Wynne-Edwards 1972; Rivers and Chown 1986; Uchi river Abitibi Bird rive ,etc ÿ Figure 2 Rivers et al., 1989), is marked by a disruption in the Winnipe Wawa `1111/C om,C Pontiac common East-West tectonic trend. The metamorphic river Lac Z> Y / Supérieur grade, typically greenschist facies, rises to amphibolite facies near the Grenville Front. 300 km The CCR (Figure A2) is the most extensively innesota River( studied part of the northern Internal Zone. Initial vaney ~ mapping was carried out by Norman (1937; 1938), Figure Al: Geology of the Superior Province Beach (1941a, 1941b) and later continued by the (Card and Ciesielski 1986). Quebec provincial survey (Gilbert