Mineralisations auriferes de la partie centrale de la Province de Grenville, Bouclier Canadien

CIM Bulletin, Vol. 78, No. 874, 1985

MICHEL GAUTHIER et GAETAN MORIN, Departement des Sciences de la Terre, Universite du Quebec a Montreal, Montreal, Quebec, PIERRE MARCOUX, Geologue-resident du Nord Quebecois, Ministere de I'Energie et des Ressources, Sept-lies, Quebec

The recent opening of Muscocho's gold mine at Montauban, as well as the discovery of several new copper-gold showings of a similar nature near the confluence of the Saguenay and St. Lawrence has revealed the existence of a new metallogenic gold province which is located within supercrustal units of Helikian age within the Grenville Province. Three metalliferous belts have been identified, each one of which is related to a series of SW-NE trending faults. The first is located in southeastern Ontario and southwestern Quebec. The second extends from the Balmat-Pierrepont mining district of New York State up to the Lac St. Jean region of Quebec, and includes the Montauban camp. The third follows the St. Lawrence river in Charlevoix County and along the north shore of the Gulf of St. Lawrence. The gold mineralization which is present in the central portion of the Grenville Province is of two types: either stratiform or vein. Deposits of the first type, of which the Muscocho is the type locality, are economically the more interesting of the two. Not only is this mineralization stratiform, but also shows a distinct affinity to Al-rich, Mg-rich or calc-silicate-rich bands. As is the case with the Bousquet and Hemlo regions of the Superior Province, they are associated with layers which are rich in sillimanite and occasionally staurolite. A second parallel between the Bousquet and Montauban deposits might be the presence of manganesian garnets, which have been recognized at the two localities. Some of the mineralization in the central Grenville Province is located within thin bands of iron formation which are rich in arsenic. The stratiform gold deposits of the central Grenville Province are of exhalative origin and are located within a volcano-sedimentary terrane. It is probable that a part of the gold present in these Helikian deposits have been derived by remobilization of Archean mineralization. The vein showings form as a consequence of the remobilization of the Helikian strata during the Grenville metamorphism.

Mots Clés: Gold mineralizalion, Gold, Melallogeny, Grenville Province, Monlauban region.