This excursion is mainly based on work done by the field trip leader between 1976 and 1977 in the framework of an M.Sc. thesis supervised by Léopold Gélinas and Jean Lajoie at l'Université de Montréal.
By that time, the association of massive sulphides and rhyolites was already well documented in the Rouyn-Noranda district. A large portion of the rhyolites were thought to be flows. However in more recent environments, such as Japan, rhyolitic volcanism is mostly explosive especially near mineralized areas. This association can be explained by the porous nature of pyroclastic breccias that facilitates the circulation of hydrothermal fluids necessary for the formation of volcanogenic deposits.
The eas i 1 y access i b 1 e Don Camp 1 ex crops, put over 90 % of the area and provides a unique opportunity to observe and study volcanic processes that could not otherwise be fully appreciated under normal outcrop conditions or with drill hole data.
Figures & Tables
Control on Base Metal and Gold Mineralizations, Bousquet—Rouyn-Noranda Area*
The Archean Abitibi belt is one of the largest and most studied greenstone terranes in the world. This is due not only to its precious and base meta 1 production, but also to its excellent bedrock exposure which permits observation of many Archean geological features in the south part of the belt lying between Rouyn-Noranda and Val d'Or.
The main objective of the regional field trips and the mine visits is to present the rna in stratigraphic, st ructura 1 and ore characteristics of the southern part of the Abitibi Belt. This regional field trip is scheduled to cover the Rouyn-Noranda and Cadi 11 ac-Bousquet mining camps. Operating mines will also be visited: Francoeur, Pierre-Beauchemin, Ansil, Mobrun, Doyon and Bousquet. The delegates will be able to examine the main volcanic, plutonic and sedimentary rocks as well as the various structural features in this part of the Abitibi. Ore deposits will include both massive sulphide and gold deposits. The various geological and structural environments of these deposits will also be examined.
The southern part of the Abitibi Belt in Quebec is dominated by a prominent deformation corridor, the Cadillac-Larder Lake Fault Zone. This zone is oriented E-W and separates a volcanic domain in the north from an essentially sedimentary domain in the south. This sedimentary domain, comprising clastic rocks and various granitic complexes, belongs to the Pontiac Subprovince. The volcanic domain is composed of various “blocks” of volcanic assemblages intruded by granitic masses, separated from one another by fault zones, discordances and inear sedimentary units. On the regional scale, the imbricated volcanic “blocks” are lozenge-shaped, with E-W orientd long axes. In most cases, the relationships between these volcanic and sedimentary “blocks” remain ambiguous.