The lower portion and base of the Blake River Group immediately south of the town of Rouyn-Noranda is composed essentially of an east trending moderate to steeply north dipping submarine volcanic sequence which includes a lowermost tholeiitic mafic segment approximately 3 000 m in thickness containing several well defined and regionally continuous variolitic marker horizons, a central intermediate ash flow tuff band up to 600 m in thickness and an overlying mafic lava sequence which interfingers with the Beauchastel Rhyolite flow complex to the west. This volcanic assemblage forms a wedge shaped block structurally bounded by the regional east trending Cadillac Break to the south and the ENE trending Horne Creek Fault to the north.
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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.