Central Mine Sequence Stratigraphy Field Trip
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Published:January 01, 1991
Abstract
The stratigraphy of the Central Mine Sequence is remarkably well preserved and we 11 exposed. A 1 though disrupted by numerous northeast and northwest striking faults, the volcanic rocks have suffered little of the penetrative deformation typically associated with greenschist-facies regional metamorphism elsewhere in the region. The volcanic stratigraphy in the tour area comprises subaqueous andes it i c and rhyo 1 it i c flows with 1 ess than 5 % pyroclastic and epiclastic rocks. In a “younging” direction, and from west to east, formations include: The Flavrian Andesite, the Northwest Rhyolite, the Rusty Ridge Andesite, the Amulet Rhyolite, the Millenbach-Waite Andesite, the Millenbach QFP RhyoliteWaite Rhyolite, the Amulet Andesite, the Newbec Rhyolite and the Newbec Andesite (Fig. 5). Formations strike north-northeast, are gently folded about east-west trending and plunging axes, and dip from 5 to 55° to the east {Fig. 4).
The stratigraphy of the Central Mine Sequence is thought to represent the infilling of a primary volcano-tectonic depression or caldera (Dimroth et al., 1982; Gibson, 1989). Hydrothermal vents are coincident with volcanic vents and both show a strong spatial association to major synvolcanic faults which were active at various stages during successive collapse of the Noranda Caldera.
Volcanogenic Massive Sulphide {VMS) deposits, although clustered above the Amulet Rhyolite formation (Fig. 5), are scattered throughout 2 000 (+) m of stratigraphy and within individual deposits massive sulphide lenses may be stacked over vertical distances approaching 300m {Amulet Upper and Lower A, Fig. 8).
VMS deposits are of the
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Contents
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.