Mass Change Profiles in the Footwall of the Kidd Creek Orebody
E. M. Marnie Muirhead, R. W. Hutchinson, 1999. "Mass Change Profiles in the Footwall of the Kidd Creek Orebody", The Giant Kidd Creek Volcanogenic Massive Sulfide Deposit, Western Abitibi Subprovince, Canada, Mark D. Hannington, C. Tucker Barrie
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The footwall to the Kidd Creek orebody comprises dominantly rhyolite volcaniclastic rocks of lapilli- to block-sized fragments and massive rhyolite flows. The deposit overlies a broad, conformable zone of alteration characterized by laterally extensive sericite and Mg-rich chlorite alteration, and locally, by strong silicification and Fe-rich chlorite alteration. Pervasive silicification of the footwall rhyolites has largely converted these rocks to fine-grained quartz. Sericite and chlorite have replaced the fine-grained, tuffa-ceous matrix of the fragmental rocks and occur as fracture fillings in the brecciated massive rhyolite flows. Mass change calculations employing the method of immobile elements delineate two broadly conformable zones of alteration: one immediately beneath the massive sulfide lenses (zone I), and the other a zone of weaker alteration 50 to 100 m stratigraphically below the lenses (zone II). Zone I is characterized by moderate to strong concentrations of SiO2 and FeO and a decrease in K2O. Zone II is characterized by concentrations of MgO and K2O. Both zones are strongly depleted in Na2O and CaO. Distinct trends of Fe increase adjacent to the ore lenses (zone I) and Mg increase at depth (zone II) are interpreted to reflect zones of high- and low-temperature fluid flow beneath the massive sulfide lenses. These zones follow the orebodies downplunge for more than 2 km and define a narrow corridor of focused hy-drothermal fluid flow along the original axis of the Kidd Creek graben.
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The Giant Kidd Creek Volcanogenic Massive Sulfide Deposit, Western Abitibi Subprovince, Canada
ARCHEAN Cu-Zn deposits are among the most important mineral deposit types in Canada. The Superior province of Canada contains nearly 80 percent of the known Archean Cu-Zn deposits in the world (about 100 of 125 deposits). These deposits are concentrated in 10 separate mining camps, including Sturgeon Lake, Manitouwadge, Mattagami Lake, Chibougamau, Joutel, Val d’Or, Bous-quet, Noranda, Kidd Creek, and Kamiskotia (Fig. 1 and Table 1). A few deposits in rocks of similar age and composition are also known in the Slave province, the Churchill province, and in the Archean of Western Australia, southern Africa, China, and Brazil. Known deposits of this age worldwide account for more than 650 million metric tons (Mt) of massive sulfides, containing 10 Mt of Cu metal, 29 Mt of Zn, 1 Mt of Pb, 33 Mkg Ag, and 750,000 kg Au. The giant Kidd Creek volcanogenic massive sulfide deposit in the western Abitibi subprovince of Canada is the largest known deposit of this age currently in production. The Superior province is the world’s largest exposed Archean craton, occupying an area of more than 1.5 million km2, bounded by the Trans-Hudson orogen to the west and the Grenville province to the east. A number of distinct subprovinces are recognized, assembled into east-west-trending granite-greenstone terranes and metasedi-mentary belts (Fig. 1). The granite-greenstone terranes are composed of gneissic rocks of plutonic origin, supracrustal rocks of dominantly volcanic origin, and a variety of syn- to late kinematic granitoids. Volcanic rocks comprise about 12 percent of the total area. The greenstone belts have been described variously as successive lateral accretions of volcano-plutonic arcs, oceanic islands, oceanic plateaus, and rift-related assemblages (e.g., Langford and Morin, 1976; Percival and Card, 1985; Ludden and Hubert, 1986; Ludden et al., 1986; Card, 1990; Jackson and Sutcliffe, 1990; Williams, 1990; Corfu, 1993; Heather et al., 1995; Jackson and Cruden, 1995). The metallogenic history of the Superior province has been described in detail by Franklin and Thorpe (1982) and Poulsen et al. (1992).
The Abitibi subprovince (94,000 km2) is the largest of the greenstone belts. It contains the major gold and base metal mining camps in Canada (Fig. 2), with production and reserves totaling more than 480 Mt of massive sulfide and 4,700 t of Au. Metal production in the western portion of the Abitibi greenstone belt is dominated by the Timmins region, which historically has accounted for 37 percent of the total gold production