Regional 18O Zoning and Hydrogen Isotope Studies in the Kidd Creek Volcanic Complex, Timmins, Ontario*
Bruce E. Taylor, David L. Huston, 1999. "Regional 18O Zoning and Hydrogen Isotope Studies in the Kidd Creek Volcanic Complex, Timmins, Ontario", The Giant Kidd Creek Volcanogenic Massive Sulfide Deposit, Western Abitibi Subprovince, Canada, Mark D. Hannington, C. Tucker Barrie
Download citation file:
Isotopic studies covering some 200 km2 of the Kidd Creek Volcanic Complex, within about 10 km of the giant Kidd Creek deposit, include the analysis of 395 whole-rock and quartz phenocryst samples for oxygen isotopes and 87 whole-rock samples for hydrogen isotopes. All of the rocks of the Kidd Creek Vol canic Complex are enriched in 18O relative to fresh or even mildly altered equivalents elsewhere, comprising a range for whole rocks of δ18Owhole rock = 6.3 to 15.7 per mil. Mapped distribution of δ18O whole rock values indicates several prominent zones of lower δ18O whole rock values located in the footwall of the Kidd Creek mine sequence and in footwall-equivalent sequences at the Chance deposit. Other zones located elsewhere suggest widespread hydrothermal activity throughout the complex. Broadly conformable zones of relative 18O increase in mafic and rhyolitic rocks, primarily in hanging wall-equivalent sequences, mark waning hydrothermal activity and cooling temperatures. These broad zones are not spatially associated with either the Kidd Creek mine or the Chance deposit, but they are nevertheless related to the evolving hydrothermal activity in the Kidd Creek Volcanic Complex. Isotopic alteration of the crust was the result of long-lived hydrothermal activity (possibly on the order of 10 m.y.) that continued past the period of sulfide mineralization at Kidd Creek. The zones of 18O enrichment are, in many cases, associated with uneconomic but anomalous occurrences of Zn that may represent the manifestation of a cooling hydrothermal system still able to mobilize minor amounts of metal.
The minimum oxygen isotope composition of rhyolitic magma in the Kidd Creek Volcanic Complex inferred from analyses of phenocrysts (δ18Oquartz) was ca. 8.5 per mil due to melting or assimilation of 18O-enriched, possibly low-temperature altered igneous crust. Quartz phenocrysts with δ18Oquartz values as high as 15.4 per mil indicate subsolidus exchange with the rock matrix during regional greenschist facies metamorphism.
Hydrogen isotope studies indicate narrow ranges in δD values for all rock types except several rhyolite flows. A rhyolite flow in the footwall ultramafics, about 1,000 m beneath the Kidd Creek mine, has δD value vs. wt percent HO characteristics that mirror rhyolites emplaced and degassed in very shallow to surficial environments. At least 1 km of subsidence is inferred to have occurred over a short period of time, prior to mineralizing hydrothermal activity at Kidd Creek. An extensional (i.e., rifting) tectonic environment would promote both subsidence of the crust and deep penetration of seawater-derived hydrothermal fluids.
Figures & Tables
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