Mississippi Valley-type Zn-Pb mineralization in northern Cornwallis Fold Belt - Genetic relationship between ore-forming fluids in different occurrences

CIM MineSpace 2001
Martine M Savard,
Abstract The Cornwallis Fold Belt in the Canadian Arctic Archipelago contains numerous Mississippi Valley-type (MVT) Zn-Pb occurrences, including the world-class Polaris deposit. The occurrences are hosted by dolostones of the Thumb Mountain Formation which spreads over 25000 km2. Success in exploration requires further understanding of the genesis of these occurrences. Are the regionally distributed, small occurrences genetically linked with the giant Polaris deposit? Syn-sulfide dolomites in regional occurrences share C-O-Sr isotopic characteristics similar with Polaris dolomites, indicating warm basinal brines enriched in 87Sr. The dolomites and sphalerites contain fluid inclusions with ice-melting temperature between -25° and -45°C, that is significantly lower than for most MVT districts in the world (-10° and -30°C). These characteristics indicate that all the Cornwallis occurrences were genetically related and produced by common fluids, i.e. same sources and/or aquifers. The deposit size was largely controlled by the rate and duration of the sulfide-forming fluid flow, and by the availability of reduced sulfur at the site of mineralization.

Keywords: Lead-zinc deposits, ore-forming fluids, Fluid inclusions, Dolomite, MVT, Polaris, Mississippi Valley-type, Arctic, stable isotopes, Cornwallis Fold Belt
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