Paul D. Bourque

Significant mineralization in the Antigonish Area, is to date, found only in the Carboniferous sediments of the basinal areas within the region. The Antigonish Highlands, made up of volcanic and sedimentary rocks of the Browns Mountain Group, show little indication of any substantial mineralization other than Cambro-Ordovician ironstones.

Several mineral groups, defining metallogenic areas are delineated. Each group comprises several mineral occurrences in similar lithological environments. With the exception of Cambro-Ordovician and Silurian ironstones, a minor Cambro-Ordovician contact metamorphic copper-zinc showing and a sedimentary copper deposit in Devonian rocks, all significant mineral groups are confined to Carboniferous lithologies.

Other mineral groups include galena in calcite cavities in Upper Windsor carbonate mounds; red bed type copper occurrences in Canso Group fluvial sediments and Kupferschiefer type mineralization along the Horton-Windsor contact.

Ore textures within the copperbelt of the Horton-Windsor contact suggest that pyrite formed contemporaneously with the sediments through the production of H₂S by bacterial action. Ore textures further indicate that the pyrite was subsequently replaced by chalcopyrite, which was in turn replaced by increasingly copper rich sulfides. Comparisons of this deposit with similar deposits, suggests a model involving dewatering of oxidized Horton sediments by compaction and expulsion of copper bearing water. Copper sulfides are precipitated upon contact with pyrite in a reducing environment.

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Pages: 466
Supervisor: Marcos Zentilli