Abstract

The Madeleine copper deposit comprises steeply plunging stockwork orebodies in cordierite-biotite hornfels adjacent to a Devonian granitic pluton. Mineralization in each orebody is zoned outward from bornite-chalcopyrite in the core through chalcopyrite to chalcopyrite-pyrrhotite and is associated with local biotite, calc-silicate, and chlorite-muscovite alteration. Sulfide deformation textures suggest that mineralization was pre- to synmetamorphic. The delta 34 S values of chalcopyrite range from -26.7 to +32.5 per mil. Higher delta 34 S values correlate with calc-silicate beds or with calc-silicate alteration. Shales corresponding to the cordierite-biotite hornfels have delta 34 S values ranging from +7.1 to -19.1 per mil and limestones delta 34 S > 14 per mil. It is proposed that cupriferous fluids, partly emanating from a granite, dissolved sulfur from the overlying sediments and rose through bedding plane-controlled permeability to deposit the ores at higher structural but similar stratigraphic levels.

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