Sulfides from the Gull Pond cupriferous iron sulfide deposit of Ordovician (?) age, associated with cordierite-anthophyllite and cordierite-andalusite + or - biotite rocks, show only a limited spread in delta 34 S values: +0.2 to +7.6 per mil with a mean of +4.2 + or - 1.8 per mil. Although the pyrite-pyrrhotite-chalcopyrite-magnetite ores have undergone recrystallization during Devonian thermal metamorphism, sulfur isotopic compositions, especially for pyrite, are considered to reflect original delta 34 S values. Much of the pyrrhotite and some of the magnetite present in the Gull Pond ores were produced during thermal metamorphism. Original ore mineral assemblages at Gull Pond were likely similar to those in ophiolitic cupriferous iron sulfide deposits (Whalesback, Little Bay, Tilt Cove, etc.) elsewhere in Notre Dame Bay (pyrite + or - magnetite) and much of the sulfur in the Gull Pond deposit, like the others, was derived from Ordovician sea-water sulfate.

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