Abstract

Sulfur isotopic compositions of 44 sulfide minerals separated from five metamorphosed cupriferous iron sulfide deposits in ophiolitic terrains in the Notre Dame Bay area have been determined. delta 34 S values from some individual deposits vary widely: Tilt Cove in the Betts Cove-Tilt Cove ophiolite (+ 5.5 to + 23.0 per mil), Rendell Jackman in the Lush's Bight ophiolitic terrain (+ 9.1 to + 18.0 per mil); others are relatively homogeneous: Little Bay and Whalesback in the Lush's Bight ophiolite (+ 12.6 + or - 1.2 per mil and + 5.3 + or - 1.7 per mil respectively). Although metamorphosed, deformed, and partly remobilized, sulfur isotopic compositions can still be related to original ore-forming processes. Much of the spread in delta 34 S values at Tilt Cove is explicable on the basis of increasing f (sub O 2 ) during ore deposition. Sulfur in the Tilt Cove, Little Bay, and Rendell Jackman deposits is derived from Ordovician sea-water sulfate and, although data are more ambiguous, a similar source is likely for the Whalesback deposit. After allowances are made for differences in sulfur isotopic compositions of contemporaneous sea-water sulfate, the Tilt Cove, Little Bay, and Rendell Jackman deposits have delta 34 S values similar to unmetamorphosed ophiolitic cupriferous iron sulfide deposits in Cyprus.

First Page Preview

First page PDF preview
You do not currently have access to this article.