Geological setting and sulphur isotope distribution for late Silurian volcanogenic massive sulphide deposits, Lachlan Fold Belt, NSW, Australia

摘要

Volcanic-hosted massive sulphide mineralisation comprises a major precious-metal enriched, base metal sulphide resource in Late Silurian felsic volcanic rocks in the eastern Lachlan Fold Belt of New South Wales. Sulphur isotope data for 12 deposits indicate a broad range in composition for ore sulphides (-1.7 to 14.1 per mil), exceeded by the δ~(34)S composition for related pyrite from ore and host rocks (range -7.4 to 20.4 per mil). The study presents a relation favouring lower S-isotopic composition and a higher inferred magmatic S contribution for ores formed in proximity to defined centres of volcanism. VMS ores are more common in the deeper marine volcano-sedimentary packages, in contrast to vein-style and disseminated mineralisation developed in inferred shallow-marine environments.