Sulfur-isotope study of Cambrian massive-sulfide and associated mineralization, western Tasmania
Conference
·
· Geol. Soc. Am., Abstr. Programs; (United States)
OSTI ID:6874172
Syngenetic massive-sulfide mineralization in the Mount Read Volcanics includes types A: pyrite + sphalerite + galena + chalcopyrite +/- barite; B: pyrite +/- chert +/- barite; C: hematite + barite +/- calcite +/- pyrite. Related epigenetic mineralization includes types D: magnetite + pyrite +/- chalcopyrite (at granite contacts); E: pyrite +/- chalcopyrite +/- magnetite; F: barite + hematite +/- chalcopyrite +/- pyrite. Type F may be associated with pervasive martitization of magnetite. Barite delta/sup 34/S values vary about the 30-35 per mil value for middle-upper Cambrian seawater sulfate, implying that evolved seawater was involved in mineralization. Type A barites were enriched in /sup 34/S through partial reduction of sulfate, and were deposited from brines denser than seawater. Types B, C, and F barites are unchanged or depleted in /sup 34/S relative to seawater, and may represent leaching and oxidation of low-delta/sup 34/S rock sulfides. Sulfide delta/sup 34/S values vary is sympathy with those of barite, indicating an approach to sulfate-sulfide equilibrium. Vertical sections of hydrothermal systems containing types A, D, and E sulfides show upward increases in delta/sup 34/S of sulfides, consistent with progressive reduction of sulfate is ascending hydrothermal fluids. In general, the oxidation state of hydrothermal fluids increased with time. Significant deposition of Zn, Pb, and Cu in syngenetic deposits occurred only in the relatively reduced systems.
- Research Organization:
- Univ. of Arizona, Tucson (USA)
- OSTI ID:
- 6874172
- Report Number(s):
- CONF-8510489-
- Conference Information:
- Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
- Country of Publication:
- United States
- Language:
- English
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