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Isotopic geochemistry of a mid-Proterozoic evaporite basin: Balmat, New York

January 1, 1990

Lenses of Proterozoic meta-evaporitic anhydrite as much as 60 m thick occur in a 1150 to 1300 Ma Grenville Series marble sequence near Balmat, New York. ??34Sanhy values in the oldest lens average 8.2 permil; progressively younger lenses average 19.6, 27.2, 26.7, and 19.1 permil. The thickest and isotopically heaviest lens displays coincident upsection increases in ??34Sanhy (24.1-30.2 permil) and ??18Oanhy (19.8-22.5 permil) values. These increases and the overall 34S enrichment of the anhydrite indicate that anhydrite precipitation was concurrent with large-scale bacterial sulfate reduction in the depositional basin. The arid climate and high evaporation rates implied by evaporite deposition result in 18O enrichment of the basin waters and the carbonates precipitated from them. The evidence of arid climate and the variability and 34S-enrichment of the anhydrite imply that the Balmat environment was a closed or restricted basin in which evaporation and bacterial sulfate reduction combined to produce a 34S-enriched, sulfate-rich brine. -from Authors

Citation Information

Publication Year 1990
Title Isotopic geochemistry of a mid-Proterozoic evaporite basin: Balmat, New York
Authors J. F. Whelan, R. O. Rye, W. De Lorraine, H. Ohmoto
Publication Type Article
Publication Subtype Journal Article
Series Title American Journal of Science
Index ID 70016329
Record Source USGS Publications Warehouse