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

American Journal of Science

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Abstract

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

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Isotopic geochemistry of a mid-Proterozoic evaporite basin: Balmat, New York
Series title:
American Journal of Science
Volume
290
Issue:
4
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
396
Last page:
424
Number of Pages:
29