First occurrence and stable isotope composition of authigenic γ-MnS in the central Gotland Deep (Baltic Sea)
✍ Scribed by Michael E. Böttcher; Hermann Huckriede
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 539 KB
- Volume
- 137
- Category
- Article
- ISSN
- 0025-3227
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✦ Synopsis
The occurrence of authigenic y-MnS in organic matter-rich sediments of the central Gotland Deep is reported for the first time. The hexagonal manganese sulfide was found in a thin sediment layer with an approximate age of 1130 years and has an isotopic composition of F34S z -13%0 vs. V-CDT. This indicates that the bonded sulfur is derived from the anaerobic microbial reduction of pore water sulfate. SEM analysis reveals that y-MnS occurs as idiomorphic crystals of about 200 pm length and 150 urn width, much larger than the diameters of co-existing calcian rhodochrosite globules (-6 urn). It is suggested that formation of y-MnS took place in a diagenetic environment which was locally free from reactive iron.