Late seafloor carbonate precipitation in serpentinites from the Rainbow and Saldanha sites (Mid-Atlantic Ridge)
| Autor: | Rex N. Taylor, Fernando J.A.S. Barriga, Isabel Ribeiro da Costa |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
geography
geography.geographical_feature_category Aragonite Seamount Geochemistry Mineralogy Mid-Atlantic Ridge engineering.material Seafloor spreading chemistry.chemical_compound chemistry Lost City Hydrothermal Field Geochemistry and Petrology Ultramafic rock engineering Carbonate Seawater Geology |
| Zdroj: | European Journal of Mineralogy. 20:173-181 |
| ISSN: | 0935-1221 |
| DOI: | 10.1127/0935-1221/2008/0020-1803 |
| Popis: | Serpentinized ultramafic rocks recovered during several recent oceanographic missions (1997-2002) on the Rainbow hydrothermal field and on the Saldanha seamount (36°14'N and 36°34'N, Mid-Atlantic Ridge) often exhibit late-stage carbonatization associated to secondary oxidation effects. These carbonate occurrences, mostly vein-filling aragonite, occasionally form dense webs almost completely engulfing and replacing the serpentinite itself. The 87Sr/86Sr (approx. 0.709) and stable isotope signatures (?13CPDB = 0.2-3.3 ‰; ?18OV-SMOW = 32.2-35.2 ‰) of the carbonate fraction in these serpentinites indicate carbonate precipitation from unmodified seawater, under abiotic conditions, and very low temperatures, close to bottom-water temperatures measured at the sampling stations. These analytical data imply that, unlike the serpentinite-hosted carbonate chimneys in the Lost City hydrothermal field (Ludwig et al., 2006), the vein-filling aragonite in the Rainbow and Saldanha serpentinites has a non-hydrothermal, low-temperature seawater origin. |
| Databáze: | OpenAIRE |
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