Sr/Ca and Mg/Ca ratios in Niger Delta sediments: Implications for authigenic carbonate genesis in cold seep environments
| Type | Article | ||||||||
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| Date | 2007-06 | ||||||||
| Language | English | ||||||||
| Author(s) | Bayon Germain1, Pierre C2, Etoubleau Joel1, Voisset Michel1, Cauquil E3, Marsset Tania 1, Sultan Nabil1, Le Drezen Eliane1, Fouquet Yves1 |
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| Affiliation(s) | 1 : IFREMER, Dept Geosci Marines, Brest, France. 2 : Univ Paris 06, LOCEAN, Paris, France. 3 : TOTAL, Paris, France. |
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| Source | Marine Geology (0025-3227) (Elsevier), 2007-06 , Vol. 241 , N. 1-4 , P. 93-109 | ||||||||
| DOI | 10.1016/j.margeo.2007.03.007 | ||||||||
| WOS© Times Cited | 112 | ||||||||
| Keyword(s) | Niger Delta, Gas hydrates, Cold seeps, Mg/Ca, Sr/Ca, Authigenic carbonates | ||||||||
| Abstract | We report on a reconnaissance analysis of the geochemical composition of authigenic carbonates and sediment samples collected from various seepage sites on the Niger deep-sea fan. Our aim has been to investigate whether evidence for the presence of authigenic carbonates and gas hydrates within sediments is discernible from solid-phase sediment geochemistry. We show that sedimentary Sr/Ca and Mg/Ca ratios can be used to infer the presence of authigenic aragonite (Sr-rich) and Mg-rich carbonate phases (high-Mg calcite, dolomite) in cold seep settings. Using Sr/Ca and Mg/Ca ratios, the proportion (wt.%) of authigenic carbonates in Niger Fan sediments can be calculated from a mixing model between sediment fractions of terrigenous material, biogenic calcite, aragonite and high-Mg calcite. This approach was applied to high-resolution geochemical profiles along sediment cores recovered from various cold seep settings (mud volcano, diapirs, pockmarks, gas-hydrate bearing sediments). Our data reveal that authigenic carbonates occur as discrete phases in sediments from gas-hydrate-bearing areas, suggesting that such carbonate-rich sediment layers may represent paleo-indicators for ancient methane seepage in marine sediments, possibly associated to gas-hydrate reservoirs. (C) 2007 Elsevier B.V. All rights reserved. | ||||||||
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