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| Blanchet, C. L.; Thouveny, N.; Vidal, L.. |
| Diagenetic processes are known to modify sedimentary records, but they can also reveal important paleoenvironmental changes. Here we investigate variations in sedimentary iron diagenesis and depositional environments for the last 35 ka by analyzing the rock magnetic and geochemical properties of two sediment cores collected in the Santa Barbara Basin (California). In organic-rich sediments, early diagenesis often leads to partial dissolution of detrital iron oxides and stepwise formation of authigenic pyrite (FeS2). The pyritization process takes place following several geochemical pathways, sometimes involving intermediate iron sulfide species such as greigite (Fe3S4). Sedimentary conditions in the basin appear to have recurrently favored preservation of... |
| Tipo: Text |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32936/31447.pdf |
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| Blanchet, C. L.; Kasten, S.; Vidal, L.; Poulton, S. W.; Ganeshram, R.; Thouveny, N.. |
| In order to evaluate the influence of diagenetic and post-sampling processes on the stable oxygen and carbon isotope compositions of biogenic carbonates, we conducted a multiproxy study of organic-rich sediments from the eastern Pacific oxygen minimum zone. Core MD02-2520, which was retrieved from the Gulf of Tehuantepec (Mexico), has seasonal laminations and covers the last 40 kyr. Together with the presence of gypsum crystals and inorganic calcite aggregates, the occurrence of large excursions in the stable oxygen and carbon isotope records of both planktonic and benthic foraminifera (as large as +3 parts per thousand in delta O-18 and -5 parts per thousand in delta C-13) point to significant secondary transformations. Storage-related gypsum... |
| Tipo: Text |
Palavras-chave: Diagenesis; Gypsum; Inorganic calcite; Laminations; Oxygen minimum zone; Sulfur reoxidation. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00139/25049/23173.pdf |
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