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| Philippot, Pascal; Avila, Janaina N.; Killingsworth, Bryan A.; Tessalina, Svetlana; Baton, Franck; Caquineau, Tom; Muller, Elodie; Pecoits, Ernesto; Cartigny, Pierre; Lalonde, Stefan; Ireland, Trevor R.; Thomazo, Christophe; Van Kranendonk, Martin J.; Busigny, Vincent. |
| The Great Oxidation Event (GOE) has been defined as the time interval when sufficient atmospheric oxygen accumulated to prevent the generation and preservation of mass-independent fractionation of sulphur isotopes (MIF-S) in sedimentary rocks. Existing correlations suggest that the GOE was rapid and globally synchronous. Here we apply sulphur isotope analysis of diagenetic sulphides combined with U-Pb and Re-Os geochronology to document the sulphur cycle evolution in Western Australia spanning the GOE. Our data indicate that, from similar to 2.45 Gyr to beyond 2.31 Gyr, MIF-S was preserved in sulphides punctuated by several episodes of MIF-S disappearance. These results establish the MIF-S record as asynchronous between South Africa, North America and... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00638/74983/75853.pdf |
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| Pace, Aurelie; Bourillot, Raphael; Bouton, Anthony; Vennin, Emmanuelle; Galaup, Serge; Bundeleva, Irina; Patrier, Patricia; Dupraz, Christophe; Thomazo, Christophe; Sansjofre, Pierre; Yokoyama, Yusuke; Franceschi, Michel; Anguy, Yannick; Pigot, Lea; Virgone, Aurelien; Visscher, Pieter T.. |
| Microbialites are widespread in modern and fossil hypersaline environments, where they provide a unique sedimentary archive. Authigenic mineral precipitation in modern microbialites results from a complex interplay between microbial metabolisms, organic matrices and environmental parameters. Here, we combined mineralogical and microscopic analyses with measurements of metabolic activity in order to characterise the mineralisation of microbial mats forming microbialites in the Great Salt Lake (Utah, USA). Our results show that the mineralisation process takes place in three steps progressing along geochemical gradients produced through microbial activity. First, a poorly crystallized Mg-Si phase precipitates on alveolar extracellular organic matrix due to a... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00347/45852/45517.pdf |
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