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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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| Sansjofre, Pierre; Cartigny, Pierre; Trindade, Ricardo I. F.; Nogueira, Afonso C. R.; Agrinier, Pierre; Ader, Magali. |
| The terminal Neoproterozoic Era (850-542 Ma) is characterized by the most pronounced positive sulfur isotope (S-34/S-32) excursions in Earth's history, with strong variability and maximum values averaging delta S-34 similar to+38 parts per thousand. These excursions have been mostly interpreted in the framework of steady-state models, in which ocean sulfate concentrations do not fluctuate (that is, sulfate input equals sulfate output). Such models imply a large pyrite burial increase together with a dramatic fluctuation in the isotope composition of marine sulfate inputs, and/or a change in microbial sulfur metabolisms. Here, using multiple sulfur isotopes (S-33/S-32, S-34/S-32 and S-36/S-32 ratios) of carbonate-associated sulfate, we demonstrate that the... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00639/75075/75603.pdf |
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| Clog, Matthieu; Aubaud, Cyril; Cartigny, Pierre; Dosso, Laure. |
| In this paper, we re-investigate the isotopic composition of hydrogen in MORB and the possible effects of contamination on delta D and water content. A suite of 40 N-MORB from the Pacific-Antarctic ridge, far from any hotspot, was analyzed for chlorine content by electron microprobe and for water content and delta D with silica tubes. Cl concentrations (from 29 to 2400 ppm) indicate widespread contamination, more intense with faster spreading rates, while water contents (from 840 to 7800 ppm) are mainly controlled by igneous processes. delta D values range from -76 to -48 parts per thousand, with an average value of -61 parts per thousand. The lack of correlation between Cl content and either H2O/Ce or SD indicate that contamination has a negligible effect... |
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Palavras-chave: Hydrogen isotopes; Mantle geochemistry; Mantle water. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00169/28045/27274.pdf |
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| Deng, Zhengbin; Moynier, Frederic; Villeneuve, Johan; Jensen, Ninna K.; Liu, Deze; Cartigny, Pierre; Mikouchi, Takashi; Siebert, Julien; Agranier, Arnaud; Chaussidon, Marc; Bizzarro, Martin. |
| Despite the abundant geomorphological evidence for surface liquid water on Mars during the Noachian epoch (>3.7 billion years ago), attaining a warm climate to sustain liquid water on Mars at the period of the faint young Sun is a long-standing question. Here, we show that melts of ancient mafic clasts from a martian regolith meteorite, NWA 7533, experienced substantial Fe-Ti oxide fractionation. This implies early, impact-induced, oxidation events that increased by five to six orders of magnitude the oxygen fugacity of impact melts from remelting of the crust. Oxygen isotopic compositions of sequentially crystallized phases from the clasts show that progressive oxidation was due to interaction with an O-17-rich water reservoir. Such an early oxidation... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00686/79855/82697.pdf |
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