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| Labidi, J.; Cartigny, P.; Hamelin, C.; Moreira, M.; Dosso, Laure. |
| To better address how Mid-Ocean Ridge Basalt (MORB) sulfur isotope composition can be modified by assimilation and/or by immiscible sulfide fractionation, we report sulfur (S), chlorine (Cl) and copper (Cu) abundances together with multiple sulfur isotope composition for 38 fresh basaltic glasses collected on the Pacific-Antarctic ridge. All the studied glasses -with the exception of 8 off-axis samples- exhibit relatively high Cl/K, as the result of pervasive Cl-rich fluid assimilation. This sample set hence offers an opportunity to document both the upper mantle S isotope composition and the effect of hydrothermal fluids assimilation on the S isotope composition of erupted basalts along segments that are devoid of plume influence. Δ33S and Δ36S yield... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00179/29013/27441.pdf |
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| Killingsworth, B. A.; Sansjofre, P.; Philippot, P.; Cartigny, P.; Thomazo, C.; Lalonde, Stefan. |
| After permanent atmospheric oxygenation, anomalous sulfur isotope compositions were lost from sedimentary rocks, demonstrating that atmospheric chemistry ceded its control of Earth's surficial sulfur cycle to weathering. However, mixed signals of anoxia and oxygenation in the sulfur isotope record between 2.5 to 2.3 billion years (Ga) ago require independent clarification, for example via oxygen isotopes in sulfate. Here we show <2.31 Ga sedimentary barium sulfates (barites) from the Turee Creek Basin, W. Australia with positive sulfur isotope anomalies of Delta S-33 up to +1.55% and low delta O-18 down to -19.5%. The unequivocal origin of this combination of signals is sulfide oxidation in meteoric water. Geochemical and sedimentary evidence suggests... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74903/76109.pdf |
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