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Marin-carbonne, Johanna; Rollion-bard, Claire; Bekker, Andrey; Rouxel, Olivier; Agangi, Andrea; Cavalazzi, Barbara; Wohlgemuth-ueberwasser, Cora C.; Hofmann, Axel; Mckeegan, Kevin D.. |
Iron and sulfur isotope compositions recorded in ancient rocks and minerals such as pyrite (FeS2) have been widely used as a proxy for early microbial metabolisms and redox evolution of the oceans. However, most previous studies focused on only one of these isotopic systems. Herein, we illustrate the importance of in-situ and coupled study of Fe and S isotopes on two pyrite nodules in a c. 2.7 Ga shale from the Bubi Greenstone Belt (Zimbabwe). Fe and S isotope compositions were measured both by bulk-sample mass spectrometry techniques and by ion microprobe in-situ methods (Secondary Ion Mass Spectrometry, SIMS). Spatially-resolved analysis across the nodules shows a large range of variations at micrometer-scale for both Fe and S isotope compositions, with... |
Tipo: Text |
Palavras-chave: Pyrite nodules; Fe and S isotopes; Archean; SIMS. |
Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00177/28824/27324.pdf |
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Othmane, Guillaume; Hull, Sharon; Fayek, Mostafa; Rouxel, Olivier; Geagea, Majdi Lahd; Kyser, T. Kurtis. |
The hydrogen isotope system is used extensively to provide information on the genesis of minerals (e.g., source of fluids and mechanisms of precipitation). The copper isotopic system is less well understood, but has the potential to provide valuable insight on mineral precipitation, particularly supergene Cu-rich minerals. Here we present a rapid and precise method for measuring hydrogen and copper isotopes in semi-precious gem-quality turquoise (Cu(Al,Fe3 +)6(PO4)4(OH)8 · 4H2O ) by secondary ion mass spectrometry (SIMS). The suitability of standards for instrumental mass fractionation (IMF) calibration was assessed by external precision of SIMS measurements for each standard (2-4‰ for δDIMF and 0.2-0.4‰ for δ65CuIMF). IMF in turquoise was correlated with... |
Tipo: Text |
Palavras-chave: Turquoise; SIMS; Copper isotopes; Hydrogen isotopes; Matrix effects. |
Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00239/35008/33546.pdf |
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