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Article dans une revue
Os-isotope variability within sulfides from podiform chromitites
Abstract : In situ laser ablation MC-ICPMS was used to measure the Os-isotope compositions of single sulfide grains (>= 5 mu m in diameter) included in unaltered primary chromite from the podiform chromitite of Caridad (eastern Cuba). The analyzed phases include PGE-sulfides (laurite and PGE-rich monosulfide solid solution) and base-metal sulfides (BM-sulfides; millerite, heazlewoodite and pentlandite). The results show that PGE-sulfides and the BM-sulfides have distinctly different Os-isotope compositions. Significant variations in Os-isotope composition are found among sulfide grains forming parts of single composite aggregates smaller than 50 mu m in diameter. A similar degree of heterogeneity was observed in some chemically and isotopically zoned sulfide grains. At such small scales, the formation of sulfides with variable Os-isotope signatures requires a heterogeneous genetic process in which individual pulses of isotopically and chemically different melts coexisted in space and/or time. This could be achieved if the podiform chromitites formed as a result of mantle-melt reactions and the subsequent melt mixing/mingling of several batches of melt.
https://hal-brgm.archives-ouvertes.fr/hal-00847360
Contributeur : Anne-Marie Pouget Connectez-vous pour contacter le contributeur
Soumis le : mardi 23 juillet 2013 - 15:12:58
Dernière modification le : mercredi 6 avril 2022 - 13:06:04
Contributeur : Anne-Marie Pouget Connectez-vous pour contacter le contributeur
Soumis le : mardi 23 juillet 2013 - 15:12:58
Dernière modification le : mercredi 6 avril 2022 - 13:06:04