Os-isotope variability within sulfides from podiform chromitites

José M. González-Jiménez*, Fernando Gervilla, William L. Griffin, Joaquín A. Proenza, Thierry Augé, Suzanne Y. O'Reilly, Norman J. Pearson

*Corresponding author for this work

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

In situ laser ablation MC-ICPMS was used to measure the Os-isotope compositions of single sulfide grains (≥ 5 μm 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 μm 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.

Original languageEnglish
Pages (from-to)224-235
Number of pages12
JournalChemical Geology
Volume291
DOIs
Publication statusPublished - 6 Jan 2012

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