Geochemical characteristics of mineral inclusions in the Luobusa chromitite (Southern Tibet): Implications for an intricate geological setting

Fahui Xiong*, Basem Zoheir*, Xiangzhen Xu, Guolin Guo, Matthias Frische, Jingsui Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The Luobusa chromitite and ophiolite present a captivating geological feature marked by peculiar mineralogical and geochemical characteristics. Abundant platinum-group minerals (PGM), base-metal sulfides (BMS), and PGE-sulfides and alloys in the chromitite reveal a multistage genesis, encompassing partial mantle melting, melt-rock interactions, and dynamic shifts in oxygen and sulfur fugacities (fO2, fS2). The geochemical signatures and PGE patterns of these mineral inclusions elucidate the evolutionary process of the Luobusa ophiolite, tracing its transition from a sub-ridge environment to a sub-Arc setting. The variable ςPGE values (40-334 ppb) in chromitite, coupled with notably lower ςPGE values (10-63 ppb) in dunite imply extensive melt fractionation and melt-rock interactions. Coexisting well-crystallized Os-Ir alloys alongside interstitial BMS likely reflect low fS2 and high temperatures during the early formational stages, whereas abundant anhedral or irregular sulfarsenide and pyrite inclusions in chromite point to lower temperatures and higher fS2 during the late stages. The trace element composition of pyrite inclusions displays some of the characteristics of mid-ocean ridge (MOR) and oceanic island rocks, manifesting the interplay of diverse magmatic sources during the evolution of the Luobusa ophiolite.

Original languageEnglish
Pages (from-to)2127-2141
Number of pages15
JournalAmerican Mineralogist
Volume109
Issue number12
DOIs
StatePublished - 1 Dec 2024

Bibliographical note

Publisher Copyright:
© 2024 by Mineralogical Society of America.

Keywords

  • Luobusa ophiolite
  • PGM and BMS inclusions
  • SW Tibet
  • chromitite
  • genetic model

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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