【摘 要】
：
We measured Fe isotopic compositions of mineral separates of harzburgite,dunite and chromitite from Luobusa,Tibet as well as two harzburgites from Zedang for comparison to constrain the origin of podi
【机 构】
：
Department of Earth Sciences,the University of Hong Kong,Pokfulam Road,Hong Kong,China;State Key Lab
【出 处】
：
International Workshop on: Ophiolites, Mantle Processes and
论文部分内容阅读
We measured Fe isotopic compositions of mineral separates of harzburgite,dunite and chromitite from Luobusa,Tibet as well as two harzburgites from Zedang for comparison to constrain the origin of podiform chromite deposits.The olivine(Ol)and orthopyroxene(Opx)of harzburgites from both localities have δ56Fe values of 0.000～0.083‰ and-0.034～+0.081‰,respectively,within normal mantle range.Olivine in the Zedang harzburgites has lower δ56Fe values than Opx,whereas the Ol in the Luobusa harzburgites is more enriched in heavy Fe than Opx.The contrasting sequence is probably related with significant peridotite-melt interaction in the Luobusa ophiolite compared to the Zedang ophiolite,which is further evidenced by their petrological and major elemental features.From harzburgite through dunite to chromitite(except one disseminated chromitite sample),δ56Fe value of the Ol displays increasing trend up to 0.215‰ and positive correlation with their Fo contents and Cr＃ of associated chromite,suggesting that the interacting melts were isotopically heavier than the mantle peridotite.The extremely low δ56Fe of the Ol in the disseminated chromitite may reflect fluid-related modification.
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