【摘要】 报导了云南丽江地区大具和仕满剖面12个苦橄岩和6个玄武岩的Re,Os含量和Os同位素组成。苦橄岩和玄武岩具有明显不同的Re-Os体系的特征。苦橄岩具有高的Os元素丰度[(1.5～3)×10-9]和低的Re元素丰度(<0.05×10-9);共生的玄武岩具有低的Os元素丰度(<0.5×10-9)和相对高的Re元素丰度(<0.8×10-9);苦橄岩具有低放射成因的Os/188Os比值(0.1233～0.1266),而玄武岩具有高放射成因的187Os/188Os比值187(0.1338～0.1577)。苦橄岩的Re-Os同位素特征与越南西北部二叠—三叠纪科马提岩具有低放射成因Os同位素特征相似,而玄武岩的Re-Os同位素特征与峨眉山大火成岩省(LIP)其他地区玄武岩的高放射成因的Os同位素特征相似。苦橄岩的Re-Os同位素特征表明,形成峨眉山LIP的地幔柱可能来自对流上地幔而不是深部的核-幔界面。换言之,峨眉山LIP的形成受控于岩石圈地幔过程而不是地幔柱过程。更多还原

【Abstract】 Here we present Re-Os abundances and Os isotopic compositions of 12 picrites and 6 associated basalts collected from Daju and Shiman sections,Lijiang area,western part of Emeishan large igneous province(ELIP Zhang et al,2006).The results show that the picrites and associated basalts have distinctive Re-Os isotopic features.The picrites have higher Os abundances(1.5×10-9～3×10-9),and sligtly lower Re abundance(<0.05×10-9)than associated basalts(<0.5×10-9and<0.8×10-9,respectively).However,the picrites have unradiogenic187Os/188Os(0.1233～0.1266),but the basalts have supradiogenic187Os/188Os(0.1338-0.1577).The Re-Os isotope geochemistry of ELIP lava may shed light on the mantle plume origin of ELIP.The mantle plume was derived from the asthenosphere rather than the deep core-mantle boundary.In other word,the ELIP eruption was controlled by interaction between lithosphere and asthenosphere(Saunders,2005).更多还原