峨眉山大火成岩省和西伯利亚大火成岩省地球化学物征的比较及其成因启示  

A geochemical comparison between the Emeishan and Siberian large igneous provinces and its petrogenetic implications

作　　者：张招崇[1] 王福生[1] 郝艳丽[1] John J.Mahoney 

机构地区：[1]中国地质科学院地质研究所 [2]School of Ocean and Earth Science and Technology,University of Hawaii,Honolulu,HI96822,USA

出　　处：《岩石矿物学杂志》2005年第1期12-20,共9页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目 ( 4 0 2 73 0 2 0 ) ;国家重点基础研究发展规划资助项目 (G19990 43 2 0 5 ) ;国土资源部百名优秀青年计划资助

摘　　要：峨眉山大火成岩省和西伯利亚大火成岩省是发生于二叠 -三叠纪之交的重要岩浆事件。它们在主要元素、微量元素和Sr、Nd、Pb同位素特征上具有相似姓 ,但是峨眉山大火成岩省的不相容元素比值和同位素比值的变化范围相对要小一些。相对而言 ,峨眉山玄武岩具有高的Fe8和Sm/Yb值 ,暗示了其熔融深度较西伯利亚大火成岩省深 ,而熔融程度较低 ,两者的源区均为石榴石二辉橄榄岩。根据Nd同位素特征估算峨眉山和西伯利亚地幔柱的 Nd≈ 2 ,接近于原始地幔特征。综合其他地球化学特征 ,认为两个大火成岩省可能起源于同一个来自于核The Emeishan and the Siberian large igneous provinces (LIP) represent two major magmatic events close to the Permian-Triassic boundary. They are characterized by similar major element,microelement,and Sr, Nd and Pb isotopic compositions. However, the variation ranges of the incompatible element ratios and isotopic ratios are much narrower in the Emeishan LIP than in the Siberian LIP. Compared with the Siberian LIP,the Emeishan basalts have somewhat higher Fe_8,and Sm/Yb ratios,suggesting a relatively greater depth and a lower degree of melting. Their source regions are garnet lherzolite. Based on the Nd isotopic characteristics, the Nd value of Emeishan and Siberian plume is estimated to be approximately 2, close to that of the primitive mantle. In combination with other geochemical characteristics, it is proposed that the two LIPs might have originated from the same super-plume derived from the core-mantle boundary.

关 键 词：地球化学特征 地幔柱 成因 峨眉山大火成岩省 西伯利亚大火成岩省 

分 类 号：P594[天文地球—地球化学] P588.1[天文地球—地质学]