亚洲3个大火成岩省(峨眉山、西伯利亚、德干)对比研究  

Comparison of Three Large Igneous Provinces ( Emeishan , Siberia , Deccan ) in Asia

作　　者：夏林圻[1] 徐学义[1] 李向民[1] 夏祖春[1] 马中平[1] 

机构地区：[1]西安地质矿产研究所,陕西西安710054

出　　处：《西北地质》2012年第2期1-26,共26页Northwestern Geology

基　　金：中国地质调查局综合研究项目(1212010611804;1212011120133)

摘　　要：峨眉山(～260Ma)、西伯利亚(～250Ma)和德干(～66Ma)大陆溢流玄武岩是世界上3个重要的大火成岩省。大火成岩省至少具有4个通常被用于识别古地幔柱的标志:(1)先于岩浆作用的地表隆升;(2)与大陆裂谷化和裂解事件相伴;(3)与生物灭绝事件联系密切;(4)地幔柱源玄武岩的化学特征。虽然这3个大火成岩省都是来源于原始地幔柱,但是它们的地球化学特征有本质上的差异,反映其地幔柱曾与不同的上地幔库相互作用。(1)峨眉山和西伯利亚大陆溢流玄武岩的母岩浆,在上升过程中经受了与地球化学上和古老克拉通岩石圈地幔相同的上地幔库(EM1型幔源)的相互作用;(2)而德干大火成岩省没有受到地壳(或岩石圈)混染的原生玄武岩则显示地幔柱和EM2之间的Sr-Nd同位素变化。这种差异有可能制约了3个大火成岩省的成矿潜力。峨眉山和西伯利亚大火成岩省含有世界级岩浆矿床,而德干大火成岩省则不含矿。The Emeishan （-260 Ma）, Siberian （-250 Ma） and Deccan （-66 Ma） continental flood ba- salts are three important Phanerozoic large igneous provinces in the word. Our summation reveals that at least four criteria, which are normally used to identify ancient mantle plumes, are met for these three large igneous provinces- （1） surface uplift prior to magmatism; （2） Accompanied with continental rifting and breakup events; （3） Closely linked with the extinction events; （4） chemical characteristics of plume de- rived basalts. Although these three large igneous provinces are equally derived from primitive plume sources, there are fundamental differences in geochemical signatures among Emeishan, Siberian and Dec- can provinces, reflecting the interaction between the mantle plumes and different upper-mantle reservoirs： （1） the parental magmas of the Emeishan and Siberian continental flood basalts have undergone, during ascent, interaction with a source geochemically identical to ancient cratonic lithospheric mantle （EMl-type source） （2） whereas the crustally （or lithosphericly） uncontaminated primitive basalts from the Deccan province display Sr-Nd isotopic variations between plume and EM2 geochemical signatures. These differences may control the mineralization potential of the three large igneous provinces. Emeishan and Siberian provinces host world-class magmatic ore deposits whereas no significant deposits have been found from the Deccan.

关 键 词：大火成岩省 大陆溢流玄武岩 地幔柱 峨眉山大火成岩省 西伯利亚大火成岩省 德干大 火成岩省 

分 类 号：P588.1[天文地球—岩石学]