塔里木早二叠世大火成岩省的时空特征和岩浆动力学  

The Temporospatial Characteristics and Magma Dynamics of the Early Permian Tarim Large Igneous Province

作　　者：厉子龙[1] 励音骐[1] 邹思远 孙浩伟[1] 李东旭[1] 

机构地区：[1]浙江大学地球科学学院,杭州310027 [2]河北地质大学资源学院,石家庄050031

出　　处：《矿物岩石地球化学通报》2017年第3期418-431,共14页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家重点基础研究发展计划项目(2011CB808902);国家自然科学基金项目(40930315;41072048;41603029);中央高校基本科研业务费专项资金(2017QNA3015)

摘　　要：塔里木早二叠世大火成岩省是继峨眉山大火成岩省之后在中国境内发现的又一个二叠纪大火成岩省。近十多年来,对塔里木大火成岩省及其与地幔柱和大规模成矿的关系受到极大关注。本文结合近年来国内外的最新研究进展,对塔里木大火成岩省的时空分布、岩石地球化学特征、成因演化和动力学过程以及成矿潜力进行综述。塔里木大火成岩省的残余分布面积达25万km2,岩石类型主要有大陆溢流玄武岩(分布广泛),长英质火山岩类(主要分布在塔里木盆地的北部)和基性-超基性及中酸性侵入岩类等(主要出露于巴楚、巴什索贡和皮羌等地区)。该大火成岩省事件的岩浆活动时间主要集中在292~285 Ma(玄武岩和第一期长英质火山岩类形成阶段)和284~274 Ma(侵入岩类、含钒钛磁铁矿床和第二期长英质火山岩类形成阶段)。系统和深入的岩石地球化学和Sr-Nd-Hf-Pb同位素研究表明,塔里木大火成岩省从早期喷发的玄武岩到晚期的侵入岩类具有明显不同的地球化学特征,指示其岩浆源区发生了从富集岩石圈地幔来源到地幔柱来源的明显转变。结合相关的地质学和岩石学证据及铂族元素(PGEs)等研究,提出了一个上涌的地幔柱不断向位于岩石圈地幔底部的岩浆源区注入亏损地幔物质、持续改变其同位素地球化学特征并最终形成塔里木大火成岩省各主要岩石类型的岩浆演化新模型。最后,巴楚瓦吉里塔格含钒钛磁铁矿的存在也表明在塔里木大火成岩省中具有找寻大型钒钛磁铁矿床的潜力。The Tarim Large Igneous Province（ TLIP） is a Permian large igneous province in NW China. The genetic relation among TLIP,mantle plume and large-scale mineralization attracted more and more attention in the world recently.This study reviewed recent research on temporospatial distribution,geochemistry,magma evolution and geodynamics of TLIP. TLIP covers the area over 2. 5×105km2,comprising continental flood basalts,felsic volcanic rocks,mafic-ultramafic and intermediate-felsic intrusions. The activity of magmatism of the TLIP is essentially concentrated in 292-285 Ma（ basaltic lava and stage1 felsic volcanic rocks）,and 284-274 Ma（ various instrusive rock,V-Ti-Fe oxide deposits,and stage2 felsic volcanic rocks）. Sr-Nd-Hf-Pb isotopes and elemental geochemistry of basalts and intrusive rocks from the TLIP show a big difference between early basalts and late intrusions,indicating a magmatic evolutional trend mainly from an enriched lithospheric mantle source（ to form OIB-like basalts） to a depleted mantle source（ to form intrusive rocks）.Combined with regional geology and PGE geochemistry,we raise a two stage model for the formation of the TLIP,in which the plume-derived continuous injection at a bottom of lithosphere mantle changed the chemical composition of subcontinental enriched lithosphere mantle,generating magmas with variable compositions at different stages. The discovery of the Wajilitag V-Ti-Fe oxide deposit indicates a potential for exploration of a large-scale oxide deposit in the TLIP.

关 键 词：时空特征 年代学 Sr-Nd-Hf-Pb同位素 岩浆源区和演化 铂族元素 找矿潜力 塔里木大火成岩省 

分 类 号：P588.1[天文地球—岩石学]