Mantle Source Components and Magmatic Evolution for the Comei Large Igneous Province:Evidence from the Early Cretaceous Niangzhong Mafic Magmatism in Tethyan Himalaya  

作　　者：Yaying Wang Lingsen Zeng Kejun Hou Li'e Gao Qian Wang Linghao Zhao Jiahao Gao Guangxu Li 

机构地区：[1]Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [2]Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [3]National Research Center for Geoanalysis,Chinese Academy of Geological Sciences,Beijing 100037,China

出　　处：《Journal of Earth Science》2022年第1期133-149,共17页地球科学学刊（英文版）

基　　金：supported by the Second Tibetan Plateau Scientific Expedition and Research(No.2019QZKK0702);the National Natural Science Foundation of China(Nos.92055202,41873023,42102059);the China Geological Survey(No.DD20190057);the National Key Research and Development Project of China(No.2016YFC0600304);the Basic Scientific Research Fund of Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources(Nos.J1901-1,J190110);the National Foundation from China Scholarship Council。

摘　　要：The Niangzhong diabase dikes,dated at 138.1±0.4 Ma,are located within the outcrop area of the Comei large igneous province(LIP).These diabase samples can be divided into two groups:samples in Group 1 show varying MgO(1.50 wt.%-10.25 wt.%)and TiO_(2)(0.85 wt.%-4.63 wt.%)contents,and enriched initial isotope compositions(^(87)Sr/^(86)Sr(t)=0.7056-0.7112,ε_(Nd)(t)=-0.3-+3.8),with OIB-like REEs and trace elements patterns,resulting from low degree melting of garnet-bearing lherzolite mantle sources;in contrast,samples in Group 2 show limited MgO(4.14 wt.%-7.75 wt.%)and TiO_(2)(0.98 wt.%-1.69 wt.%)contents,and depleted initial isotope compositions(^(87)Sr/^(86)Sr(t)=0.7075-0.7112,ε_(Nd)(t)=+5.5-+6.2),with N-MORB-like REEs and trace elements patterns,resulting from relatively high degree melting of spinel-bearing lherzolite mantle source.Combined with the published representative data about Comei LIP,we summarize that the source components for Comei LIP products include OIB end-member,enriched OIB end-member,and N-MORB end-member,respectively.Melts modeling suggests that magmas in the Comei LIP evolve in a relatively high oxygen fugacity condition,which influenced their fractionation sequences and led to systematic changes of TiO_(2)contents,Ti/Y and Ti/Ti*ratios.From the spatial and temporal distribution of above three end-member samples,deep process of Kerguelen plume during the Comei LIP formation can be interpreted as the interaction among the Kerguelen plume,the overlying lithospheric mantle,and the upwelling asthenosphere.The magmatism of Comei LIP began at~140 Ma and then lasted and peaked at~132 Ma with the progressively lithospheric thinning of eastern Gondwana upon the impact of Kerguelen plume.

关 键 词：Comei large igneous province mafic magmatic evolution low-Ti and high-Ti mafic rocks Kerguelen plume geochemistry TECTONICS 

分 类 号：P588.11[天文地球—岩石学]