Geochronology,Geochemistry and Petrogenesis of Diabase Dyke Swarms in East Tianshan,Xinjiang,NW China  

作　　者：ZHANG Zuoheng CHAI Fengmei WANG Tuanhua CHENG Yanbo XU Lingang YUAN Shunda 

机构地区：[1]MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences [2]Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt,Xinjiang University [3]China Mining Association

出　　处：《Acta Geologica Sinica(English Edition)》2012年第6期1500-1514,共15页地质学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 40973028);the Central Public-interest Scientific Institution Basal Research Fund (K1107)

摘　　要：Diabase dyke swarms are widespread in the East Tianshan and Beishan regions. LA-ICP-MS zircon U-Pb ages of these diabase vary from 305 Ma to 278 Ma, showing that these dykes were formed during Late Carboniferous-Early Permian magmatism. All diabase samples are subalkali calc-alkali, characterized by slight LREE and LILEs enrichment, and weak negative Ti, Nb and Ta anomalies. The diabase samples have positive ＊＇Nd（t）values （〉＋3）, high Sr isotopic compositions （initial 87Sr/S6Sr values=0.7030-0.7097）, and large variation of Pb isotopic compositions, indicating they were derived from a deplete mantle source. Regional geology and geochemistry evidences indicate that these diabase dyke swarms were generated in a lithosphere extensional setting and had the same magma sources. Initial magmas may be a mixture of depleted asthenosphere mantle and enriched lithospheric mantle during rapid magma ascending.Diabase dyke swarms are widespread in the East Tianshan and Beishan regions. LA-ICP-MS zircon U-Pb ages of these diabase vary from 305 Ma to 278 Ma, showing that these dykes were formed during Late Carboniferous-Early Permian magmatism. All diabase samples are subalkali calc-alkali, characterized by slight LREE and LILEs enrichment, and weak negative Ti, Nb and Ta anomalies. The diabase samples have positive ＊＇Nd（t）values （〉＋3）, high Sr isotopic compositions （initial 87Sr/S6Sr values=0.7030-0.7097）, and large variation of Pb isotopic compositions, indicating they were derived from a deplete mantle source. Regional geology and geochemistry evidences indicate that these diabase dyke swarms were generated in a lithosphere extensional setting and had the same magma sources. Initial magmas may be a mixture of depleted asthenosphere mantle and enriched lithospheric mantle during rapid magma ascending.

关 键 词：DIABASE GEOCHEMISTRY LA-ICP-MS zircon U-Pb dating East Tianshan 

分 类 号：P597.3[天文地球—地球化学]