The discovery of Palaeoproterozoic volcanic rocks in the Bulunkuoler Group from the Tianshuihai Massif in Xinjiang of Northwest China and its geological significance

查看全文 作　　者：JI [1]WenHua;LI [1]RongShe;CHEN [1]ShouJian;HE [1]ShiPing;ZHAO [1]ZhenMing;BIAN [2]XiaoWei;ZHU [2]HaiPing;CUI [2]JiGang;REN [2]JuanGang

机构地区：[1]Xi'an Institute of Geology and Mineral Resource, Xi'an 710054, China;[2]Shaanxi Institute of Geological Survey, Xianyang 712000, China

出　　处：《Science China Earth Sciences》索引2011年第54卷第1期,共12页

基　　金：supported by the China Geological Survey (Grant No. 1212010610102);National Natural Science Foundation of China (Grant No. 40872084) 摘　　要：In the Dabudaer region of the Tianshuihai Massif (Xinjiang, Northwest China), metavolcanic rocks within the mainly meta-sedimentary Bulunkuoler Group are basalt, basaltic andesite, and rhyolite. In situ zircon U-Pb LA-ICP-MS dating on rhyolite magmatic zircons yielded an age of 2481±14 Ma, interpreted as the eruption age of the Bulunkuoler Group volcanic rocks. The basalt and basaltic andesite are low-Al tholeiite series and the rhyolite is low-Al calc-alkaline series. All of rocks are charac-terized by enrichment of LREE and LILE (Rb, Th and Ba), depletion of P, Nb, Ta and Ti, and absence of Eu anomalies. The εNd(t) of basalts ranges from 3.14 to 4.88 indicating a depleted mantle source. The trace element signatures show that these magmas experienced intense crustal contamination during their ascent. Direct evidence for crustal contamination is the xenocrystic zircons in the ryholite, with ages back to ca. 3300 Ma. The primitive-mantle normalized and Zr/Y-Zr diagrams for the basic volcanic rocks show that they formed in an intra-continental tectonic setting. Combined with the previous studies and compared with North China Craton Neoarchean basic volcanic rocks, it is supposed that the Bulunkuoler Group volcanic rocks reflect the Palaeoproterozoic mantle magma underplating and interaction with felsic crust. 关键词：中国西北地区变质火山岩地质意义古元古代甜水新疆玄武安山岩基性火山岩

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The discovery of Palaeoproterozoic volcanic rocks in the Bulunkuoler Group from the Tianshuihai Massif in Xinjiang of Northwest China and its geological significance

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