Early Carboniferous intra-oceanic arc and back-arc basin system in the West Junggar,NW China
作者单位：State Key Laboratory of Lithospheric EvolutionInstitute of Geology and GeophysicsChinese Academy of Sciences College of Earth SciencesChang'an University
会议名称：《中国科学院地质与地球物理研究所2013年度（第13届）学术年会》
会议日期：2014年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：supported by research grants from the Innovative Project of the Chinese Academy of Sciences(Grant No.KZCX-EW -LY02) National Natural Science Foundation of China(Grant No.41272109,40972064,41230207,40725009,41190071, 41190072) National International Cooperation in Science and Technology Project(Grant No.2010DFB23390) National 305 Project(Grant No.2011BAB06801).Contribution to IGCP 592
关 键 词：arc magmas back-arc basin basalt trace elements isotope geochemistry SIMS zircon U-Pb dating West Junggar
摘 要：A series of Lower Carboniferous volcanic rocks occur in the Hatu,Darbut,and Baogutu areas of Xinjiang Province. Secondary ion mass spectrometry(SIMS)zircon U-Pb isotopic data indicate that two samples of these rocks coevally erupted at 324.0±2.8 Ma and 324.9±3.4 *** detailed profile measurements show that the volcanics include the Ham basalt, the Baogutu andesite and dacite,and the Darbut ***-rock compositions suggest that the Hatu volcanics are tholeiites and have a mid-ocean ridge basalt(MORB)-like signature with a small negative Nb anomaly,suggesting formation in a back-arc *** isotopic compositions(cNd(t)=+2.2 to+4.0,(Sr/Sr)i=0.70414 to 0.70517)suggest a mixing origin from depleted to enriched mantle *** contrast,the Baogutu and Darbut rocks are andesite and dacite possessing a transitional tholeiite to calc-alkaline character and have E-MORB-like and OIB *** a marked negative Nb anomaly and Th/Yb-enrichment,indicating that they were generated in a subduction zone ***,they display consistently depleted Sr-Nd isotopic compositions[(Sr/Sr)i=0.70377-0.70469,εNd(t)=1.0-5.2],suggesting that they were derived from a depleted *** that fluid and sediments were involved in their *** fea- tures suggest that an early Carboniferous intra-oceanic arc and back-arc basin system generated the studied volcanic units in the West Junggar.