Geochronology and Petrogenesis of Late Carboniferous to Early Permian Basalts in the Central Lhasa Subterrane, Southern Tibet: Implications for the Evolution of the Sumdo Paleo-Tethys Ocean  

作　　者：MA Wang LIU Yingchao YANG Zhusen Jan-Marten HUIZENGA LI Zhenqing YUE Longlong ZHAO Sibo 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China [2]Institute of Geology,Sinoprobe Laboratory,Chinese Academy of Geological Sciences,Beijing 100037,China [3]MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [4]Faculty of Environmental Sciences and Natural Resource Management,Norwegian University of Life Sciences,NO-1432Ås,Norway [5]Economic Geology Research Centre(EGRU),College of Science and Engineering,James Cook University,Townsville,Queensland 4811,Australia [6]Department of Geology,University of Johannesburg,Auckland Park 2006,South Africa

出　　处：《Acta Geologica Sinica(English Edition)》2024年第4期955-968,共14页地质学报（英文版）

基　　金：the National Key Research and Development Program of China (Grant No. 2022YFF0800903);the National Natural Science Foundation of China (Grant Nos. 42302107, 92162322, 42261144669, 41922022, 42003036);the China Geological Survey (Grant Nos. DD20243512, DD20230008);the National Postdoctoral Research Program of China (Grant No. GZC20232489);the Second Tibetan Plateau Scientific Expedition and Research (Grant No. 2021QZKK0304);Xing Dian Youth Talent Plan of Yunnan Province (Grant No. XDYC-QNRC-2022-0136);the UNESCO: IUGS IGCP-662 Program。

摘　　要：Basalts from the Late Carboniferous to Early Permian are extensively developed in the central Lhasa subterrane, southern Tibet. Studying the petrogenesis of these rocks may have implications for the late Paleozoic arc magmatism along the central Lhasa subterrane uncovering more of the evolution of the Sumdo Paleo-Tethys Ocean and its dynamic mechanism. Basalt samples from the Luobadui Formation in the Leqingla area, NW of Linzhou City in the central Lhasa subterrane, southern Tibet exhibit arc-like geochemical signatures in a subduction-zone tectonic setting characterized by high Al_(2)O_(3) and low TiO_(2) contents, fractionated REE patterns with low Nb/La ratios and high LREE concentrations, and negative HFSE anomalies. Based on their higher Th/Ce, Nb/Zr, and lower Ba/Th, Pb/Nd ratios, slightly negative to positive ε_(Nd)(t) values, and the relatively high Sr-Pb isotopic compositions, these samples were probably derived from partial melting of a depleted mantle source of garnet + spinel lherzolite, metasomatized by subducted sediments around 297 Ma. Modeling of the trace elements indicates that these basalts experienced fractional crystallization of olivine, clinopyroxene and minor plagioclase during magma ascent and eruption. It is proposed that these Late Carboniferous–Early Permian basalts are associated with the northward subduction of the Sumdo Paleo-Tethys Ocean seafloor along the southern margin of the central Lhasa subterrane.

关 键 词：geochemistry northward subduction Sumdo Paleo-Tethys Ocean Lhasa terrane Tibet 

分 类 号：P588.145[天文地球—岩石学] P534.46[天文地球—地质学]