Carboniferous and Permian evolutionary records for the Paleo‐Tethys Ocean constrained by newly discovered Xiangtaohu ophiolites from central Qiangtang, central Tibet

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• 作者：Xiu‐Zheng Zhang ; Yong‐Sheng Dong ; Qiang Wang ; Wei Dan ; Chunfu Zhang ; Ming‐Rong Deng ; Wang Xu ; Xiao‐Ping Xia ; Ji‐Peng Zeng ; He Liang
• 刊名：Tectonics
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：35
• 期：7
• 页码：1670-1686
• 全文大小：3.0MB
• ISSN：1944-9194

文摘

Reconstructing the evolutionary history of the Paleo-Tethys Ocean remains at the center of debates over the linkage between Gondwana dispersion and Asian accretion. Identifying the remnants of oceanic lithosphere (ophiolites) has very important implications for identifying suture zones, unveiling the evolutionary history of fossil oceans, and reconstructing the amalgamation history between different blocks. Here we report newly documented ophiolite suites from the Longmu Co-Shuanghu Suture zone (LSSZ) in the Xiangtaohu area, central Qiangtang block, Tibet. Detailed geological investigations and zircon U-Pb dating reveal that the Xiangtaohu ophiolites are composed of a suite of Permian (281–275 Ma) ophiolites with a nearly complete Penrose sequence and a suite of Early Carboniferous (circa 350 Ma) ophiolite remnants containing only part of the lower oceanic crust. Geochemical and Sr-Nd-O isotopic data show that the Permian and Carboniferous ophiolites in this study were derived from an N-mid-ocean ridge basalts-like mantle source with varied suprasubduction-zone (SSZ) signatures and were characterized by crystallization sequences from wet magmas, suggesting typical SSZ-affinity ophiolites. Permian and Carboniferous SSZ ophiolites in the central Qiangtang provide robust evidence for the existence and evolution of an ancient ocean basin. Combining with previous studies on high-pressure metamorphic rocks and pelagic radiolarian cherts, and with tectonostratigraphic and paleontological data, we support the LSSZ as representing the main suture of the Paleo-Tethys Ocean which probably existed and evolved from Devonian to Triassic. The opening and demise of the Paleo-Tethys Ocean dominated the formation of the major framework for the East and/or Southeast Asia.