Geochemistry and Geochronology of the Jinghong Ophiolites:Implications for the Tectonic Evolution of the Eastern Paleo-Tethys  

作　　者：ZHU Jianjiang LIU Fulai WANG Fang XIE Shiwen CAI Jia JI Lei WANG Huining 

机构地区：[1]Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China

出　　处：《Acta Geologica Sinica(English Edition)》2021年第5期1509-1526,共18页地质学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant 91855206);National Key Research and Development Project of China(Grant 2016YFC0600310);the Foundation of Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources(No.J1901-18,J1901-23)。

摘　　要：The Jinghong mafic-ultramafic complex,exposed in the eastern margin of the Lancangjiang tectonic belt,is related to the subduction of the Paleo-Tethys Ocean.Its petrogenesis plays a key role in constraining the tectonic evolution of the eastern Paleo-Tethys Ocean in southwestern China.In this study,we present petrological,geochemical and geochronological results of the Jinghong complex rocks,in order to decipher their origin and tectonic significance.The Jinghong mafic-ultramafic complex was composed of peridotite,gabbro,basalt and minor plagiogranite.Whole-rock geochemical data of the mafic rocks indicate that they have both MORB and IAB affinities and plot in the back-arc basin basalt(BABB)field in the FeO^(*)/MgO vs.TiO_(2) diagram.Combined with their trace element characteristics,it can be concluded that the Jinghong mafic-ultramafic complex represents an ophiolite suite that was formed in a back-arc ocean basin.Precise LA-ICP-MS zircon U-Pb dating yielded weighted mean ^(206)Pb/^(238)U ages of 298.4±1.7 Ma,294.3±1.6 Ma,and 292.8±2.0 Ma for gabbroic rocks from this complex,which indicates that the Jinghong ophiolites were formed during the early Permian(298-293 Ma).We propose that during subduction of the main Paleo-Tethys Ocean,a back-arc ocean basin was formed at the east of the Lancangjiang tectonic belt.

关 键 词：OPHIOLITE zircon U-Pb dating back-arc basin Lancangjiang belt PALEO-TETHYS 

分 类 号：P587[天文地球—岩石学] P542[天文地球—地质学] P597.3