Petrogenesis of the Early Jurassic Longtang and Menglong Peraluminous Granites in Tengchong Terrane,and their Tectonic Implication  

作　　者：WANG Guochang LIU Zheng TAN Shucheng HE Xiaohu WANG Yuchao QI Changshi YE Hui 

机构地区：[1]Institute of Palaeontology,Yunnan Key Laboratory for Palaeobiology,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment,Yunnan University,Kunming 650500,China [2]School of Earth Science,Yunnan University,Kunming 650500,China [3]Institute of International Rivers and Eco-security,Yunnan University,Kunming 650500,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第6期1979-1990,共12页地质学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.41903032);Science(Engineering)Research Project of Yunnan University(Grant No.2017YDQN08);Applied Basic Research Programs of Science and Technology Department of Yunnan Province(Grant No.2018FD009).

摘　　要：A comprehensive study of zircon U-Pb geochronology,in situ Hf isotopes,whole-rock major and trace element geochemistry,and Nd isotopes was carried out for two Early Jurassic two-mica granites(Longtang and Menglong)in the southern part of the Tengchong terrane,which is in the northern part of the larger Sibumasu terrane.We assess the origin of the granites and explore their possible genetic relationship to the Paleo-Tethyan regime.LA-ICP-MS zircon U-Pb dating shows that they were simultaneously emplaced in the Early Jurassic(ca.199 Ma).They have SiO2 contents of 69.7–75.1 wt%and are mainly strongly peraluminous with alumina saturation index(ASI)values ranging from 1.06 to 1.46.They show similar Mg#(0.29–0.42)to experimental partial melts of metasedimentary rocks under continental pressuretemperature(P-T)conditions.They are enriched in light rare earth elements(LREEs)relative to heavy rare earth elements(HREEs),with moderately negative Eu anomalies and flat HREEs patterns.They show negativeεNd(t)values(−9.0 to–12.4)andεHf(t)values(−8.0 to−9.1).Elemental and isotopic data suggest that they most likely to formed by muscovitedehydration melting of a metapelitic source at lower temperatures in the range of 700℃to 750℃.The granites might represent a post-collisional tectonic setting response to Paleo-Tethyan regime.

关 键 词：peraluminous granites POST-COLLISION Early Jurassic PALEO-TETHYS Tengchong terrane 

分 类 号：P534.52[天文地球—古生物学与地层学] P588.121[天文地球—地质学]