Geochronological and geochemical constraints on the petrogenesis of late Mesoproterozoic mafic and granitic rocks in the southwestern Yangtze Block  

作　　者：Guichun Liu Jing Li Xin Qian Qinglai Feng Wei Wang Guangyan Chen Shaobin Hu 

机构地区：[1]Guargdong Provincial Key lab of Geodynamics and Geohazards,School of Eorth Scliences and Engheerng Sun Yat-sen Unbversity,Guangzhou,510275,China [2]Yurnan Ins diute of Geolbgical Survey,Kuruming 650216,China [3]Southem Marine Sciance and Engineerirg Guangiong Laboratory(Zhuhai),Zhuhai,519082,China [4]State Key Laboratonry of Geological Processes and Mineral Resources,China University of Geosdences,Wuhan,430074,China

出　　处：《Geoscience Frontiers》2021年第1期39-52,共14页地学前缘（英文版）

基　　金：supported by the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2019B1515120019,2018B030312007);National Natural Science Foundation of China(Grant Nos.U1701641,41830211,41702230);the District Summary and Service Product Develop of Yunnan Region Geologic Survey,China(Grant No.121201102000150012-02)。

摘　　要：Late Mesoproterozoic igneous rocks in the SW Yangtze Block are important for understanding the role of it in reconstruction of the Rodinia supercontinent.In the present study,we report new geochronological,geochemical,and Nd-Hf isotopic data for the Cuoke plagioclase amphibolites and granites in the SW Yangtze Block.Geochronological results show that the plagioclase amphibolites and granites have similar late Mesoproterozoic zircon U-Pb ages of 1168-1162 Ma,constituting a bimodal igneous assemblage.The plagioclase amphibolites have high and variable TiO2 contents(1.15-4.30 wt.%)and Mg#(34-66)values,similar to the tholeiitic series.They are characterized by enrichment in LREEs and LILEs,and have OIB-like affinities with positive Nb and Ta anomalies.The plagioclase amphibolites have positive whole-rockεNd(t)(+3.2 to+4.3)and zirconεHf(t)(+4.3 to+10.7)values,indicating that they were derived from an OIB-like asthenospheric mantle source.The granites belong to the reduced peralkaline A-type series and have negativeεNd(t)value of-6.0 andεHf(t)values of-5.8 to-13.8,indicating a derivation from the partial melting of ancient mafic lower crust.In combination with the~1.05-1.02 Ga bimodal igneous assemblage in the SW Yangtze Block,we propose that the Cuoke 1168-1162 Ma igneous rocks were likely formed in a continental rift basin and argue against the existance of Grenvillian Orogen in the SW Yangtze Block during the late Mesoproterozoic.

关 键 词：Late Mesoproterozoic Zircon U-Pb geochronology Elemental and isotopic data Within-plate igneous rocks Continental rift Yangtze Block 

分 类 号：P588.121[天文地球—岩石学] P534.4[天文地球—地质学]