Petrogenesis and Tectonic Implications of the Latest Cretaceous Intrusive Rocks from the Eastern Gangdese Belt,Southeast Tibet  

作　　者：CHEN Yanfei CHEN Xuanhua ZHANG Zeming SHAO Zhaogang TIAN Zuolin DONG Xin QIN Shengkai YUAN Yuelei 

机构地区：[1]Chinese Academy of Geological Sciences,Beijing 100037,China [2]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China [3]Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第3期891-903,共13页地质学报（英文版）

基　　金：This study is co-supported by the National Key Research and Development Project of China(Grant Nos.2018YFC0603700,2016YFC0600310);the China Geological Survey(Grant No.DD20190011);the National Natural Science Foundation of China(Grant Nos.91855210,41872029,41202035。

摘　　要：The latest Cretaceous magmatic activity in the eastern segment of the Lhasa terrane provides important insights for tracking the magma source and geodynamic setting of the eastern Gangdese batholith,eastward of eastern Himalayan Syntaxis.Detailed petrological,geochemical and geochronological studies of the intrusive rocks(monzodiorites and granodiorites)of the eastern Gangdese batholith are presented with monzodiorites and granodiorites giving zircon U-Pb crystallization dates of 70-66 Ma and 71-66 Ma withεHf(t)values of−4.8 to+6.2 and−1.9 to+5.3,respectively.These rocks are metaluminous to weakly peraluminous I-type granites showing geochemically arc-related features of enrichment in LREEs and some LILEs,e.g.,Rb,Th,and U,and depletion in HREEs and some HFSEs,e.g.,Nb,Ta,and Ti.The rocks are interpreted to be derived from partial melting of mantle material and juvenile crust,respectively,which are proposed to be triggered by Neo-Tethyan slab rollback during northward subduction,with both experiencing ancient crustal contamination.The studied intrusive rocks formed in a transitional geodynamic setting caused by Neo-Tethyan oceanic flat subduction to slab rollback beneath the eastern Gangdese belt during the latest Cretaceous.

关 键 词：Neo-Tethyan ocean slab rollback regional tectonics eastern Gangdese batholith Tibet 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.12[天文地球—地质学]