Petrogenesis and Geodynamic Implications of Early Cretaceous(~130 Ma)Magmatism in the Baingoin Batholith,Central Tibet:Products of Subducting Slab Rollback  

作　　者：LI Faqiao TANG Juxing WANG Nan LIU Zhibo SONG Yang ZHANG Jing MA Xudong FU Bin LI Haifeng HAN Songhao 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China [2]MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [3]Research School of Earth Sciences,Australian National University,Canberra,ACT 2601,Australia [4]China’s 19th Metallurgical Corporation,Chengdu 617000,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第6期1960-1978,共19页地质学报（英文版）

基　　金：supported by grants from the National Key R&D Program of China(Nos.2022YFC2905001,2018YFC0604106 and 2018YFC0604101);the Program of the Chinese Geological Survey(Nos.DD20190167 and DD20221684);the Basic Research Fund of the Institute of Mineral Resources,Chinese Academy of Geological Sciences(Nos.SYSCR2019-03 and KK2017);the National Natural Science Foundation of China(No.41902097).

摘　　要：The Baingoin batholith is one of the largest granitic plutons in the North Lhasa terrane.Its petrogenesis and tectonic setting have been studied for decades,but remain controversial.Here we report data on geochronology,geochemistry and isotopes of Early Cretaceous granitoids within the Baingoin batholith,which provide more evidence to uncover its petrogenesis and regional geodynamic processes.The Early Cretaceous magmatism yields ages of 134.4–132.0 Ma and can be divided into I-type,S-type and highly fractionated granites.The I-and S-type granites exhibit medium SiO2,high K_(2)O/Na_(2)O with negativeεNd(t)andεHf(t)values,whereas,the albite granites have very high SiO_(2)(79.04%–80.40%),very low K_(2)O/N_(2)O,negativeεNd(t)and a large variation inεHf(t).Our new data indicate that these granitoids are derived from unbalanced melting in a heterogeneous source area.The granodiorites involved had a hybrid origin from partial melting of basalt-derived and Al-rich rocks in the crust,the porphyritic monzogranites being derived from partial melting of pelitic rocks.The albite granites crystallized from residual melt separated from K-rich magma within the‘mush’process and underwent fractionation of K-feldspar.We believe that the Early Cretaceous magmatism formed in an extensional setting produced by the initial and continuous rollback of a northward-subducting slab of the NTO.

关 键 词：petraluminous granites highly fractionated granites Baingoin batholith subducting slab rollback TIBET 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.11[天文地球—地质学]