Petrogenesis of an Early Cretaceous Xiabie Co I-type Granite in Southern Qiangtang,Tibet:Evidence from Geochemistry,Geochronology,Rb-Sr,Sm-Nd,Lu-Hf and Pb isotopes  

作　　者：LIU Hong LI Youguo LI Wenchang LI Guangming HUANG Hanxiao MA Dongfang HUANG Yong ZHOU Qing FU Jiangang 

机构地区：[1]College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China [2]Chengdu Center,China Geological Survey,Chengdu 610081,China [3]College of Land and Resources Engineering,Kunming University of Science and Technology,Kunming 650093,China [4]Applied Geology Research Center,China Geological Survey,Chengdu 610036,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第3期919-937,共19页地质学报（英文版）

基　　金：This study was financially supported in part by the National Key Research and Development Program of China(Grant Nos:2021YFC2901803,2021YFC2901903,2019YFC0605201);National Natural Science Foundation of China(Grant Nos:92055314,91955208,42002097);China Geological Survey Project(Grant Nos:DD20221776,DD20190542,DD20190147);Special Project of Strategic Leading Science and Technology of Chinese Academy of Sciences(Grant No:XDA20070304);the International Scientific Plan of the Qinghai-Xizang(Tibet)Plateau of Chengdu Center,China Geological Survey.

摘　　要：Cretaceous magmatism is widely distributed on both sides of the Bangong-Nujiang suture zone(BNSZ).These rocks record the subduction to closure history of the Bangong-Nujiang Tethys Ocean(BNO)and the collisional history between the Lhasa(LS)and Qiangtang(QT)terranes.The Xiabie Co granite in Nyima County,which located on the southern margin of the QT terrane,Tibet.In this study,whole-rock geochemistry;Rb-Sr,Sm-Nd,and Pb isotopes;and laser ablation inductively coupled mass spectrometry(LA-ICP-MS)zircon U-Pb ages and Lu-Hf isotopes of the Xiabie Co granite in the Nyima area have been studied to constrain its petrogenesis and tectonic setting.Our study can help explain the tectonic evolution of the BNSZ and crust-mantle interaction.Zircon U-Pb dating indicates that the granite was emplaced at ca.120 Ma.The granite contains a small amount of hornblende and has high silicon(SiO2=73.97-78.03 wt%),potassium(K_(2)O=4.75-6.53 wt%),and total alkali(K_(2)O+Na_(2)O=7.98-8.98 wt%)contents;low calcium content(CaO=2.33-4.11 wt%);and variable A/CNK(1.00-1.18)and A/NK(1.09-1.22)values.The P_(2)O_(5) content of the granite negatively correlated with the SiO_(2)content.Thus,the Xiabie Co granite is a weakly peraluminous I-type granite belonging to the high-K calcalkaline to Shoshone series.It is enriched in light rare earth elements(LREEs)and relatively depleted in heavy rare earth elements(HREEs),with LREE/HREE ratios of 8.03-16.40 and La_(N)/Yb_(N) ratios of 10.2-27.1.Samples show right-leaning chondrite-normalized rare earth element patterns with pronounced negative Eu anomalies(Eu/Eu*=0.67-0.76).The primitive-mantle-normalized trace element spider diagrams of the samples are right-leaning zigzag curves,showing relative enrichment in large-ion lithophile elements(LILEs,e.g.,Rb,Th,U,and K)and depletion in high-field-strength elements(HFSEs,e.g.,Nb,P,Ti,and Yb)and displaying striking Sr and Ba negative anomalies.The graniteεHf(t)values were positive(2.9-9.9),whereas the whole-rockεNd(t)values were negative(−2.841 to−2.33).The

关 键 词：I-type granite Lhasa-Qiangtang collision Bangong-Nujiang Tibet(Xizang) 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.121[天文地球—地质学] P597.3