Early Eocene crustal thickening in southern Tibet:New age and geochemical constraints from the Gangdese batholith
作者单位：State Key Laboratory of Lithospheric EvolutionInstitute of Geology and GeophysicsChinese Academy of Sciences Department of GeosciencesNational Taiwan University
会议名称：《中国科学院地质与地球物理研究所2012年度（第12届）...》
会议日期：2013年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：supported by research grants from the Chinese Academy of Sciences(KZCX2-YW-Q09-06) the National Natural Science Foundation of China(No. 40721062)
关 键 词：Eocene Crustal thickening Gangdese batholith Zircon U-Pb age and Hf isotope Geochemistry Lhasa terrene Tibet
摘 要：The Lhasa terrane,southern Tibet is where the thickest part of the Earth’s crust occurs as a result of the India-Asia *** paper reports zircon U-Pb age and geochemical data of samples collected from the Gangdese batholith,southern Lhasa terrane,a subset of which has already been dated at 65-41 Ma using zircon U-Pb geochronology(Ji,W.Q.,Wu,F.Y.,Chung,S.L.,Li,J.X.,Liu,C.Z.,*** U-Pb chronology and Hf isotopic constraints on the pedogenesis of Gangdese batholiths,southern *** Geology 262,229-245),to constrain the timing and mechanism(s) responsible for crustal thickening beneath southern *** new data indicate that the Gangdese magmatism lasted continuously from ca.65 to 34 Ma,during which geochemical evidence forcrustal thickening is *** thickening is best illustrated by the progressive increase in La/Yb and Sr/Y of the Early to latest Eocene magmatic rocks,associated with the decrease in Hf isotopic ratios of Paleocene to Eocene magmatic *** also identify in this study the oldest(ca.51 Ma),post-collislonaladakitic granitoids in the Gangdese batholith, interpreted as products from partial melting of underplated basaltic lower ***,a thickened crust likely existed by that time,at least locally,in the southern Lhasa terrane,Tibet.