Demarcation of North Boundary for Western Jiangnan Orogen:Evidence from Granitic Xenolith in Daping Area,East Guizhou
Wang Kun
Zhang Jiawei
Xiang Lu
Shi Lei
Ye Taiping
Li Haibo
Chen Jianshu
Dai Yaran
Zhang Tingting
ZhuYuhua
Abstract：Mantle-derived magmas can serve as a"lithoprobe"for acquiring information about deep Earth materials.In this study,a newly discovered granite xenolith from the Late Ordovician(449 Ma)lamproite at Daping,East Guizhou,was investigated.Zircon U-Pb geochronology,Lu-Hf isotope,and trace element analyses were conducted on the granite xenolith.The results indicate that the concordant zircon U-Pb age of the granite xenolith is(833±2.6)Ma(MSWD=1.3,n=26).The εHf(t)values range from-11.4 to-2.30,and the depleted mantle model ages(TDM)vary from 2 457 to 1 893 Ma.The trace element compositions of zircon,including REEs,U,Th,Pb,Nb,and Hf,suggest that the granite xenolith is an S-type granite related to orogenic processes.The similarity in crystallization ages and Hf isotopic compositions between this granite xenolith and the Neoproterozoic granites exposed in the Fanjingshan region implies that they may collectively form a large granitic batholith at depth.This batholith provides crucial evidence for delineating the northern boundary of the western segment of the Jiangnan Orogen.It is proposed that the boundary between the northern side of the western Jiangnan Orogen and the Yangtze Block should be defined by the Zhangjiajie-Guiyang fault.
Keywords：Yangtze BlockNeoproterozoiclithoprobexenolithboundary of orogen beltgranitic batholithisotopesgeochronology
Publication Date：2025-11-30
Online Publishing Date：2025-12-15(First online date of this platform, not the publication date of the document)
Pages：17( 4370-4386 )