In this study,zircon U-Pb dating of volcanic rocks from the Zhongba ophiolite of the Yarlung Zangbo Suture Zone(YZSZ)in southern Xizang(Tibet)yielded an age of 247±3 Ma.According to whole rock geochemical and Sr-Nd-Pb isotopic data,the Early Triassic samples could be divided into two groups:Group 1 with P-MORB affinity,showing initial 87Sr/86Sr ratios of 0.70253-0.70602,εNd(t)values of 4.2-5.3,(206Pb/204Pb)t ratios of 16.353-18.222,(207Pb/204Pb)t ratios of 15.454-15.564,and(208Pb/204Pb)t ratios of 35.665-38.136;Group 2 with OIB affinity,showing initial 87Sr/86Sr ratios of 0.70249-0.70513,εNd(t)values of 4.4-4.9,(206Pb/204Pb)t ratios of 17.140-18.328,(207Pb/204Pb)t ratios of 15.491-15.575,and(208Pb/204Pb)t ratios of 36.051-38.247.Group 2 rocks formed by partial melting of the mantle source enriched by a former plume,and assimilated continental crustal material during melt ascension.The formation of Group 1 rocks corresponds to the mixing of OIB melts,with the same components as Group 2 and N-MORBs.The Zhongba Early Triassic rocks belong to the continental margin type ophiolite and formed in the continental-oceanic transition zone during the initial opening of the Neo-Tethys in southern Xizang(Tibet).
HE Juan;LI Yalin;HOU Yunling;ZHOU Aorigele;WEI Yushuai;CHEN Xi;DAI Jingen
School of Civil Engineering and Architecture,West Yunnan University of Applied Sciences,Dali,Yunnan 671006,China||School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100080,ChinaSchool of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100080,ChinaWest Yunnan University of Applied Sciences,Dali,Yunnan 671006,ChinaMLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100080,China
rift;Early Triassic magmatism;Yarlung Zangbo Suture Zone;Neo-Tethys;Southern Xizang;Tibet
《地质学报（英文版）》 2024 (002)
324-336 / 13
This work is granted by the National Natural Science Foundation of China(Grant Nos.91955206,41603038),Second Tibetan Plateau Scientific Expedition and Research program(Grant No.2019QZKK0803),Scientific Research Foundation for Advanced Scholars,West Yunnan University of Applied Sciences(Grant No.2022RCKY0004),and Yunnan Fundamental Research Projects(Grant No.202301AT070012).We thank Yang Zaiyue and Ni Wenchao for their assistance in format modification during the preparation of this manuscript.
10.1111/1755-6724.15141
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