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Zircon U‐Pb Geochronology and Hf Isotopic Constraints on Petrogenesis of Plagiogranite from the Cuomuqu Ophiolite, Bangong Lake Area, North Tibet
Author(s) -
Zhengxin YIN,
Yajuan YUAN,
Baofeng LÜ,
Zhourong CAI,
Hao ZHENG,
Qiangtai HUANG,
Bin XIA,
Yun ZHONG,
Zhongyu XIA,
Xiaolong SHI,
Yao GUAN
Publication year - 2015
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12439
Subject(s) - zircon , ophiolite , geology , geochemistry , geochronology , mafic , petrogenesis , gabbro , massif , oceanic crust , partial melting , petrology , crust , subduction , mantle (geology) , igneous rock , tectonics , paleontology
Field observation, geochemical signatures and zircon Hf isotope data indicate that Cuomuqu ophiolite in the Bangonghu area was formed in a back‐arc basin (BAB) above a supra‐subduction zone (SSZ). Zircon U‐Pb dating of the diabase from the Cuomuqu massif yielded an age of 164.3±1.9 Ma, thus indicating that the ophiolite complex was formed in the Middle Jurassic during back‐arc extension of the mature Bangonghu‐Nujiang Ocean. The zircon ε Hf ( t ) and TDMC values of the plagiogranite are similar to the ε Hf ( t ) and TDM of the diabase, respectively. The mode of occurrence of plagiogranites and their bulk‐rock and Hf isotope characteristics indicate that they were derived from the mantle, associated with the surrounding gabbro and diabase, and were formed by partial melting of altered and hydrated mafic rocks under shear conditions during lateral drifting of the oceanic crust. The zircon U‐Pb age of the plagiogranite is 156.4±1.4 Ma, and it is 7.9 Ma younger than the hosting diabase. In this study, zircon chronological and Hf isotopic data were tentatively analyzed to determine the genesis of plagiogranites in the Cuomuqu ophiolite complex.