气候变化领域集成服务门户(CCPortal): Early Jurassic high-pressure metamorphism of the Amdo terrane, Tibet: Constraints from zircon U-Pb geochronology of mafic granulites

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DOI	10.1016/j.gr.2013.08.003
	Early Jurassic high-pressure metamorphism of the Amdo terrane, Tibet: Constraints from zircon U-Pb geochronology of mafic granulites
	Zhang, Xiaoran; Shi, Rendeng; Huang, Qishuai; Liu, Deliang; Gong, Xiaohan; Chen, Shengsheng; Wu, Kang; Yi, Guoding; Sun, Yali; Ding, Lin
通讯作者	Zhang, XR (通讯作者)
发表日期	2014
ISSN	1342-937X
EISSN	1878-0571
起始页码	975
结束页码	985
卷号	26 期号:3-4
英文摘要	The Amdo terrane holds one of the important keys to understand the tectonic evolution of Central Tibet. Here we report the results from a combined study of Cathodoluminescence imaging, LA-ICPMS U-Pb dating, and trace element analysis of zircons from high-pressure (HP) mafic granulites from the Amdo terrane. Zircons from the mafic granulite are rounded or anhedral and show sector or planar domains with low Th/U ratios, low REE contents, and flat HREE patterns, and can be divided into two types. The first type of zircons shows negative Eu anomalies, indicating that they coexisted with garnet and symplectitic plagioclase during the retrograde stage of metamorphism, whereas the second type possesses positive Eu anomalies, implying that they formed during the peak-metamorphic stage of the HP granulite. U-Pb data yielded a weighted mean Pb-206/U-238 age of 190.7 +/- 3.0 Ma (MSWD = 2.8, n = 8) for zircons with positive Eu anomalies, interpreted as the time of the peak metamorphism, and a mean age of 181.4 +/- 1.8 Ma (MSWD = 2.2, n = 16) for zircons with negative Eu anomalies corresponding to the amphibolite-facies retrogression. Combining with previous data, we suggest that the Amdo terrane became a microcontinent in the Tethys Ocean during the Permian-Triassic rifting between the Lhasa and Qiangtang terranes, and then the Amdo terrane subducted to about 50-km-depth beneath the Qiangtang terrane experiencing HP granulite-facies metamorphism in the Early Jurassic at 190 Ma. The region was then uplifted to the mid-crustal levels (similar to 20 km) with an exhumation rate of ca. 3 mm/year. The presence of Early Jurassic HP granulite shows that the Amdo terrane is related to the Bangong-Nujiang Suture zone instead of with the Mid-Qiangtang Suture zone. (C) 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
关键词	HIGH-GRADE METAMORPHISM TRACE-ELEMENT ANALYSES OCEANIC UPPER-MANTLE OS-IR ALLOYS TECTONIC EVOLUTION DONQIAO OPHIOLITE CENTRAL QIANGTANG KOKCHETAV MASSIF MULTIPLE EVENTS BASEMENT ROCKS
英文关键词	High-pressure granulites; Early Jurassic; Zircon U-Pb dating; Amdo terrane; Central Tibet
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:000342524200010
来源期刊	GONDWANA RESEARCH
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/258311
推荐引用方式 GB/T 7714	Zhang, Xiaoran,Shi, Rendeng,Huang, Qishuai,et al. Early Jurassic high-pressure metamorphism of the Amdo terrane, Tibet: Constraints from zircon U-Pb geochronology of mafic granulites[J]. 中国科学院青藏高原研究所,2014,26(3-4).
APA	Zhang, Xiaoran.,Shi, Rendeng.,Huang, Qishuai.,Liu, Deliang.,Gong, Xiaohan.,...&Ding, Lin.(2014).Early Jurassic high-pressure metamorphism of the Amdo terrane, Tibet: Constraints from zircon U-Pb geochronology of mafic granulites.GONDWANA RESEARCH,26(3-4).
MLA	Zhang, Xiaoran,et al."Early Jurassic high-pressure metamorphism of the Amdo terrane, Tibet: Constraints from zircon U-Pb geochronology of mafic granulites".GONDWANA RESEARCH 26.3-4(2014).