Eocene-Oligocene granitoids in southern Tibet: Constraints on crustal;anatexis and tectonic evolution of the Himalayan orogen

	Eocene-Oligocene granitoids in southern Tibet: Constraints on crustal;anatexis and tectonic evolution of the Himalayan orogen
	Hou, Zeng-Qian; Zheng, Yuan-Chuan; Zeng, Ling-Sen; Gao, Li-E; Huang, Ke-Xian; Li, Wei; Li, Qiu-Yun; Fu, Qiang; Liang, Wei; Sun, Qing-Zhong
刊名	EARTH AND PLANETARY SCIENCE LETTERS
	2012
卷号	349 页码:38-52
关键词	U-Pb zircon dating Ar-Ar dating Eocene-Oligocene granitoids exhumation Himalayan orogen
ISSN号	015ZI
英文摘要	Tectonic models for the evolution of the Himalayan orogen interpret the Greater Himalayan crystalline complex (GHC) to be the result of either thick-skinned thrusting involved Indian basement, thin-skinned thrusting involving exotic terranes, middle-crustal ductile flow, or wedge extrusion of the Indian crust during India-Asia collision. Two key pieces of information needed to test the validity of these models is the temporal-spatial distribution of, and the identification of the dynamic mechanisms involved in, regional melting under southern Tibet. Here, we document an Eocene-Oligocene melting event in southern Tibet, which forms a 150-km-long, NW-SE-trending granitoid belt along the Zedong-Lhunze traverse between the Indus-Yarlung suture (IYS) and the south Tibetan detachment (STD). U-Pb dating of magmatic zircons indicates that this granitoid belt youngs northward from similar to 46 Ma (in Lhunze) to similar to 30 Ma (in Zedong). Ar-40/Ar-39 dating of deformed biotite within 42-46 Ma granitoids constrains the timing of shearing to similar to 39-41 Ma.;The granitoid belt of southern Tibet is dominated by Eocene two-mica granites in the Tethyan Himalaya, with minor similar to 30 Ma granodiorites along the IYS and similar to 35 Ma granites in the Yelaxiangbo dome, where Indian mid-crustal rocks are exposed. The similar to 35 Ma granites are characterized by variable Na2O/K2O ratios (1.03-4.44), relatively high Sr concentrations, and high Sr/Y (14.0-126.3) and La/Yb (11.1-42.8) ratios, which distinguish these granitoids from Miocene leucogranites in the Himalaya. Comparison of the Sr-Nd isotopic compositions of these granites with mid-crustal amphibolites exposed in the Yelaxiangbo dome suggests that the granites were derived from melting of the amphibolites at similar to 880 degrees C and similar to 10 kbar. The similar to 30 Ma granodiorites and similar to 42-46 Ma two-mica granites are Na-rich and peraluminous, and are adakitic. They contain inherited Proterozoic zircons, and have a much wider range in epsilon(Nd(t)) of -14.9 to -2.5 and (Sr-87/Sr-86)(i) of 0.7062-0.7188, and have a Nd isotopic model age of 1486-1978 Ma, indicating that these magmas were derived from a thickened Indian lower crust and were subsequently mixed with amphibolite-derived granite melts or were contaminated by the middle crust under southern Tibet. An apparent northward-younging age trend and shearing of the Eocene-Oligocene granitoids requires the southward migration of slices of middle crustal material, in which the Eocene granitoid magmas were emplaced and stored. Our data, along with structural, metamorphic, and intrusive histories of the Himalaya, lead us to propose a model for crustal anatexis and tectonic evolution of the Himalayan orogen, controlled by a number of large-scale events, such as slab break-off, buoyancy-driven uplift, lateral movement, and subsequent exhumation of slices of the subducted Indian crust during Indo-Asia collision at 55-40 Ma. (C) 2012 Elsevier B.V. All rights reserved.
学科主题	火成岩岩石学
WOS关键词	CONTINENTAL COLLISION ZONES ; MANTLE SOURCE CHARACTERISTICS ; FOLD-THRUST ; BELT ; U-PB ; SOUTHEASTERN TIBET ; CHANNEL FLOW ; STRUCTURAL GEOMETRY ; EXHUMATION HISTORY ; DUCTILE EXTRUSION ; TETHYAN HIMALAYA
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	This study is supported by grants from the Ministry of Science and;Technology of China (2011CB4031006), IGCP/SIDA-600, NSFC (40730419; 40425014), the Program of the China Geological Survey (1212011121255),;and the Funds for Creative Research Groups of China (40921001) We are;most grateful to the two anonymous reviewers for critical and;constructive reviews of this manuscript.
WOS记录号	WOS:000309486500005
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39853]
专题	中国地质科学院地质研究所
作者单位	Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China.
推荐引用方式 GB/T 7714	Hou, Zeng-Qian,Zheng, Yuan-Chuan,Zeng, Ling-Sen,et al. Eocene-Oligocene granitoids in southern Tibet: Constraints on crustal;anatexis and tectonic evolution of the Himalayan orogen[J]. EARTH AND PLANETARY SCIENCE LETTERS,2012,349:38-52.
APA	Hou, Zeng-Qian.,Zheng, Yuan-Chuan.,Zeng, Ling-Sen.,Gao, Li-E.,Huang, Ke-Xian.,...&Sun, Qing-Zhong.(2012).Eocene-Oligocene granitoids in southern Tibet: Constraints on crustal;anatexis and tectonic evolution of the Himalayan orogen.EARTH AND PLANETARY SCIENCE LETTERS,349,38-52.
MLA	Hou, Zeng-Qian,et al."Eocene-Oligocene granitoids in southern Tibet: Constraints on crustal;anatexis and tectonic evolution of the Himalayan orogen".EARTH AND PLANETARY SCIENCE LETTERS 349(2012):38-52.