Building of the Deep Gangdese Arc, South Tibet: Paleocene Plutonism and;Granulite-Facies Metamorphism

doi:10.1093/petrology/egt056

	Building of the Deep Gangdese Arc, South Tibet: Paleocene Plutonism and;Granulite-Facies Metamorphism
	Zhang, Zeming 5; Dong, Xin ; Xiang, Hua ; Liou, J. G.; Santosh, M.
刊名	JOURNAL OF PETROLOGY
	2013
卷号	54 期号:12 页码:2547-2580
关键词	Gangdese magmatic arc crustal growth granulite S-type granite south Tibet
ISSN号	0022-3530;EI 1460-2415
DOI	10.1093/petrology/egt056
英文摘要	The Nyingchi complex, forming the eastern segment of the Gangdese magmatic arc, occurs within the southern Lhasa terrane in south Tibet, and is composed dominantly of plutons and their metamorphosed equivalents. Together with some metasedimentary units these rocks record multiple Mesozoic and Cenozoic magmatic and metamorphic events during northward subduction of Neo-Tethyan oceanic lithosphere beneath the Eurasian continent. Petrological and geochronological studies reveal that the Nyingchi complex experienced intense Paleocene subduction-related magmatism and almost synchronous granulite-facies metamorphism accompanied by the formation of S-type granites. Subduction-related I-type granitoids show geochemical features typical of continental magmatic arcs; zircon separates from them yield Pb-206/U-238 ages from c. 65 to c. 56 Ma, and commonly display positive epsilon(Hf)(t) values ranging from -1 center dot 7 to +13 center dot 0. The occurrence of magmatic epidote, as well as the syn-intrusion high-grade metamorphism, indicates that the plutons were emplaced at middle to lower crustal depths within the Lhasa terrane. Associated S-type granitoids are peraluminous and contain garnet and muscovite; their zircons yield Pb-206/U-238 ages ranging from c. 66 to c. 55 Ma, and these have distinct but mostly negative epsilon(Hf)(t) values from -18 center dot 4 to +2 center dot 1. The zircons from the associated metasedimentary rocks include both detrital and metamorphic types; the detrital zircons yielded variable inherited Pb-206/U-238 ages ranging from c. 2910 to c. 235 Ma, constraining the maximum depositional age to the Triassic. The metamorphic zircons from the metaplutonic and metasedimentary rocks yielded ages from c. 67 to 52 Ma. Phase equilibria modeling shows that the Nyingchi complex experienced peak granulite-facies metamorphism and partial melting under conditions of 800-830 degrees C and 9-10 center dot 5 kbar, and then cooled isobarically to c. 700 degrees C in the lower crust at depths of > 30 km. We argue that rollback of the flat-subducted Neo-Tethyan oceanic slab during Early Paleogene times resulted in a contractional orogeny and intrusion of voluminous mantle-derived magmas, which caused large-scale crustal heating, partial melting and granulite-facies metamorphism within the deep crust of the Gangdese arc. The Nyingchi complex represents the exposed lower crust of the Gangdese magmatic arc, and links the granulite-facies metamorphism with silicic magmatism and crustal growth during Paleocene arc accretion.
学科主题	变质岩岩石学
WOS关键词	ZIRCON U-PB ; EASTERN HIMALAYAN SYNTAXIS ; HIGH-PRESSURE METAMORPHISM ; HIGH-GRADE METAMORPHISM ; MAFIC GARNET GRANULITE ; NAMCHE-BARWA SYNTAXIS ; KOHISTAN ISLAND-ARC ; TSANGPO SUTURE ZONE ; LA-ICP-MS ; CONTINENTAL-CRUST
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	OXFORD UNIV PRESS
WOS记录号	WOS:000327853800005
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/40086]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China. 2.Liou, J. G.] Stanford Univ, Dept Geol & Environm Sci, Stanford, CA 94305 USA. 3.Santosh, M.] Kochi Univ, Fac Sci, Div Interdisciplinary Sci, Kochi 7808520, Japan. 4.Santosh, M.] China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China. 5.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Zhang, Zeming,Dong, Xin,Xiang, Hua,et al. Building of the Deep Gangdese Arc, South Tibet: Paleocene Plutonism and;Granulite-Facies Metamorphism[J]. JOURNAL OF PETROLOGY,2013,54(12):2547-2580.
APA	Zhang, Zeming,Dong, Xin,Xiang, Hua,Liou, J. G.,&Santosh, M..(2013).Building of the Deep Gangdese Arc, South Tibet: Paleocene Plutonism and;Granulite-Facies Metamorphism.JOURNAL OF PETROLOGY,54(12),2547-2580.
MLA	Zhang, Zeming,et al."Building of the Deep Gangdese Arc, South Tibet: Paleocene Plutonism and;Granulite-Facies Metamorphism".JOURNAL OF PETROLOGY 54.12(2013):2547-2580.