Early Oligocene Na-rich peraluminous leucogranites in the Yardoi gneiss dome, southern Tibet Formation mechanism and tectonic implications

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	Early Oligocene Na-rich peraluminous leucogranites in the Yardoi gneiss dome, southern Tibet Formation mechanism and tectonic implications
	Gao, LE (Gao LiE); Zeng, LS (Zeng LingSen); Liu, J (Liu Jing); Xie, KJ (Xie KeJia)
刊名	ACTA PETROLOGICA SINICA
	2009
卷号	25 期号:9 页码:2289-2302
关键词	Tibet North Himalayan Gneiss Dome Yardoi gneiss dome Leucogranite Crustal anatexis
ISSN号	1000-0569
英文摘要	The east-west trending Northern Himalayan Gneiss Dome (NHGD) consists of a series Of Semi-continuous gneiss domes within the Tethyan Himalayan Belt. The Yardoi gneiss dome, the easternmost one among these domes, consists of garnet two-mica gneiss, garnet amphibolite, two-mica granite and leucogranite. Available SHRIMP zircon U/Pb data show that the Yardoi leucogranite formed at 35.3 +/- 1.1Ma, older than those similar leucogranites to the west (commonly with ages <25Ma). Bulk element and Sr and Nd isotope analyses show that (1) a majority of the Yardoi leucogranites are Na-rich and peraluminous; (2) similar to the wall-rock gneisses, the Yardoi Ieucogranites are enriched in LILE (e.g. K, Sr, Rb, and Ba), but highly depleted in Ti, Y, Yb, Sc, and Cr; (3) as compared to those either in the gneisses or in the amphibolites, the Yardoi leucogranites are depleted both in LREE and in HREE. However, they are enriched in LREE relative to HREE; (4) the Yardoi leucogranites have initial Sr isotope compositions ranging from 0.71195 to 0.71934, similar to those in the amphibolites, whereas they have relatively lower epsilon(Nd)(i) values ( -8.9 similar to 15. 0), which is intermediate between those in the amphibolites and the gneisses. Two end member simple mixing calculations indicate that partial melting of a source mixed of garnet amphibolite with subordinate pelitic gneiss could account for the formation of the Yardoi Na-rich peraluminouis melts. The Yardoi leucogranites have an average Zr saturation temperature of 673 degrees C. At this temperature, both H(2)O-fluxed melting of metapelite at high-pressures ( similar to 10kbar) and amphibolite parting melting can produce Na-rich peraluminous granitic melts. However, amphibolite partial melting dominated the similar to 35 Ma anatectic event in the Yardoi gneiss dome. This event might be a major factor that led to the transition from compressional to extensional deformation in the overthickened Himalayan belt.
学科主题	变质岩岩石学
WOS关键词	HIMALAYAN LEUKOGRANITES ; ZIRCON SATURATION ; LANGTANG VALLEY ; GEOCHEMICAL CONSTRAINTS ; METAMORPHIC SEQUENCE ; CONTINENTAL-CRUST ; TETHYAN HIMALAYA ; ANATEXIS ; ORIGIN ; MAGMAS
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000270044500021
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38931]
专题	中国地质调查局
作者单位	Chinese Acad Sci, Inst Tibetan Plateau Res, Beijing 100085, Peoples R China
推荐引用方式 GB/T 7714	Gao, LE ,Zeng, LS ,Liu, J ,et al. Early Oligocene Na-rich peraluminous leucogranites in the Yardoi gneiss dome, southern Tibet Formation mechanism and tectonic implications[J]. ACTA PETROLOGICA SINICA,2009,25(9):2289-2302.
APA	Gao, LE ,Zeng, LS ,Liu, J ,&Xie, KJ .(2009).Early Oligocene Na-rich peraluminous leucogranites in the Yardoi gneiss dome, southern Tibet Formation mechanism and tectonic implications.ACTA PETROLOGICA SINICA,25(9),2289-2302.
MLA	Gao, LE ,et al."Early Oligocene Na-rich peraluminous leucogranites in the Yardoi gneiss dome, southern Tibet Formation mechanism and tectonic implications".ACTA PETROLOGICA SINICA 25.9(2009):2289-2302.