Crustal thickening prior to 38 Ma in southern Tibet: Evidence from lower   crust-derived adakitic magmatism in the Gangdese Batholith

doi:10.1016/j.gr.2011.07.004

CORC > 北京大学 > 地球与空间科学学院

	Crustal thickening prior to 38 Ma in southern Tibet: Evidence from lower crust-derived adakitic magmatism in the Gangdese Batholith
	Guan, Qi ; Zhu, Di-Cheng ; Zhao, Zhi-Dan ; Dong, Guo-Chen ; Zhang, Liang-Liang ; Li, Xiao-Wei ; Liu, Min ; Mo, Xuan-Xue ; Liu, Yong-Sheng ; Yuan, Hong-Lin
刊名	gondwana research
	2012
关键词	Zircon U-Pb geochronology Eocene adakite Mafic enclave Gangdese Batholith Southern Tibet ZIRCON U-PB MANTLE SOURCE CHARACTERISTICS CONTINENTAL COLLISION ZONES LACHLAN FOLD BELT S-TYPE GRANITES LA-ICP-MS LHASA TERRANE VOLCANIC-ROCKS HF ISOTOPES I-TYPE
DOI	10.1016/j.gr.2011.07.004
英文摘要	The petrogenesis and geodynamic implications of the Cenozoic adakites in southern Tibet remain topics of debate. Here we report geochronological and geochemical data for host granites and mafic enclaves from Wolong in the eastern Gangdese Batholith, southern Tibet Zircon LA-ICP-MS dating indicates that the Wolong host granites and enclaves were synchronously emplaced at ca. 38 Ma. The host granites are medium- to high-K calc-alkaline, metaluminous (A/CNK = 0.93-0.96), with high Al2O3 (15.47-17.68%), low MgO (0.67-118%), very low abundances of compatible elements (e.g., Cr = 3.87-8.36 ppm, Ni = 3.04-5.71 ppm), and high Sr/Y ratios (127-217), similar to those typical of adakite. The mafic enclaves (SiO2=51.08-56.29%) have 3.83-5.02% MgO and an Mg-# of 48-50, with negative Eu anomalies (delta Eu = 0.59-0.79). The Wolong host granites and enclaves have similar Sr-Nd isotopic compositions (initial Sr-87/Sr-86 = 0.7053-0.7055, epsilon(Nd)(t) = -2.7 to -1.4), with varying zircon epsilon(Hf)(t) values, ranging from +6.0 to +12.6. A comprehensive study of the data available for adakitic rocks from the Gangdese Batholith indicates that the Wolong adakitic host granites were derived from partial melting of a thickened lower crust, while the parental magmas of the mafic enclaves were most likely derived from lithospheric mantle beneath southern Tibet. The Wolong granitoids are interpreted as the result of mixing between the thickened lower crust-derived melts and lithospheric mantle-derived mafic melts, which are likely the protracted magmatic response to the break-off of the Neo-Tethyan oceanic slab at about 50 Ma. Our results suggest that the crustal thickening in southern Tibet occurred prior to similar to 38 Ma, and support the general view that the India-Asia collision must have occurred before 40 Ma. (C) 2011 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000300204400007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; Geosciences, Multidisciplinary; SCI(E); 76; ARTICLE; 1; 88-99; 21
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/394053]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Guan, Qi,Zhu, Di-Cheng,Zhao, Zhi-Dan,et al. Crustal thickening prior to 38 Ma in southern Tibet: Evidence from lower crust-derived adakitic magmatism in the Gangdese Batholith[J]. gondwana research,2012.
APA	Guan, Qi.,Zhu, Di-Cheng.,Zhao, Zhi-Dan.,Dong, Guo-Chen.,Zhang, Liang-Liang.,...&Yuan, Hong-Lin.(2012).Crustal thickening prior to 38 Ma in southern Tibet: Evidence from lower crust-derived adakitic magmatism in the Gangdese Batholith.gondwana research.
MLA	Guan, Qi,et al."Crustal thickening prior to 38 Ma in southern Tibet: Evidence from lower crust-derived adakitic magmatism in the Gangdese Batholith".gondwana research (2012).