Age and petrogenesis of A-type granites in the middle segment of the;Bangonghu-Nujiang suture, Tibetan plateau

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	Age and petrogenesis of A-type granites in the middle segment of the;Bangonghu-Nujiang suture, Tibetan plateau
	Qu, Xiao-Ming; Wang, Rui-Jiang; Xin, Hong-Bo; Jiang, Jun-Hua; Chen, Hua
刊名	LITHOS
	2012
卷号	146 页码:264-275
关键词	A-type granites Zircon U-Pb dating Geochemistry Petrogenesis Bangonghu-Nujiang suture Tibet plateau
ISSN号	975UL
英文摘要	During geological investigations conducted over the past several years, the authors found a group of A-type granites in the middle segment of the Bangonghu-Nujiang suture on the Tibetan plateau. These granitic plutons occur as stocks with exposed areas of less than 1 km(2) and lithologically include biotite granite and granodiorite porphyry, which had intruded into Cretaceous sedimentary rocks. Petrogeochemically, the A-type granites contain high SiO2 levels varying from 68.62%-75.36 wt.%. Moreover, they contain relatively high Fe2O3T (0.86-5.39 wt.%) and low Al2O3 (12.76-15.54 wt.%) levels and are weak peraluminous to metaluminous. A trace element N-MORB-normalized spider diagram showed apparent enrichment of the large ion lithophile elements (LILE) Rb, Th, U. K, and Pb with marked depletions of Ba and Sr. The high field strength elements (HFSE) Nb, Ta and Ti were sharply depleted, with relative enrichment of Zr and HE These signatures are characteristic of A-type granite. The granite samples had high rare earth element (REE) contents with Sigma REE = 122.37-291.19 ppm. Light REE were rich relative to heavy REE with LREE/HREE = 4.89-9.58. And negative Eu anomalies were sharp with delta Eu varying from 0.14-05 and a mean value of 0.34. Their chondrite-normalized rare earth element distribution patterns appear as gently right-dipping V-types.;Zircon U-Pb IAICPMS dating for three granitic plutons yielded weighted mean ages of 109.6 +/- 1.4 Ma (MSWD = 3.7), 112.3 +/- 0.51 Ma (MSWD = 0.21) and 113.73 +/- 0.5 Ma (MSWD = 0.21), indicating that they formed in the late stage of the early Cretaceous epoch. The Nd, Sr and Pb isotopic results showed that the granites were rich in radiogenic isotopes. The Sr-87/Sr-86 and I-Sr ratios varied from 0.719842-0.786395 and 0.706900-0.710378, respectively. The Nd-143/Nd-144 ratios were from 0.512123-0.512392, with relatively large negative epsilon(Nd) values (-3.37 to -10.34). The Pb-206/Pb-204, Pb-207/Pb-204, and Pb-208/Pb-204 ratios ranged from 18.703-19.070, 15.680-15.732 and 39.121-39.576, respectively, exhibiting isotopic signatures typical of crustal sources. All of the data demonstrated unanimously that these granites were derived from partial melting of arc basaltic rocks underplated in the lower crust during oceanic crust subduction. The high-temperature heat source for melting of anhydrous basaltic rocks of the lower crust was from upwelling asthenosphere through slab windows formed as a result of slab break-off during post-collisional extension of the orogenic zone. (C) 2012 Elsevier B.V. All rights reserved.
学科主题	火成岩岩石学
WOS关键词	ISOTOPE GEOCHEMISTRY ; CHINA IMPLICATIONS ; WESTERN TIBET ; MAGMATISM ; CONSTRAINTS ; GENERATION ; ND ; DISCRIMINATION ; GEOCHRONOLOGY ; AUSTRALIA
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	The authors wish to thank Prof. Dargahi S, Zhao X F, and another;anonymous reviewer for their critical and constructive reviews. We also;benefit greatly from discussion with Prof. Xu JF from Guangzhou;Institute of Geochemistry, Chinese Academy of Sciences. The study was;supported financially by National Support Program of Science and;Technology (2006BAB01A05), National Basic Research Program;(2011CB403103), and Special Project of Investigation on Geology and;Mineral Resources of the Tibet Plateau from the China Geological Survey;(1212010818097).
WOS记录号	WOS:000306536900019
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39544]
专题	中国地质科学院矿产资源研究所
作者单位	CAGS, Inst Mineral Resources, MLR Key Lab Metallogeny & Mineral Assessment, Beijing 100037, Peoples R China.
推荐引用方式 GB/T 7714	Qu, Xiao-Ming,Wang, Rui-Jiang,Xin, Hong-Bo,et al. Age and petrogenesis of A-type granites in the middle segment of the;Bangonghu-Nujiang suture, Tibetan plateau[J]. LITHOS,2012,146:264-275.
APA	Qu, Xiao-Ming,Wang, Rui-Jiang,Xin, Hong-Bo,Jiang, Jun-Hua,&Chen, Hua.(2012).Age and petrogenesis of A-type granites in the middle segment of the;Bangonghu-Nujiang suture, Tibetan plateau.LITHOS,146,264-275.
MLA	Qu, Xiao-Ming,et al."Age and petrogenesis of A-type granites in the middle segment of the;Bangonghu-Nujiang suture, Tibetan plateau".LITHOS 146(2012):264-275.