Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis

CORC > 南海海洋研究所 > 中国科学院南海海洋研究所 > 中科院边缘海地质重点实验室

	Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis
	Zhao, L ; Guo, F ; Fan, WM ; Li, CW ; Qin, XF ; Li, HX
刊名	LITHOS
	2012
卷号	150 页码:209-226
关键词	Crustal anatexis P-T path Restite Granulite enclaves Indo-Sinian peraluminous granites South China
ISSN号	0024-4937
通讯作者	guofengt@263.net
中文摘要	Metasedimentary granulite enclaves hosted in the Indo-Sinian Darongshan-Shiwandashan granite belt from the southeastern Guangxi province, South China, experienced a three-stage metamorphic evolution: (1) the early prograde metamorphism in the stability field of sillimanite at similar to 800 degrees C; (2) the peak metamorphism with a mineral assemblage of spinel + quartz at 7.5-8.0 kbar and 950-1000 degrees C (260-250 Ma); and (3) a near-isothermal decompression stage with orthopyroxene + plagioclase and orthopyroxene + cordierite symplectic textures at 3.2-3.7 kbar and 790-820 degrees C (240-230 Ma). The clockwise P-T-t path suggested that the granulite enclaves have undergone initial crustal thickening and subsequent rapid exhumation and cooling history. The granulite enclaves show peraluminous affinities (A/CNK = 1.11-3.14, A/CNK=Al2O3/(CaO + Na2O + K2O) in molecular ratio) with Al2O3 up to 25.31%; chondrite-normalized REE patterns similar to those of upper continental crust: relative Rb, Ba, Th, LREE, K, Zr and Hf enrichment and Sr, Nb, Ta, P and Ti depletion in primitive mantle-noimalized spidergrams; and highly radiogenic Sr (Sr-87/Sr-86(i)= 0.71295-0.74273) and nonradiogenic Nd (epsilon(Nd)(t) = -14.8 to -11.2). Systematic elemental variation trends from the granulite enclaves to the host granites, and similar Sr-Nd isotope compositions in the enclaves and the host granites, indicate that the two have a coherent origin the granulites were restites of the host granites. The granulite enclaves can also be subdivided into two groups: high-Sr-87/Sr-86(i) (>0.7303) and low-Sr-87/Sr-86(i) groups (<0.7135). The estimated magma source for the host granites may contain 10-40% low-Sr-87/Sr-86(i) and 60-90% high-Sr-87/Sr-86(i) granulites. P-T-t path and geochemical features of the granulite enclaves, temperature estimation for the host granites, and previous geochronological data, indicate limited dehydration melting of the metasedimentary protoliths during the prograde and peak metamorphic stages. Instead, large scale crustal melting may have occurred during the stage of exhumation and uplifting of the lower-middle crust. (C) 2012 Published by Elsevier B.V.
学科主题	Geochemistry & Geophysics; Mineralogy
语种	英语
WOS记录号	WOS:000309616000015
公开日期	2013-08-28
内容类型	期刊论文
源URL	[http://ir.scsio.ac.cn/handle/344004/10305]
专题	南海海洋研究所_中科院边缘海地质重点实验室
推荐引用方式 GB/T 7714	Zhao, L,Guo, F,Fan, WM,et al. Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis[J]. LITHOS,2012,150:209-226.
APA	Zhao, L,Guo, F,Fan, WM,Li, CW,Qin, XF,&Li, HX.(2012).Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis.LITHOS,150,209-226.
MLA	Zhao, L,et al."Origin of the granulite enclaves in Indo-Sinian peraluminous granites, South China and its implication for crustal anatexis".LITHOS 150(2012):209-226.