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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; guofengt@263.net
2012
发表期刊LITHOS
ISSN0024-4937
卷号150页码:209-226
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.
部门归属[Zhao, Liang; Guo, Feng; Fan, Weiming; Li, Chaowen; Li, Hongxia] Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Peoples R China; [Zhao, Liang] Chinese Acad Sci, S China Sea Inst Oceanol, Key Lab Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China; [Qin, Xiaofeng] Chinese Acad Geol Sci, Inst Mineral Resources, Beijing 100037, Peoples R China
关键词Crustal Anatexis P-t Path Restite Granulite Enclaves Indo-sinian Peraluminous Granites South China
学科领域Geochemistry & Geophysics ; Mineralogy
语种英语
资助项目海洋地质
WOS记录号WOS:000309616000015
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文献类型期刊论文
条目标识符http://ir.scsio.ac.cn/handle/344004/10305
专题中科院边缘海地质重点实验室
通讯作者guofengt@263.net
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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.,...&guofengt@263.net.(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.
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