Early Cretaceous low-Mg adakitic granites from the Dabie orogen, eastern China: Petrogenesis and implications for destruction of the over-thickened lower continental crust

doi:10.1016/j.gr.2011.12.009

	Early Cretaceous low-Mg adakitic granites from the Dabie orogen, eastern China: Petrogenesis and implications for destruction of the over-thickened lower continental crust
	Xu, Haijin 1,2; Ma, Changqian 1,2; Zhang, Junfeng 1,2; Ye, Kai 3
刊名	GONDWANA RESEARCH
	2013
卷号	23 期号:1 页码:190-207
关键词	Low-Mg adakitic granites Lower continental crust Partial melting Foundering of the eclogitized residues Dabie orogen
ISSN号	1342-937X
DOI	10.1016/j.gr.2011.12.009
文献子类	Article
英文摘要	It is generally accepted that the low-Mg adakitic rocks were derived from the partial melting of metabasalts/eclogites. In this study, we demonstrate that the early Cretaceous low-Mg adakitic granites in the North Dabie Complex (NDC) were generated by the partial melting of the NDC orthogneisses. Here we present in-situ U-Pb and Lu-Hf isotopes in zircon with whole-rock geochemical and Sr-Nd isotopic compositions were carried out for the Tiantangzhai porphyritic monzogranites from the Dabie orogen, eastern China. The monzogranites are characterized by high Sr (576-988 ppm), low Y (7.3-19.0 ppm), and depletion in HREE (Yb: 0.50-1.78 ppm) (thus resulting in high Sr/Y (34.3-135.2) and (La/Yb)(N) (17.0-105.2) ratios) without a negative Eu anomaly. They also exhibit high SiO2 (66.5-73.5 wt.%) and K2O (2.7-4.7 wt.%), and low MgO (0.4-1.6 wt.%) or Mg-# (28.2-45.3, mostly < 40) values. Whole-rock geochemical compositions suggest that the monzogranites represent low-Mg adakitic rock with high-Si and rich-K features equilibrated with residues rich in garnet. Sr-Nd isotopic compositions (epsilon(Nd) (t) = - 16.2 to - 20.3, (Sr-87/Sr-86)(i) = 0.707798-0.708804, t(DM2)(Nd) = 2.3-2.6 Ga) of the monzogranites are distinct from that of the eclogites and amphibolites in the Dabie orogen, but similar to that of the Neoproterozoic (700-800 Ma) gneisses in the NDC, U-Pb dating of zircons gives a consistent age of 130.0 +/- 3.4 Ma with discordia upper intercept age of 716 +/- 34 Ma for inherited cores identified by CL imaging. Correspondingly, in-situ Lu-Hf analyses of early Cretaceous young age-spots from zircons yield initial Hf-176/Hf-177 ratios from 0.281898 to 0.282361, epsilon Hf(t) values from - 28.1 to - 17.6 and two-stage "crust" Hf model ages (t(DM2)) from 2293 +/- 89 to 2949 +/- 108 Ma, which are generally in agreement with values of 0.281891 to 0.282218, - 28.2 to - 11.7 and 1927 +/- 87 to 2963 +/- 92 Ma for the pre-Mesozoic inherited cores, respectively. As for individual core-rim pairs in zircon, Th/U ratios increase from the inherited cores to the young growth rims possibly due to variable degrees of partial melting, whereas Lu-176/Hf-177 ratios greatly decrease because of the garnet effect in residues. Thus, we suggest that the early Cretaceous low-Mg adakitic granites were derived from the partial melting of the NDC Neoproterozoic (700-800 Ma) gneisses, and the foundering of the garnet-bearing residues could have caused the destruction of the over-thickened lower continental crust. (c) 2012 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
WOS关键词	ZIRCON U-PB ; PRESSURE METAMORPHIC TERRANE ; UNDERPLATED BASALTIC CRUST ; NORTH CHINA ; ISOTOPE EVIDENCE ; TRACE-ELEMENT ; HF-ISOTOPE ; POSTCOLLISIONAL GRANITOIDS ; EXPERIMENTAL CONSTRAINTS ; MANTLE INTERACTION
WOS研究方向	Geology
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000312746000014
资助机构	National Natural Science Foundation of China(41072046 ; National Natural Science Foundation of China(41072046 ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; 40603002 ; 40603002 ; 90714005 ; 90714005 ; 40334037) ; 40334037) ; National Natural Science Foundation of China(41072046 ; National Natural Science Foundation of China(41072046 ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; 40603002 ; 40603002 ; 90714005 ; 90714005 ; 40334037) ; 40334037) ; National Natural Science Foundation of China(41072046 ; National Natural Science Foundation of China(41072046 ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; 40603002 ; 40603002 ; 90714005 ; 90714005 ; 40334037) ; 40334037) ; National Natural Science Foundation of China(41072046 ; National Natural Science Foundation of China(41072046 ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; Foundation of the Ministry of Education of China for Outstanding Young Teachers in China University of Geosciences(CUGL090216) ; 40603002 ; 40603002 ; 90714005 ; 90714005 ; 40334037) ; 40334037)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/87608]
专题	中国科学院地质与地球物理研究所
通讯作者	Xu, Haijin
作者单位	1.China Univ Geosci, Fac Earth Sci, Wuhan 430074, Peoples R China 2.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Wuhan 430074, Peoples R China 3.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Xu, Haijin,Ma, Changqian,Zhang, Junfeng,et al. Early Cretaceous low-Mg adakitic granites from the Dabie orogen, eastern China: Petrogenesis and implications for destruction of the over-thickened lower continental crust[J]. GONDWANA RESEARCH,2013,23(1):190-207.
APA	Xu, Haijin,Ma, Changqian,Zhang, Junfeng,&Ye, Kai.(2013).Early Cretaceous low-Mg adakitic granites from the Dabie orogen, eastern China: Petrogenesis and implications for destruction of the over-thickened lower continental crust.GONDWANA RESEARCH,23(1),190-207.
MLA	Xu, Haijin,et al."Early Cretaceous low-Mg adakitic granites from the Dabie orogen, eastern China: Petrogenesis and implications for destruction of the over-thickened lower continental crust".GONDWANA RESEARCH 23.1(2013):190-207.