Zircon U-Pb age, element and C-O isotope geochemistry of post-collisional mafic-ultramafic rocks from the Dabie orogen in east-central China

doi:10.1016/j.lithos.2004.12.014

	Zircon U-Pb age, element and C-O isotope geochemistry of post-collisional mafic-ultramafic rocks from the Dabie orogen in east-central China
	Zhao, ZF ; Zheng, YF ; Wei, CS ; Wu, YB ; Chen, FK ; Jahn, BM
刊名	LITHOS
	2005-07-01
卷号	83 期号:1-2 页码:1-28
关键词	Continental Subduction Mesozoic Magmatism Geochemical Recycling Collisional Orogen
ISSN号	0024-4937
DOI	10.1016/j.lithos.2004.12.014
文献子类	Review
英文摘要	Origin and genesis of post-collisional mafic-ultramafic rocks in the Dabie orogen of China are controversial issues with respect to Mesozoic transport of mass and energy between mantle and crust. Zircon U-Pb age, whole-rock major and trace elements, mineral and whole-rock oxygen isotopes, and carbon concentrations and isotope compositions of apatite and whole-rock were determined for these igneous rocks in order to find a resolution. The results show that the Dabie mafic-ultramafic rocks are characterized by strong LREE enrichment and negative HFSE (Nb, Zr, Ti and P) anomalies but positive anomalies of Pb and Ba. Zircon U-Pb dating yields consistent ages of 122-128 Ma for magma crystallization and 105-116 Ma for postmagmatic hydrothermal alteration. There is a large variation in oxygen isotope ratios of minerals and their host rocks, with whole-rock delta O-18 values of 1.1-6.6 parts per thousand, clinopyroxene 3.85-5.7 parts per thousand, plagioclase 2.8-7.3 parts per thousand, and zircon 3.85-6.04 parts per thousand. Most of the zircons have delta O-18 values different from the normal mantle values. Equilibrium oxygen isotope fractionations between minerals have been preserved for some of the samples, but the others show significant disequilibrium indicating post-magmatic subsolidus alteration. Carbon concentrations and isotope compositions vary widely from 0.03 to 0.18% and from -27.0 to -5.8 parts per thousand, respectively. Most of the samples are characterized by the low delta C-13 values typical of organic carbon. A comparison of the element and isotope data for the Cretaceous mafic-ultramafic rocks with the Triassic metamorphosed eclogites from the Dabie-Sulu orogenic belt shows that they share many geochemical and isotopic features in common, pointing to a genetic relationship in protolith origin between them. No signature of depleted mantle has been detected from Nd and Sr isotopes in the post-collisional igneous rocks. Protoliths of the Cretaceous mafic-ultramafic rocks and the Triassic eclogites are thus considered the mid-Neoproterozoic mafic-ultramafic rocks that were the products of rift magmatism along the northern margin of the Yangtze plate. Partial melting of the subducted lithosphere itself is proposed to produce the post-collisional igneous rocks. The Early Cretaceous superplume event is hypothesized to provide a heat source to trigger the melting of a large scale and a short period beneath the collisionally thickened orogen. (c) 2005 Elsevier B.V. All rights reserved.
WOS关键词	ULTRAHIGH-PRESSURE METAMORPHISM ; SUBDUCTED CONTINENTAL-CRUST ; A-TYPE GRANITES ; OXYGEN-ISOTOPE ; LOW DELTA-O-18 ; TRACE-ELEMENT ; SM-ND ; MIDCRETACEOUS SUPERPLUME ; GEOLOGICAL IMPLICATIONS ; CHEMICAL GEODYNAMICS
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000230333500001
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/65188]
专题	中国科学院地质与地球物理研究所
通讯作者	Zhao, ZF
作者单位	1.Univ Sci & Technol China, Sch Earth & Space Sci, Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China 2.Chinese Acad Geol Sci, Beijing SHRIMP Ctr, Beijing 100037, Peoples R China 3.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China 4.Acad Sinica, Inst Earth Sci, Taipei, Taiwan
推荐引用方式 GB/T 7714	Zhao, ZF,Zheng, YF,Wei, CS,et al. Zircon U-Pb age, element and C-O isotope geochemistry of post-collisional mafic-ultramafic rocks from the Dabie orogen in east-central China[J]. LITHOS,2005,83(1-2):1-28.
APA	Zhao, ZF,Zheng, YF,Wei, CS,Wu, YB,Chen, FK,&Jahn, BM.(2005).Zircon U-Pb age, element and C-O isotope geochemistry of post-collisional mafic-ultramafic rocks from the Dabie orogen in east-central China.LITHOS,83(1-2),1-28.
MLA	Zhao, ZF,et al."Zircon U-Pb age, element and C-O isotope geochemistry of post-collisional mafic-ultramafic rocks from the Dabie orogen in east-central China".LITHOS 83.1-2(2005):1-28.