Heterogeneous Pb isotope composition in the Archean lower crust of the North China Craton induced by Cenozoic basaltic magma underplating

doi:10.1016/j.jseaes.2016.05.016

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	Heterogeneous Pb isotope composition in the Archean lower crust of the North China Craton induced by Cenozoic basaltic magma underplating
	Zhang, Yu-Lin 1; Zhang, Hong-Fu 1,2; Bao, Zhi-An 1; Santosh, M.3,4; Yuan, Hong-Lin 1
刊名	JOURNAL OF ASIAN EARTH SCIENCES
	2016-08-01
卷号	125 页码:71-86
关键词	Granulite xenoliths Plagioclase Pb isotope fLA-MC-ICP-MS Lower crust North China Craton
DOI	10.1016/j.jseaes.2016.05.016
文献子类	Article
英文摘要	Granulite xenoliths entrained in Cenozoic basaltic rocks in several regions of the North China Craton (NCC) provide important constraints to evaluate the evolution of lower crust. Here we employ the Pb isotopic composition of plagioclase in granulite xenoliths from Yangyuan obtained through fLA (femtosecond laser ablation)-MC-ICPMS analyses to probe the Phanerozoic lower crustal evolution in the NCC. The newly-discovered granulite xenoliths from Yangyuan can be classified into felsic granulites, garnet bearing pyroxene granulites and garnet-free pyroxene granulites. Our results show a large variation in plagioclase Pb isotopes ((206)pb/Pb-204 = 15.3-18.8; (207)pb/Pb-204 = 14.9-15.9; Pb-208/Pb-204 = 35.0-39.9) among and within samples. Common Pb in plagioclase and the single stage Pb evolution model indicate that the mantle from which the lower crust of the NCC was extracted had a U-238/Pb-204 ratio of 9.3 at 2.65 +/- 0.14 Ga (all uncertainties are 2 sigma). The isotopic heterogeneity reflects the diverse formation and evolution history of the xenoliths. The felsic granulites show the least radiogenic Pb isotopes (Pb-206/Pb-204 = 15.3-15.8; Pb-207/Pb-204 = 14.9-15.2; Pb-208/Pb-204 = 35.0-35.9; U-238/Pb-204 = 11.5 and Th-232/U-238 = 4)) among the entire xenolith suite with their Pb isotopes lying close to those of the exposed Archean granulite terranes of the NCC, suggesting that the granulites might have inherited the Pb isotope composition of ancient lower crust. The plagioclase from garnet-bearing pyroxene granulites shows the most radiogenic Pb isotopes (Pb-206/Pb-204 = 16.5-18.8; Pb-207/Pb-204 = 15.3-15.9; Pb-208/Pb-204 = 36.5-39.9; (U-238/Pb-204 = 18.2; Th-232/U-238 = 4.3) in comparison to those of their garnet-free counterparts (Pb-206/Pb-204 = 15.9-17.3; Pb-207/Pb-204 = 15.1-15.5; Pb-208/Pb-204 = 36.1-37.5). The Pb isotopes for the former fall within or even above the fields of the I-MORB (Indian Mid-Ocean Ridge Basalt) and OIB (Ocean Island basalt) in Pb-206/Pb-204 vs. Pb-207/Pb-204 or Pb-208/Pb-204, whereas the latter fall in the fields between the felsic and garnet-bearing pyroxene granulites. We consider that the linear correlation reflects the mixing of the ancient crust with radiogenic Pb in the melt rather than representing an isochron. The garnet-bearing pyroxene granulites might represent the lower crust which was likely modified by the underplating of basaltic magma during Cenozoic. Such extensive magma underplating might have significantly modified the Pb isotopic composition of the ancient lower crust. Individual plagioclase crystals from the garnet-bearing pyroxene granulites show variation in isotopic composition from less radiogenic Pb in the core to more radiogenic in the rim. Together with electron microprobe data, a decompressional melting of the lower crust is inferred in response to the lithosphere extension, with input of radiogenic Pb component. (C) 2016 Elsevier Ltd. All rights reserved.
WOS关键词	LITHOSPHERIC MANTLE BENEATH ; FEMTOSECOND LASER-ABLATION ; SINO-KOREAN CRATON ; PLASMA-MASS SPECTROMETRY ; MELT-PERIDOTITE INTERACTIONS ; TECTONIC EVOLUTION ; CONTINENTAL-CRUST ; EASTERN CHINA ; ICP-MS ; MESOZOIC BASALTS
WOS研究方向	Geology
语种	英语
WOS记录号	WOS:000378953000005
资助机构	Natural Science Foundation of China(41473003 ; Natural Science Foundation of China(41473003 ; Program for Changjiang Scholars and Innovative Research Team in University(IRT1281) ; Program for Changjiang Scholars and Innovative Research Team in University(IRT1281) ; 91214203 ; 91214203 ; 91414301) ; 91414301) ; Natural Science Foundation of China(41473003 ; Natural Science Foundation of China(41473003 ; Program for Changjiang Scholars and Innovative Research Team in University(IRT1281) ; Program for Changjiang Scholars and Innovative Research Team in University(IRT1281) ; 91214203 ; 91214203 ; 91414301) ; 91414301)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/53396]
专题	地质与地球物理研究所_岩石圈演化国家重点实验室
作者单位	1.NW Univ Xian, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China 2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, POB 9825, Beijing 100029, Peoples R China 3.Univ Adelaide, Dept Earth Sci, Adelaide, SA 5005, Australia 4.China Univ Geosci, Sch Earth Sci & Resources, Beijing, Peoples R China
推荐引用方式 GB/T 7714	Zhang, Yu-Lin,Zhang, Hong-Fu,Bao, Zhi-An,et al. Heterogeneous Pb isotope composition in the Archean lower crust of the North China Craton induced by Cenozoic basaltic magma underplating[J]. JOURNAL OF ASIAN EARTH SCIENCES,2016,125:71-86.
APA	Zhang, Yu-Lin,Zhang, Hong-Fu,Bao, Zhi-An,Santosh, M.,&Yuan, Hong-Lin.(2016).Heterogeneous Pb isotope composition in the Archean lower crust of the North China Craton induced by Cenozoic basaltic magma underplating.JOURNAL OF ASIAN EARTH SCIENCES,125,71-86.
MLA	Zhang, Yu-Lin,et al."Heterogeneous Pb isotope composition in the Archean lower crust of the North China Craton induced by Cenozoic basaltic magma underplating".JOURNAL OF ASIAN EARTH SCIENCES 125(2016):71-86.