Common Pb of UHP metamorphic rocks from the CCSD project (100-5000 m) suggesting decoupling between the slices within subducting continental crust and multiple thin slab exhumation

doi:10.1016/j.tecto.2008.09.016

	Common Pb of UHP metamorphic rocks from the CCSD project (100-5000 m) suggesting decoupling between the slices within subducting continental crust and multiple thin slab exhumation
	Li, Shuguang 1; Wang, Chenxiang 1; Dong, Feng 1; Hou, Zhenhui 1; Li, Qiuli 2; Liu, Yican 1; Huang, Fang 3; Chen, Fukun 2
刊名	TECTONOPHYSICS
	2009-09-25
卷号	475 期号:2 页码:308-317
关键词	Chinese Continental Scientific Drilling (CCSD) project UHP metamorphic rocks Common Pb isotopes Dabie-Sulu Detachment within continental crust
ISSN号	0040-1951
DOI	10.1016/j.tecto.2008.09.016
文献子类	Article
英文摘要	In order to understand the vertical structure of the Dabie-Sulu ultrahigh-pressure metamorphic (UHPM) belt, common Pb isotopic compositions of omphacites in eclogites and feldspars in gneisses from the Chinese Continental Scientific Drilling (CCSD) project (100-5000 m) have been investigated in this study. Samples from 0 to 800 m (unit 1) in the drilling core have moderately high radiogenic Pb isotopes with small variations of (206)Pb/(204)Pb (16.82-17.38), (207)Pb/(204)Pb (15.37-15.49), and (208)Pb/(204)Pb (37.21-37.72), indicating either high mu ((238)U/(204)Pb) or high initial Pb isotope ratios of their protoliths. In contrast, the samples from 1600 to 2040 m (unit 3) and most of samples from 3200 to 5000 m (unit 5) have moderately or very unradiogenic Pb (unit 3: (206)Pb/(204)Pb from 16.05 to 16.46, (207)Pb/(204)Pb from 15.22 to 15.29, and (208)Pb/(204)Pb from 36.68 to 37.48; unit 5: (206)Pb/(204)Pb from 15.52 to 15.69, (207)Pb/(204)Pb from 15.15 to 15.27, and (208)Pb/(204)Pb from 36.48 to 37.20), indicating either low mu or low initial Pb isotope ratios of their protoliths. Pb isotopes of samples from 800 to 1600 m (unit 2) and from 2040 to 3200 m (unit 4) in the drilling core with abundant ductile shear zones are intermediate between those of units I and 3 or 5 and display larger variations. Pb isotopes combined with the published oxygen isotope data of the CCSD samples reveal the original positions of the five units before the Triassic continental subduction. Units 1, 3, and 5 as three UHPM rock slabs could be derived from the subducted upper continental crust, upper-middle continental crust and lower-middle continental crust, respectively. The ductile shearing zones in units 2 and 4 could be the interfaces where the detachment and decoupling took place between the upper, upper-middle and lower-middle continental crusts. The detachment between the upper slab and subducting continental lithosphere probably occurred during continental subduction, and the upper slab (unit 1) was uplifted to a shallow depth along the detachment surface by thrusting. Units 3 and 5 may be detached later from the subducted middle and lower crust and uplifted to a shallow level underneath unit 1. The low delta(18)O values (-4.0 to -7.4%.) [Xiao, Y.-L., Zhang, Z.-M., Hoefs, J., Kerkhof, A., 2006. Ultrahigh-pressure Metamorphic Rocks from the Chinese Continental Drilling Project-II Oxygen Isotope and Fluid Inclusion Distributions through Vertical Sections. Contribution Mineral Petrology 152, 443-458.; Zhang, Z.-M., Xiao, Y.-L, Zhao, X-D., Shi, C., 2006. Fluid-rock interaction during the continental deep subduction: oxygen isotopic profile of the main hole of the CCSD project. Acta Petrologica Sinica 22 (7), 1941-1951.] in units 2 and 4 suggest that the detachment interfaces could be developed along an ancient fault zones which were the channels of meteoric water activity during the Neoproterozoic. (C) 2008 Elsevier B.V. All rights reserved.
WOS关键词	SCIENTIFIC DRILLING PROJECT ; ULTRAHIGH-PRESSURE ROCKS ; EAST-CENTRAL CHINA ; DABIE MOUNTAINS ; COOLING HISTORY ; TRACE-ELEMENT ; SULU TERRANE ; MAIN HOLE ; ISOTOPIC COMPOSITIONS ; MINERAL INCLUSIONS
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000271331800010
资助机构	State Key Basic Research Developed Program(2003CB716500) ; State Key Basic Research Developed Program(2003CB716500) ; Natural Science Foundation of China(40634023 ; Natural Science Foundation of China(40634023 ; Chinese Academy of Science(kzcx2-yw-131) ; Chinese Academy of Science(kzcx2-yw-131) ; 40773013) ; 40773013) ; State Key Basic Research Developed Program(2003CB716500) ; State Key Basic Research Developed Program(2003CB716500) ; Natural Science Foundation of China(40634023 ; Natural Science Foundation of China(40634023 ; Chinese Academy of Science(kzcx2-yw-131) ; Chinese Academy of Science(kzcx2-yw-131) ; 40773013) ; 40773013) ; State Key Basic Research Developed Program(2003CB716500) ; State Key Basic Research Developed Program(2003CB716500) ; Natural Science Foundation of China(40634023 ; Natural Science Foundation of China(40634023 ; Chinese Academy of Science(kzcx2-yw-131) ; Chinese Academy of Science(kzcx2-yw-131) ; 40773013) ; 40773013) ; State Key Basic Research Developed Program(2003CB716500) ; State Key Basic Research Developed Program(2003CB716500) ; Natural Science Foundation of China(40634023 ; Natural Science Foundation of China(40634023 ; Chinese Academy of Science(kzcx2-yw-131) ; Chinese Academy of Science(kzcx2-yw-131) ; 40773013) ; 40773013)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/71132]
专题	中国科学院地质与地球物理研究所
通讯作者	Li, Shuguang
作者单位	1.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China 2.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China 3.Univ Illinois, Dept Geol, Urbana, IL 61801 USA
推荐引用方式 GB/T 7714	Li, Shuguang,Wang, Chenxiang,Dong, Feng,et al. Common Pb of UHP metamorphic rocks from the CCSD project (100-5000 m) suggesting decoupling between the slices within subducting continental crust and multiple thin slab exhumation[J]. TECTONOPHYSICS,2009,475(2):308-317.
APA	Li, Shuguang.,Wang, Chenxiang.,Dong, Feng.,Hou, Zhenhui.,Li, Qiuli.,...&Chen, Fukun.(2009).Common Pb of UHP metamorphic rocks from the CCSD project (100-5000 m) suggesting decoupling between the slices within subducting continental crust and multiple thin slab exhumation.TECTONOPHYSICS,475(2),308-317.
MLA	Li, Shuguang,et al."Common Pb of UHP metamorphic rocks from the CCSD project (100-5000 m) suggesting decoupling between the slices within subducting continental crust and multiple thin slab exhumation".TECTONOPHYSICS 475.2(2009):308-317.