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Metamorphic growth and recrystallization of zircons in extremely O-18-depleted rocks during eclogite-facies metamorphism: Evidence from U-Pb ages, trace elements, and O-Hf isotopes

文献类型：期刊论文

作者Chen, Yi-Xiang1; Zheng, Yong-Fei1; Chen, Ren-Xu1; Zhang, Shao-Bing1; Li, Qiuli2; Dai, Mengning3; Chen, Lu4
刊名GEOCHIMICA ET COSMOCHIMICA ACTA
出版日期2011-09-01
卷号75期号:17页码:4877-4898
ISSN号0016-7037
DOI10.1016/j.gca.2011.06.003
文献子类Article
英文摘要A combined in situ SIMS and LA-(MC)-ICPMS study of U-Pb ages, trace elements, O and Lu-Hf isotopes was conducted for zircon from eclogite-facies metamorphic rocks in the Sulu orogen. The two microbeam techniques sampled various depths of zircon domains, revealing different element and isotope relationships between residual magmatic cores and new metamorphic rims and thus the geochemical architecture of metamorphic zircons which otherwise cannot be recognized by the single microbeam technique. This enables discrimination of metamorphic growth from different subtypes of metamorphic recrystallization. Magmatic cores with U-Pb ages of 769 +/- 9 Ma have positive delta O-18 values of 0.1-10.1 parts per thousand, high Th/U and Lu-176/Hf-177 ratios, high REE contents, and steep MREE-HREE patterns with negative Eu anomalies. They are interpreted as crystallizing from positive delta O-18 magmas during protolith emplacement. In contrast, newly grown domains have concordant U-Pb ages of 204 +/- 4 to 252 +/- 7 Ma and show negative delta O-18 values of -10.0 parts per thousand to -2.2 parts per thousand, low Th/U and Lu-176/Hf-177 ratios, low REE contents, and flat HREE patterns with weak to no Eu anomalies. They are interpreted as growing from negative delta O-18 fluids that were produced by metamorphic dehydration of high-T glacial-hydrothermally altered rocks during continental subduction-zone metamorphism. Differences in delta O-18 between different domains within single grains vary from 0.8 parts per thousand to 12.5 parts per thousand, suggesting different degrees of O isotope exchange between the positive delta O-18 magmatic core and the negative delta O-18 metamorphic fluid during the metamorphism. The magmatic zircons underwent three subtypes of metamorphic recrystallization, depending on their accessibility to negative delta O-18 fluids. The zircons recrystallized in solid-state maintained positive delta O-18 values, and REE and Lu-Hf isotopes of protolith zircon, but their U-Pb ages are lowered. The zircons recrystallized through dissolution exhibit negative delta O-18 values similar to the metamorphic growths, almost completely reset U-Pb ages, and partially reset REE systems. The zircons recrystallized through replacement show variably negative delta O-18 values, and partially reset REE, and U-Pb and Lu-Hf isotopic systems. Therefore, this study places robust constraints on the origin of metamorphic zircons in eclogite-facies rocks and provides a methodological framework for linking the different types of metamorphic zircons to petrological processes during continental collision. (C) 2011 Elsevier Ltd. All rights reserved.
WOS关键词SUBDUCTION-ZONE METAMORPHISM ; ULTRAHIGH-PRESSURE ECLOGITE ; NEOPROTEROZOIC RIFT MAGMATISM ; WESTERN DABIE MOUNTAINS ; HIGH-GRADE METAMORPHISM ; COESITE-BEARING ZIRCON ; EAST-CENTRAL CHINA ; SULU UHP TERRANE ; HYDROGEN ISOTOPE ; CONTINENTAL-CRUST
WOS研究方向Geochemistry & Geophysics
语种英语
WOS记录号WOS:000293732500011
出版者PERGAMON-ELSEVIER SCIENCE LTD
资助机构Chinese Ministry of Science and Technology(2009CB825004) ; Chinese Ministry of Science and Technology(2009CB825004) ; Natural Science Foundation of China(40830318 ; Natural Science Foundation of China(40830318 ; 40921002) ; 40921002) ; Chinese Ministry of Science and Technology(2009CB825004) ; Chinese Ministry of Science and Technology(2009CB825004) ; Natural Science Foundation of China(40830318 ; Natural Science Foundation of China(40830318 ; 40921002) ; 40921002) ; Chinese Ministry of Science and Technology(2009CB825004) ; Chinese Ministry of Science and Technology(2009CB825004) ; Natural Science Foundation of China(40830318 ; Natural Science Foundation of China(40830318 ; 40921002) ; 40921002) ; Chinese Ministry of Science and Technology(2009CB825004) ; Chinese Ministry of Science and Technology(2009CB825004) ; Natural Science Foundation of China(40830318 ; Natural Science Foundation of China(40830318 ; 40921002) ; 40921002)
源URL[http://ir.iggcas.ac.cn/handle/132A11/74120]  
专题中国科学院地质与地球物理研究所
通讯作者Zheng, Yong-Fei
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, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
3.NW Univ Xian, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China
4.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Wuhan 430076, Peoples R China
推荐引用方式
GB/T 7714		 Chen, Yi-Xiang,Zheng, Yong-Fei,Chen, Ren-Xu,et al. Metamorphic growth and recrystallization of zircons in extremely O-18-depleted rocks during eclogite-facies metamorphism: Evidence from U-Pb ages, trace elements, and O-Hf isotopes[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2011,75(17):4877-4898.
APA Chen, Yi-Xiang.,Zheng, Yong-Fei.,Chen, Ren-Xu.,Zhang, Shao-Bing.,Li, Qiuli.,...&Chen, Lu.(2011).Metamorphic growth and recrystallization of zircons in extremely O-18-depleted rocks during eclogite-facies metamorphism: Evidence from U-Pb ages, trace elements, and O-Hf isotopes.GEOCHIMICA ET COSMOCHIMICA ACTA,75(17),4877-4898.
MLA Chen, Yi-Xiang,et al."Metamorphic growth and recrystallization of zircons in extremely O-18-depleted rocks during eclogite-facies metamorphism: Evidence from U-Pb ages, trace elements, and O-Hf isotopes".GEOCHIMICA ET COSMOCHIMICA ACTA 75.17(2011):4877-4898.

入库方式： OAI收割

来源：地质与地球物理研究所

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