Adakitic signature formed by fractional crystallization: An interpretation for the Neo-Proterozoic meta-plagiogranites of the NE Jiangxi ophiolitic melange belt, South China
文献类型：期刊论文
| 作者 | Gao, Jun1; Klemd, Reiner2; Long, Lingli3; Xiong, Xianming4; Qian, Qing1 |
| 刊名 | LITHOS
 |
| 出版日期 | 2009-06-01 |
| 卷号 | 110期号:1-4页码:277-293 |
| 关键词 | Adakitic signature Fractional crystallization Neo-Proterozoic meta-plagiogranites The NE Jiangxi ophiolitic melange belt |
| ISSN号 | 0024-4937 |
| DOI | 10.1016/j.lithos.2009.01.009 |
| 文献子类 | Article |
| 英文摘要 | The low-temperature/high-pressure metamorphic rocks which are exposed as exotic blocks within the serpentinite matrix of the NE Jiangxi ophiolitic melange belt consist of enclave-bearing and -free metaplagiogranites. Both rock types are characterized by a metamorphic mineral assemblage consisting of Ab-rich plagioclase + quartz +/- clinopyroxene + amphibole while rutile, titanite and zircon occur as accessories. The former primary magmatic mineral parageneses for the meta-mafic enclaves and the meta-plagiogranites are similar and consist of An-rich-plagioclase + hornblende + ilmenite + monazite + apatite. However, the Ab-rich plagioclase abundance of the meta-mafic enclave is much lower and the hornblende and accessory mineral abundances are higher compared with those of the meta-plagiogranite host rocks. Meta-plagiogranites with malic enclaves have a chemical composition similar to that of typical adakites, with elevated Al(2)O(3) (15.86 wt.%), Mg# (53.5) and Sr contents (485 ppm) and a positive Eu anomaly. The rare earth element patterns are highly fractionated with ((La/Yb)(N)>12) and low Y (<4 ppm) and Yb (<0.4 ppm). The mafic enclave has a basaltic composition with a negative Eu anomaly and has ca. 10 times higher HREE and Y concentrations than the plagiogranite host rocks. Enclave-free meta-plagiogranites also have high Al(2)O(3) (16.08 wt.%), Na(2)O (8.88 wt.%) and Mg# (52.3) values without obvious Eu enrichment or depletion. The Y and Yb concentrations (13 and 1.33 ppm, respectively) are higher than those of the enclave-bearing metaplagiogranites and slightly lower than those of the mafic enclave. Zircon of the enclave-bearing metaplagiogranites gives a weighted mean (206)Pb/(238)U crystallization age of 970 +/- 21 Ma. These metaplagiogranites have low (87)Sr/(86)Sr value of similar to 0.7026 and high epsilon(Nd)(970 Ma) of 6.6 to 7.4. The meta-mafic enclave has a similar isotope composition with a (87)Sr/(86)Sr value of 0.7023 and a epsilon(Nd)(T) of 6.2. The enclave-free meta-plagiogranites have relatively higher (87)Sr/(86)Sr (0.7037 to 0.7045) and lower epsilon(Nd)(T) (-1.22 to -1.28) values. Trace element data of the minerals and whole rocks suggest that Y and Yb are hosted in amphibole, apatite and titanite, Nb in rutile, titanite and amphibole and Sr mainly in plagioclase. Petrographic and geochemical evidence indicates that the meta-mafic enclaves are 'schlieren', which formed by the early crystallization of accessory minerals and hornblende, in the meta-plagiogranites. The adakitic signature of enclave-bearing meta-plagiogranites is interpreted to be due to fractional crystallization of hornblende and accessory minerals such as apatite and ilmenite from the parent magmas, instead of the melting of subducted, spilitized oceanic crust with residual garnet and amphibole. The plagiogranitic magma may have evolved from a basaltic parent magma which had originated in the mantle wedge beneath the Neoproterozoic (ca. 970 Ma) island arc along the southern margin of the Yangtze block. (C) 2009 Elsevier B.V. All rights reserved. |
| WOS关键词 | MESOZOIC OVERTHRUST TECTONICS ; VOLCANIC ZONE ; MAGMAS ; COMPLEX ; ND ; GEOCHEMISTRY ; PETROGENESIS ; PHILIPPINES ; SUBDUCTION ; YANGTZE |
| WOS研究方向 | Geochemistry & Geophysics ; Mineralogy |
| 语种 | 英语 |
| WOS记录号 | WOS:000266541500019 |
| 出版者 | ELSEVIER SCIENCE BV |
| 资助机构 | National Natural Science Foundation of China(40721062) ; National Natural Science Foundation of China(40721062) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Chinese Academy of Sciences ; Chinese Academy of Sciences ; National Natural Science Foundation of China(40721062) ; National Natural Science Foundation of China(40721062) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Chinese Academy of Sciences ; Chinese Academy of Sciences ; National Natural Science Foundation of China(40721062) ; National Natural Science Foundation of China(40721062) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Chinese Academy of Sciences ; Chinese Academy of Sciences ; National Natural Science Foundation of China(40721062) ; National Natural Science Foundation of China(40721062) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Former Ministry of Geology and Mineral Resources(Qn979824) ; Chinese Academy of Sciences ; Chinese Academy of Sciences |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/71636]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Gao, Jun |
| 作者单位 | 1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China 2.Univ Erlangen Nurnberg, GeoZentrum Nordbayern, D-91054 Erlangen, Germany 3.Beijing Inst Geol Mineral Resources, Beijing 100012, Peoples R China 4.Guizhou Univ, Coll Resources & Environm Engn, Guiyang 550003, Peoples R China |
| 推荐引用方式 GB/T 7714 | Gao, Jun,Klemd, Reiner,Long, Lingli,et al. Adakitic signature formed by fractional crystallization: An interpretation for the Neo-Proterozoic meta-plagiogranites of the NE Jiangxi ophiolitic melange belt, South China[J]. LITHOS,2009,110(1-4):277-293. |
| APA | Gao, Jun,Klemd, Reiner,Long, Lingli,Xiong, Xianming,&Qian, Qing.(2009).Adakitic signature formed by fractional crystallization: An interpretation for the Neo-Proterozoic meta-plagiogranites of the NE Jiangxi ophiolitic melange belt, South China.LITHOS,110(1-4),277-293. |
| MLA | Gao, Jun,et al."Adakitic signature formed by fractional crystallization: An interpretation for the Neo-Proterozoic meta-plagiogranites of the NE Jiangxi ophiolitic melange belt, South China".LITHOS 110.1-4(2009):277-293. |
入库方式： OAI收割
来源：地质与地球物理研究所
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