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首页> 外文期刊>Journal of Asian earth sciences >Alkaline basalts in the Karamay ophiolitic melange, NW China: A geological, geochemical and geochronological study and implications for geodynamic setting
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Alkaline basalts in the Karamay ophiolitic melange, NW China: A geological, geochemical and geochronological study and implications for geodynamic setting

机译：中国西北部克拉玛依蛇纹岩混杂岩中的碱性玄武岩：地质，地球化学和年代学研究及其对地球动力学背景的启示

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摘要

Alkaline basalts are common constituents in many ophiolite belts and accretionary complexes. Here we report geological, geochronological, geochemical, and whole-rock Sr-Nd isotopic data for alkaline basalts from the Karamay ophiolitic melange of West Junggar, southern Central Asian Orogenic Belt (CAOB). In the ophiolitic melange, imbricate thrusts, duplexes, "web" structures, pinch-and-swell structures, tilted structures in pillow metabasalts, and shear band cleavages are widely developed. U-Pb analyses of zircon grains from a representative basalt by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) yielded crystallization age of ca. 395 +/- 3 Ma, suggesting formation during the Middle Devonian. Geochemically, all the samples bear the signature of ocean island basalt (OIB), and are characterized by alkaline affinity with high concentrations of Na2O + K2O (4.22-7.28 wt.%) and TiO2 (1.72-2.89 wt.%), LILE and LREE enrichment and HREE depletion ((La/Yb)(N) = 8.4-15.6), with very strong or no Eu anomalies (Eu/Eu* = 0.6-1.1), and no obvious Nb, Ta or Ti negative anomalies. The rocks display consistent Sr-Nd isotopic compositions (initial Sr-87/Sr-86 ratios = 0.70326-0.70453, epsilon Nd(t) = + 3.1-+7.6). The results suggest that all the alkaline basalts were derived from a mantle plume-related source in an intra-oceanic setting with ca. 1-3% degree partial melting of garnet Iherzolite. These observations, in combination with previous work, indicate that the alkaline basalts from Karamay ophiolitic melange can be correlated to a Middle Devonian mantle plume-related magmatism within Paleo-Asian Ocean. We further suggest that the plume-related activity in the CAOB was generally continuous during the development of the Paleo-Asian Ocean. (c) 2014 Elsevier Ltd. All rights reserved.
机译：碱性玄武岩是许多蛇绿岩带和增生复合物中的常见成分。在这里，我们报告了中亚南部造山带（CAOB）西准gar尔的克拉玛依蛇绿岩混杂岩中碱性玄武岩的地质，地质年代，地球化学和全岩Sr-Nd同位素数据。在片石质混杂岩中，广泛发育了成岩状的逆冲，双相，“网状”结构，夹挤结构，枕形玄武岩中的倾斜结构以及剪切带分裂。用激光烧蚀-电感耦合等离子体质谱法（LA-ICP-MS）对代表性玄武岩中锆石的U-Pb分析得出大约为。 395 +/- 3 Ma，表明在泥盆纪中期形成。从地球化学角度看，所有样品均具有大洋洲玄武岩（OIB）的特征，并具有高浓度的Na2O + K2O（4.22-7.28 wt。％）和TiO2（1.72-2.89 wt。％），LILE和LREE富集和HREE耗竭（（La / Yb）（N）= 8.4-15.6），具有非常强或没有Eu异常（Eu / Eu * = 0.6-1.1），并且没有明显的Nb，Ta或Ti负异常。岩石显示出一致的Sr-Nd同位素组成（初始Sr-87 / Sr-86比= 0.70326-0.70453，εNd（t）= + 3.1- + 7.6）。结果表明，所有碱性玄武岩都来自与洋幔相关的地幔柱源，洋内环境约有。石榴石Izozolite的1-3％度部分熔化。这些观察结果与先前的研究相结合，表明克拉玛依蛇绿岩玄武岩的碱性玄武岩可能与古亚洲洋中泥盆纪地幔羽相关的岩浆作用有关。我们进一步建议，在古亚洲海洋的发展过程中，CAOB中与羽流有关的活动通常是连续的。 （c）2014 Elsevier Ltd.保留所有权利。

著录项

  • 来源
    《Journal of Asian earth sciences》 |2015年第1期|110-125|共16页
  • 作者

    Yang Gaoxue; Li Yongjun; Santosh M.; Xiao Wenjiao; Yang Baokai; Tong Lili; Zhang Shenglong;

  • 作者单位

    Minist Educ, Key Lab Western Chinas Mineral Resources & Geol E, Xian 710054, Peoples R China|Changan Univ, Sch Earth Sci & Resources, Xian 710054, Peoples R China;

    Minist Educ, Key Lab Western Chinas Mineral Resources & Geol E, Xian 710054, Peoples R China|Changan Univ, Sch Earth Sci & Resources, Xian 710054, Peoples R China;

    China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China;

    Chinese Acad Sci, State Key Lab Lithospher Evolut, Inst Geol & Geophys, Beijing 100029, Peoples R China|Chinese Acad Sci, Xinjiang Res Ctr Mineral Resources, Xinjiang Inst Ecol & Geog, Urumqi 830011, Peoples R China;

    Changan Univ, Sch Earth Sci & Resources, Xian 710054, Peoples R China;

    Minist Educ, Key Lab Western Chinas Mineral Resources & Geol E, Xian 710054, Peoples R China|Changan Univ, Sch Earth Sci & Resources, Xian 710054, Peoples R China;

    Changan Univ, Sch Earth Sci & Resources, Xian 710054, Peoples R China;

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  • 正文语种 eng
  • 中图分类
  • 关键词

    Ophiolitic melange; Mantle plume; Zircon geochronology; Geochemistry; West Junggar; Central Asian Orogenic Belt;

    机译：蛇绿混杂岩;幔幔羽;锆石年代学;地球化学;西准gar尔;中亚造山带;

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