地学前缘 ›› 2011, Vol. 18 ›› Issue (3): 189-200.

• 论文 • 上一篇    下一篇

新疆坡十铜镍硫化物含矿岩体岩浆源区特征及构造背景探讨

颉炜，宋谢炎，聂晓勇，程松林   


  1. 1中国科学院 地球化学研究所 矿床地球化学国家重点实验室， 贵州 贵阳 550002
    2中国科学院研究生院， 北京 100049
    3武警黄金第八支队， 新疆 乌鲁木齐 830000
    4新疆地质矿产勘查开发局， 新疆 乌鲁木齐 830000
  • 收稿日期:2010-10-11 修回日期:2011-02-10 出版日期:2011-05-22 发布日期:2011-05-20
  • 作者简介:颉炜（1985—），男，博士研究生，矿床地球化学专业。Email：NiCuPGE@qqcom
  • 基金资助:

    国家自然科学基金重点项目（40730420，40973038）；中国科学院“百人计划”；中国科学院知识创新方向性项目（KZCX2YWQ04）；矿床地球化学国家重点实验室课题（KCZX20090105）

Features of the mantle source and tectonic setting of the Poshi NiCu sulfidebearing intrusion， Xinjiang, China.

1State Key Laboratory of Ore Deposit Geochemistry， Institute of Geochemistry， Chinese Academy of Sciences， Guiyang 550002， China
2Graduate University of Chinese Academy of Sciences， Beijing 100049， China
3NO8 Team of Peoples Armed Police Gold Force， Urümqi 830000， China
4Xinjiang Bureau of Geology and Exploration， Urümqi 830000， China     

  1. 1State Key Laboratory of Ore Deposit Geochemistry， Institute of Geochemistry， Chinese Academy of Sciences， Guiyang 550002， China
    2Graduate University of Chinese Academy of Sciences， Beijing 100049， China
    3NO8 Team of Peoples Armed Police Gold Force， Urümqi 830000， China
    4Xinjiang Bureau of Geology and Exploration， Urümqi 830000， China
  • Received:2010-10-11 Revised:2011-02-10 Online:2011-05-22 Published:2011-05-20

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摘要：

新疆坡北辉长岩体位于塔里木古陆东北缘的北山裂谷带中，坡一和坡十铜镍硫化物含矿超镁铁岩体位于坡北岩体内。尽管坡十超镁铁岩体与坡北辉长岩呈侵入接触，但两者的微量元素和同位素组成显示良好的一致性，表明两岩相虽然分不同阶段侵入就位，但仍为同源岩浆的产物。MnOTiO2P2O5及ThHfTa判别图解显示坡北及坡十岩体的母岩浆具有岛弧火山岩岩浆的特点，而塔里木大火成岩省的巴楚层状侵入体、镁铁超镁铁岩墙群则为板内火山岩岩浆系列。在微量元素蛛网图上，坡北及坡十岩体则均表现出大离子亲石元素(Rb、Sr、Ba)的相对富集和高场强元素(Nb、Ta、Zr、Hf、HREEs)的相对亏损，并显示强烈的Nb、Ta负异常，这些地球化学特点与典型的岛弧火山岩以及阿拉斯加型杂岩体显示出很强的相似性，而巴楚层状侵入体和镁铁超镁铁岩墙群的微量元素特征则与OIB非常相似，表明其岩浆源区为受俯冲事件改造过的交代地幔，而与塔里木地幔柱无关。Sr、Nd同位素则表明岩浆在上升侵位的过程中受到了元古代变质岩3%～10%的混染。

关键词: 北山裂谷带, 坡十岩体, 塔里木大火成岩省, 交代地幔

Abstract:

The Pobei gabbroic intrusion is located in the Beishan rift zone of the northeastern margin of Tarim cratonThe Poyi and Poshi NiCu bearing ultramafic bodies are situated in the western portion of the Pobei intrusionIt is sharp contact between the Poshi ultramafic body and the Pobei gabbroHowever，both the Poshi ultramafic rocks and the Pobei gabbros have similar trace element and isotope compositions，indicating that they are comagmaticThe triangle plots of MnOTiO2P2O5 and ThHfTa show that the parental magmas of the Pobei and Poshi intrusions have features of island arc magmaIn contrast，the layered intrusions and maficultramafic dykes in the Bachu area of the Tarim large igneous province (TLIP) show that the intraplate volcanic featuresIn the trace element spider diagram，the Pobei gabbros and Poshi wehrlites are relatively  enriched in large ion lithophile elements (such as Rb，Sr，Ba) and depleted in high field strength element (such as Nb，Ta，Zr，Hf，HREEs)，and show extensive negative NbTa anomaliesThese geochemical features are similar to the typical island arc volcanics and Alaskantype intrusionsHowever，the layered intrusions and maficultramafic dykes in the Bachu area are similar to the ocean island basalt (OIB)These geochemical features indicate that the parental magmas of the Pobei gabbros and Poshi ultramafic rocks were derived from a metasomatized mantle modified by subduction events，rather than the Tarim mantleData of SrNd isotopes show that the magmas of the Pobei and Poshi intrusion underwent 3% to 10% contamination of the Proterozoic metamorphic rocks of the Tarim craton

Key words: the Beishan rift zone, the Poshi intrusion, the Tarim large igneous province, a metasomatized mantle

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