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干旱区地理 ›› 2014, Vol. 37 ›› Issue (6): 1182-1190.

• 地表过程研究 • 上一篇    下一篇

东天山企鹅山群火山岩地球化学特征及对古亚洲洋构造演化的指示意义

齐文涛1,2,木合塔尔·扎日1,3,尼加提·阿布都逊1,3,吴兆宁1,傅雪海1   

  1. (1 新疆大学地质与矿业工程学院,新疆乌鲁木齐830047; 2 海南省九三四地质大队,海南海口570206;3 新疆中亚造山带大陆动力学与成矿预测自治区重点实验室,新疆乌鲁木齐830046)
  • 收稿日期:2013-12-19 修回日期:2014-03-02 出版日期:2014-11-25
  • 通讯作者: 木合塔尔·扎日(1960-),男,维吾尔族,博士,教授,硕士生导师,从事区域地质构造及成矿预测领域的教学科研工作.Email:mhtrz_xju@sina.com
  • 作者简介:齐文涛(1986-),男,硕士,现从事地质勘查工作. Email:qwt2010@sina.cn
  • 基金资助:

    国家自然科学基金项目(No. 41162006,No.40862006);新疆中亚造山带大陆动力学与成矿预测自治区重点实验室开放基金项目(XJDX1102-2013-01)联合资助

Geochemical characteristics of the volcanics from Qi’eshan Group in the East Tianshan and its revelation to the tectonic evolution of Paleo-Asian Ocean

QI Wen-tao1,2,Muhtar ZARI1,3,Nijat ABDURSUL1,3,WU Zhao-ning1,FU Xue-hai1   

  1. (1 Geology and Mining Engineering Institute of Xinjiang University, Urumqi 830047, Xinjiang, China;2 No.934 Geological Brigade of Hainan Province, Haikou 570206, Hainan, China;3 Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt, Urumqi 830046, Xinjiang, China )
  • Received:2013-12-19 Revised:2014-03-02 Online:2014-11-25

摘要: 研究了东天山企鹅山群火山岩的主量元素、微量元素和Sr-Nd 同位素特征。结果显示:火山岩SiO2含量介于47.75%~57.78%,Al2O3含量为17.92%~19.88%,MgO 含量为3.96%~6.46%,Mg# 值介于52.16~58.20,属于亚碱性系列;微量元素分析表明,火山岩轻稀土元素(LREE)富集、重稀土元素(HREE)相对亏损、轻重稀土元素分馏较强,富集大离子亲石元素(LILE),而亏损高场强元素。Sr-Nd同位素组成表明,火山岩ISr( t)变化范围为0.702 386~0.704 264,εNd( t)变化范围为5.61~8.66。地球化学研究表明,企鹅山群火山岩可能源于长期亏损的地幔,而且含有洋中脊和火山弧的物质成分,是软流圈地幔熔体和被俯冲板片流体/熔体交代过的岩石圈地幔楔熔体的混合物。企鹅山群火山岩的母体可能形成于不同的时期和不同的大地构造位置,是板块碰撞后洋脊和火山弧物质在一狭长地带上的混杂堆积。结合前人研究成果,认为企鹅山群火山岩属于古亚洲洋南缘洋壳向北俯冲消减作用的产物,这为古亚洲洋南缘古生代构造演化研究提供了约束。

关键词: 企鹅山群, 岩石地球化学, 古亚洲洋, 构造演化, 东天山

Abstract: This paper has studied the geochemical data including major and trace elements and Sr-Nd isotopes of the volcanics from Qi’eshan Group occurred in east Tianshan,Xinjiang,NW China. The results indicate that the volcanics belong to calc-alkaline series with SiO2 content of 47.75%-57.78% and A12O3 content of 17.92%-19.88%. MgO changes from 3.96% to 6.46%,and Mg# changes from 52.16 to 58.20. The chondrite-normalized REE patterns show that the volcanics are enriched in LREE but depleted in HREE,with intense fractionation between LREE and HREE. The primitive mantle-normalized spider diagrams are characterized by LILE enrichment and HFSE depletion. Isotopic geochemistry shows that values of ISr( t)range from 0.702 386 to 0.704 264 and εNd(t)from 5.61 to 8.66. Based on our geochemical study,the volcanics may derive from the long term depleted mantle,and also contain materials both from mid-ocean ridge and volcanic arc,indicating that they were most plausibly formed by mixing between the asthenospheric mantle-derived and metasomatized lithosphere mantle derived melts(or fluids). The matrix of volcanics previously formed in different stages and tectonic units represent mélanges of materials both frommid-ocean ridge and volcanic arc,which were cumulated along long and narrow belt after amalgamation of different plates. Combining with previous studies,we suggest the formation of volcanics from Qi’eshan Group was related to northward subduction of southern Paleo-Asian oceanic crust,which would be well constraint for Paleozoic tectonic evolution of southern Paleo-Asian Ocean.

Key words: volcanic rocks, geochemistry, Nd-Sr isotopes, Qi’eshan Group

中图分类号: 

  • P595