| 祁漫塔格地区十字沟蛇绿岩地质特征 |
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| 引用本文： | 宋泰忠,赵海霞,张维宽,白旭东,安守文,杨明.祁漫塔格地区十字沟蛇绿岩地质特征[J].西北地质,2010,43(4):124-133. |
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| 作者姓名： | 宋泰忠 赵海霞 张维宽 白旭东 安守文 杨明 |
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| 作者单位： | 青海省地质调查院,青海西宁810012 |
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| 基金项目： | 青海1:5万滩北雪峰地区四幅区调项目 |
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| 摘 要： | 十字沟蛇绿岩产出于东昆仑西段祁漫塔格结合带东部,主要由蛇纹岩、辉长岩、辉绿岩、基性火山岩及硅质岩等组成。其中,从超基性岩—基性岩—基性火山岩,具稀土总量逐渐增加,轻稀土弱亏损型特征,基性火山岩为洋脊玄武岩,总体岩石化学成分与大洋中脊低钾拉斑玄武岩相当,三者的配分型式基本一致,说明其继承了源区地幔的特征,微量元素显示基性火山岩具弧后盆地玄武岩特点。Nεd(t)比值表明玄武岩来自亏损地幔源区,总体地球化学特征显示以N-M ORB型为主,兼具有E-M ORB型的特征,形成于与俯冲作用有关的弧后盆地环境,形成时代为晚奥陶世。后期至少经历了3期以上构造变形变质作用的叠加改造,于早志留世运移至地表。
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| 关 键 词： | 十字沟蛇绿岩 变质变形 弧后盆地 |
The Geological Features of Shizigou Ophiolites in Qimantage Area |
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| SONG Tai-zhong,ZHAO Hai-Xia,ZHANG Wei-kuan,BAI Xu-dong,An Shou-wen,YANG ming.The Geological Features of Shizigou Ophiolites in Qimantage Area[J].Northwestern Geology,2010,43(4):124-133. |
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| Authors: | SONG Tai-zhong ZHAO Hai-Xia ZHANG Wei-kuan BAI Xu-dong An Shou-wen YANG ming |
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| Institution: | (Qinghai Institute of Geological Survey,Xining 810012,China) |
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| Abstract: | The Shizigou ophilite occurs in the western of East Kunlun,that is the eastern of the suture zone in Qimantage.Its L-RRE elements have weakly depleted features,with a gradual increase of the total of REE from ultra-basic rocks to basic rocks and basic volcanic rocks,which belong to MORB and the whole rock chemical compositions of which are consistent with low-K tholeiite of the MORB.They all inherit the characteristic of the source of the mantle with the same distribution patterns,and their REE show a characteristic of basic volcanic rocks and back-arc basin basalts.The ratio of the εNd（t） shows the source of basalts is from D-mantle,and the overall geochemical features suggest the main composition feature of N-MORB with the characteristic of E-MORB at the same time.They formed at the subduction-related environment of the back-arc basin at Late Ordovician and experienced more than three superposition and transformation of the tectonic deformation and the metamorphism and finally transported to the surface at Early-Silurian. |
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| Keywords: | Shizigou ophiolites deformation-metamorphism back-arc basin |
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