| 羌塘东部治多县直根尕卡一带二叠纪栖霞期火山岩地球化学特征及其构造意义 |
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| 引用本文： | 李,莉 白云山 马丽艳 牛志军 段其发.羌塘东部治多县直根尕卡一带二叠纪栖霞期火山岩地球化学特征及其构造意义[J].中国地质,2009,36(6):1289-1301. |
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| 作者姓名： | 李 莉 白云山 马丽艳 牛志军 段其发 |
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| 作者单位： | 宜昌地质矿产研究所,湖北,宜昌,443005 |
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| 基金项目： | 2008年度国土资源部"百名优秀青年科技人才"计划项目资助 |
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| 摘 要： | 羌塘东部治多县直根尕卡一带二叠纪栖霞期火山岩主要由中基性火山碎屑岩及熔岩组成,火山岩地球化学研究表明,其主元素表现为高TiO_2和低TiO_2两种特征,球粒陨石标准化稀土配分模式为LREE富集型.MORB标准化的微量元素配分型式为大洋隆起型,显示岩浆形成于板内裂谷构造环境.Sr、Nd、Pb同位素地球化学研究表明火山岩显示明显的亏损地幔源区特征.综合研究表明直根尕卡一带二叠纪栖霞期火山岩形成于大陆边缘拉张构造(或陆缘始裂谷)环境,岩浆起源于地幔,属地幔柱作用的产物.
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| 关 键 词： | 二叠纪 裂谷 构造环境 羌塘东部 |
Geochemical characteristics and tectonic significance of Qixianian volcanic rocks in Zhigengaka area, Zhiduo County, eastern Qiangtang |
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| LI Li,BAI Yun-shan,MA Li-yang,NIU Zhi-jun,DUAN Qi-fa.Geochemical characteristics and tectonic significance of Qixianian volcanic rocks in Zhigengaka area, Zhiduo County, eastern Qiangtang[J].Chinese Geology,2009,36(6):1289-1301. |
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| Authors: | LI Li BAI Yun-shan MA Li-yang NIU Zhi-jun DUAN Qi-fa |
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| Institution: | Yichang Institute of Geology and Mineral Resources, Yichang 443005, Hubei, China |
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| Abstract: | Qixianian volcanic rocks in Zhigengaka area consist of pyroclastic rocks and lava. Geochemical researches on major elements, trace elements and Sr, Nd, Pb isotopes suggest that these volcanic rocks originated from the mantle in an extension or fresh rift basin environment on the continental margin and were induced by mantle plume upwelling. On the basis of major elements, the volcanic rocks can be divided into two types characterized respectively by high TiO_2 and low TiO_2. Chondrite normalized REE patterns show light REE enrichment, with MORB normalized trace elements like the pig back, indicating that these volcanic rocks were formed in an intra-continental rift environment. Sr, Nd, Pb isotopic geochemistry suggests that they were derived from a depleted mantle source. |
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| Keywords: | eastern Qiangtang Permian rift tectonic environment |
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