西藏日喀则地区雅鲁藏布蛇绿岩地球化学特征及其源区性质 |
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引用本文: | 李文霞,赵志丹,朱弟成,刘栋,莫宣学,路远发.西藏日喀则地区雅鲁藏布蛇绿岩地球化学特征及其源区性质[J].现代地质,2016,30(2):294-302. |
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作者姓名: | 李文霞 赵志丹 朱弟成 刘栋 莫宣学 路远发 |
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作者单位: | (1. 长江大学地球环境与水资源学院,湖北 武汉430100;2. 长江大学分析测试研究所,湖北 武汉430100;
3. 中国地质大学(北京)地质过程与矿产资源国家重点实验室,中国地质大学(北京)地球科学与资源学院,北京100083) |
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基金项目: | 国家重点基础研究发展规划项目(2015CB452604);国家自然科学基金项目(41273044,41225006);中国地质调查局综合研究项目(1212011121260);长江大学博士启动基金项目(801240010117);长江大学青年基金项目(2015cqn23)。 |
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摘 要: | 日喀则地区的蛇绿岩是西藏南部雅鲁藏布蛇绿岩带出露较好的蛇绿岩之一。对日喀则地区白朗蛇绿岩的主量、微量元素及Sr-Nd同位素研究表明,其基性岩石为钙碱性系列,主要氧化物具有低钛(0.6%~1.1%)和富镁(6.6%~8.7%)、高铝(15.3%~16.0%),以及烧失量普遍较高(2.8%~4.6%)的特征。岩石微量元素配分型式与N-MORB类似,又具有岛弧玄武岩的地球化学特征,表明蛇绿岩受到了俯冲作用的影响。Sr-Nd同位素特征表明源区为略富集的MORB型地幔。白朗蛇绿岩所代表的特提斯地幔域与印度洋地幔域具有相似的地球化学性质,进一步证实了现今的印度洋继承了特提斯地幔域的地球化学特征。
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关 键 词: | 白朗蛇绿岩 地球化学特征 源区性质 雅鲁藏布蛇绿岩 西藏 |
Study on the Geochemistry and Source Characteristics of the Yalung Zangpo Ophiolite in Xigaze,Tibet |
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Institution: | (1. School of Earth Environment and Water Resources, Yangtze University, Wuhan, Hubei 430100, China; 2. Analysis and Testing Institute of Yangtze University, Wuhan, Hubei 430100, China; 3. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, School of Earth Sciences and Resources, China University of Geosciences, Beijing100083, China) |
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Abstract: | Ophiolite from Xigaze is one of well-outcropped rocks in the Yalung Zangpo ophiolite, southern Tibet. Elemental and Sr-Nd isotopic compositions of the basaltic rocks from Bainang ophiolite in Xigaze were studied in this paper. The rocks are calc alkalic series, with low TiO2(0.6%-1.1%), high MgO(6.6%-8.7%), Al2O3(15.3%-16.0%) and LOI(2.8%-4.6%). The primitive mantle-normalized multi-element pattern of basaltic rocks is similar to that of the normal Mid-Ocean Ridge Basalt(N-MORB)with the characteristics of island arc, which suggests that the rocks are related to subduction processes. The geochemical characteristics of Sr-Nd reflect that mantle source of Bainang ophiolite is a little enriched MORB mantle. The geochemical characteristics of Tethyan Ocean are similar to those of the Indian sub-oceanic mantle, which further confirms that the Indian sub-oceanic mantle is inherited from the Tethyan Ocean geochemical domain. |
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Keywords: | Bainang ophiolite geochemical characteristic source characteristic Yalung Zangpo ophiolite Tibet |
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