| 印度与欧亚板块东部碰撞边界——腾冲火山岩的Nd-Sr同位素与微量元素研究 |
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| 引用本文： | 朱炳泉,毛存孝.印度与欧亚板块东部碰撞边界——腾冲火山岩的Nd-Sr同位素与微量元素研究[J].地球化学,1983(1):1-14. |
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| 作者姓名： | 朱炳泉 毛存孝 |
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| 摘 要： | The Tengchong volcanies in western Yunnan Province, China, are located in the eastern part of the collision margin between Indian and Eurasian Plates. Alternating extention and compression controlled the eruption, from late Tertiary to Holeeno, of at least 5 groups of volcanics consisting of a Major series of hlgh-Al basalts (3 groups), a high-K andesite-dacite group and a high-Mg basalt group. The Major series has a range of GNd from 0.7 to-6.7 and Sr^87/Sr^86 from 0.70595 to 0.70881, exhibiting good linear correlations between Zr/Ni and Zr as well as between Nd. and both Sm/Nd and 1/Nd and similar chondrite-normalized incompatible element patterns. This suggests an ecologitic source metasomatized with fluids derived from parts of thesubducted Indian plate.The high-K andesite-dacite group shows a more extreme isotopic composition of GNd=-12.3, Sr^87/Sr^66=0.71124. It is chemically comparable to the calc-alkaline lavas in Xizang and could be resulted from mixing between shallow mantle zones and lower crust. The high-Mg basalt group has Sr^87/Sr^86-0.708 and slightly negative GNd (-2). They are similar, in chemical composition and possibly also in source, to the intraplate basalts in east China. A partial melting model of isotopic tmequilibrium system has been proposed to explain the isotope and trace element correlations of Tengchong volcanics.
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| 关 键 词： | 火山岩 岩石化学 电子探针 围岩 Nd-Sr同位素 |
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