内蒙古早二叠纪火山熔岩痕量元素地球化学

The Trace Element Geochemistryof the Permian Volcanic Lavas in Inner Mongolia

本文报道了内蒙古东部早二叠纪火山岩的痕量元素地球化学特征,讨论了该区火山岩的源区特征,结果表明,内蒙古东部早二叠纪火山岩是不同性质组成的地幔不同程度部分熔融的产物。基性熔岩主要是具有亏损地幔性质的E—MORB高度部分熔融的产物,而中酸性火山岩的源区物质具有OIB特征。具有OIB型富集地幔特征的中酸性火山岩的源区可能是循环到地幔与海水发生强烈作用的古洋壳物质。这一结果表明,中晚古生代时期中朝板块与西伯利亚板块拼合后,俯冲到地幔中的古洋壳在早二叠纪以火山作用的方式返回到地壳环境中。

This paper reports the trace element geochemistry characteristics of the Permian volcanic lavas in Inner Mongolia, North China, and disscusses the chemical characteristics of the lava source region, which demonstrates that the Permian volcanic rocks were the production of mantle partial melting with different melting percentages. The mafic rocks show the depleted mantle characteristics with high melting parcentages of E-MORB, and the felsic rocks desplay the characteristics of OIB mantle with low melting parcentages, which probably have undergone the contamination of crustal material.