额尔古纳地区中生代火山岩形成环境的研究

FORMING BACKGROUND OF MESOZOIC VOLCANIC ROCKS IN ERGUN REGION

额尔古纳地区中生代火山活动强烈，其主要的活动期间为晚侏罗世至早白垩世（１５０～１００Ｍａ）。根据新的岩石化学、稀土、微量元素、稳定同位素、构造等方面的分析结果得出以下认识：１．该区中生代火山岩来源较深，具幔源特征，岩浆形成在总体呈挤压背景的环境中，使得岩浆在演化过程中混入了大量的壳源物质；２．中生代火山岩大致分两个亚旋回，其中塔木兰沟组（Ｊ３ｔ）火山岩和上库力组（Ｋ１ｓ）火山岩是同一岩浆亚旋回的产物。

In Ergun region the volcanic activities are very violent in Mesozoic era ,the volcanic rocks are mainly formed in late Jurassic to early Cretaceous (150-100Ma).According to the analysis on petrochemistry, REE, trace element, stable isotope,tectonics, the conclusions can be drawn as following: 1.The Mesozoic volcanic rocks source from the mantle,the magma are formed in pressed background.That is why there is much materials of crust source added in the Mesozoic magma. 2.The Mesozoic volcanic activities can be divided into two subcircles, among them, Tamulangou Formation(J 3 t ) and shangkuli Formation(K 1 s )are formed in the same subcircle.