内蒙古满洲里地区中生代中基性火山岩成因及构造地质背景

Genesis and tectonic geological setting of Mesozoic intermediate-basic volcanics in Manzhouli region,Inner Mongolia

内蒙古满洲里地区位于大兴安岭中生代火山岩带的中北段,晚侏罗世—早白垩世火山岩浆活动强烈,由于NE向切壳断裂长期活动,导致中基性火山岩沿断裂呈线状分布。就上侏罗统塔木兰沟组、上库力组中段及下白垩统伊列克得组中基性火山岩浆岩的组合、旋回和岩石地球化学等方面的特征,论证了该地区中生代中基性火山岩浆岩形成的构造地质背景和成因。因此,认为晚侏罗世中基性火山岩形成于板内拉张的构造环境,岩浆来源于上地幔,且有地壳物质混熔。

Manzhouli region in Inner Mongolia is located at the mid-northern segment of Mesozoic volcanic belt in Da Xing＇anling area. Due to the long-term activities of a NE-trending crustal fault,Late Jurassic-Early Cretaceous volcanic magma activity of intermediate-basic volcanics is strong and distributes along the fault as linear. Through analyzing the feature of the rock assemblage,cycles and petrogeochemistry of volcanic magmatism in Upper Jurassic Tamulangou Formation,middle segment of Upper Kuli Formation and Lower Cretaceous Yiliekede Formation,the tectonic geological setting and magama genesis are elaborated,Late Jurassic volcanics is considered to form in the tectonic setting of intraplate tension and the magma comes from the upper mantle with some melted crustal materials.