吉林省第三纪火山岩年代地层及构造环境

Tertiary Volcanic Rock Chronohorizon and Tectonic Setting in Jilin Province

本文对吉林省第三纪年代地层、岩石地层、火山事件地层提出了新的划分方案。建立了15个火山事件地层序列。依据区域性地层角度不整合及构造岩浆活动的性质,划分出三个构造发展阶段。对比吉林省及邻区与日本列岛各阶段主要地质事件的特征,获得了第三纪的火山活动构造环境新认识:第一阶段(62～34Ma)总体上为挤压造山环境,由初期的弧后拉张转为后期的挤压,与太平洋板块的俯冲和斜冲地球动力学机制有关。第二阶段(34～5.2Ma)为拉张环境,受日本海盆的打开和演化直接控制。第三阶段(5.2～1.64Ma)为挤压抬升环境,对应着菲律宾海板块向日本岛弧下的俯冲。

A new stratigraphic division scheme for the Tertiary chronohorizon, petrostratigraphy, volcanic accident strata in Jilin Province is proposed. 15 volcanic accident stratigraphic sequences were set up. Three stages of tectonic development are identified according to the regional strata angular discordance and the characters of tectonomagmatic movement. In constrast with the characteristics of the main geologic events in different stages in Jilin Province and its neighbouring areas and the islands of Japan, we got a new understanding of the Tertiary tectonic setting of volcanic activity. It is generally believed that the first stage is a compressional structural setting (62 ～34 Ma), from the early back-arc extension to the late compression, which is related to the subduction of the Pacific plate and the geodynamic mechanism of oblique subduction. The second stage is an extension setting (34～5. 2 Ma), which is directly controlled by the open and evolution of the Japan sea basin. The third stage is a compressional uplift setting (5. 2～1. 64 Ma), which corresponds to the subduction of the Philippine sea plate towards the Japan land low-arc.