大兴安岭北段根河地区中生代构造应力场特征

以1∶25万额尔古纳左旗幅区调资料为基础,结合大兴安岭北段区域地质特征,在综合厘定测区主要基底断裂的存在及展布特征时,根据大小构造配套关系,对全区共轭剪节理系统进行了详细的测量和综合研究,将研究区中生代构造应力场划分了三期,即早侏罗世、晚侏罗世和早白垩世,构造线方向由NE-NW-NE变化。通过研究再造了测区中生代古构造应力场,重塑了中生代构造发生、发展的力学机制。同时,认为这三期构造应力场的转换是形成各时代地质体的动力学基础,并提出中生代三期构造应力场的形成转换与鄂霍茨克海的扩张、封闭及伊泽纳吉板块的俯冲紧密相关,以及大兴安岭火山岩带就是在这种快速应力转换机制下形成的新观点。

MESOZOIC STRUCTURAL STRESS FIELD CHARACTERISTICS OF THE GENGHE AREA OF THE NORTH DAXINGANLING

Based on the regional geological survey of 1∶250000 Ergunazuoqi sheet and the regional geological data of the north Daxinganling, the main basement faults and their distribution characteristics in the study area were fixed, the joints in the whole region were carefully measured and studied through correlation of both large-scale structures and small-scale structures. The structural stress field of the study area in Mesozoic was divided into three stages, i.e., Upper Indosinian, Middle Yanshannian, and Upper Yanshanian.The directions of the structure lines changed from NE to NW to NE. The palaeostress field and the occurrence and evolution mechanisms of the Mesozoic structures in the study area were also investigated. We propose that the structural stress field transformation at the three stages forms the dynamic basis for the geologic bodies at each period, and put forword a new viewpoint that it was well correlated with the expansion of the Okhotsk Sea and the subduction of Izanagi Plate. The Daxinganling volcanic zone was resulted from the speedy stress transformation mechanism.