长江三峡坝区断裂构造的形成和演变的最新研究

基底岩体内存在4组断裂构造。这些断裂、裂隙并非岩体的原生构造，而属于构造成因。根据断裂内岩脉侵入、岩石蚀变作用、结构面特征和构造岩类型的分析研究，认为断裂具有多期活动性的特点。对比基底岩体和沉积盖层的构造，确认岩体中的断裂构造在晚元古代晋宁期就已基本形成，以后在燕山期黄陵背斜出现时，喜马拉雅期断块构造产生时，断裂多次重新活动，演变为新的断裂系统。

NEW STUDY OF FORMATION AND EVOLUTION FOR THE STRUCTURES IN THE DEM AREAOFTHEYANG TZE THREE GORGES

There are four fracture associations in the basement magmatic body.These fractures aren't primary fractures and cracks,but belong to structural origin.According to research of the dyke injection,rock alteration,tectonite type and structure plane in fractures,they have characteristics of polystage activity.To contrast the basement magmatic body with the sedimentary cover in the tectonic framework,it may be considered that,the fractures of the magmatic body were formed in the Jinning stage of Late Proterozoic.Subsequently they have been activated for many times,such as in the Yanshan stage forming the Huangling anticline and in the Himalayan stage occurring the fault blocks,and finally evolving into new fracture systems.