鄂西利川齐岳山高陡背斜带的古应力分析

Paleostress Analysis of the Qiyue Shan High-angle Anticline in the Lichuan Area,Western Hubei Province,China

鄂西利川地区位于湘鄂西构造带与川东构造带的过渡部位,叠加褶皱发育,地处两大构造带分界处的齐岳山高陡背斜带断裂发育。本文以利川地区褶皱和断裂为研究对象,在野外观测和分析的基础上,采用断层滑动数据反演方法,对构造应力场进行了恢复;结合区域构造演化历史,提出该区侏罗纪以来经历了五期构造应力作用,从早到晚分别为:北西-南东向挤压(J3-K1)、近东西向挤压(K1)、近南北向挤压(K1-K2)、北西-南东向引张(K2)和北东-南西向挤压(E3)。该区侏罗纪以来构造变形序列的建立,为深入认识齐岳山高陡背斜带地质灾害形成的地质背景提供了构造地质学证据。

The Lichuan area,located in the transition zone between the western Hunan-Hubei and eastern Sichuan province tectonic belts,is characterized by the abundant superposed folds.The Qiyue Shan high-angle anticline as the boundary of the two belts is faulted extensively.Based on field observation and structural studies,we reconstructed the tectonic stress field using the fault-slip data of the Lichuan area.Furthermore,combining with the regional tectonic evolution,we proposed that the Lichuan area underwent five phases of tectonic stress since Jurassic：NW-SE trending tectonic compression during the Late Jurassic to Early Cretaceous（J3-K1）,nearly EW trending compression during the Early Cretaceous（K1）,nearly SN trending compression during the Early Cretaceous to Late Cretaceous（K1-K2）,NW-SE trending extension during the Late Cretaceous（K2） and NE-SW trending compression during the Late Paleogene（E3）.The establishment of the structural deformation sequence of Lichuan area since Jurassic provides structural geology evidence for probing into the geological settings of geohazards in the Qiyue Shan high-angel anticline.