STUDY OF STRUCTURAL CHARACTERISTICS OF XIANGFAN-GUANGJI FAULT IN HUBEI PROVINCE

As one of boundary faults in the southern margin of Qinling-Dabie Orogenic Belt,Xiangfan-Guangji Fault is the most crucial one,which has long been debated on its property.For purpose of solving this issue,further study is made on geological structure characteristics of the southern margin of East Qinling and Dabie,and in the paper,combined with results of regional survey in recent years,the Cretaceous basin in Qingfeng and Sanligang are selected as cases to determine the property of Xiangfan-Guangji Fault again,by adopting plate tectonic theory and modern research method of orogenic belt.The results show as follows: the Xiangfan-Guangji Fault,formed in Himalayan stage,is an extra-large scale brittle fault with the feature of thrusting from south to north.In earth's surface,it not only is the line to divide Yangtze platform and Qinling approximately,but also covers the boundary between orogenic belt of Yanshannian Movement and stable platform.Moreover,its control on sedimentation since Proterozoic is found to be insignificant.In Qingfeng and areas west,its deformation appears to multi-phase structural feature,which in fact is product under different tectonic systems,causing by superposition of Xiangfan-Guangji Fault with tectonics of Yanshannian orogenic period.