襄樊—广济断裂湖北段构造特征研究

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

襄樊—广济断裂是秦岭—大别造山带南缘最重要的边界断裂之一,长期以来,地质工作者对其属性有不同的认识。为了查明其属性,深化研究东秦岭大别南缘的地质结构特点,选择了青峰和三里岗一带白垩纪盆地进行解剖研究,结合近年的区域调查成果,运用板块构造理论和现代造山带研究方法,重新对其属性进行了认定:目前的襄樊—广济断裂形成于喜马拉雅期,是一条规模巨大的脆性断层,具由南向北逆冲的特点,地表上大致构成扬子台地区与秦岭区的分划,同时掩盖了燕山运动造山带和稳定陆台的边界,且它对元古代以来的沉积作用控制不明显;在青峰及以西的地区,与燕山造山期构造叠加在一起,造成其变形具有多期的构造特点,实属不同构造体系下的产物。

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, hut 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 multiphase structural feature, which in fact is product under different tectonic systems, causing by superposition of Xiangfan--Guangji Fault with tectonics of Yanshannian orogenic period.