西淋岗第四纪错断面特征及其成因

FEATURE AND FORMATION MECHANISM OF THE QUATERNARY FAULT PLANE AT XILINGANG,FOSHAN CITY

西淋岗第四纪错断面位于佛山市顺德区陈村镇,有研究者认为这是晚第四纪活动断裂。为了进一步探明该错断面形成的机理,进行了大比例尺地质地貌填图、探槽开挖、浅层地震探测和第四纪地层年代测定等工作。结果表明,该点及其周边地貌上没有最新构造活动的迹象,但符合重力活动的特征。第四纪地层的错断和基岩中的断裂不能配套,不是统一构造应力场的产物。两侧物探反射特征表明,基岩断裂并未错断第四纪地层。根据基础地质条件、工程地质类比和高陡稳定性计算结果判断,该错断面的产生具备重力活动的条件,是重力失衡的结果,而并非由构造作用形成。

A Quaternary fault plane was found located at Chencun Town of Foshan City,which is thought as a late Quaternary active fault by many researchers. To explain the formation mechanism of this fault plane,a series of work was carried out,such as geomorphologic survey,validation by exploratory trench,shallow seismic reflection and dating of Quaternary system,etc. According to the analysis of the geomorphologic features,the contrast between bedrock fault and Quaternary fault,and the characteristics of shallow seismic reflection,there are few geomorphologic signs of recent tectonic activities. The displacement of Quaternary bottom and the rupture in the rocks were not formed in the same tectonic stress field,and the bedrock fault didn＇t offset the Quaternary formation according to the shallow seismic reflection characteristics. Thus,a conclusion is drawn that the Xilingang Fault plane wasn＇t generated by tectonic movement but the gravity inequilibrium.