广州礌岗断裂的晚第四纪活动证据OA

The Leigang Fault is a branch of the southern section of the Guangzhou-Conghua fault zone,which is located in the center of the Pearl River Delta fault basin,a special tectonic position where several groups of NE-and NW-trending structures meet.Existing evidence shows that most of the NW-trending faults in the Pearl River Delta fault basin are Late Pleistocene active faults,and whether the conjugate NE-trending faults have been active since the Late Pleistocene has become a scientific problem to correctly elucidate the Late Quaternary tectonic activity pattern and dynamic environment in the region and also affects the scientific assessment of seismic risk in the Pearl River Delta.During the exploration of the Leigang Fault in Nanhai District,Foshan City,multiple detailed drilling surveys were conducted based on shallow seismic exploration.The Leigang Fault faulted the Late Pleistocene strata in the joint profiles of the fourth,third,and second drilling groups.The latest stratigraphic age of the faulted strata is between 40 ka and 50 ka,belonging to the early and middle stages of the Late Pleistocene.The nature of Leigang Fault is reverse and right-lateral,and the maximum vertical displacement is 0.9-2.3 m.The estimated average vertical sliding rate since the early and middle stages of the Late Pleistocene is 0.02-0.06 mm/a.Although the sliding rate of the Leigang Fault is relatively low,it belongs to the Late Pleistocene active fault,and it is necessary to keep aware of the possibility of future earthquakes with magnitude of 6.