Characteristics Of The Quaternary Stratigraphy And Quaternary Active Faults In The Nansha Area Of The Pearl River Delta

Nansha New Area is located in the geographic geometric center of the Pearl River Delta.It is the sixth national-level new area and also a demonstration area for comprehensive cooperation between Guangdong,Hong Kong and Macao,with huge development potential.However,the new tectonic activity in Nansha New Area is strong,and the interaction between land and sea is complicated.In this paper,the Quaternary Stratigraphic Division and Sedimentary Characteristics of the Nansha New Area are studied by using the NS-WQS-007 borehole micro-paleontological assemblage and the thickness contour map of each section in the area,and the Quaternary stratigraphic activity in the area is analyzed.Fractured response.The activities of the Shawan Fault and Tianhougong Fault were analyzed through field geological survey,geophysical exploration,and combined hole profile drilling,which provided a basis for major engineering construction and earthquake prevention and mitigation in the Nansha New Area.Tectonic movement controls the distribution and thickness of sediments to a certain extent,so the Quaternary strata can better reflect the law of active fault movement.The Quaternary deposits in areas where active faults are distributed in the Nansha New Area are often thicker,and the sedimentary centers are often formed at structural intersections,which are arranged in an elliptical and beaded shape,and result in a stepped fault in the triangular layer of variegated clay in the Late Pleistocene.Through the analysis of the micro-paleontological assemblage of borehole NS-WQS-007,it can be seen that there was only one transgression in the Holocene in the area.The lateral phase transition of the late Pleistocene transgressive layer was complicated and the scale of transgression was small.The high-density electrical device is used to detect hidden active faults.The Wenner device has a higher lateral resolution,and the effect of delineating abnormal resistance bands is better.The interpretation results of the four high-density electrical method sections show that the Shawan fault and the Tianhougong fault should be tensile normal faults.The two active faults in the area are still active since the Quaternary in the northwest-trending Shawan fault and the north-east-trending Tianhougong fault.The NW-trending fault has strong activity and the degree of cleavage cementation is weak,indicating that the latest activity of the fault is closer to the present time The north-east trending fault was active in the early Paleogene and formed a long and narrow fault basin with a fault distance of over 600 m.Since the Quaternary,the activity has been weak and has inherited characteristics.