PROGRESS OF CENOZOIC TECTONIC STUDIES IN QIONGDONGNAN BASIN

The Qiongdongnan Basin is an extensional one located at the northern margin of the South China Sea. Due to its specific evolutionary history and the impact of the Red River Fault, It has its own structural characteristics quite different from the eastern marginal basins. It is known that the Qiongdongnan Basin is different in crustal structure and basement characteristics with the Pearl River Mouth Basin, but the reasons for the difference remain unclear. Cenozoic sedimentation rate suffered severe changes for several times in the basin, and there existed post-rift anomalous subsidence and subsidence delays. In a plane view, there is horizontal migration of structures, but the direction of migration in different geological periods remains controversial. The subsidence centers fitted well with the depocenters in the rifting period, but became separated since the early stage of post rifting, until the complete separation in the late stage of post rifting. The relationship between Basin formation and mantle flow, and the impact of Red River Fault to post-rift subsidence migration remain in question. According to the data acquired so far, further study is necessary to disclose the relationship between the Qiongdongnan Basin and the Nansha Basin, and to reveal the anomalous subsidence, effects of Red River Fault and the influence of internal structure transition on structural migration. Comparative study of the Qiongdongnan Basin and the Pearl River Mouth Basin is also recommended.