The Kaiping Sag is located in the western Zhu?Ⅱ depression in the Pearl River Mouth Basin and is situated in the continental?ocean transition zone, most of which is in the sloped deepwater area. The study of tectono-stratigraphic sequence and basin evolution in Kaiping Sag is of great significance to the understanding of the basin structure and the petroleum exploration and also helps to the understanding of structural characteristics and genetic mechanisms of the continental-ocean transition of the northern South China Sea. This paper documents the stratigraphic framework of the Kaiping Sag using the latest seismic profiles in addition to drilling data integrated with the regional geological background. The tectono-stratigraphic sequence is constrained based on the regional unconformities. The tectonic evolution of Kaiping Sag since the Eocene is mainly discussed according to the balanced cross-section technique. Three regional unconformities including the bottom of the Eocene Wenchang Formation, the bottom of the Oligocene Zhuhai Formation and the bottom of the Upper Miocene Yuehai Formation, according to which four tectonic layers are recognized basement tectonic layer, rift tectonic layer, depression tectonic layer and accelerate subsidence tectonic layer. This study demonstrates that tectonic evolution of the Kaiping Sag can be divided into four stages: basement formation stage, Eocene rifting stage, Oligocene-Middle Miocene depression stage and Late Miocene-Quaternary accelerated subsidence stage. Rifting in the Kaiping Sag is mainly controlled by the differential activity of the extensional detachment fault.
Nie Guoquan He Dengfa Li Xiaopan Zhang Zhiye He Min. Tectono-stratigraphic sequence and basin evolution of Kaiping Sag in the Pearl River Mouth Basin[J]. Chinese Journal of Geology, 2020, 55(1): 122-144.