为探究珠江口盆地开平凹陷构造沉降特征以及主控因素,以2条地震剖面的最新解释成果为基础,在地震剖面上共选取43个虚拟井进行构造沉降史计算,并进行综合分析.结果 表明:①开平凹陷裂陷期(49～30 Ma)构造沉降量较大,各洼陷构造沉降差异性较大,裂后期(30 Ma至今)构造沉降量相对较小,各洼陷构造沉降差异性较小,②开平凹陷文昌组沉积期(裂陷一幕,49～39 Ma)为最大构造沉降期,恩平组沉积期(裂陷二幕,39～30 Ma)构造沉降速率显著减小,漂移期(30～17.5 Ma)和新构造运动期(17.5 Ma之后)构造沉降量均出现了不同程度的增大,③差异性沉降是开平凹陷的一个基本特征,多期次构造运动和拆离断层分段性、差异性活动是主控因素.

In order to study the characteristics of tectonic subsidence and its main controlling factors of Kaiping Sag in Pearl River Mouth Basin, based on the latest interpretation results of two seismic sections, 43 virtual wells were selected on the two seismic sections to calculate the tectonic subsidence and conduct a comprehensive analysis. The results show that: (1) The tectonic subsidence of Kaiping Sag is large at the rifting stage (49-30 Ma), and the tectonic subsidence of each sag is quite different. The tectonic subsidence is relatively small at the post-rifting stage (30 Ma to present), and the differences of tectonic subsidence in each sub-sag are small. (2) The first episode of the rift stage (deposition period of Wenchang Formation, 49-39 Ma) was the period of maximum tectonic subsidence. The tectonic subsidence rate decreases significantly in the second episode of the rift stage (deposition period of Enping formation, 39-30 Ma). The tectonic subsidence increases in varying degrees in the drift period (30-17.5 Ma) and Neotectonic Movement period (after 17.5 Ma). (3) Differential subsidence is a basic feature of Kaiping sag, and the multi-stage tectonic movement and segmented and differential activities of detachment fault are the major factors of differential subsidence in Kaiping Sag.