南沙海槽构造?地层格架及其动力学意义

为了明确南沙海槽的构造?地层格架和成因机制，以区域二维地震剖面的解释为基础，进行断层活动性和沉降史的定量计算，在南沙海槽盆地中确定出Tg、T60、T50和T0四个一级层序界面，以这4个一级层序界面为界，将南沙海槽盆地划分出3个盆地原型:古新世?渐新世（Tg?T60）断陷盆地、早中新世（T60?T50）拗陷盆地和中中新世（T50?T0）前陆盆地；新生代以来，南沙海槽盆地的沉降中心由NW向SE逐渐迁移. 区域资料对比分析表明南沙海槽前陆盆地是由多期前陆盆地叠置而成，以沙捞越造山不整合、区域深部不整合和区域浅部不整合这3个不整合面为界，划分出渐新世?早中新世、中中新世?上新世早期和上新世晚期?现今3期前陆盆地；南沙海槽属于第三期前陆盆地的组成单元，目前仍处于发育演化过程中. 

Tectono-Stratigraphic Framework in Nansha Trough and Its Dynamic Significance

In order to clarify the tectono-stratigraphic framework and genetic mechanism of the Nansha trough basin, in this paper, the quantitative calculation of fault activity and subsidence history is carried out based on the interpretation of regional 2D seismic data in the Nansha trough. Four first-order sequence interfaces (Tg, T60, T50 and T0) have been identified in the Nansha trough basin. On the basis of these four first-order sequence interfaces, the Nansha trough basin can be divided into three basin prototypes: the Paleocene-Oligocene (Tg?T60) rift basin, the Early Miocene (T60?T50) depression basin and the Middle Miocene (T50?T0) foreland basin. From the Cenozoic, the Nansha trough basin has gradually migrated from NW to SE. Comparative analysis from the previous study shows that the Nansha trough foreland basin is formed by the superposition of multi-phased foreland basins. Bounded by the Sarawak orogenic unconformity, the deep regional unconformity and the shallow regional unconformity, the Nansha trough foreland basin can be divided into three stages of the foreland basin: the Early Oligocene to Miocene, the Middle Miocene to the Early Pliocene and the Late Pliocene to present. The Nansha trough belongs to the third phase of the whole foreland basin and is still developing now.