The widely distributed unconformity (T7) in Pearl River Mouth Basin, formed at ~ 30 Ma, is one of the most important unconformities of northern South China Sea related to the evolution of basin dynamics. Based on seismic data and logs, this study documents the distribution of the unconformity in Pearl River Mouth Basin (PRMB) and discusses the mechanism of the breakup unconformity in the evolution of the basin. The study verifies that the T7 boundary is a breakup unconformity: (1) most fault tips end at T7 unconformity or the offset diminishes markedly across the unconformity, and (2) these faults control the stratal thickness, reflected by the wedge shape formation. The T7 unconformity can be divided into three zones according to different structures and contact relationships: (1) the angular unconformity zone, (2) the local unconformity and onlap zone, and (3) the conformity zone, these three correspond to strong erosion zone, weak erosion zone, and non-erosion zone respectively. The distribution pattern of the breakup unconformity in this study area is controlled by the tectonic and geomorphology in the different zones of a basin: The angular erosion zone in the north is controlled by fault activity, but in local unconformity and onlap zone the erosion is mainly caused by diapir or local uplift. The conformity zone is located at the depression center in an underwater environment. This pattern indicates that the mechanism of the breakup unconformity is related to the erosion on shoulder uplift structure at the basin margin in rift stage.

中文翻译：

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南海珠江口盆地渐新世末期的破裂不整合面：裂谷-漂移过渡过程中盆地动力学和构造地理演化的意义

珠江口盆地的不整合面（T7）形成于〜30 Ma，是南海北部与盆地动力学演化有关的最重要不整合面之一。根据地震数据和测井资料，本文记录了珠江口盆地不整合面的分布，并探讨了盆地不整合面破裂的机理。该研究证实T7边界是破裂不整合面：（1）大多数断层尖端终止于T7不整合面或偏移量在不整合面上明显减小，（2）这些断层控制地层厚度，反映为楔形。根据不同的结构和接触关系，T7不合格可分为三个区域：（1）角度不合格区域；（2）局部不整合区和重叠区，以及（3）整合区，这三个分别对应于强侵蚀区，弱侵蚀区和非侵蚀区。该研究区破裂不整合面的分布模式受盆地不同区域的构造和地貌控制：北部的角蚀带受断层活动控制，但局部不整合面和上覆带的侵蚀主要是由底盘或局部隆起引起。合格区位于水下环境中的凹陷中心。这种模式表明，裂谷不整合的机理与裂谷期盆地边缘肩部抬升结构的侵蚀有关。和非侵蚀区。该研究区破裂不整合面的分布模式受盆地不同区域的构造和地貌控制：北部的角蚀带受断层活动控制，但局部不整合面和上覆带的侵蚀主要是断层活动。由底盘或局部隆起引起。合格区位于水下环境中的凹陷中心。这种模式表明，裂谷不整合的机理与裂谷期盆地边缘肩部抬升结构的侵蚀有关。和非侵蚀区。该研究区破裂不整合面的分布模式受盆地不同区域的构造和地貌控制：北部的角蚀带受断层活动控制，但局部不整合面和上覆带的侵蚀主要是断层活动。由底盘或局部隆起引起。合格区位于水下环境中的凹陷中心。这种模式表明，裂谷不整合的机理与裂谷期盆地边缘肩部抬升结构的侵蚀有关。但在局部不整合面和上覆带中，侵蚀主要是由底辟或局部隆升引起的。合格区位于水下环境中的凹陷中心。这种模式表明，裂谷不整合的机理与裂谷期盆地边缘肩部抬升结构的侵蚀有关。但在局部不整合面和上覆带中，侵蚀主要是由底辟或局部隆升引起的。合格区位于水下环境中的凹陷中心。这种模式表明，裂谷不整合的机理与裂谷期盆地边缘肩部抬升结构的侵蚀有关。