Offshore Fault Geometrics in the Pearl River Estuary, Southeastern China: Evidence from Seismic Reflection Data
Offshore Fault Geometrics in the Pearl River Estuary, Southeastern China: Evidence from Seismic Reflection Data
复制标题
中国东南部珠江口近海断层几何特征：来自地震反射数据的证据
DOI：
10.1007/s11802-018-3499-5
复制
发表时间：
2018-08-01
影响因子：
1.6
通讯作者：
Xu, Huilong
中科院分区：
文献类型：
--
作者：
Cao, Jinghe;Xia, Shaohong;Xu, Huilong
珠江口位于华南与南海盆地的海陆过渡带，对探讨华南陆块与南海陆块的构造关系及珠江口近海活动断裂沿着的地震活动具有重要价值。然而，对该地区近海断裂几何特征的研究却极为缺乏。为了更详细地调查PRE中的海上断层分布及其几何特征，我们在2015年获得了13个地震反射剖面。本文结合地震反射和自由空间重力异常资料的分析，揭示了沿岸的断裂带和其他近海断裂在PRE中的位置、连续性和几何形态。沿岸的断裂带由主要的丹干群岛断裂和多条平行的高角度正断层组成，主要走向为北东-北东-东，倾向为南东，位移大。北西向断裂将断裂带分为三段。此外，当岸群岛周围的基底深度很浅，但沿岛向西和向南沿着基底深度突然增加。这些都导致了岛屿和邻近地区成为应力容易积累的地方。该区的孕震图象与断层交切和低速层的综合作用密切相关。
The Pearl River Estuary (PRE) is located at the onshore-offshore transition zone between South China and South China Sea Basin, and it is of great significant value in discussing tectonic relationships between South China block and South China Sea block and seismic activities along the offshore active faults in PRE. However, the researches on geometric characteristics of offshore faults in this area are extremely lacking. To investigate the offshore fault distribution and their geometric features in the PRE in greater detail, we acquired thirteen seismic reflection profiles in 2015. Combining the analysis of the seismic reflection and free-air gravity anomaly data, this paper revealed the location, continuity, and geometry of the littoral fault zone and other offshore faults in PRE. The littoral fault zone is composed of the major Dangan Islands fault and several parallel, high-angle, normal faults, which mainly trend northeast to northeast-to-east and dip to the southeast with large displacements. The fault zone is divided into three different segments by the northwest-trending faults. Moreover, the basement depth around Dangan Islands is very shallow, while it suddenly increases along the islands westward and southward. These has resulted in the islands and neighboring areas becoming the places where the stress accumulates easily. The seismogenic pattern of this area is closely related to the comprehensive effect of intersecting faults together with the low velocity layer.