海南岛东部近浅海单道地震层序特征分析

Analysis of Single-Channel Seismic Sub-Layer Characteristics in the Nearshore and Shallow Sea Areas of Eastern Hainan Island

摘要: 单道地震是研究近浅海海域地层结构的主要手段，本文主要对海南岛东部文昌–琼海近浅海海域1419 km单道地震剖面进行精细解释，解释了8个特征明显的区域性不整合地震反射界面，由上至下依次命名为H0、H10、H11、H20、H21、H30、H40和H50，再根据各反射层的地震波组、振幅、频率、地层的连续性、地层之间的接触关系等反射特征，划分出与之相对应的层序为A1 (H0~H10)、A2 (H10~H11)、A3 (H11~H20)、A4 (H20~H21)、A5 (H21~H30)、A6 (H30~H40)、A7 (H40~H50)等7个地震反射亚层。通过对各地震反射亚层厚度空间展布特征的分析发现，研究区地层的沉积中心主要位于研究区南部，整体呈南厚北薄的格局。需要指出的是，由于研究区缺乏直接的钻孔资料控制，文中涉及的地质时代划分(如全新统、更新统等)是基于区域地质对比的推断结果，存在一定的不确定性。

Abstract: Single-channel seismic survey is a primary method for studying the stratigraphic structure of nearshore and shallow sea areas. This paper focuses on the detailed interpretation of 1419 km of single-channel seismic profiles in the nearshore and shallow sea areas of Wenchang-Qionghai in eastern Hainan Island. A total of 8 regionally significant unconformable seismic reflection interfaces with distinct characteristics are identified, named H0, H10, H11, H20, H21, H30, H40, and H50 from top to bottom. Based on reflection characteristics, such as seismic wave groups, amplitude, frequency, stratigraphic continuity, and contact relationships between strata of each reflection layer, the corresponding sequences are defined as seven seismic reflection sub-layers (units): A1 (H0~H10), A2 (H10~H11), A3 (H11~H20), A4 (H20~H21), A5 (H21~H30), A6 (H30~H40), and A7 (H40~H50). Analysis of the spatial distribution characteristics of each seismic reflection sublayer thickness reveals that the depocenter of the study area’s strata is mainly located in the southern part of the study area, showing an overall pattern of thicker strata in the south and thinner strata in the north. It is important to note that the assignment of geological ages (e.g., Holocene, Pleistocene) mentioned in this paper is inferred from regional geological correlation due to the lack of direct borehole control within the study area, and thus carries inherent uncertainties.