摘要
顺德北凹位于珠江口盆地珠二坳陷,处于南海北部被动陆缘洋陆过渡带。洼陷结构及成盆机制认识不清楚,是长期制约顺德凹陷勘探的关键问题。本文主要基于三维地震资料的精细解释,运用构造剖面复原分析法、断裂发育特征定量评价法等,重点对顺德北凹的洼陷结构和断裂体系进行深入分析,揭示顺德北凹断裂发育特征及古近纪演化过程。研究表明,顺德北凹经历多期构造运动并叠加应力场旋转,构造发育复杂。区域内发育NE向、NEE向、NW向和近EW向四组走向断裂系统,形成走滑、伸展两类构造样式。主干断裂活动性呈现“双峰”特征,在文昌组二段和恩平组活动强。顺北断裂早期分段生长并控制凹陷内各洼陷形成半地堑结构,文昌组二段沉积时期顺北1号断裂和顺北2号断裂活动性增强,并分别控制北3、4洼和北2洼沉积。北1洼晚始新世以来快速沉降,最大深埋超5000 m,生烃潜力强,且沉积中心始终受顺北断裂控制。研究区古近系呈现“两期三幕”演化过程,洼陷差异演化过程明显,部分洼陷早期发育双断构造。该研究可为顺德凹陷下一步油气勘探提供一定借鉴意义。
The Northern Shunde Sag is located in the Zhu-ⅡDepression of the Pearl River Mouth Basin,within the ocean-continent transition zone on the northern passive continental margin of the South China Sea.Unclear understanding of the structure and basin-forming mechanism of the sag is a key issue that has long restricted oil and gas exploration in the Shunde Sag.Based on the detailed interpretation of 3 D seismic data,this study applies methods such as structural prof ile restoration analysis and quantitative evaluation of fault development characteristics,and focuses on in-depth analysis of the sag structure and fault system of the Northern Shunde Sag,and reveals the fault development characteristics and Paleogene evolutionary process of the Northern Shunde Sag.Studies have shown that the Northern Shunde Sag has experienced multiple tectonic movements and super-imposed stress field rotation,resulting in complex structural development.Four sets of faults striking NE,NEE,NW,and nearly EW are developed in the region,forming two types of structural styles:strike-slip faults and extensional faults.The activity of the major faults exhibits a“bimodal”feature,with intense activity during the depositional periods of the Member 2 of the Wenchang Formation and the Enping Formation.In the early stage,the Shunbei Faults grew in segments and controlled the formation of a half-graben structures in each sub-sag.During the depositional period of Member 2 of the Wenchang Formation,the Shunbei Fault No.1 and Shunbei Fault No.2 showed increased activity,and they respectively controlled the sedimentation of the Sub-sags North 3,North 4,and North 2.Since the Late Eocene,Sub-sag North 1 has experienced rapid subsidence,with a maximum burial depth exceeding 5,000 m.It has high hydrocarbon generation potential,and its sedimentary center has always been controlled by the Shunbei Faults.The Paleogene in the study area has undergone an evolutionary process of“two stages and three episodes”,with significant differences in the evolutionary processes of sub-sags.Some sub-sags developed double-fault structures in the early stage.This study can provide a reference for future oil and gas exploration in the Shunde Sag.
作者
李孟辉
余一欣
甘军
金秋月
王玉磊
王畅
闫浩霖
卫晨玺
LI Menghui;YU Yixin;GAN Jun;JIN Qiuyue;WANG Yulei;WANG Chang;YAN Haolin;WEI Chenxi(Hainan Institute of China University of Petroleum(Beijing),Sanya,Hainan 572025,China;National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Hainan Branch,CNOOC China Limited,Haikou,Hainan 570312,China)
出处
《现代地质》
北大核心
2025年第6期1648-1660,共13页
Geoscience
基金
国家科技重大专项油气重大专项(2025 ZD1402702)。
关键词
顺德凹陷
洼陷结构
断裂
古近系
构造演化
Shunde Sag
sag structure
fault
Paleogene
tectonic evolution
