珠江口盆地惠州凹陷西南部地区古近纪构造特征及其演化模式  

Characteristics and evolutionary model of Paleogene structures in southwestern Huizhou Depression,Pearl River Mouth Basin

作　　者：陈翔 张成 秦成岗[3] 刘坊 朱雪颖 李赫男 CHEN Xiang;ZHANG Cheng;QIN Chenggang;LIU Fang;ZHU Xueying;LI Henan(College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China;Key Laboratory of Tectonics and Petroleum Resources （ China University of Geosciences）, Ministry of Education, Wuhan 430074, China;Institute of Shenzhen Branch of China National Offshore Oil Company Ltd., Guangzhou 510240, China)

机构地区：[1]中国地质大学(武汉)海洋学院,武汉430074 [2]中国地质大学(武汉)构造与油气资源教育部重点实验室,武汉430074 [3]中海石油(中国)有限公司深圳分公司研究院,广州510240

出　　处：《海洋地质与第四纪地质》2018年第2期88-95,共8页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金"南海北部陆缘大型深水峡谷体系形成机制及充填构型对比研究"(41002031;41372112)

摘　　要：研究区位于珠江口盆地惠州凹陷西南部,毗邻西江凹陷,属于NEE走向和NE走向两组构造体系的转换部位。该地区古近系主要发育近EW走向、NW走向和NE走向的3组断裂,剖面上总体呈平直和铲状两种形态。3组断裂共同控制了研究区古近系不同时期的断陷结构特征。断层活动性和构造沉降分析表明,文昌组沉积期研究区东部北倾断层和西部南倾断层活动强烈,沉降量和沉降速率均较大;恩平组沉积期,受南海扩张影响,总体呈现南倾断层,即向海倾断层活动明显增强,沉降量和沉降速率显著增大的特点;至珠海组沉积期断层活动总体较弱。构造格局及其演化明显控制沉积物充填。快速生长断层因两盘差异沉降显著,其下降盘往往地层厚度大,以发育扇三角洲沉积体系为特征;慢速生长断层下降盘的地层厚度相对较薄,以发育沿断层转换带延伸的辫状河三角洲沉积体系为主。研究区古近纪的构造演化并非简单继承,而是重大转换(T80面是重要的构造变革面),且这种转换是被动大陆边缘近端带对南海扩张作用远程响应的结果。The study area is located in the southwest of the Huizhou Depression of the Pearl River Mouth Basin next to the Xijiang Depression at the transitional part of two tectonic systems trending in NEE and NE respectively.Three sets of fault systems,trending in EW and NW as well as NE directions,have been identified within the Depression.The faults may be classified into flat-type and shovel-type according to their profile patterns.And the three sets of faults jointly control the structural features of the Paleogene fault depression in different stages.The activity of N-dipping faults is stronger than the S-dipping faults in the east of the study area whereas the S-dipping faults are more active in the west of the study area during the stage when the WenChang Formation was deposited.With a high settlement rate,the activity of S-dipping faults,i.e.,the seafaced-dipping faults,were obviously intensified during the Enping stage because of the spreading of the South China Sea.The settlement and sedimentation rate increased significantly in the Zhuhai stage,although the activities of all faults were weakened.The sediment infilling is obviously controlled by the tectonic framework and its evolution.For rapid growing faults,due to the large difference between the hanging wall and footwall,thick deltaic depositional system will be developed on the subsiding plate.However,for the faults which grow slowly,thin braided river and its deltaic depositional system will develop on the declining plate along the fault transfer zone.The structural pattern of the study area in the Paleogene is not a simple copy of the former,but a significant structural conversion taking T80 as an important tectonic interface,as a long distance response to the South China Sea spreading.

关 键 词：断层活动性 演化模式 古近系 惠州凹陷 珠江口盆地 

分 类 号：X141[环境科学与工程—环境科学]