莺歌海盆地新生代构造沉积演化及动力学机制分析  

Analysis of the Cenozoic tectonic sedimentary evolution and its dynamic mechanism in the Yinggehai Basin

作　　者：蒋国忠 谢辉 赵中贤[4] 石红才 潘荟[1] Jiang Guozhong;Xie Hui;Zhao Zhongxian;Shi Hongcai;Pan Hui(College of Chemistry and Environment,Guangdong Ocean University,Zhanjiang 524088,China;Laboratory for Coastal Ocean Variation and Disaster Prediction,College of Ocean and Meteorology,Guangdong Ocean University,Zhanjiang 524088,China;Key Laboratory of Climate,Resources and Environment in Continental Shelf and Deep Sea of Department of Education of Guangdong Province,Guangdong Ocean University,Zhanjiang 524088,China;Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China)

机构地区：[1]广东海洋大学化学与环境学院,广东湛江524088 [2]广东海洋大学海洋与气象学院近海海洋变化与灾害预警实验室,广东湛江524088 [3]广东海洋大学广东省高等学校陆架及深远海气候、资源与环境重点实验室,广东湛江524088 [4]中国科学院南海海洋研究所边缘海与大洋地质重点实验室,广东广州510301

出　　处：《海洋学报》2023年第12期44-57,共14页

基　　金：广东省自然科学基金项目(2023A1515030124,2016A030310331);国家自然科学基金项目(41606065,41704085);中国科学院边缘海地质重点实验室开放基金项目(MSGL15-02);广东海洋大学博士启动基金项目;广东海洋大学海洋科学科研团队项目(002026002004)。

摘　　要：南海西北陆缘构造演化极其复杂,受到红河断裂、海南地幔柱和南海形成演化等多种因素的控制。莺歌海盆地位于南海西北部,发育了巨厚的新生代沉积物,详细记录了南海西北陆缘新生代的演化历史。但是莺歌海盆地新生代以来主要受到何种构造因素的控制目前还不太清楚。本文在莺歌海盆地较为均匀地选择了7口钻井和23口模拟井,通过空盆构造沉降方法重建了莺歌海盆地的构造沉降量、构造沉降速率和沉积速率,同时运用重力反演方法模拟了莺歌海盆地深部地壳结构,并结合前人研究成果进行了综合分析。结果发现莺歌海盆地在裂陷期(45-23 Ma BP),盆地北部和中部沉降速率较大,南部沉降速率较小;在裂后期(23-0 Ma BP),盆地北部和中部沉降速率存在两期“台阶式”上升,分别为23-11.7 Ma BP和11.7 Ma BP至今,北部裂后期构造沉降速率最大可达80 m/Ma,中部最大可达110 m/Ma;南部地堑和隆起裂后期分别在11.7-5.7 Ma BP和15.9-11.7 Ma BP构造沉降速率最大可达70 m/Ma。莺歌海盆地新生代整体上表现为沉降速率与沉积速率变化基本一致,说明构造沉降对沉积速率具有显著的控制作用。重力反演发现莺歌海盆地可能存在下地壳高密度异常体,结合盆地沉积物内部钻遇玄武岩,我们推测下地壳高密度异常体为基性侵入体。通过与南海周边其他沉积盆地沉降速率对比发现,几乎所有盆地都在中中新世-晚中新世(15.9-11.7 Ma BP)发生了加速沉降事件,我们认为这可能跟南海海盆停止扩张导致大陆边缘次生地幔对流消失有关。莺歌海盆地5.7 Ma BP至今的加速沉降则可能与红河断裂右旋走滑活动有关。The tectonic evolution of the northwestern continental margin of the South China Sea were controlled by many factors,such as the Red River Fault,the Hainan mantle plume and the formation and evolution of the South China Sea.The Yinggehai Basin is located in the northwest of the South China Sea,where thick Cenozoic sediments were deposited.The Cenozoic evolution history of the northwestern continental margin of the South China Sea was recorded in detail in the Yinggehai Basin.However,which factor has mainly controlled the evolution of the Yinggehai Basin since the Cenozoic is still ambiguous.In this paper,7 drilling wells and 23 simulated wells were selected in the Yinggehai Basin,and the sedimentation rate and subsidence rate of the Yinggehai Basin were reconstructed by empty basin tectonic subsidence analysis method.The deep structure of the Yinggehai Basin was simulated by gravity inversion method based on previous study.The results show that during the rift period,the subsid-ence rate of the Yinggehai Basin in the north and middle sections is larger than in the south section.There are two stages of“step acceleration subsidence”in the north and middle sections,which are 23–11.7 Ma BP and 11.7 Ma BP–present,respectively.The maximum tectonic subsidence rate can be up to 80 m/Ma in the post rift stage in the north section and about 110 m/Ma in the middle section.The maximum tectonic subsidence rate of the Southern Graben and Uplift is both close to 70 m/Ma during the periods of 11.7–5.7 Ma BP and 15.9–11.7 Ma BP,respectively.The Cenozoic subsidence of the Yinggehai Basin is consistent with the change of sedimentary rate,indicates that tectonic subsidence plays a significant role on sedimentary evolution.According to the results of gravity inversion,it may be lower crust high density anomaly intrusion underlying the Yinggehai Basin.We suggested it may be basic rock according to the drilling basalts in the sediments.By comparing with the subsidence rate of surrounding basins in the South China Sea,the ac

关 键 词：莺歌海盆地 红河断裂 构造沉积演化 重力反演 

分 类 号：P736.21[天文地球—海洋地质]