摘要
南海西北部陆缘盆地的地层格架与沉积充填特征对理解新生代以来南海的伸展张裂过程及红河断裂、南海西缘走滑断裂的活动具有重要意义。本文以琼东南盆地西部、中建南盆地北部以及两盆地结合区域为例,通过井震对比和构造‒地层解析,统一了两盆地的地层系统,并对比分析了新生代主要构造演化阶段的断裂活动与沉积充填特征。结果表明:①古近纪‒早中新世,多数凹陷沉积中心的延伸方向与NE-NEE走向的伸展断裂一致。始新世‒早渐新世,研究区西部的琼东南盆地崖南、乐东、华光凹陷以及中建南盆地北部坳陷的沉积中心呈串珠状分布,其延伸方向分别与近NW向右旋走滑的红河断裂和NNW向左旋走滑的南海西缘断裂一致,且走滑方向的差异导致华光凹陷沉积中心向北靠近陵南低凸起,北部坳陷沉积中心向南靠近北部隆起。中中新世以来,走滑断裂活动与沉积厚度之间无明显对应关系;②研究区断拗转换界面存在差异,在琼东南盆地、中建南盆地北部和西部,断裂活动截止于T6(约23.6 Ma),而在中建南盆地中部坳陷则持续到T5(16 Ma)。因此,南海西北部古近纪‒早中新世沉积主要受伸展性质断裂控制,同时在琼东南盆地西部崖南、乐东、华光凹陷以及中建南盆地北部坳陷叠加了红河‒南海西缘走滑断裂的影响,中中新世以来断裂活动基本不再控制沉积。16 Ma西南次海盆停止扩张事件在西北方向的影响可能终止于中建南盆地北部隆起。
The stratigraphic framework and sedimentary filling characteristics of the continental margin basins in the northwestern of the South China Sea play a pivotal role in understanding the extensional tectonics and strike-slip faulting associated with the Red River and the western margin of the South China Sea since the Cenozoic era.This study focuses on the western Qiongdongnan Basin,the northern Zhongjiannan Basin,and the transitional zone between these two basins.By integrating well-seismic correlation and structural-stratigraphic interpretation,we have established a unified stratigraphic framework of the two basins and conducted a comparative analysis of fault activity and sedimentary filling patterns during key tectonic evolutionary stages of the Cenozoic.The results indicate that:(1)From the Paleogene to the Early Miocene,most sedimentary centers within the sags were distributed parallel to NE-NEE-trending extensional faults.During the Eocene to the Early Oligocene,sedimentary centers in the Yanan,Ledong,and Huaguang Sags,as well as the northern sag of the Zhongjiannan Basin in the western study area,displayed a beaded distribution.Their orientations corresponded with the nearly NW-trending dextral strike-slip Honghe Fault and the nearly SN-trending sinistral strike-slip Western Margin Fault of the South China Sea.This variation in strike-slip directions correlates with the following observations:the sedimentary center of the Huaguang Sag is proximal to the Lingnan low uplift to the north,while the sedimentary center of the northern sag is closer to the southern uplift to the south.Furthermore,since the Middle Miocene,no significant correlation has been observed between strike-slip fault activity and sedimentary thickness.(2)Differences exist in the fault-sag transition interfaces within the study area.Fault activity terminated at T6(23.6 Ma)in the Qiongdongnan Basin,as well as in the northern and western parts of the Zhongjiannan Basin,but persisted until T5(16 Ma)in the central sag of the Zhongjiannan Basin.In summary,sedimentation in the northwest of the South China Sea from the Paleogene to the Early Miocene was predominantly controlled by extensional faults.Additionally,the Yanan,Ledong,and Huaguang Sags in the western Qiongdongnan Basin,along with the northern sag in the Zhongjiannan Basin,were jointly controlled by the Red River strike-slip fault and the strike-slip fault along the western margin of the South China Sea.Since the Middle Miocene,faults have exerted limited control over sedimentation.The impact of the cessation of spreading in the Southwest sub-basin at 16 Ma may have propagated northwestward and terminate at the northern uplift of the Zhongjiannan Basin.
作者
李佳伟
王利杰
姚永坚
路允乾
LI Jiawei;WANG Lijie;YAO Yongjian;LU Yunqian(Guangzhou Marine Geological Survey,Key Laboratory of Marine Mineral Resources of the Ministry of Natural Resources,Guangzhou 511458,Guangdong,China;National Engineering Research Center for Gas Hydrate Exploration and Development,Guangzhou 511458,Guangdong,China)
出处
《大地构造与成矿学》
北大核心
2026年第2期263-284,共22页
Geotectonica et Metallogenia
基金
国家自然科学基金项目(U20A20100)
中国地质调查局国家海洋专项项目(DD20201118,DD20230069,DD20240090)
海南省科技专项项目(ZDYF2025GXJS013)
广州海洋地质调查局局长基金项目(2024GMGS-ZD-03)联合资助。
关键词
中建南盆地
南海西缘断裂
断拗转换界面
构造变形
沉积特征
Zhongjiannan Basin
western margin fault of the South China Sea
fault-depression transition interface
tectonic deformation
sedimentary characteristics
