【摘要】 琼东南盆地位于南海北部大陆边缘西部,其深水区是重要的油气勘探新领域。利用琼东南盆地高密度的多道地震资料,阐明了琼东南盆地海底地形地貌特征,分析了盆地内深水沉积体的类型、特征、形成机制和空间展布,探讨了地形地貌对深水沉积的控制作用,对深入理解深水沉积过程,尤其是该区深水油气储层的预测具有重要意义。研究结果表明,琼东南盆地海底地形总体可以划分为陆架、陆坡和深海平原。在该地形地貌控制下,研究区内主要发育6种深水沉积体:浊流沉积、陆坡峡谷充填、滑塌沉积、滑移沉积、沉积物波和碎屑流沉积。进一步的研究表明,这些沉积体的空间发育部位和规模与陆坡的坡度有关。地形坡度通过控制重力流流体的流态产生各类型重力流沉积,进而控制了陆坡体系的调整过程。研究结果还表明,由于地形坡度的变化,重力流流态会发生相应变化,并进而导致各种类型重力流沉积在其形成过程中发生相互转化,其一般转化顺序通常为滑塌-碎屑流-浊流。更多还原

【Abstract】 The Qiongdongnan Basin is located in the northwest of the South China Sea,and the deepwater area of the basin is a new favorable prospect for hydrocarbon exploration.Based on seismic and bathymetric data,the authors focused in this paper on the deep water topography of the Basin and the control of topography over the deepwater sedimentation.Various landform types were distinguished and their distribution pattern described.Discussed are also the depositional mechanism of the gravity deposits and their types,distribution and lithological characteristics,so as to reveal the control of topography on the deepwater depositional systems.Results show that the submarine topography of the Qiongdongnan Basin can be divided into three units of the continental shelf,the continental slope and the deep-sea plain.Under the control of topography,there are 6 types of sediments in the Qiongdongnan continental slope system: slope canyon,turbidite fan,slumping block,debris flow deposits,sliding mass and sedimentary waves.Our results prove that the types of sedimentary facies are closely related to the gradient of the slope.The gradient not only controls the distribution of types of gravity flow deposits,but also the adjustment of slope system.In addition,the gravity flow may change from one to another due to the change of landforms,for example,change from turbidity-current to sediment waves,or from slumping and/or debris flow to turbidity current.更多还原