南海北部西沙海槽盆地新生代层序地层及地震相
发布时间：2019-03-30 10:35
【摘要】：西沙海槽盆地是南海北部陆坡西段的一个勘探程度较低的大型新生代深水沉积盆地。基于新采集的高精度多道地震资料并结合周边地区地质特征对盆地进行了层序地层分析,在研究区内识别出8个地震反射界面,结合地震剖面振幅旋回性变化,将研究区新生代地层划分了3个超层序和8个层序,并进一步论述了各层序的顶底接触关系、地震反射特征、地层厚度、层速度及砂岩含量等。在层序格架内识别出5类典型的地震相:平行-亚平行相、楔状发散相、前积相、杂乱相及水道充填相。在地震相划分和沉积相分析的基础上,通过对各层序沉积特征和沉积发育史的分析,认为始新世研究区呈现出陆相湖盆沉积体系特征;渐新世,盆地遭受海侵,研究区接受滨海相和浅海相沉积;早中新世,盆地中部沉积大规模半深海相沉积;中中新世末海平面出现下降,陆坡半深海环境的范围有所减小,西沙海槽浊积水道的雏形形成;晚中新世之后,研究区进入稳定的区域沉降阶段,主要发育了一套半深海-深海相泥岩沉积。此外,由研究区南北缘隆起区提供物源在层序内部还发育有近岸水下扇、三角洲、扇三角洲等沉积体,由地形高差控制作用在陡坡带或断层下降盘还形成了斜坡扇、浊积体。
[Abstract]:Xisha trough basin is a large Cenozoic deep-water sedimentary basin with low exploration degree in the western part of the northern continental slope of the South China Sea. Based on the newly acquired high-precision multi-channel seismic data and combined with the geological characteristics of the surrounding area, the sequence stratigraphy of the basin is analyzed. Eight seismic reflection interfaces are identified in the study area, and combined with the cyclic variation of the amplitude of the seismic section, the sequence stratigraphy of the basin is analyzed. The Cenozoic strata in the study area are divided into 3 supersequences and 8 sequences, and the top-bottom contact relationship, seismic reflection characteristics, stratigraphic thickness, bed velocity and sandstone content of each sequence are further discussed. Five types of typical seismic facies are identified in the sequence framework: parallel-sub-parallel facies, wedge-shaped divergence facies, pre-product facies, disordered facies and channel filling facies. On the basis of seismic facies division and sedimentary facies analysis, it is concluded that the Eocene study area has the characteristics of continental lacustrine basin sedimentary system through the analysis of the sedimentary characteristics and depositional development history of each sequence. In Oligocene, the basin suffered transgression, and the study area received coastal and shallow marine facies deposits, and early Miocene, large-scale semi-deep-sea facies deposits in the middle of the basin. The sea level decreased at the end of Miocene, the range of semi-deep sea environment on continental slope decreased, and the rudimentary form of turbidite channel in Xisha trough was formed. After the late Miocene, the study area entered a stable regional subsidence stage, mainly developed a set of semi-deep-sea-deep-sea facies mudstone deposits. In addition, the provenance from the upwelling area of the north and south margin of the study area also has inshore subaqueous fan, delta, fan delta and other sedimentary bodies within the sequence. The slope fan and turbidite body are also formed in the steep slope zone or fault descending plate controlled by the topographic height difference.
【作者单位】： 国土资源部海底矿产资源重点实验室;中国地质调查局广州海洋地质调查局;
【基金】：国家自然科学基金项目(91328205)
【分类号】：P618.13;P631.4;P736.2
本文编号：2450043
[Abstract]:Xisha trough basin is a large Cenozoic deep-water sedimentary basin with low exploration degree in the western part of the northern continental slope of the South China Sea. Based on the newly acquired high-precision multi-channel seismic data and combined with the geological characteristics of the surrounding area, the sequence stratigraphy of the basin is analyzed. Eight seismic reflection interfaces are identified in the study area, and combined with the cyclic variation of the amplitude of the seismic section, the sequence stratigraphy of the basin is analyzed. The Cenozoic strata in the study area are divided into 3 supersequences and 8 sequences, and the top-bottom contact relationship, seismic reflection characteristics, stratigraphic thickness, bed velocity and sandstone content of each sequence are further discussed. Five types of typical seismic facies are identified in the sequence framework: parallel-sub-parallel facies, wedge-shaped divergence facies, pre-product facies, disordered facies and channel filling facies. On the basis of seismic facies division and sedimentary facies analysis, it is concluded that the Eocene study area has the characteristics of continental lacustrine basin sedimentary system through the analysis of the sedimentary characteristics and depositional development history of each sequence. In Oligocene, the basin suffered transgression, and the study area received coastal and shallow marine facies deposits, and early Miocene, large-scale semi-deep-sea facies deposits in the middle of the basin. The sea level decreased at the end of Miocene, the range of semi-deep sea environment on continental slope decreased, and the rudimentary form of turbidite channel in Xisha trough was formed. After the late Miocene, the study area entered a stable regional subsidence stage, mainly developed a set of semi-deep-sea-deep-sea facies mudstone deposits. In addition, the provenance from the upwelling area of the north and south margin of the study area also has inshore subaqueous fan, delta, fan delta and other sedimentary bodies within the sequence. The slope fan and turbidite body are also formed in the steep slope zone or fault descending plate controlled by the topographic height difference.
【作者单位】： 国土资源部海底矿产资源重点实验室;中国地质调查局广州海洋地质调查局;
【基金】：国家自然科学基金项目(91328205)
【分类号】：P618.13;P631.4;P736.2
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1 邱燕;吴进民;;南沙海域方安盆地地震相解释及沉积相分析[J];南海地质研究;1995年00期
，本文编号：2450043
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