赵忠泉, 钟广见, 冯常茂, 涂广红, 金华峰. 南海北部西沙海槽盆地新生代层序地层及地震相[J]. 海洋地质与第四纪地质, 2016, 36(1): 15-26. DOI: 10.16562/j.cnki.0256-1492.2016.01.002
引用本文: 赵忠泉, 钟广见, 冯常茂, 涂广红, 金华峰. 南海北部西沙海槽盆地新生代层序地层及地震相[J]. 海洋地质与第四纪地质, 2016, 36(1): 15-26. DOI: 10.16562/j.cnki.0256-1492.2016.01.002
ZHAO Zhongquan, ZHONG Guangjian, FENG Changmao, TU Guanghong, JIN Huafeng. CENOZOIC SEQUENCE STRATIGRAPHY AND SEISMIC FACIES ANALYSIS OF XISHA TROUGH BASIN IN NORTHERN SOUTH CHINA SEA[J]. Marine Geology & Quaternary Geology, 2016, 36(1): 15-26. DOI: 10.16562/j.cnki.0256-1492.2016.01.002
Citation: ZHAO Zhongquan, ZHONG Guangjian, FENG Changmao, TU Guanghong, JIN Huafeng. CENOZOIC SEQUENCE STRATIGRAPHY AND SEISMIC FACIES ANALYSIS OF XISHA TROUGH BASIN IN NORTHERN SOUTH CHINA SEA[J]. Marine Geology & Quaternary Geology, 2016, 36(1): 15-26. DOI: 10.16562/j.cnki.0256-1492.2016.01.002

南海北部西沙海槽盆地新生代层序地层及地震相

CENOZOIC SEQUENCE STRATIGRAPHY AND SEISMIC FACIES ANALYSIS OF XISHA TROUGH BASIN IN NORTHERN SOUTH CHINA SEA

  • 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: The Xisha Trough Basin is a large Cenozoic deep-water sedimentary basin with lower exploration degree, which is located in the western part of the north slope of the South China Sea. New high-precision multichannel seismic data combined with geological character of the surrounding area were used to analyze the sequence stratigraphy of the basin. 8 seismic reflection interfaces were identified in the study area. Combined with seismic amplitude cyclic changes, 3 seismic super sequences and 8 seismic sequences were divided for the Cenozoic of the study area, and the top-bottom contact relationship, reflection characteristics, formation thickness, velocity and Ps of each seismic sequence were described in detail. 5 types of typical seismic facies were identified within the sequence framework:parallel and sub-parallel facies, wedge-shaped divergent facies, foreset facies, chaotic configuration and channel-filled facies. Based on the analysis of seismic facies and sedimentary facies, the sedimentary characteristics and sedimentary history of each sequence were analyzed, it suggested that since Eocene, the study area showed the characteristics of nonmarine facies lake basin sedimentary system. Oligocene period, the basin suffered transgression and accepted the littoral and shallow marine deposition. Early Miocene, bathyal deposits were developed widely in central of the basin. In the late middle Miocene, the sea level decline and slope-bathyal environment reduced, Xisha Trough turbidite channel brought its prototype. From late Miocene to Quaternary, it came into stable regional subsidence stage in the study area, and bathyal-abyssal mudstone were developed mainly. In addition, as a result of uplifted area in the north and south edges of the study area provided provenance, nearshore submerged aprons and delta and fan delta also developed inside the sequences. Controlled by the terrain elevation difference the slope fans and turbidite bodies formed in steep slope belt or fault lower plate.

     

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