【摘要】 珠江口盆地西部新近系主要为陆架浅海沉积环境,发育良好的海相砂岩储集层和多套储盖组合。因此,对这些砂体的成因及赋存位置的海平面变化研究至关重要。在有孔虫及钙质超微化石资料所建立的珠江口盆地西部新生代年代地层格架基础上,以有孔虫个体大于0.25mm的浮游有孔虫丰度和百分含量为依据,参照微体古生物化石带、岩性、电测和地震资料,总结出三级旋回边界和最大海泛面识别标志,从而提出具有国际对比意义的三级层序划分对比方案,对盆地内18口井进行了层序划分,识别出了2个完整的二级层序和15个三级层序。根据南海海域表层沉积物建立起的浮游有孔虫含量与水深的定量关系,得出量化古水深数据,辅以古生态成因相及特征沉积构造分析、海岸上超分析编制了海平面变化曲线,指出珠江口盆地西部新近系受拗陷阶段持续沉降影响,形成不同于海退型全球海平面变化的台阶式海侵特征。更多还原

【Abstract】 The Neogene in the Western Pearl River Mouth Basin is dominated by neritic shelf sediments, in which favorable marine sand reservoirs and multi-sets of reservoir-cap combinations are discovered. Therefore, it is the key to study the sea-level changes which control the origin and position of sand bodies. In order to understand the sea level changes, a chronostratigraphic framework of the western Pearl River Mouth Basin has been set up based on the abundance and percentage of foraminifera and calcareous nannofossils(>0.25 mm) combined with bio-events and age data, lithological data, logging data and seismic data. Single well analysis of sequence stratigraphy is carried out for the data from eighteen wells. Two 2 nd-order sequences and 15 3 rd-order sequences are identified. The sea-level change curve was then established in cooperation with the study of the ancient ecological facies and depositional structures as well as the on-lap relationship, recognized on the reflection seismic profile. Paleo-water depth was quantified through comparison of the fossil foraminifera to present species in the western South China Sea, for which the living conditions are known. The Neogene in the western part of the Pearl River Mouth Basin is affected by the continuous subsidence during the depression stage and a stepped transgression sequence is formed, different from the sequences formed in global regressive stages.更多还原