东海陆架盆地瓯江凹陷古近系层序地层学与沉积特征研究

Research on sequence stratigraphy and depositional features of Paleogene System of Oujiang Sag in the East China Sea

应用层序地层学方法,通过钻井、测井、地震反射等标志,识别出层序界面和最大海泛面,将东海陆架盆地瓯江凹陷古近系划分为3个层序,层序界面分别为T20、T40、T42、T50,并以地层叠置样式、岩性、岩相的变化为依据在单井上将每个三级层序细分为低位、湖侵和高位3个体系域;在层序格架内利用钻井和古生物资料分析了沉积体系在瓯江凹陷的平面展布:月桂峰组主要是三角洲相和湖泊相沉积,灵峰组和明月峰组是三角洲相和滨海相沉积,瓯江组和温州组为三角洲相和滨海相沉积,其中瓯江凹陷东次凹为浅海相沉积;沉积物源主要以西向东注入和西北方向向东南注入,同时揭示了古近系两次大规模海侵分别是古新世中期灵峰组沉积时期和始新世中期瓯江组沉积时期。

The strata of Oujiang Sag are divided into three sequences by identifying the sequence surfaces and the most flooding faces based on drilling data,logging data and seismic data.The sequence faces are recognized in the seismic section,they are T20,T40,T42,T50.Each sequence is divided into three tracts based on the changes of lithology facies,overlying model and so on.Due to the research on the drilling cores,the logging data and paleontologic evidence,we define some depositional systems such as delta,lacustrine and marine in the Paleogene System of Oujiang Sag.Yueguifeng group consistss of delta facies and lacustrine facies sediments,Lingfeng group and Mingyuefeng group consists of delta facies and littoral facies sediments,Oujiang group and Wenzhou group consists of delta facies and littoral facies sediments,and neritic facies deposited in the east sag.Sediments sourced from west and northwest.In the Paleogene System,two large marine transgressions happed in middle Paleocene and middle Eocene.