本文以沟鞭藻生态为基础,结合我国东部第三纪盆地的地球化学、古生物、岩相古地理、区域地质和全球海平面变化,论证东部含油气盆地在第三纪时不存在海水侵进。出现有“海相”沟鞭藻、有孔虫和钙质超微化石是由于当时湖泊咸化及富养料造成的。同时认为沟鞭藻是广盐性生物,其最适应于半咸水环境。 Based on the ecology of Daphniphyllum algae and combining with the geochemistry, palaeontology, palaeogeography, regional geology and global sea level changes in the Tertiary Basin in the eastern part of China, this paper argues that there is no seawater intruded into the petroliferous basins in the eastern China . Appeared to “marine ” ditchfly, foraminifera and calcareous nanofossils is due to the lakes salinization and nutrient-rich material caused. At the same time that dinoflagellate is widely salt biological, its most suitable for brackish water environment.