BIOTA AND DEPOSITIONAL ENVIRONMENT IN BEIJIN- GTIANJIN-BAXIAN AREA DURING LATE EOCENE AND EARLY OLIGOCENE

The present paper deals with the paleoecology using the fossils of ostraco-da,algae,pelecypoda and fishes from more than dozen cores in Beijing-Tianjin-Baaian area.according to the eculogical characteristcs and geochemical norms,the late IJocene and early Oligocene sediments are divided into the"ecological facies groups"and the "ecologicalsequence groups",and the depositional environ- went in this area are reconstructed.