Evidence of Transgression Lake of Subei Basin During Late Cretaceous and Paleocene Epoch and Its Geological Significance

Key words: 
• Subei Basin /
• late Cretaceous and Paleocene Epoch /
• transgression lake /

Abstract: Based on the analysis of core of Subei basin during late Cretaceous and Paleocene Epoch, the authors conclude that Subei Basin was linked with the sea and the deposit was affected by transgression. The causes of marine transgression may be the tension power have predominated the groundstress condition of the east China and develop a series of halfgrabenlike basin which was filled by huge thick sediment of early Tertiary in shelf of HuabeiBohai gulf , Subeisouth yellow sea and East China sea. Consequently, seawater transgresses from East China Sea to yellow sea and connects half grabenlike basin on the shelf and sea during short period. During the sediment of late Cretaceous Taizhou Formation and Paleocene Epoch Funing Formation, Subei Basin have formed dark shale containing lots of ostracoda that include predominated whole basin E1f2 Formation and E1f4 Formation and local K2t2 Formation, which have become main source rocks of the basin. The evidences of paleontology, minerals in rocks and geochemistry can ascertain the environment of lake basin which develops during late Cretaceous and Paleocene Epoch. This environment was generally designated "near sea lake basin" or the layer and member that was transgressed by sea was called "transgression lake basin", whereas, which was generally called inland lake and river alluvium plain during sediment of Eocene Dainan Formation and Sanduo Formation. Based on the analysis and sufficiency cognition of Transgression Lake of late Cretaceous and Paleocene Epoch of Subei Basin, the research is important to not only paleogeographic reconstruction of Subei basin during late Cretaceous and Paleocene Epoch but also the comment to make upon development and distribution of the source rocks and potential of oil and gas generation.