Characteristics of lithofacies paleogeography during Paleogene-Neogene in the area of North China platform

Abstract: Paleogene-Neogene strata in the area of North China platform is very thick in Bohai Bay basin, but relatively thin in southern North China. In the Ordos basin, however, Paleogene-Neogene strata are only developed in northwest area. During Paleogene, the main sedimentary type in Bohai Bay basin was rift-type deposition and the main sedimentary facies were shore-shallow lake, whose source came from multiple areas, such as Yanshan fold belt in the north, Taihang Mountain uplift in the west, Luxi uplift in the south, Liaodong uplift in the east and Cangxian uplift and Chengning uplift in the interior of the basin. Thesouthern North China was divided into many depressions with different sizes during Paleogene, with the development of sediments of fluvial facies. During Paleogene, the deposition only occurred in the northwest of Ordos basin, where fluvial sediments were developed. During Neogene, sedimentary zones were mainly located in the Bohai Bay basin, southern North China and the peripheral graben of Erdos basin, mainly with the development of fluvial facies and shore-shallow lacustrine facies. Large areas of Bohai Bay basin were uplifted during early Neogene, leading to the shrinkage of the lake basin and the denudation of parts of the areas. During the mid-late Neogene the basin formed a unified depression, the sedimentary facies were mainly fluvial facies and locally shore-shallow lacustrine facies. Southern North China entered into the depression development stage after rifting during Neogene, when large areas accepted deposition and developed fluvial facies. The western region along the periphery of the basin of Ordos formed a set of fluvial facies and shore shallow lake facies foreland basin deposits. Favorable exploration region of oil and gas was Bohai Bay basin during Paleogene-Neogene.