Distribution characteristics and depositional environment of the Late Paleozoic coal-measure source rocks in the Bohai Bay Basin region

Based on outcrop, well logging, and mud logging data, this study investigates the sedimentary environment, the distribution patterns and the depositional environment of the Late Paleozoic coal-measure source rocks in the Bohai Bay Basin region. Coal-measure source rocks are mainly developed in the Taiyuan and Shanxi formations, consisting of coal and dark mudstone. Affected by frequent fluctuations of sea level, individual coal-measure source rock beds in the eastern region are relatively thin while the layers are numerous. Coal seams in the western region are relatively thick, but the cumulative thickness of dark mudstone is thinner than that in the eastern region. According to the characteristics of coal-measure source rocks, the depositional environments include tidal flat, lagoon, peat swamp, and subaqueous distributary bay. The Late Paleozoic coal-measure source rocks in the Bohai Bay Basin region has a large residual thickness and distributes widely. Under the influence of the Mesozoic and Cenozoic tectonic movement, some areas suffered from severe denudation. The residual coal-measure source rocks are mainly distributed in the Huanghua, Jizhong, and Linqing depressions.