Sequence stratigraphy, paleogeography, and coal accumulation regularity of major coal-accumulating periods in China

There are 9 major coal-accumulating periods during geological history in China, including the Early Carboniferous, Late Carboniferous-Early Permian, Middle Permian, Late Permian, Late Triassic, Early-Middle Jurassic, Early Cretaceous, Paleogene and Neogene. The coal formed in these periods were developed in different coal-accumulating areas (CAA) including the North China, South China, Northwest China, Northeast China, the Qinghai–Tibet area, and China offshore area. In this paper, we investigated depositional environments, sequence stratigraphy, lithofacies paleogeography and coal accumulation pattern of five major coal-accumulating periods including the Late Carboniferous to Middle Permian of the North China CAA, the Late Permian of the South China CAA, the Late Triassic of the South China CAA, the Early-Middle Jurassic of the North and Northwest China CAA, and the Early Cretaceous in the Northeast China CAA. According to distribution of the coal-bearing strata and the regional tectonic outlines, we have identified distribution range of the coal-forming basins, sedimentary facies types and coal-accumulating models. The sequence stratigraphic frameworks of the major coal-accumulating periods were established based on recognition of a variety of sequence boundaries. The distribution of thick coals and migration patterns of the coal-accumulating centers in the sequence stratigraphic framework were analyzed. The lithofacies paleogeography maps based on third-order sequences were reconstructed and the distribution of coal accumulation centers and coal-rich belts were predicted.