The association of coal and oil shale had been a hot topic for a long time. Various types of association of coal
and oil shale can be found in one basin, for instance, the coal can act as the roof or floor or interlayer of the oil shale, etc.
The most crucial factor for the formation of oil shale is stratification and seasonal blooming of lower plankton, while the
final formation of the coal still need a hypoxia restored deposition environment. We take Huangxian and Fushun basins as
typical examples to study the coal and oil shale sedimentary mechanisms controlled by the boundary fault. We found that
the sedimentary mechanisms are different in different stages during the process of basin evolution. In the early stage, the
association of coal and oil shale with thinner layers can be found. In the late part of early stage, thick layer coal seams and
oil shale can be formed because of the relative stable faults. In the middle stage, thicker oil shale can be formed in deep
lake and thicker coal seams can be formed in the lacustrine shore. In the late stage of basin evolution, the association of
thickest coal seams and oil shale can be formed as the stable tectonic environment. Compared with the depression basin,
more active fault and short cycle subsidence controlled by the episodic tectonic movements are the obvious characteristics.
Higher rate of tectonic subsidence and a vast difference between sedimentary (peat-bearing) supply rate and accommodation
space change rate are in favor of forming oil shale, and slower rate of tectonic subsidence is favor of forming
coal. The study found that faulted structures obviously control the development, thickness and distribution characteristics
of oil shale and coal. As mentioned the above, the episodic tectonic movement of continental rift basin controls the types
and filling and evolution of deposits.
Depositional history of the Janggi Conglomerate controlled by tectonic subsidence, during the early stage of Janggi Basin evolution