Structural characteristics and coal-bearing boundaries of Taiyuan Formation in Datong coalfield

Through analyzing the structural zones, tratigraphic pattern, tectonic evolution and stress field features of Datong coalfield in combination with the data of core, outcrop and 3D seismic exploration, the formation mechanism of Permian coal-bearing boundary is revealed. Studies show that Datong coalfield was reformed mainly in the Indosinian, Yanshanian, and Himalayan tectonic orogenies since late Paleozoic, and Yanshanian tectonic movement was the most complicated with the episodic activities and the alternation of extension and compression, which controls the present tectonic framework. Datong coalfield consists of eastern thrust fault zone, central anticline-syncline fold belt and western uplift zone. Fractures inside were mainly developed in NW-NWW and NE-NEE, and the former was formed earlier and with a larger scale. The tectonic stress in different stage controlled the occurrence characteristics of Permian coal seam, NS-trending compression in the early Indosinian dominated the northeastern margin of the coalfield, while the stress in Yanshanian period controlled the eastern, western and southwestern boundaries.