Tectonic characteristics and their control on coal in the north of Ningwu coalfield

In order to investigate the tectonic characteristics and their role in controlling Carboniferous-Permian coal, the tectonic zone division, stratigraphic structure, tectonic evolution and stress field characteristics of Ningwu coalfield were analyzed based on the field outcrop, borehole lithology, 3d seismic data to clarify the coal-controlling structures of the main coal seam in the northern part of Ningwu coalfield. The study shows that since the Late Paleozoic, Ningwu coalfield has experienced three phases of tectonic movements of Indosinian, Yanshanian and Himalayan, in which the structure of Yanshan period is the most complex, with episodic and compressive extension, controlling the current tectonic pattern of the coalfield. The boundary of coalfield is mainly controlled by NE and near NS trending thrust fault zones, the interior is made up of three coal enrichment areas, such as Pinglu syncline, Suoxian syncline, and Ningwu syncline. The normal faults of NE-NEE trending, near NS and EW trending are developed in the coalfield, with the characteristics of superposition modification and differential distribution. These faults are cross and parallelly distributed in the plane, and vertically they are mostly presented as horst-graben structure or forward and reverse fault bench, which control the coal seam stability in different mine fields.