Hydrogeological and Hydrogeochemical Characteristics of Deep Buried Coal Seam Roof in Shaanxi and Inner Mongolia Contiguous Area

In order to make clear the hydrogeological and hydrogeochemical characteristics of deep buried coal seam roof in Shaanxi and Inner Mongolia contiguous area, hydrogeochemical data are used to carry out a comprehensive research. The results showed that Cretaceous Zhidan group has close hydraulic connection with Quaternary aquifer and the water chemical characteristic is HCO₃-Ca type water with low degree of mineralization. The hydrogeochemical characteristics were not related with floor elevation of Zhidan group aquifer. Anding group can effectively cut off the upper aquifer water supply into Zhiluo formation aquifer and Yanan formation aquifer. The distance from main mining coal seam to Anding formation roof was larger (>250 m), and the height of diversion fissure zone could not reach Zhidan group aquifer. There was a negative correlation between total dissolved solids (TDS) and stratum elevation in the roof aquifer of main mining coal seam. The water chemical characteristic was SO₄-Na type water in most coal mines. But the water chemical characteristic was SO₄-Na·Ca type water in Yubei Mining Area, and the value of Cl/HCO₃ was small. There was better hydraulic connection in Yubei Mining Area than other areas.