The age and isotopic characteristics of groundwater in Taiyuan Formation limestone aquifer of the Huaibei coalfield

For the purpose of understanding the age, hydrochemical characteristics and evolution of groundwater in Taiyuan Formation limestone aquifer in the Huaibei coalfield, twenty nine groundwater samples were collected from the Huaibei coalfield, and concentrations of major ions, hydrogen and oxygen isotopes and ¹⁴C radio isotopes were analyzed. The traditional graphic and statistical methods were used to discuss the evolution of groundwater and hydrochemical characteristics as well as the age and runoff characteristics of groundwater. Some conclusions have been reached:the ages of groundwater samples in Taiyuan Formation limestone aquifer vary from 2900a to 21920a, the hydrochemical characteristics of groundwater are different in different mining areas. The groundwater samples in the Zhahe mining area have lower TDS concentrations, the minimum age and the highest values of δD and δ¹⁸O, and hence this area could be regarded as the recharge area in the Huaibei coalfield. The groundwater samples in the Suntuan mine and Taoyuan mine have largest age, higher concentrations of TDS and lower δD and δ¹⁸O values, and such areas could be considered to be the drainage areas. The contour diagrams about TDS concentrations and groundwater age show consistent patterns, suggesting that the main recharge area of groundwater in Taiyuan Formation limestone aquifers lies in the northeast area of the Huaibei coalfield. The groundwater runoff characteristics in Taiyuan Formation are mainly controlled by the tectonic setting, and the recharge conditions and water-rock interaction degrees of groundwater are main factors for the concentrations of TDS and hydrogen and oxygen isotopes.