Evolution Mechanism and Circulation Characteristics of Ordovician Limestone Water in Zhuozishan Coalfield

In order to research the hydro-geological characteristics of Ordovician limestone water of Zhuozishan Coalfield in the western margin of Ordos Basin, the evolution mechanism and circulation characteristics of Ordovician limestone water were discussed in this paper by using the methods of the reconstruction of the geologic history, the comparison of regional surface and the deep analysis of the key areas.The results showed that the Ordovician deposit of Zhuozishan Coalfield was an open oceanic basin, it was transformed from the eastern continental shelf to the western continental slope environment, which clearly influenced the compositions of the calcite, dolomite and so on in the water-bearing strata. The main geological processes which influenced the hydro-chemical evolution of Ordovician limestone water included the lixiviation, the alternating absorption of cations and redox reaction, which caused the constant evolution of the chemical compositions of the Ordovician limestone water in runoff process.The evolution rule of the chemical compositions Ordovician limestone water in both Luotuoshan and Pinggou Coal Mining Areas from east to west were characterized by the degree of the minera lization increasing gradually from less than 1.0 g/L to 3.0 g/L, the hydro-chemical type transforming from HCO₃·Cl·SO₄-Mg·Na to Cl·SO₄-Na. The make-up runoff conditions of the Ordovician limestone water in the north-west of Limin and Qipanjing Coal Mining Areas were better, the degree of the mineralization was less than 1.0 g/L and gradually increased in the runoff process from northwest to southeast, and the hydro-chemical type was mainly Cl·SO₄-Na. The results can provide the basis for the future research on the prevention and control of the Ordovician limestone water hazards of Zhuozishan Coalfield in the western margin of Ordos Basin.