The Geochemica! and Isotopic Evidences of Groundwater Circulation in Ordos Plateau Cretaceous Basin, P.R of China

摘要

The hydrological cycling of groundwater in Ordos Cretaceous Basin show obvious stratification, the cycle can be divided into three layers by cycling depth, the shallow, the intermediate and the deep. In this paper, a classification standard formed with geochemical and isotopic information is described. The standard is based on a large number of borehole investigation and stratified sampling. In the shallow layer, the groundwater mostly is fresh water with lower amount of total dissolved solids, the dominated anion is HCO_3, tritium and ~(14)C features show a high or rich properties; in the intermediate layer, the geochemical type of groundwater are SO_4 or SO_4-Cl, the age of groundwater calculated by ~(14)C is less than 5000a; in the deep groundwater cycling, dominated anion show a complete evolution processes along the flow direction (HCO_3-SO_4-Cl) from recharge to discharge area, the groundwater age is commonly bigger than 5000a and even bigger than 10000a in the discharge area.