LAUSR

Abstract The hydrogen and oxygen stable isotopes are the indicative evidences of paleoclimate change. δD and δ18O composition of groundwater is commonly used to provide information on the climate record. This study focuses on the isotopic evidences of paleoclimate variations in the Northern Ordos Basin, where the Cretaceous groundwater have different ages since the middle age of Late Pleistocene. The hydrogen/oxygen stable isotopic compositions are analyzed and groundwater age is calculated by 14C based on 59 groups of data collected from 16 boreholes in the study area. The δD and δ18O data indicate that the temperature is relatively low in the middle age of Late Pleistocene, and it became to get warmer since the Holocene, which coincides with the variation of global scale. It is also found that the δD and δ18O could be divided into two groups in terms of groundwater age, the Holocene (