Abstract: The uranium deposits in the southern and northern parts of the Ordos Basin are located in the northern margin of the southern Weibei uplift and eastern part of the northern Yimeng uplift. Their geological features are similar to each other and uranium is hosted in the Middle Jurassic Zhiluo Formation (J²z). Both the present and ancient geothermal fields are different in the two areas. The present heat flow contour and the geothermal evolution degree in the southern part of the basin are higher than those in the northern part. Data from the coal-bearing strata of the Lower Jurassic Yan’an and the Carboniferous-Permian formations show that the vitrinite reflectance in the southern area is higher than that in the northern area. The maximum ancient geothermal temperature experienced, and the corresponding ancient geothermal gradient, both reconstructed from R_o data, also reveal that the southern area are higher than those in the northern basin. The present geothermal is lower than the paleo-geothermal because of the general uplifting in the Lower Cretaceous period. Because the erosion in the south is more intense than that in the north, the difference between the present and the ancient geothermals in the south is larger than that in the north. It is the tectonic thermal movement in the Qingyang and Fuxian areas in the south of the basin that leads to the formation of the abnormal geothermal fields and the higher geothermal evolution degree in the south.

Key words: Huangling and Dongsheng region, oil, gas, coal and uranium deposit, pale geothermal, geothermal evolution, geothermal field