| Abstract |
In this paper, a comprehensive comparison between geothermal temperature distribution and basin structure has been carried out by using modeling a typical geothermal- geological section. It is found that the geothermal field of the Beijing-Tianjin-Hebei Plain is characterized by zoning from east to west, segmentation from south to north, and vertical layering of the strata. From west to east, the geothermal field can be divided into five belts: the western sag, the central bulge, the eastern sag belt, the Cangxian uplift belt and the Cangdong sag belt. It is discovered that heat flow and cap-rock geothermal gradient are relatively high at basal bulge belts, but relatively low at sag belts. From north to south, the geothermal field of the Jizhong depression is divided into north, middle and south segments by the Xushui - Anxin and the Hengshui faults. Geothermal distribution in these segments also exhibits alternations between high and low values, which are similar to their basement structures. Vertically, the geothermal field within the overburden and underburden of the basal bulge belts displays a hierarchical structure of "mirror reflection". Abnormal geothermal field distributions are found to be confined to basement uplift belts, which is caused by the inhomogeneous heat conduction of the shallow basin deposits in both horizontal and vertical directions after tectonic movements. Therefore, according to the relationship between the degree of the basement uplift and the geothermal gradient of the cap rock, the geothermal type of the Beijing-Tianjin-Hebei Plain can be sub-divided into 5 types: the high convex, the convex, the low convex, the deep imbedded and the exposed. Among these, the high convex and the convex are the primary targets for geothermal exploration and development. |