| Abstract |
Xilinhot City is a typical area of volcanic geothermal anomaly in northern China. Now, the degree of research in the area of geothermal resources is very low, basically a blank area of geothermal research. With the development of society and economy, especially for the scale development of tourism, it is urgently needed to carry out research on the development conditions of geothermal resources exploration in urban and surrounding areas. Therefore, the study has important academic significance and social value. The study consists of the following three steps. First of all, according to the regional geological data collection and field reconnaissance and other means, at the same time combining the previous geophysical exploration and drilling data, we analyzed the landform, stratum lithology, fracture structure, hydrologic geology and geological conditions in study area and basically grasped the geophysical survey. Then, by collecting water samples in the field, laboratory testing, water quality and geothermal iconic components classifying and stable isotope analyzing, etc., we analyzed the hydrogeochemical characteristics in the study area and preliminarily delineated the geothermal anomaly area. Finally, combining with the geophysical and hydrogeochemical conditions, the geothermal geological conditions in the study area were comprehensively analyzed from the gheat, cover, storage, connectionh four basic elements and the preliminary evaluation on the geothermal resources was made. The research shows that: the region has the basic conditions of geothermal resources occurrence. The heat source mainly comes from the heat released from the mantle and bedrock. The cover is the Quaternary, Tertiary, Cretaceous and partly Jurassic formations and the insulation layer is mainly the Cretaceous strata. Affected by new cathaysian tectonic system, deep fractures which along the direction of north-east, north-west and east-west are likely exist in this area and form the underground hot water upwelling channels. In addition, the thermal storage situation is preliminarily evaluated in the study as follows: there may be two different heat storage in the north and south sides of Xilinhot, the pore type (K) and the tectonic fracture type (Pz).(1)The pore thermal storage is distributed on the fault basin on the the northern side of urban areas. There are two heat reservoirs in this area:‡@Cretaceous sandstone and sandy conglomerate layers, depth of less than 1600m, porosity is between 10%`20%, but the water yield is not large, the salinity is relatively high, so the exploitation conditions are general.‡AThe yield of fracture-karst water in Paleozoic carbonate rocks of buried hill underlying the cretaceous strata is better, but the buried depth is larger (more than 2000 m) and the salinity ranges from 3.5 to 13.5 g/L. This water can be used for medical mineral water. (2) Structural fissure heat reservoir is mainly distributed in bedrock fissure water area in the south of urban area. There are granite intrusions Shallow concealed at depth of 400`500 m. The thermal storage in the form of fracture belt occurs in granite rock fractured zone which controlled by Shangdewenduo thrust fault and limekiln normal fault. The quality and quantity of water is good. This water has good workability. |