## 3 Results and Analysis
### Geological Structure Characteristics of Zhongtang and Wentang Hotsprings
#### 3.2.3 Geological Characteristics of Xiatang Geothermal Field  
(a) General Situation of Xiatang Hotspring  
Xiatang hotspring is located 10.5 km to the east of Zhongtang hotspring, exposed at the northwest corner of Xiatang Street on the North Bank of Sha River, 150 m from the Bank of Sha River. The altitude is 179 m, about 4 m higher than Shahe. Xiatang hotspring outcrops in the form of spring group. According to the collected data, there were seven spring holes distributed in a nearly east-west linear direction, with a total flow of 30.71 m\({}^{3}\)/h and a water temperature of 64 \({}^{\circ}\)C. In this survey, the measured water temperature was 61-63 \({}^{\circ}\)C, there were 13 geothermal wells and 3-4 wells were in normal use. According to the investigation and statistics of the utilization of local water intake structures, the water flow was 200-350 m\({}^{3}\)/h, the average value was about 250 m\({}^{3}\)/h, and the daily water consumption was 5000 m\({}^{3}\)/d; the water level drawdown was about 29 m, and the maximum value was 38.2 m. The hotspring group was distributed in the range of 40 m from east to west and about 10 m from south to north. According to the previous drilling data, only cold water (mainly groundwater in the upper Quaternary loose layer) or no groundwater was found in the strata out of this range.  
(b) Geological Structure Characteristics of Xiatang Hotspring  
Xiatang hotspring outcrops in the middle porphyry biotite monzogranite of Yanshan period. Except that the area of Lianhua and Laozhaung villages in the north is the andesite porphyrite of Xionger group, which is distributed in the north-west direction, the rest surrounding area of the hot spring is all Yanshanian granite. Xiatang hotspring is 3100 m away from Checun-Xiatang fault (F1-1) in the north, 500 m away from Shuimozhuang-Lichun fault (F1-3) in the south, and the north-west direction Yangzhuang fault (F2-2) passes through the west of the spring. About 500 m east of the hot spring, it is a joint intensive belt with a width of 1 m, strike of 70\({}^{\circ}\), incline to southeast, dip angle of 83\({}^{\circ}\). Five to ten meters to the north of the belt is an east-west compressed foliation belt, with a dip angle of 80-84\({}^{\circ}\). According to this, it can be inferred that the joint intensive belt and the compressed foliation  
Figure 7: Resistivity profile of Zhongtang and Wentang geothermal fields.  
belt are a near east-west fault zone, but the exposure conditions are not good, and the fault plane is not clear. Xiatang hotsprings mainly outcrop along the fault zone, and this fault and Yangzhuang fault (F2-2) should be the main control structures of Xiatang geothermal field (Figure 8).  
The drilling data collected revealed the strata of Xiatang field. 0-4.0 m, the rock core was loose and composed of deluvial silty clay mixed with gravel and gravel; the main component pebble was granite with a diameter of 2-15 mm. 4.0-150.0 m, the rock core was grayish brown and variegated granite, and it was columnar and massive; the main mineral composition was quartz, feldspar, pyroxene, hornblende, and mica. Among them, the core below 80 m was broken, fault fracture zone was visible, fracture was developed, and calcite vein distribution was visible. Geothermal water gushed out below this depth. A large number of pyrite was distributed on fracture surface, pore was developed, and fault breccia could be clearly seen (Figure 9).  
Figure 8: Geological structure of Xiatang geothermal field.