Fomation mechanism of fault-controlled circulation geothermal spring: evidence from tectonics, thermal model, and isotopes

The effective utilization of geothermal energy helps reduce carbon emissions and mitigate climate change. Understanding the formation mechanism of geothermal systems is a prerequisite for effective exploitation. The formation of geothermal systems is influenced by various factors such as tectonic characteristics, heat sources, and water circulation, making it necessary to comprehensively analysis its mechanism by integrating these factors. Tangquan ,a natural geothermal spring in Zhangjiakou City, China, has great potential in geothermal exploitation. However, previous studies have offered incomplete explanations of its genesis. Therefore, this study investigated the stratigraphic properties and structural distribution of the study area through geophysical exploration surveys, mapped the distribution of the low-temperature field using geothermal geological modeling methods and inferred that the heat source in the study area is radioactive; and through isotope analysis methods, clarified that the water source in the study area is atmospheric precipitation. By integrating these information, the formation mechanism of the Tangquan, a deep circulation type geothermal system controlled by faults, is revealed. These results can guide the further development and utilization of Tangquan, while also enhancing the understanding of fault-controlled and deep circulation type geothermal systems.