Occurrence characteristics of thermal springs in the mountain areas around the capital and their development and utilization prospects

This paper is the result of geological survey engineering.

Objective The mountain areas around the capital form an ecological conservation zone within the Beijing−Tianjin−Hebei region, encompassing several contiguous poverty-stricken areas. Despite relatively abundant thermal spring resources, their exploration and development remain limited. Research on the distribution patterns and occurrence characteristics of these springs is significant for guiding future geothermal exploration and development in mountain areas.

Methods Based on compiled data of thermal springs and deep-seated structures in the mountain areas of Beijing, Tianjin and Hebei, overlay analysis was employed to elucidate the correlations between thermal spring distribution and deep tectonic thermal setting. Supplementary field surveys, sampling, and comprehensive analysis were conducted to characterize the springs’ occurrence conditions and probe their heat sources and genetic mechanisms. Site-specific development strategies are proposed accordingly.

Results The thermal springs are mainly aligned along NE- and EW-trending deep major faults in linear or beaded distributions. 90% of the thermal springs are located within zones of Moho discontinuity variation. The temperature of thermal springs exhibits a correlation with Curie isotherm depth: high-temperature springs in the northern Yanshan area correspond to a Curie depth of 20 km, whereas moderately elevated temperatures in the Yanshan-Taihang transition zone relate to depths of 22−24 km. Lower-temperature springs in the Taihang and southeastern Yanshan regions associate with Curie depths of 22−26 km. Heat sources primarily originate from mantle−derived heat or anomalous “low−velocity, high−conductivity” layers, with mantle upwelling and deep faults facilitating upward heat transfer. At the regional scale, no direct correlation exists between spring discharge temperature and their circulation depth. Sedimentary rock reservoirs in intermountain basins exhibit relatively low thermal storage temperatures yet substantial discharge rates, reaching up to 120 m³/h; in contrast, metamorphic rock reservoirs often exceed 100°C but yield lower flow rates. Most thermal springs in the study area possess balneological value. Northern Yanshan Mountains and intermountain basins show significant space heating potential, while areas such as Chengde’s Qijia–Maojingba hold promise for combined heat and power generation.

Conclusions The distribution and occurrence characteristics of thermal springs in the mountain areas surrounding the capital city are influenced by the deep tectonic structures and regional geology. Favorable prospects for development and utilization exist particularly in the northern Yanshan Mountains and intermountain basins.