Structural controls on geothermal fluid circulation: A case study from the Leibo geothermal system, eastern Chuan-Dian geothermal belt, China

The Leibo region, located on the eastern margin of the Tibetan Plateau. Geothermal resources, a vital renewable resource, are pivotal to Earth’s future sustainable energy development. The Leibo region is an uplifted mountain-type mid-low temperature geothermal zone with abundant hot springs, yet its complex geological structure has restricted geothermal resource development and utilization, necessitating urgent clarification of the structural control on geothermal water circulation here. To investigate the geothermal geological conditions in the Leibo region, a comprehensive approach was applied, integrating structural analysis, geophysical surveys, hydrogeochemistry, and drilling. The findings reveal that the Dengying Formation reservoir, overlain by multiple thermal caprock successions, contains an extensive dissolution-enhanced pore-vug-fracture network. Meteoric water from the southern mountainous area infiltrates downward through the fault, mainly converging within the damage zone of the Ebian-Jinyang fault and the Shangtianba syncline in its footwall, and then undergoes deep circulation of approximately 2500 m along the Ebian-Jinyang fault zone, driven by a topographic gradient exceeding 1100 m. After migrating over 20 km northward to the Majingzi dome, the geothermal water ascends through structural pathways or fractured porous reservoirs, mixes with shallow cold water, and emerges as hot springs with temperatures of 35.7–57 °C. Finally, a conceptual model of the Leibo geothermal system was developed, revealing its hydrothermal circulation mechanism governed by coupled structural-topographic controls. • AMT reveals the distribution of aquifers within the superimposed folds of Majingzi. • Ebian-Jinyang fault provides the main pathway for the circulation of thermal water. • The carbonate rocks of the Dengying Formation are high-quality geothermal reservoirs. • Leibo's geothermal water is recharged by southern highland meteoric water.