| Abstract |
Geothermal systems in half-graben settings present unique challenges due to complex geological structures and fluid dynamics. To address these challenges, we utilized a combination of geological, geophysical, and hydrochemical data to develop a comprehensive model that elucidates the system's recharge mechanisms and heat source dynamics, using the Songwe geothermal field in southwest Tanzania as a case study. This research advances the understanding of geothermal processes in half-graben systems and demonstrates the efficacy of interdisciplinary methodologies in identifying and characterizing geothermal resources. The integration of gravity and hydrogeochemical data provided detailed subsurface models, revealing critical faults within the graben zones, which act as conduits for geothermal fluid discharge. Hydrogeochemical analyses revealed the stable isotopes δ18O and δ2H in the geothermal water, confirming its meteoric origin. These isotopes also define the recharge zones along fault flanks at elevations of ca. 1400 and 2400 meters above sea level. The geothermal water undergoes dilution and interactions before the discharge. Gravity data analysis further identified the location of heat sources with low anomalous gravity, which is linked to young magmatic intrusions at depth within the graben. In contrast, high gravity anomalies were observed away from the graben. This interdisciplinary approach facilitated a comprehensive understanding of the geothermal fluid circulation and heat transfer within the system, aiding in predictive zoning for artificial recharge and strategic resource management. This study not only advances the understanding of geothermal processes in half-graben systems but also demonstrates the effectiveness of employing interdisciplinary methodologies in identifying and characterizing geothermal resources. |