Hydrothermal Characterization of the Jazan Geothermal System, Saudi Arabia

Abstract Al Ardah region in Southwestern Saudi Arabia is known for its hot springs, indicating an active geothermal system. However, there is no established conceptual model to explain how this system works. Therefore, the main objective of this study is to understand the hydrothermal characteristics of the area and develop a conceptual model by integrating hydrochemical analyses with geological information. To achieve this, water samples were collected from the hot springs and analyzed in the laboratory using geochemical techniques. This analysis allowed us to characterize hydrothermal system and estimate the geothermal reservoir temperature. In addition, outcrop observations were collected near the hot springs and possible recharge areas to investigate fractures and potential pathways for fluid flow based on the orientation of open fractures (joints). Our findings indicate that the thermal waters are characterized by Na-Cl water, suggesting that the water is discharged from a significant depth of the reservoir. The estimated reservoir temperature ranges from 140°C to 180°C. The high levels of Li and Sr imply a strong interaction between the thermal water and the granitic rock. Furthermore, precipitation is found to be the primary source of recharge for this system. Based on our analysis of various elements, we believe the thermal water flows from the east to the west through joints and faults, indicating the recharge zone is in the eastern part of the hot spring area. This study greatly enhances the understanding of the Al Ardah geothermal system in Jazan by integrating hydrochemical analysis and structural geology observations.