| Title | Geochemistry of the North Western Algerian Geothermal System |
|---|---|
| Authors | Mohamed BELHAI, Yasuhiro FUJIMITSU, Fatima Zohra BOUCHAREB-HAOUCHINE, Tatsuto IWANAGA and Masami NOTO |
| Year | 2014 |
| Conference | Stanford Geothermal Workshop |
| Keywords | western Algeria, geothermometer, isotopes, mixing, shifting. |
| Abstract | The western Algerian low enthalpy geothermal system is geographycally divided into four important geothermal fields: the Hammam bouhdjar, Hammam Bouhnifia , Hammam Boughrara and Hammam Rabbi geothermal fields, geologically located in the Occidental Tell of the Alpine-Magrebide belt. The upper Jurassic limestones constitute the main reservoir rocks of the geothermal area. The thermal water surface temperatures ranged between 42.9 to 66.1°C, with a near-neutral pH (6.2 to 7.56). The thermal water samples studied show a high total dissolved solids (TDS) of up to 4003 mg/kg. The water chemistry revealed four types of waters: Na-HCO3-Cl, Na-Ca-HCO3, Na-Ca-SO4-HCO3 and a few Na-Mg-HCO3 facies. The isotopic results indicate a meteoric origin of the thermal water of the western Algerian geothermal systems. The δ O18 and δD shifting is due to the residence time of the thermal water in the reservoir, the faraway of the recharge zone area, and mixing with shallow groundwater. The estimated temperature, given by silica and cationic geothermometers, ranges between 125 to 250°C. The deep circulation of water in the study area is supplied by the high geothermal gradient around 4.4 °C per 100 m, which is supported by the NE reverse faults of Miocene age. |