Essais d’interprétation des anomalies hydrogéothermales de la région de Ghardaia, Algérie.

Abstract

In southern Algeria, the geological formation of the Intercalary Continental constitutes an important reserve of thermal water. Syntheses are defining the main geothermal resources of the region at the basis of geothermal, geological, hydrogeological and geochemical studies. The evaluation of the thermal performance of the site studied is analyzed in detail and compared with those carried out in various studies. Through this thesis, it is proposed to study these reservoirs in the Saharan site of Ghardaïa, located in a semi-arid to arid region and its existence implies a potential recording of the large-scale climatic variability, to present the study of the thermal regime of the Basin from a reassessment of deep temperatures. This research has revealed the appropriate hypothesis for the warming of these waters. Previous predictions of deep temperatures show positive thermal anomalies. The results are mapped in a systematic way, their analysis makes it possible to highlight important major features, present on a large scale a significant surface geothermal potential that characterizes the site and another related to deep geothermal anomalies. To the south of the site studied, the values of the heat flux, the geothermal gradients, and the thermal conductivities determine the existence of an anomaly of deep origin. The study of the chemistry of water shows that the points observed testify to a deep origin of these waters. The relatively high values of the electrical conductivity of the water and of the mineralization in the North and NE point related to an important supply of saline waters. Finally, circulations and hydrothermal systems in fault zones associated with anisotropic sediments could explain the shape, the depth evolution and the intensity of the thermal anomalies identified. However, the cause of warming of the Intercalary Continental waters in the study area is depth.