Sur la migration des éléments par thermodiffusion. Etat et perspectives d'un modèle géochimique

Abstract

In the lithosphère, particularly in great geothermal activity zones, there exist possibilities of quasi permanent thermal diffusion natural convection couplage which is able to develop a thermogravitational effect. The study of concrete cases requires a good knowledge of physical parameters introduced in thermogravitational-effect theoretical relations, as well as hydrothermal convective circuits, the nature of solutions, and local thermal gradient values. A thermogravitational schematic model has been developed and applied to Salton-Sea geothermal system. This model is supported by some simple geometric dispositions fitted to convective cell development and underlining the effect of geometric and thermal parameters on estimate concentration extent. This model provides the rough estimate concentrations of brines, like those observed in-situ, in agreement with most geochemical and geological local contingencies. The refining of this model will be linked to a better knowledge of the organization and stability of convective circuits in underground fluids.