BOURGAS HYDROTHERMAL BASIN - STRUCTURE AND GEOTHERMAL POTENTIAL, BULGARIA

Abstract

Six hydrothermal deposits and nine hydrothermal occurrence outcroppings are available in the Bourgas hydrothermal basin. The area doesn't contain many surface expressions of hydrothermal activity, such as hot springs and altered rocks. The temperature of the water is within the range of 20?C to 49?C. Because of its special geological structure, tectonic and hydrogeological conditions, the total dynamic resources of the thermal and sub-thermal water were estimated at about 110 l/s. Exploitation is still on a very limited scale, 47% of the geothermal potential of the basin, and the basic application is related to bathing, spas and for bottling potable water. The work carried out in the Bourgas hydrothermal basin consisting of geological and hydrogeological mapping, geophysical investigations and water sampling of ion of thermal springs and wells for geochemical analysis. Silica and cation geothermometers were applied to predict possible subsurface temperatures. The equilibrium state of thermal water was studied by means of log Q/K diagrams and Na-K-Mg triangular diagram. It was found that water with temperature 80-100oC could be obtained by drilling.