Geothermal map - Depths of the 90°C isotherm

The underground geothermal conditions can be presented, irrespective of the aquifers' position, with the appropriate geothermal maps. This map shows the expected depths of the isotherm of 90 °C and is made with data from 191 boreholes. In a way, it is the inverse of those ordinary temperature maps showing the temperature at certain depths. It is made on the basis of measured temperatures in accessible boreholes throughout the country. However, since the temperature field depends on the geological structure in the depths and tectonic characteristics, the course contours result of many influences, such as thermal conductivity of rocks, permeability and fracturing of rocks, all of which are reflected in the measured temperatures in boreholes. The distribution of boreholes, which were useful for the measurement of temperature, is very uneven, and different as regard the depths. The map of depths to 90 °C isotherm shows a positive anomaly in the northeastern part of Slovenia. As a result of thin Earth's crust in the area and the higher conductive heat flow from the Earth's mantle, there are higher temperatures and thus are inversely smaller depths to isotherm of 90 °C.