Speaking about heat flow density maps

Abstract

The conventional method of creating maps of heat flow values uses data obtained in boreholes, lakes and / or galleries of mines. Due to uneven geographical distribution of data it is necessary to use average values in some regions and to try to obtain information in other regions using indirect methods. In order to obtain more detailed information, aeromagnetic data have been used to find the Curie depth and through Curie point temperature to obtain information about the temperature gradient and the heat flow in the region. As the methods mentioned are based on completely different techniques, it is natural that the results obtained are not exactly coincident. There are, however, regions where the results obtained are contradictory. This work analyses some of the problems that arose using as an example the Northern region of Portugal and part of Galicia region in Spain. It is a region with a very heterogeneous upper crust and where hot water reservoirs were detected. Curie point depths achieved with temperature values obtained from measured heat flow density values are higher (values from 1 Km to 5 Km ) than values found from magnetic data.