Heat flow, heat production, and lithospheric thermal regime in the Iberian Peninsula

The first heat-flow and heat-production maps of the Iberian Peninsula and its margins using previously acquired data are presented. The surface heat-flow map includes 553 determinations carried out on water and mining exploration wells, oil exploration wells and on the seafloor. The surface heat flow varies noticeably from the Iberian mainland (65 ± 10 mW m^-2) to the Atlantic and the Mediterranean margins, where the heat flow reaches values of about 40-50 mW m^-2 and 80-100 mW m^-2, respectively. The heat-production map consists of 664 determinations carried out on rock samples from the Varscan Iberian Massif and the Betics. The higher values are obtained for granitic rocks (2.5-3.5 μW m^-3), whereas metasediments and basic rocks reach values of 1-2.5 μW m^-3 and nearly zero, respectively. The lithospheric structure deduced for the Iberian Peninsula by combining heat-flow, heat-production and elevation data indicates that most of the Iberian mainland is characterized by a lithospheric thickness of 110 ± 5 km. This value is maintained across the West Atlantic margin, whereas towards the Mediterranean margin, the lithospheric thickness decreases down to 60-40 km. This study also suggests that the heat production in the southern Variscan Iberian Massif must be noticeably higher (3.7 ± 0.5 μW m^-3) than the rest of the areas in order to fit the measured heat-flow, crustal thickness and elevation data.