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 surf ace heat-flow map includes 553 determinations carried out on water and mining exploration wells, oil exploration wells and on the seafloor T he surface heat flow varies noticeably from the Iberian mainland (65 /- 10 mW m(-2)) to the Atlantic and the Mediterranean margins, where t he heat flow reaches values of about 40-50 mW m(-2) and 80-100 mW m(-2 ), respectively. The heat-production map consists of 663 determination s carried out on rock samples from the Variscan Iberian Massif and the Betics. The higher values are obtained for granitic rocks (2.5-3.5 mu W m(-3)), whereas metasediments and basic rocks reach values of 1-2.5 mu W m(-3) and nearly zero, respectively. The lithospheric structure deduced for the Iberian Peninsula by combining heat-flow, heat-product ion 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 Medit erranean margin, the lithospheric thickness decreases down to 60-40 km . This study also suggests that the heat production in the southern Va riscan Iberian Massif must be noticeably higher (3.7 +/- 0.5 mu W m(-3 )) than in the rest of the areas in order to fit the measured heat-flo w, crustal thickness and elevation data. (C) 1998 Elsevier Science B.V . All rights reserved.