Thermal effects of linked lithospheric and upper crustal–scale processes: Insights from numerical modeling of the Cenozoic Central Catalan Coastal Ranges (NE Spain)

Abstract

Processes influencing the thermal state of the continental crust, such as heat upwelling related to rifting and isotherm reorganization due to mass redistribution by erosion, deposition, and (fault‐)tectonic transport, operate at different scales, and their effects overlap. In this paper, we use lithospheric‐ as well as crustal‐scale numerical modeling tools in order to quantify the contributions of these various factors to the geothermal field, establishing their relative relevance. We apply the models to address the thermal evolution of the Catalan Coastal Ranges (NE Spain) during the Cenozoic, a period that is characterized by a change in tectonic style, from Pyrenean compression to extension related to the western Mediterranean rifting. Results of the lithospheric‐scale thermal model for extensional basins show an increase in the geothermal surface gradient of about 11°C/km in the Catalan Coastal Ranges during the Neogene, related to extensional thinning of the lithosphere in the Valencia Trough (western Mediterranean). Predictions of the upper crustal–scale thermal model, incorporating fault motions and surface mass redistribution (erosion and sedimentation), point to little changes in the isotherms due to fault block movements in the Paleogene and Neogene. In contrast, erosion appears to have a significant effect on the thermal history of basement rocks sited in the shallowest crust. Comparison of the integrated lithospheric‐ and upper crustal–scale modeling results with apatite fission track and apatite (U‐Th)/He thermochronology data reveals larger amounts of Neogene to present cooling than predicted by the models. On the basis of this unresolvable mismatch, we suggest that, similar to present, forced fluid convection along fault planes played an important role in the evolution of the geothermal field during the Neogene stage of rifting.