Profundidad de la transición dúctil-frágil en la corteza de Béticas-Rif y Mar de Alborán

Abstract

A three dimensional rheological model has been developed in the Betic-Rif and Alboran Sea region to characterize the brittle-ductile transition (BDT) in the upper crust; calculating a multiple set of regularlyspaced strength profiles based on a synthetic 3D lithospheric structure that gathers most of the available geological and geophysical data in the region. This is the first numerical modelling calculated in the region, for either compressional or tensional tectonic regimes, to characterize the rheological layering of the crust in the Betic-Rifean belt. The model results in a BDT topology highly constrained by the lithospheric thickness. The upper-crust brittle domain gets thinnest in the East Alboran Basin and the transition to the South Balearic Basin (7 and 6 km for tensional and compressional tectonic regimes), and becomes thicker westwards, getting the major values in the West Alboran Basin, near the Gibraltar Arc (18-16 km). In the onshore Betics, the BDT deeps towards the NW, with a general trend that results to be oblique to the shore line and to the main orientation of the mountain ranges, with a maximum value in the Southiberian Domain (~15-12 km) continued by a gently thinning of the brittle domain towards the Iberian foreland