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