Deep structure of crust and mantle beneath Iberian Peninsula and surrounding regions from P and S receiver functions

The lithosphere of Iberia has been formed through a number of processes of continental collision and extension. In Lower Paleozoic, the collision of three tectonics blocks produced the Variscan Orogeny, the main event of formation of the Iberian lithosphere. The subsequent Mesozoic rifting and breakup of the Pangea had a profound effect on the continental crust of the south border of Iberia. Since the Miocene, the southern interaction between Africa and Iberia is characterized by a diffuse convergent margin that originates a vast area of deformation. The impacts of these processes on the deep structure of Iberia remain largely unknown. To understand deep structure and processes beneath Iberian Peninsula and surroundings region we process seismic recordings at 19 VBB stations located in this area, with P and S receiver function (PRF and SRF) techniques. The compilation of a dataset of nearly 2200 P receiver functions and nearly 2000 S receiver functions from these 19 stations yields a reliable and stable image of western Mediterranean transition zone. We determine the isotropic structure by joint inversion of P and S receiver functions. The inversion is conducted with a simulated annealing technique. This method operates in a depth range of long-period surface waves but differs by much higher lateral and radial resolution. We found Moho depths varying from ~30 km under the Iberian Massif, to 33-35 km under the Betics and reaching shallower depths of ~20 km southwards under the Balearic Island. Under north Africa the Moho depth changes from ~20 km beneath the easternmost part of the Rif region in the coastline to ~35 km beneath the Moroccan Meseta. The boundary between the high-S-velocity mantle lid and the LVZ in Iberian Peninsula is found at ~70 km. The lid is poorly expressed in the Mediterranean with implication that it is destroyed by rifting. This work is partially supported by the Portuguese Fundação para a Ciência e Tecnologia and under project TOPOMED (TOPOEUROPE/0001/2007).