Imaging the crustal structure of the Central Iberian Zone (Variscan Belt): The ALCUDIA deep seismic reflection transect

ALCUDIA is a 230 km long, vertical incidence deep seismic reflection transect acquired in spring 2007 across the southern Central Iberian Zone (part of the pre-Mesozoic Gondwana paleocontinent) of the Variscan Orogen of Spain. The carefully designed acquisition parameters resulted in a 20 s TWTT deep, 60–90 fold, high-resolution seismic reflection transect. The processed image shows a weakly reflective upper crust (the scarce reflectivity matching structures identified at surface), a thick, highly reflective and laminated lower crust, and a flat Moho located at 10 s TWTT (30 km depth). The transect can be divided into three segments with different structural styles in the lower crust. In the central segment, the lower crust is imaged by regular, horizontal and parallel reflectors, whereas in the northern and southern segments it displays oblique reflectors interpreted as an important thrust (north) and tectonic wedging involving the mantle (south). The ALCUDIA seismic image shows that in an intracontinental orogenic crust, far from the suture zones, the upper and lower crust may react differently to shortening in different sectors, which is taken as evidence for decoupling. The interpreted structures, as deduced from surface geology and the seismic image, show that deformation was distributed homogeneously in the upper crust, whereas it was concentrated in wedge/thrust structures at specific sectors in the lower crust. The seismic image also shows the location of late Variscan faults in spatial association with the lower crustal thickened areas

Crustal structure beneath the Iberian Peninsula and surrounding waters: A new compilation of deep seismic sounding results

We present here an updated compilation of crustal parameters beneath the Iberian Peninsula and surrounding waters, inferred from extensive deep seismic exploration performed in the last three decades. Firstly, the more relevant experiments developed in both terrestrial and marine domains are revisited, together with the corresponding seismic velocity–depth models published that reveal the characteristics of the different tectonic domains sampled, including oceanic zones, continental margins, orogenic and rift belts. The results are summarized in three crustal transects sketched along representative directions. Secondly, we compiled the Moho depths along all the available seismic profiles to produce a geo-referred database. This database has then been interpolated using kriging algorithms to obtain a continuous Moho depth model, in the form of a regular grid file. This integrative Moho map for a key area in the Western Mediterranean documenting the interaction between European and African plates can contribute to constrain further regional studies, either at crustal, lithospheric or mantle scales.This is a contribution of the Team Consolider-Ingenio 2010 TOPO-IBERIA (CSD2006-00041). Additional founding provided by Generalitat de Catalunya (2005SGR00874) and by SIBERIA project (CGL2006-01171).Peer reviewe