The shear-wave velocity structure of the lithosphere–asthenosphere system in the Iberian area and surroundings

Abstract

The S-wave velocity model, to the depth of 300 km for the Iberian area and surroundings, is obtained with the non-linear inversion of Rayleigh wave tomographic data in the period range from 5 to 150 s. The three-dimensional model of the region is assembled from 74 juxtaposed one-dimensional cellular structures, sized 1°9 1°, by means of a local smoothing optimisation. The S-wave velocity model shows the almost constant velocity (*4.40 km/s) in the upper mantle beneath the Iberian Massif, the welldeveloped low-velocity zones in the Valencia Trough and under northwest Africa, and specific features of the upper mantle layering in the zone of the Iberian range. The thickness of the crust varies between 25 and 35 km with exceptions in the zones of the Valencia Trough (11-18 km) and Pyrenees (35-45 km). Our Vs models are well correlated with the geological structure along Transmed I and evidence several features of the lithosphere-asthenosphere system in the Betic-Rif domain: quite distinct Iberian, Alboran and Meseta crustal domains; relatively thin, well-developed lithosphere under the Rif system; and clearly defined boundary between the upper and lower asthenosphere. The cellular velocity model of the Betics, where ultrapotassic lamproitic magmatism is observed, has features similar to those of other three areas in the western Mediterranean where ultrapotassic lamproitic magmatism of different age is observed. The crust and upper mantle models in these four areas can be correlated with the age of the magmatism and the local heat flow, and outline how, starting from a naturally quite undifferentiated mantle where magma genesis is currently in progress, the differentiation in lithosphere and asthenosphere can take place in time.

Neotectonics of the SW Iberia margin, Gulf of Cadiz and Alboran Sea: a reassessment including recent structural, seismic and geodetic data

“…On the other hand, the thick lithosphere extending from offshore NW Morocco to the Gulf of Cadiz and the Betic chain (>140 km thick) is not confirmed by recent tomography (e.g. Raykova & Panza 2010) and receiver function studies (Dündar et al 2011). Dündar et al (2011), in particular, based on observations from stations surrounding the Alboran Sea, central Iberia and Morocco, suggests a lithosphere–asthenosphere boundary around 90–100 km depth under NW Morocco and southern Portugal, shallowing to 60 km in the Alboran, consistent with the predictions from our model.…”

Seismic Imprints of Plume‐Lithosphere Interaction Beneath the Northwestern Deccan Volcanic Province

“…We did not apply the local smoothing optimization (Boyadzhiev et al, ; Raykova & Panza, ) technique, due to the presence of distinct geological and tectonic features in the study region and the fact that this technique merely performs mathematical smoothing for a homogenous 3‐D model. Raykova and Panza () also mentioned that the local smoothing optimization procedure needs to be repeated many times to validate the selected models against well‐known structural features within the model uncertainties, incorporating constraints such as Moho depth, seismic energy distribution versus depth. Hence, we preferred to present the accepted models without applying any constraints and smoothing.…”

Imaging a relic of complex tectonics: the lithosphere‐asthenosphere structure in the Eastern Mediterranean

“…The tomographic maps were discretized with a grid of 1 o ×1 o and at each cell local group velocity dispersion curves have been computed. The error in the cellular dispersion values is computed as in Raykova and Panza (2010); where the single error is estimated as the sum of the root‐mean‐square of the measurement error and the standard deviation of the cellular dispersion curve at each period. The cellular dispersion curves obtained along the TransMed profiles VII and VIII, (Cavazza et al.…”