A shear wave velocity model of the European upper mantle from automated inversion of seismic shear and surface waveforms

Abstract

SUMMARY We present a new, S‐velocity model of the European upper mantle, constrained by inversions of seismic waveforms from broad‐band stations in Europe and surrounding regions. We collected seismograms for the years 1990–2007 from all permanent stations in Europe for which data were available. In addition, we incorporated data from temporary experiments. Automated multimode inversion of surface and S‐wave forms was applied to extract structural information from the seismograms, in the form of linear equations with uncorrelated uncertainties. The equations were then solved for seismic velocity perturbations in the crust and mantle with respect to a 3‐D reference model with a realistic crust. We present two versions of the model: one for the entire European upper mantle and another, with the highest resolution, focused on the upper 200 km of the mantle beneath western and central Europe and the circum Mediterranean. The mantle lithosphere and asthenosphere are well resolved by both models. Major features of the lithosphere–asthenosphere system in Europe and the Mediterranean are indentified. The highest velocities in the mantle lithosphere of the East European Craton (EEC) are found at about 150 km depth. There are no indications for a deep cratonic root below about 330 km depth. Lateral variations within the cratonic mantle lithosphere are resolved as well. The locations of kimberlites correlate with reduced S‐wave velocities in the shallow cratonic mantle lithosphere. This anomaly is present in regions of both Proterozoic and Archean crust, pointing to an alteration of the mantle lithosphere after the formation of the craton. Strong lateral changes in S‐wave velocity are found at the northwestern margin of the EEC and may indicate erosion of cratonic mantle lithosphere beneath the Scandes by hot asthenosphere. The mantle lithosphere beneath western Europe and between the Tornquist–Teisseyre Zone and the Elbe Line shows moderately high velocities and is of an intermediate character, between cratonic lithosphere and the thin lithosphere of central Europe. In central Europe, Caledonian and Variscian sutures are not associated with strong lateral changes in the lithosphere–asthenosphere system. Cenozoic anorogenic intraplate volcanism in central Europe and the circum Mediterranean is found in regions of shallow asthenosphere and close to changes in the depth of the lithosphere–asthenosphere boundary. Very low velocities at shallow upper‐mantle depths are present from eastern Turkey towards the Dead Sea transform fault system and Sinai, beneath locations of recent volcanism. Low‐velocity anomalies extending vertically from shallow upper mantle down to the transition zone are found beneath the Massif Central, Sinai and the Dead Sea, the Canary Islands and Iceland.

Upper mantle structure around the Trans-European Suture Zone obtained by teleseismic tomography

“…The higher velocity values in this area are observed down to about 200 km, which coincides well with the studies by WildePiórko et al (2010), Majorowicz et al (2003) and Koulakov et al (2009). Legendre et al (2012) found the highest velocity values in the mantle of the EEC at about 150 km depth. Further to the northeast of the TESZ, the high-velocity area goes deeper, and beneath the territory of Lithuania, we find the thickest lithosphere of about 300 km or more (Fig.…”

“…Koulakov et al (2009) observed the positive P wave velocity anomaly beneath the EEC down to at least 300 km, which indicates even thicker lithosphere compared to . Legendre et al (2012) find no indications of a deep cratonic root below about 330 km for the EEC, while Geissler et al (2010) do not observe any clear indications of deep seismic LAB beneath the EEC either.…”

Receiver function images of the Hellenic subduction zone and comparison to microseismicity

“…Meier et al (2007) identified two slab segments and proposed that they are associated with laterally varying properties of the African slab. Furthermore, in the Mediterranean southeast of Crete, Rhodes and south of western Anatolia, high velocities in the mantle lithosphere -typical for cold oceanic lithosphere -are found by tomographic studies (Bijward et al, 1998;Marone et al, 2004;Endrun et al, 2008;Legendre et al, 2012), whereas south of Peloponnese and western Crete velocities in the mantle lithosphere are lower Legendre et al, 2012).…”

Subduction or delamination beneath the Apennines? Evidence from regional tomography

“…More recently, Koulakov et al (2009) have constructed P and S tomography models for the upper mantle beneath Europe, which took into account a newly obtained crustal model by Tesauro et al (2008). In parallel there were several models of Europe created based on surface-wave data (Boschi et al, 2004(Boschi et al, , 2009Marone et al, 2004;Legendre et al, 2012). Adjoint tomography has been used for studying the European region by Zhu et al (2012).…”