10 research outputs found
Moho depth across the Trans-European Suture Zone from P-and S-receiver functions
The Mohorovicic discontinuity, Moho for short, which marks the boundary between crust and mantle, is the main first-order structure within the lithosphere. Geodynamics and tectonic evolution determine its depth level and properties. Here, we present a map of the Moho in central Europe across the Teisseyre-Tornquist Zone, a region for which a number of previous studies are available. Our results are based on homogeneous and consistent processing of P- and S-receiver functions for the largest passive seismological data set in this region yet, consisting of more than 40 000 receiver functions from almost 500 station. Besides, we also provide new results for the crustal Vp/Vs ratio for the whole area. Our results are in good agreement with previous, more localized receiver function studies, as well as with the interpretation of seismic profiles, while at the same time resolving a higher level of detail than previous maps covering the area, for example regarding the Eifel Plume region, Rhine Graben and northern Alps. The close correspondence with the seismic data regarding crustal structure also increases confidence in use of the data in crustal corrections and the imaging of deeper structure, for which no independent seismic information is available. In addition to the pronounced, stepwise transition from crustal thicknesses of 30km in Phanerozoic Europe to more than 45 beneath the East European Craton, we can distinguish other terrane boundaries based on Moho depth as well as average crustal Vp/Vsratio and Moho phase amplitudes. The terranes with distinct crustal properties span a wide range of ages, from Palaeoproterozoic in Lithuania to Cenozoic in the Alps, reflecting the complex tectonic history of Europe. Crustal thickness and properties in the study area are also markedly influenced by tectonic overprinting, for example the formation of the Central European Basin System, and the European Cenozoic Rift System. In the areas affected by Cenozoic rifting and volcanism, thinning of the crust corresponds to lithospheric updoming reported in recent surface wave and S-receiver function studies, as expected for thermally induced deformation. The same correlation applies for crustal thickening, not only across the Trans-European Suture Zone, but also within the southern part of the Bohemian Massif. A high Poisson’s ratio of 0.27 is obtained for the craton, which is consistent with a thick mafic lower crust. In contrast, we typically find Poisson’s ratios around 0.25 for Phanerozoic Europe outside of deep sedimentary basins. Mapping of the thickness of the shallowest crustal layer, that is low-velocity sediments or weathered rock, indicates values in excess of 6km for the most pronounced basins in the study area, while thicknesses of less than 4km are found within the craton, central Germany and most of the Czech Republic.Peer reviewe
Passive Seismic Experiment “13 BB Star” in the Margin of the East European Craton, Northern Poland
2-D seismic tomographic and ray tracing modelling of the crustal structure across the Sudetes Mountains basing on SUDETES 2003 experiment data
Traces of the crustal units and the upper-mantle structure in the southwestern part of the East European Craton
The presented study is a part of the passive seismic
experiment PASSEQ 2006–2008, which took place around
the Trans-European Suture Zone (TESZ) from May 2006 to
June 2008. The data set of 4195 manually picked arrivals of
teleseismic P waves of 101 earthquakes (EQs) recorded in
the seismic stations deployed to the east of the TESZ was
inverted using the non-linear teleseismic tomography algorithm
TELINV. Two 3-D crustal models were used to estimate
the crustal travel time (TT) corrections. As a result,
we obtain a model of P-wave velocity variations in the upper
mantle beneath the TESZ and the East European Craton
(EEC). In the study area beneath the craton, we observe up
to 3% higher and beneath the TESZ about 2–3% lower seismic
velocities compared to the IASP91 velocity model. We
find the seismic lithosphere–asthenosphere boundary (LAB)
beneath the TESZ at a depth of about 180 km, while we observe
no seismic LAB beneath the EEC. The inversion results
obtained with the real and the synthetic data sets indicate a
ramp shape of the LAB in the northern TESZ, where we observe
values of seismic velocities close to those of the craton
down to about 150 km. The lithosphere thickness in the EEC
increases going from the TESZ to the NE from about 180 km
beneath Poland to 300 km or more beneath Lithuania. Moreover,
in western Lithuania we find an indication of an uppermantle
dome. In our results, the crustal units are not well
resolved. There are no clear indications of the features in the
upper mantle which could be related to the crustal units in the
study area. On the other hand, at a depth of 120–150 km we
indicate a trace of a boundary of proposed palaeosubduction
zone between the East Lithuanian Domain (EL) and theWest
Lithuanian Granulite Domain (WLG). Also, in our results,
we may have identified two anorogenic granitoid plutons