scholarly journals Traces of the crustal units and the upper-mantle structure in the southwestern part of the East European Craton

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 821-836 ◽  
Author(s):  
I. Janutyte ◽  
E. Kozlovskaya ◽  
M. Majdanski ◽  
P. H. Voss ◽  
M. Budraitis ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Synthetic Data ◽  
Velocity Model ◽  
East European Craton ◽  
P Wave ◽  
Seismic Velocities ◽  
P Waves ◽  
Data Set ◽  
Teleseismic Tomography ◽  
East European

Abstract. 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 upper-mantle 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 the West Lithuanian Granulite Domain (WLG). Also, in our results, we may have identified two anorogenic granitoid plutons.

scholarly journals Traces of the crustal units and the upper mantle structure in the southwestern part of the East European Craton

2014 ◽  
Vol 6 (1) ◽  
pp. 985-1021
Author(s):  
I. Janutyte ◽  
E. Kozlovskaya ◽  
M. Majdanski ◽  
P. H. Voss ◽  
M. Budraitis ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Velocity Model ◽  
P Wave ◽  
Seismic Velocities ◽  
P Waves ◽  
Teleseismic Tomography ◽  
East European ◽  
Seismic Experiment ◽  
Passive Seismic ◽  
Synthetic Datasets

Abstract. 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 dataset of 4195 manually picked arrivals of teleseismic P waves of 101 earthquakes (EQs) recorded in the PASSEQ 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 obtained a model of P wave velocity variations in the upper mantle beneath the TESZ and the EEC. In the study area beneath the craton we observed 5 to 6.5% higher and beneath the TESZ about 4% lower seismic velocities compared to the IASP91 velocity model. We found the seismic lithosphere-asthenosphere boundary (LAB) beneath the TESZ at a depth of about 180 km, while we observed no seismic LAB beneath the EEC. The inversion results obtained with the real and the synthetic datasets indicated a ramp shape of the LAB in the northern TESZ where we observed 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 possibly found an upper mantle 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 with the crustal units in the study area. On the other hand, at a depth of 120–150 km we possibly found a trace of a boundary of proposed palaeosubduction zone between the East Lithuanian Domain (EL) and the West Lithuanian Granulite Domain (WLG). Also, in our results we may have identified two anorogenic granitoid plutons.

scholarly journals A new model of the upper mantle structure beneath the western rim of the East European Craton

Solid Earth ◽  
2014 ◽  
Vol 5 (1) ◽  
pp. 523-535
Author(s):  
M. Dec ◽  
M. Malinowski ◽  
E. Perchuc
Keyword(s):  
Upper Mantle ◽  
Seismic Velocity ◽  
Seismic Station ◽  
Velocity Model ◽  
East European Craton ◽  
P Wave ◽  
Mantle Structure ◽  
Reflected Waves ◽  
East European ◽  
Upper Mantle Structure

Abstract. We present a new 1-D P wave seismic velocity model (called MP1-SUW) of the upper mantle structure beneath the western rim of the East European Craton (EEC) based on the analysis of the earthquakes recorded at the Suwałki (SUW) seismic station located in NE Poland which belongs to the Polish Seismological Network (PLSN). Motivation for this study arises from the observation of a group of reflected waves after expected P410P at epicentral distances 2300–2800 km from the SUW station. Although the existing global models represent the first-arrival traveltimes, they do not represent the full wavefield with all reflected waves because they do not take into account the structural features occurring regionally such as 300 km discontinuity. We perform P wave traveltime analysis using 1-D and 2-D forward ray-tracing modelling for the distances of up to 3000 km. We analysed 249 natural seismic events from four azimuthal spans with epicentres in the western Mediterranean Sea region (WMSR), the Greece and Turkey region (GTR), the Caucasus region (CR) and the part of the northern Mid-Atlantic Ridge near the Jan Mayen Island (JMR). For all chosen regions, except the JMR group for which 2-D modelling was performed, we estimate a 1-D average velocity model which will characterize the main seismic discontinuities. It appears that a single 1-D model (MP1-SUW model) explains well the observed traveltimes for the analysed groups of events. Differences resulting from the different azimuth range of earthquakes are close to the assumed picking uncertainty. The MP1-SUW model documents the bottom of the asthenospheric low-velocity zone (LVZ) at the depth of 220 km, 335 km discontinuity and the zone with the reduction of P wave velocity atop 410 km discontinuity which is depressed to 440 km depth. The nature of the regionally occurring 300 km boundary is explained here by tracing the ancient subduction regime related to the closure of the Iapetus Ocean, the Rheic Ocean and the Tornquist Sea.

scholarly journals Determination of rock densities in the Carpathian-Pannonian Basin lithosphere: based on the CELEBRATION 2000 experiment

2016 ◽  
Vol 46 (4) ◽  
pp. 269-287 ◽  
Author(s):  
Barbora Šimonová ◽  
Miroslav Bielik
Keyword(s):  
Lower Crust ◽  
Pannonian Basin ◽  
Average Density ◽  
East European Craton ◽  
P Wave ◽  
Seismic Velocities ◽  
Upper Crust ◽  
East European ◽  
P Wave Velocity

Abstract The international seismic project CELEBRATION 2000 brought very good information about the P-wave velocity distribution in the Carpathian-Pannonian Basin litosphere. In this paper seismic data were used for transformations of in situ P-wave velocities to in situ densities along all profiles running across the Western Carpathians and the Pannonian Basin: CEL01, CEL04, CEL05, CEL06, CEL09, CEL11 and CEL12. The calculation of rock densities in the crust and lower lithosphere was done by the transformation of seismic velocities to densities using the formulae of Sobolev-Babeyko, Christensen-Mooney and in the lower lithosphere also by Lachenbruch-Morgan’s formula. The density of the upper crust changes significantly in the vertical and horizontal directions, while the interval ranges of the calculated lower crust densities narrow down prominently. The lower lithosphere is the most homogeneous - the intervals of the calculated densities for this layer are already very narrow. The average density of the upper crust (ρ̅ = 2.60 g · cm−3) is the lowest in the Carpathian Foredeep region. On the contrary, the highest density of this layer (ρ̅ = 2.77 g · cm−3) is located in the Bohemian Massif. The average densities ρ̅ of the lower crust vary between 2.90 and 2.98 g · cm−3. The Palaeozoic Platform and the East European Craton have the highest density (ρ̅ = 2.98 g · cm−3 and ρ̅ = 2.97 g · cm−3, respectively). The lower crust density is the lowest (ρ̅ = 2.90 g · cm−3) in the Pannonian Basin. The range of calculated average densities ρ̅ for the lower lithosphere is changed in the interval from 3.35 to 3.40 g · cm−3. The heaviest lower lithosphere can be observed in the East European Craton (ρ̅ = 3.40 g · cm−3). The lower lithosphere of the Transdanubian Range and the Palaeozoic Platform is characterized by the lowest density ρ̅ = 3.35 g · cm−3.

scholarly journals A new model of the upper mantle structure beneath the western rim of the East European Craton

2014 ◽  
Vol 6 (1) ◽  
pp. 559-598
Author(s):  
M. Dec ◽  
M. Malinowski ◽  
E. Perchuc
Keyword(s):  
Upper Mantle ◽  
Seismic Velocity ◽  
Seismic Station ◽  
Structural Features ◽  
East European Craton ◽  
P Wave ◽  
Mantle Structure ◽  
Reflected Waves ◽  
East European ◽  
Upper Mantle Structure

Abstract. In this article we present a new 1-D P wave seismic velocity model (called MP1-SUW) of the upper mantle structure beneath the western rim of the East European Craton (EEC) based on the analysis of the earthquakes recorded at the Suwałki (SUW) seismic station located in NE Poland which belongs to the Polish Seismological Network (PLSN). This analysis was carried out due to the fact that in the wavefield recorded at this station we observed a group of reflected waves after expected P410P at epicentral distances 2300–2800 km from SUW station. Although the existing global models represent the first arrivals, they do not represent the full wavefield with all reflected waves because they do not take into account the structural features occurring regionally such as 300 km discontinuity. We perform P wave traveltime analysis using 1-D forward ray-tracing modelling for the distances up to 3000 km. We analysed 249 natural seismic events that were divided into four azimuthal spans with epicentres in the western Mediterranean Sea region (WMSR), the Greece and Turkey region (GTR), the Caucasus region (CR) and the part of the North Atlantic Ridge near the January Mayen Island (JMR). Events from each group were sorted into four seismic sections respectively. The MP1-SUW model documents bottom of the asthenospheric low velocity zone (LVZ) at the depth of 220 km, 335 km discontinuity and the zone with the reduction of P wave velocity atop 410 km discontinuity which is depressed to 440 km depth. The nature of a regionally occurring 300 km boundary here we explained by tracing the ancient subduction regime related to the closure of the Iapetus Ocean, the Rheic Ocean and the Tornquist Sea.

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

2014 ◽  
Vol 6 (2) ◽  
pp. 1723-1763 ◽  
Author(s):  
I. Janutyte ◽  
M. Majdanski ◽  
P. H. Voss ◽  
E. Kozlovskaya ◽  
PASSEQ Working Group
Keyword(s):  
Upper Mantle ◽  
Western Europe ◽  
Velocity Model ◽  
Suture Zone ◽  
P Wave ◽  
Mantle Structure ◽  
The West ◽  
Lower Velocity ◽  
Teleseismic Tomography ◽  
Upper Mantle Structure

Abstract. The presented study aims to resolve the upper mantle structure around the Trans-European Suture Zone (TESZ) which is the major tectonic boundary in Europe. The data of 183 temporary and permanent seismic stations operated during the period of the PASsive Seismic Experiment PASSEQ 2006–2008 within the study area from Germany to Lithuania was used to compile the dataset of manually picked 6008 top quality arrivals of P waves from teleseismic earthquakes. We used the non-linear teleseismic tomography algorithm TELINV to perform the inversions. As a result, we obtain a model of P wave velocity variations up to about ±3% compared to the IASP91 velocity model in the upper mantle around the TESZ. The higher velocities to the east of the TESZ correspond to the older East European Craton (EEC), while the lower velocities to the west of the TESZ correspond to younger Western Europe. We find that the seismic lithosphere-asthenosphere boundary (LAB) is more distinct beneath the Phanerozoic part of Europe than beneath the Precambrian part. To the west of the TESZ beneath the eastern part of the Bohemian Massif, the Sudetes Mountains and the Eger Rift the negative anomalies are observed from the depth of at least 70 km, while under the Variscides the average depth of the seismic LAB is about 100 km. We do not observe the seismic LAB beneath the EEC, but beneath Lithuania we find the thickest lithosphere of about 300 km or more. Beneath the TESZ the asthenosphere is at a depth of 150–180 km, which is an intermediate value between that of the EEC and Western Europe. The results imply that the seismic LAB in the northern part of the TESZ is of a shape of a ramp dipping to the NE direction. In the southern part of the TESZ the LAB is shallower, most probably due to younger tectonic settings. In the northern part of the TESZ we do not recognize any clear contact between Phanerozoic and Proterozoic Europe, but further to the south we may refer to a sharp and steep contact on the eastern edge of the TESZ. Moreover, beneath Lithuania at the depth of 120–150 km we observe the lower velocity area following the boundary of the proposed palaeosubduction zone.

Velocity model building for a single-offset 3C VSP data via deformable-layer tomography: a Texas salt dome example

Geophysics ◽  
2021 ◽  
pp. 1-44
Author(s):  
Yukai Wo ◽  
Jingjing Zong ◽  
Hao Hu ◽  
Hua-Wei Zhou ◽  
Robert R. Stewart
Keyword(s):  
Velocity Model ◽  
Salt Dome ◽  
P Wave ◽  
Velocity Variation ◽  
Shear Mode ◽  
P Waves ◽  
Data Set ◽  
Image Domain ◽  
Vsp Data ◽  
Geometric Variation

We have applied multiscale deformable-layer tomography (DLT) to build a laterally varying velocity model, using a single-offset vertical seismic profile (VSP) data set acquired for a salt proximity survey in southern Texas. The purpose of the VSP survey is to delineate the 2D salt flank using the P-wave reflections. Previous study has identified an anhydrate layer as the cap rock of the salt dome. The large impedance contrasts of this anhydrite layer generate strong downgoing P (sediment)-S (anhydrite)-P (salt) waves recorded by downhole geophones. Incidentally, the P-S-P-waves have similar traveltimes as those of the P-wave salt flank reflections, thus contaminating the imaging of the salt flank. Identifying shear-mode contamination requires an accurate velocity model of anhydrite. However, the extremely poor coverage of the single-offset VSP greatly challenges tomographic techniques to determine the lateral velocity variation. We tackle this problem using multiscale DLT, which characterizes the velocity field by a set of deformable layers. We constrain the layer velocities using the check-shot data and invert for the geometric variation. The inverted model indicates that the anhydrite layer has a “thick-thin-thick” lateral variation with offset, and the S-wave in the anhydrite layer helps in imaging the P-S-P-waves along the well track. The estimated anhydrite layer geometry is validated by the kinematic accuracies of P-waves in the data domain and P-S-P-waves in the image domain. Some in-salt dipping structures are determined by multiscale DLT as well. This field data example indicates that multiscale DLT is feasible for estimating velocities using VSP data of the single-offset situation. An accurate velocity model is the key for modeling and adaptive subtraction of the shear-mode contamination related to the salt geometry.

scholarly journals Imaging the Mediterranean upper mantle by p- wave travel time tomography

1997 ◽  
Vol 40 (4) ◽  
Author(s):  
C. Piromallo ◽  
A. Morelli
Keyword(s):  
Travel Time ◽  
Upper Mantle ◽  
Three Dimensional ◽  
Velocity Model ◽  
Structural Heterogeneity ◽  
Linear Interpolation ◽  
P Wave ◽  
Travel Times ◽  
P Waves ◽  
Tectonic Lineament

Travel times of P-waves in the Euro-Mediterranean region show strong and consistent lateral variations, which can be associated to structural heterogeneity in the underlying crust and mantle. We analyze regional and tele- seismic data from the International Seismological Centre data base to construct a three-dimensional velocity model of the upper mantle. We parameterize the model by a 3D grid of nodes -with approximately 50 km spacing -with a linear interpolation law, which constitutes a three-dimensional continuous representation of P-wave velocity. We construct summary travel time residuals between pairs of cells of the Earth's surface, both inside our study area and -with a broader spacing -on the whole globe. We account for lower mantle heterogeneity outside the modeled region by using empirical corrections to teleseismic travel times. The tomo- graphic images show generai agreement with other seismological studies of this area, with apparently higher detail attained in some locations. The signature of past and present lithospheric subduction, connected to Euro- African convergence, is a prominent feature. Active subduction under the Tyrrhenian and Hellenic arcs is clearly imaged as high-velocity bodies spanning the whole upper mantle. A clear variation of the lithospheric structure beneath the Northem and Southern Apennines is observed, with the boundary running in correspon- dence of the Ortona-Roccamonfina tectonic lineament. The western section of the Alps appears to have better developed roots than the eastern, possibly reflecting à difference in past subduction of the Tethyan lithosphere and subsequent continental collision.

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

Solid Earth ◽  
2015 ◽  
Vol 6 (1) ◽  
pp. 73-91 ◽  
Author(s):  
I. Janutyte ◽  
M. Majdanski ◽  
P. H. Voss ◽  
E. Kozlovskaya ◽  
Keyword(s):  
Upper Mantle ◽  
Western Europe ◽  
Suture Zone ◽  
P Wave ◽  
Mantle Structure ◽  
The West ◽  
Data Set ◽  
Lower Velocity ◽  
Teleseismic Tomography ◽  
Upper Mantle Structure

Abstract. The presented study aims to resolve the upper mantle structure around the Trans-European Suture Zone (TESZ), which is the major tectonic boundary in Europe. The data of 183 temporary and permanent seismic stations operated during the period of the PASsive Seismic Experiment (PASSEQ) 2006–2008 within the study area from Germany to Lithuania was used to compile the data set of manually picked 6008 top-quality arrivals of P waves from teleseismic earthquakes. We used the TELINV nonlinear teleseismic tomography algorithm to perform the inversions. As a result, we obtain a model of P wave velocity variations up to about ±3% with respect to the IASP91 velocity model in the upper mantle around the TESZ. The higher velocities to the east of the TESZ correspond to the older East European Craton (EEC), while the lower velocities to the west of the TESZ correspond to younger western Europe. We find that the seismic lithosphere–asthenosphere boundary (LAB) is more distinct beneath the Phanerozoic part of Europe than beneath the Precambrian part. To the west of the TESZ beneath the eastern part of the Bohemian Massif, the Sudetes Mountains and the Eger Rift, the negative anomalies are observed from a depth of at least 70 km, while under the Variscides the average depth of the seismic LAB is about 100 km. We do not observe the seismic LAB beneath the EEC, but beneath Lithuania we find the thickest lithosphere of about 300 km or more. Beneath the TESZ, the asthenosphere is at a depth of 150–180 km, which is an intermediate value between that of the EEC and western Europe. The results imply that the seismic LAB in the northern part of the TESZ is in the shape of a ramp dipping to the northeasterly direction. In the southern part of the TESZ, the LAB is shallower, most probably due to younger tectonic settings. In the northern part of the TESZ we do not recognize any clear contact between Phanerozoic and Proterozoic Europe, but further to the south we may refer to a sharp and steep contact on the eastern edge of the TESZ. Moreover, beneath Lithuania at depths of 120–150 km, we observe the lower velocity area following the boundary of the proposed paleosubduction zone.

scholarly journals Structure of the mantle and tectonic zoning of the central Alpine-Himalayan belt

2018 ◽  
Vol 9 (4) ◽  
pp. 1127-1145 ◽  
Author(s):  
V. G. Trifonov ◽  
S. Yu. Sokolov
Keyword(s):  
Seismic Tomography ◽  
Upper Mantle ◽  
Tien Shan ◽  
P Wave ◽  
Rift System ◽  
Western Himalayas ◽  
East African Rift System ◽  
Low Velocity ◽  
P Waves ◽  
East European

The Alpine-Himalayan orogenic belt is characterized by longitudinal zoning and transverse segmentation. Using the 3D seismic tomography model, we compiled the sections showing the deviations of seismic P-wave velocities from the average values in the mantle, and analyzed the sections in comparison with the data on the crustal inhomogeneities expressed in geological structures. The sections go across of the central part of the belt from Adriatic to Western Tien Shan, Pamirs, Western Himalayas, and the adjacent territories of the East African rift system, the Arabian, Turanian and Scythian plates, and the East European platform. Our model based on the seismic tomography data is mainly targeted at studying the inhomogeneities in the upper mantle, considering the fact that the resolution of mantle differentiation in terms of P-waves is higher in the upper mantle than in the lower one. Based on the analysis of the sections, we determine the directions of seismically low-velocity upper-mantle flows spreading from the Ethiopian-Afar super-plume, which differ in intensity. The relationships are revealed between these flows and the high-velocity bodies that are subsided into the mantle due to subduction and collision of the plates. The deep-seated features that give evidence of transverse segmentation of the belt are detected.

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