is the teisseyre tornquist zone an ancient plate boundary of baltica the teisseyre tornquist zone ttz is generally regarded as a fossil plate boundary in europe that extends 2000 km from the baltic sea to the black sea we used an integrated approach merging potential fields and seismic data to explore crustal architecture across the ttz in central poland the aim of the study was to test whether the ttz coincides with an early paleozoic caledonian suture formed through the closure of the tornquist ocean along the sw baltica margin the suture is presumed to separate the east european craton eec from the paleozoic terranes of western europe two seismic reflection lines from the polandspan experiment were used to image the deep structure at the sw margin of the eec lines pl 5300 and pl 5400 run ne sw in central and northern poland respectively the seismic interpretation down to top of basement was integrated with 2 d gravity and magnetic modeling to highlight the structure of the deep crust both the gravity and magnetic models show a suture that welds together two blocks at the base of crust however top of basement above the suture dips uniformly to the sw and is overlain by undisturbed lower paleozoic and younger sediments by implication the suture must have developed in the precambrian and both crustal blocks amalgamated belong to the eec consequently the caledonian suture formed by the closure of the tornquist ocean between avalonia and baltica must be located farther southwest beneath thick upper paleozoic and mesozoic sediments

regional and teleseismic events recorded across the tesz during polonaise 97 abstract 20 polish short period three component stations were continuously operating for three weeks during polonaise 97 in the contact zone between palaeozoic and precambrian platforms in poland the distances between seismometers were about 20 km and the digitization interval was 0 02 s besides the shots a few regional events from the lubin area and teleseismic events mainly from the se backazimuth were also recorded interpretation of traveltimes for p and s waves for regional events using a simplified lt 7 model of crustal structure for theoretical calculation allowed correction of their origin time the same model can also explain the traveltime residuals of p waves for teleseismic events the main features of the division of poland into two platforms by the teisseyre tornquist tectonic zone ttz is seen both in the shape of residuals of teleseismic phases and in the receiver function a passive seismic experiment made during polonaise 97 as a reconnaissance for future teleseismic tomography experiment tor 2 gave quite promising results however to make a traveltime tomography and receiver function analysis the duration of data acquisition should be about half a year

errata neogene fjordal sedimentation on the western margin of the lambert graben east antarctica the lambert graben is occupied by the world s largest fjord system through which flows the lambert glacier the amery ice shelf and their tributaries along the western margin of the graben in the northern prince charles mountains remnants of uplifted miocene and pliocene strata of the glacigenic fjordal pagodroma group total more than 800 m in thickness these sediments provide evidence for a dynamic east antarctic ice sheet during the neogene period each of the four pagodroma group formations defined from this region rests unconformably on either proterozoic or permo triassic rocks the unconformity surfaces represent parts of the walls and floors of neogene fjords for these surfaces to have been eroded the ice must have been grounded out as far as the continental shelf in prydz bay the pagodroma group was deposited by wet based glaciers discharging into a fjordal setting and includes lithofacies that are quite different from those produced by modern antarctic ice masses the principal lithofacies are massive diamicts and soulder gravels deposited both close to a calving grounded glacier terminus and from icebergs the few stratified diamicts are the product of more distal iceberg sedimentation an ice transported gravel lithofacies includes rockfall debris derived from palaeofjord walls and mixed with subglacially derived diamicts some lithofacies contain evidence of subaquatic slumping and gravity flowage volumetrically minor lithofacies include laminites with some exposures exhibiting large ice rafted clasts the laminites represent less proximal mainly ice free fjordal sediments resulting either from tidal current sorting of suspended sediment originating from subaquatic glaciofluvial discharge or from turbidity currents derived from unstable subaquatically deposited glacigenic sediment the pagodroma group provides a record of multiple glaciation by dynamic sliding glaciers carrying large amounts of both basal and supraglacial debris the closest modern analogues in terms of the thermal and dynamic characteristics of the neogene lambert glacier appear to be the fast flowing tidewater glaciers of east greenland these glaciers originate from the interior ice sheet and discharge large volumes of icebergs the resulting lithofacies are predominantly diamicts

shear wave velocity variations in the upper mantle beneath central europe summary a new model eur s91 of shear wave velocity variations in the upper mantle beneath central europe and surrounding regions down to a depth of 670km is presented the model is derived from the inversion of the waveforms of 217 seismograms using the partitioned waveform inversion method for the seismogram in the time window from the s wave arrival to the fundamental mode of the rayleigh wave the seismograms were mostly assembled from digitally recording long period and broad band stations in europe the resulting 3 d model accurately predicts most of the observed waveforms in a wide band of frequencies body waves were fit for frequencies up to 60mhz the fundamental rayleigh mode which at high frequencies is more prone to scattering and multipathing was generally low passed at 25 mhz the resolving power of the data set depends strongly on the density of available wave paths and varies as a function of geographical position small scale heterogeneities like the subducted lithosphere in the hellenic collision zone were imaged in the region with the highest density of wave paths which indicates an optimum resolution of better than 200 km the main new results of this study pertain to the transition between east and central europe we present new information about the structure below the tornquist teisseyre zone ttz the ttz is generally regarded as the boundary between the precambrian crust of the baltic shield russian platform and the younger crust of central europe our 3 d s velocity model reveals that below this line a sharp lateral boundary extends down to at least 140 km depth with high velocities beneath the baltic shield and russian platform contrasting to the low velocities beneath the younger regions of europe the observed velocity contrast across the ttz is largest between the pannonian basin and the russian platform where it is equal to 12 per cent at 80 km depth at depths of 300 400 km the ttz is underlain by a zone of low s velocity which indicates a local thinning of the deeply rooted high velocity structure or tectosphere that underlies most of eastern europe in addition to these new results on the transition region between east and central europe a number of features that are present in other tomographic results have been confirmed the precambrian provinces of europe are characterized by high s velocities low velocities are found beneath the pannonian basin the western mediterranean northern aegean sea turkey and a small region south west of the massif central the lithosphere beneath the paris basin has a positive s velocity anomaly the resolution of all these anomalies has been established with sensitivity tests

lg wave modelling for the north sea summary theoretical seismograms for inhomogencous 2 d media are computed via summation of surface wave modes and use of transmission coefficient matrices in an attempt to explain the observed lg wave barrier within thc continental structure of the north sea where other scientists have been able to trcat lg wave propagation in the north sea for one frequency many surface wave modes and a complicated structural model of the north sea grabens our method takes into account many frequencies and is consequentiy limited to a few significant modes and a relatively simple structural model

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 30 km 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 v p v s ratio 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

anisotropy across the sorgenfrei tornquist zone from shear wave splitting abstract during the tor 1 passive seismic experiment in 1996 97 a maximum of 139 temporary seismograph stations were operating over the sorgenfrei tornquist zone stz in an area extending from northern germany through denmark to central sweden one of the objectives was to study horizontal anisotropy directions in the subcrustal lithosphere and asthenosphere across the trans european suture zone to achieve this goal broad band and intermediate period 5 s data of the tor 1 stations and additional stations of permanent networks grsn geofon were analysed for splitting of sks and skks phases as a result of the relatively dense station spacing the method offers good lateral resolution of anisotropy preliminary results suggest that the directions of the fast horizontal s wave velocity are affected by the stz in central europe and southern sweden far away from the stz fast s wave directions are approximately e w while they turn more northerly closer to the stz where they are approximately parallel to the trend of the stz no significant shear wave splitting was observed north of 57 n and east of 14 e small delay times between 0 2 and 0 5 s observed at the northernmost tor 1 station t40s and t60s may be controlled by anisotropy in a thickened crust the mantle contribution of horizontal anisotropy within the stz is probably constrained to an approximately 60 km thick zone in the depth range between 70 and 300 km the observations are consistent with a model where azimuthal anisotropy is not governed by present day mantle flow in the asthenosphere but rather is frozen into the subcrustal lithosphere during the last episode of tectonic activity

lower lithospheric structure beneath the trans european suture zone from polonaise 97 seismic profiles abstract the large scale polonaise 97 seismic experiment investigated the velocity structure of the lithosphere in the trans european suture zone tesz region between the precambrian east european craton eec and palaeozoic platform pp in the area of the polish basin the p wave velocity is very low vp 8 25 km s in the palaeozoic platform and 8 1 km s in the precambrian platform good quality record sections were obtained to the longest offsets of about 600 km from the shot points with clear first arrivals and later phases of waves reflected refracted in the lower lithosphere two dimensional interpretation of the reversed system of travel times constrains a series of reflectors in the depth range of 50 90 km a seismic reflector appears as a general feature at around 10 km depth below moho in the area independent of the actual depth to the moho and sub moho seismic velocity ringing reflections are explained by relatively small scale heterogeneities beneath the depth interval from 90 to 110 km qualitative interpretation of the observed wave field shows a differentiation of the reflectivity in the lower lithosphere the seismic reflectivity of the uppermost mantle is stronger beneath the palaeozoic platform and tesz than the east european platform the deepest interpreted seismic reflector with zone of high reflectivity may mark a change in upper mantle structure from an upper zone characterised by seismic scatterers of small vertical dimension to a lower zone with vertically larger seismic scatterers possible caused by inclusions of partial melt

deep temperature distribution along three profiles crossing the teisseyre tornquist tectonic zone in poland abstract the teisseyre tornquist tectonic zone is a large deep fracture zone separating the precambrian east european craton from the variscan system of central europe with the use of ample deep seismic sounding data the detailed crustal temperature distribution was calculated for three profiles crossing this zone in its northern central and southern segments the conversion technique of transforming the reported seismic velocities p into heat production values a was used together with the temperature dependent thermal conductivity structure and the observed surface heat flow pattern in addition to the obtained 2 d temperature distribution this work allowed a more reliable estimate of the crustal contribution to the surface heat flow and thus the characteristic moho heat flow q m 26 mw m 2 to be assessed in this region the results can also serve as an independent confirmation of the necessity of applying the p a conversion separately for phanerozoic and for precambrian rocks

constraints on the velocity structure beneath the tornquist teisseyre zone from beam forming analysis summary the primary indicators of lateral heterogeneity in the earth are the slowness and azimuth of incoming seismic signals on a regional scale surface waves in the upper mantle and crust are often scattered and or refracted which results in deviations from the great circle azimuth the slowness and direction of propagation of an arriving wave packet provides information about the lateral heterogeneity and can be measured by performing beam forming on the recordings across an array of stations the azimuthal deviation gives a constraint on the transverse velocity gradient along the path in addition its frequency dependence gives information on the depth dependence of the heterogeneity we have performed beam forming of fundamental mode rayleigh waves in the period range of 20 to 100 s travelling from the south east of europe to the nars nl array in the netherlands the purpose of this study is to obtain new information about the velocity structure beneath the tornquist teisseyre zone ttz the ttz is known to be a transition between the higher seismic velocities in the thicker and older precambrian crust of the east european platform eep and the lower velocities in the thinner and younger palaeozioc crust of central and western europe tectonic europe te however the lateral velocity gradient and the depth extent of this transition are not very well constrained we have used events located at both sides of the ttz and both the direct rayleigh wave and its coda have been analysed on the one hand the deviation of the wave propagation paths relative to the great circle observed in the direct wave for the events on the eastern side of the ttz confirms earlier results i e it gives independent evidence for a thicker crust and up to 10 per cent higher velocities in the first 150 km of the upper mantle beneath the eep than beneath the te such a contrast also explains observed surface head waves refracted along the ttz on the other hand no energy reflected at the ttz is detected in the coda for the events on the western side from synthetic experiments based on a linearized theory we conclude that from this absence of reflections no lower bound can be imposed on the width of the transition zone across the ttz at different depths source mechanisms other than the ones for the events used are needed to observe these reflections at different depths for both a sharp and a smooth transition

crustal structure of the mid polish trough beneath the teisseyre tornquist zone seismic profile abstract a new seismic refraction and wide angle reflection experiment in the teisseyre tornquist zone ttz in poland was conducting during july 1993 as an international polish finnish german and swedish co operation the ttz profile running in an se nw direction was exactly located in the central part of the mid polish trough in the zone of maximum subsidence from upper permian to upper cretaceous 19 shot points were placed along the 450 km profile the interval between the shot points was about 25 km 31 explosions 90 to 1000 kg of dynamite were recorded in two deployments using 135 modern three component seismic stations with spacing of the recording sites of about 1 7 km in this area the depth of the consolidated basement with a velocity of about 5 7 5 8 km s is 5 to 12 km deep nevertheless the p wave velocity is very low vp

the exceptional earthquakes in kaliningrad district russia on september 21 2004 abstract the earthquakes of magnitudes m w 5 0 and 5 2 in the kaliningrad enclave of russia on september 21 2004 were unexpected in a low seismicity area the earthquakes caused moderate damage in the kaliningrad enclave and smaller damage in northern poland and in southern and western lithuania the largest earthquake was the strongest ever recorded instrumentally in the region and it was felt at distances up to 800 km in directions towards the west and south the perceptibility area is abruptly cut off by the tornquist teisseyre zone the south west margin of the east european craton the earthquakes are instrumentally located at depths 16 20 km under the central northern part of the sambia peninsula in the kaliningrad enclave for these events it is noted that the macroseismic calculations of 10 19 km depths are in reasonable agreement the source mechanism of the largest earthquake was determined to be a right lateral strike slip on a wnw ese near vertical fault of orientation almost parallel to the tornquist teisseyre zone and to the north coast of the sambia peninsula based on available stress information it is interpreted that the underlying cause of the earthquakes is the absolute plate motion historical information is scanty it is searched in an attempt to evaluate past seismic activity in the region and to evaluate vulnerable weakness zones in the geological structures

geophysical and petrological modeling of the lower crust and uppermost mantle in the variscan and proterozoic surroundings of the trans european suture zone in central europe abstract high quality seismic data on the lower crust and uppermost lithospheric mantle in the central european part of the trans european suture zone together with thermal and gravimetric data enables the quantitative modeling of the rocks occurring in those parts of the lithosphere including their mineral compositions and the chemical composition of individual minerals the p3 seismic profile is located at the sw margin of the east european craton the lower crust is dominated by gabbronoritic intrusions plagioclase an 45 ab 55 clinopyroxene di 80 hed 20 orthopyroxene en 74 fs 26 and the uppermost mantle is harzburgitic olivine and orthopyroxene mg 0 91 the lower crust and upper mantle of the p1 seismic profile belong to the trans european suture zone albeit the upper crust is of variscan affinity the p1 lower crust has gabbronoritic composition which is layered from plagioclase rich compositions on the top to the orthopyroxene rich ones at the bottom plagioclase an 45 ab 55 clinopyroxene di 80 hed 20 orthopyroxene en 85 fs 15 and is lithologically different proterozoic and variscan surroundings the 100 200 km eclogite slice garnet alm 48 gr 25 py 27 clinopyroxene di 51 hed 10 jd 39 with a thickness of 5 10 km occurs in the uppermost mantle sampled by the p1 profile the nied wied massif is located at the ne margin of the bohemian massif which shows an exposed variscan basement the lower crust beneath the nied wied massif consists of gabbroic rock of variable proportions of plagioclase an 45 ab 55 and clinopyroxene di 80 hed 20 whereas the uppermost mantle is supposedly spinel harzburgite olivine ortho and clinopyroxene mg 0 90 our models show that the lowermost crust and uppermost mantle of the east european craton do not continue to the sw into the trans european suture zone in its central european section in poland

lithospheric structure of the trans european suture zone along the ttz cel03 seismic transect from nw to se poland abstract the large scale celebration 2000 seismic experiment investigated the velocity structure of the crust and upper mantle between western portion of the east european craton eec and the eastern alps this area comprises the trans european suture zone the carpathian mountains the pannonian basin and the bohemian massif this experiment included 147 chemical shots recorded by 1230 seismic stations during two deployments good quality data along 16 main and a few additional profiles were recorded one of them profile cel03 was located in southeastern poland and was laid out as a prolongation of the ttz profile performed in 1993 this paper focuses on the joint interpretation of seismic data along the nw se trending ttz cel03 transect located in the central portion of the trans european suture zone first arrivals and later phases of waves reflected refracted in the crust and upper mantle were interpreted using two dimensional tomographic inversion and ray tracing techniques this modelling established a 2 d quasi 3 d p wave velocity lithospheric model four crustal units were identified along the transect from northwest to southeast thickness of the crust varies from 35 km in the pomeranian unit nw to 40 km in the kuiavian unit to 50 km in the radom ysogory unit and again to 43 km in the narol unit se the first two units are thought to be proximal terranes detached from the eec farther to the southeast and re accreted to the edge of the eec during the early palaeozoic the origin of the remaining two units is a matter of dispute they are either portions of the eec or other proximal terranes in the area of the polish basin first two units the p wave velocity is very low vp

deep seismic survey images crustal structure of tornquist zone beneath southern baltic sea the tornquist zone is europe s longest tectonic lineament and bisects the continent in a nw se direction from the north sea off nw denmark to the black sea new deep seismic reflection and coinci

contrasting sources of late paleozoic rhyolite magma in the polish lowlands evidence from u pb ages and hf and o isotope composition in zircon the polish lowlands located southwest of the teisseyre tornquist zone within trans european suture zone were affected by bimodal but dominantly rhyolitic magmatism during the late paleozoic thanks to the inherited zircon they contain these rhyolitic rocks provide a direct source of information about the pre permian rocks underlying the polish lowland this paper presents zircon u pb geochronology and hf and o isotopic results from five drill core samples representing four rhyolites and one granite based on the ratio of inherited vs autocrystic zircon the rhyolites can be divided into two groups northern rhyolites where autocrystic zircon is more abundant and southern rhyolites where inherited zircon dominates we suggest that the magma sources and the processes responsible for generating high silica magmas differ between the northern and southern rhyolites isotopically distinct sources were available during formation of northern rhyolites as the hf and o isotopes in magmatic zircon differ between the two analysed localities of northern rhyolites a mixing between magmas formed from baltica derived mudstone siltstone sediments and avalonian basement or mantle can explain the diversity between the zircon compositions from the northern localities daszewo and wysoka kamienska conversely the southern rhyolites from our two localities contain zircon with similar compositions and these units can be further correlated with results from the north east german basin suggesting uniform source rocks over this larger region based on the ages of inherited zircon and the isotopic composition of magmatic ones we suggest that the dominant source of the southern rhyolites is variscan foreland sediments mixed with baltica avalonia derived sediments

large scale waveform inversions of surface waves for lateral heterogeneity 2 application to surface waves in europe and the mediterranean linear surface wave scattering theory is used to reconstruct the lateral heterogeneity under europe and the mediterranean using surface wave data recorded with the network of autonomously recording seismographs nars the waveform inversion of the phase and the amplitude of the direct surface wave leads to a variance reduction of approximately 40 and results in phase velocity maps in the period ranges 30 40 s 40 60 s and 60 100 s a resolution analysis is performed in order to establish the lateral resolution of these inversions using the phase velocity perturbations of the three period bands a two layer model for the s velocity under europe and the mediterranean is constructed the s velocity perturbations in the deepest layer 100 200 km are much more pronounced than in the top layer 0 100 km which confirms that the low velocity zone exhibits pronounced lateral variations in both layers the s velocity is low under the western mediterranean while the s velocity is high under the scandinavian shield in the deepest layer a high s velocity region extends from greece under the adriatic to northern italy several interesting smaller features such as the massif central are reconstructed one of the spectacular features of the reconstructed models is a sharp transition in the layer between 100 and 200 km near the tornquist tesseyre zone this would indicate that there is a sharp transition at depth between central europe and the east european platform the waveform inversion of the surface wave coda leads to good waveform fits but the reconstructed models are chaotic this is due both to a lack of sufficient data for a good imaging of the surface wave energy on the heterogeneities and to an appreciable noise component in the surface wave coda

random heterogeneity of the lithosphere across the trans european suture zone summary data from the passive teleseismic experiment tor across the trans european suture zone tesz which took place in 1996 1997 are used to study the random structure of the lithosphere ne of the tesz the baltic shield beneath southern sweden and beneath the north german danish basin p coda waves from deep teleseismic events give information on the small scale heterogeneity of the near receiver lithosphere on scales of one wavelength using an energy ux model the time and frequency behaviour of the p coda has been interpreted in terms of scattering qs and anelastic attenuation qi estimates of qs were obtained for the frequency range 0 5 3 hz for the north german danish basin and 0 5 7 hz for the baltic shield the two areas show a diierent scattering behaviour in denmark northern germany the scattering qs 125 200 is stronger than in southern sweden qs 275 500 and the peak of q 1 s occurs at higher frequencies ne of the tesz anelastic attenuation is negligible for the baltic shield whereas for the north german danish basin anelastic attenuation is present but still much weaker than scattering attenuation with a modi ed energy ux model for depth dependent scattering and assuming an exponential autocorrelation function the depth variation of correlation length a and rms velocity uctuation e can in principle be resolved for the baltic shield the scattering is mostly con ned to the crust with a 1k m ande 4 per cent the subcrustal lithosphere only shows weak uctuations the data from the north german danish basin cannot be explained by strong scattering within the crust only crustal parameters are a 5 10 km and e 8 per cent for the subcrustal lithosphere correlation lengths of 10 20 km and rms velocity uctuations of 6 8 per cent are found additional tests con rmed that the thick sedimentary cover in this area has no signi cant eiect on these results for the deeper structure correlation lengths for the sediments are smaller than 5 km and rms velocity uctuations e are 7 8 per cent

lateral heterogeneity of europe s upper mantle as inferred from modelling of broad band body waves summary the upper mantle velocity structure beneath europe is investigated by body wave modelling of broad band seismograms from earthquakes in the eastern mediterranean recorded by stations in north west europe the gross features of the p and s wave velocity distribution as inferred from the data show a high velocity lid a low velocity zone and two discontinuities at depths of approximately 420 and 650 km the seismograms also present evidence for lateral heterogeneity of at least a few per cent 2 5 per cent for p 4 per cent for s to a depth of approximately 400 km many of the inferred velocity variations can be related to the tectonic setting of the region between source and receiver broad band seismograms are essential for such detailed study of upper mantle structure using body wave modelling

design and siting of a new regional array in central europe abstract in recent years increased interest has emerged in the evaluation of high frequency seismic signals from events at regional distances small sized and many element arrays like noress in scandinavia have proven capable of taking advantage of the very efficient propagation of high frequency seismic phases after an extensive field survey the bavarian forest bf area at the southeastern border of the federal republic of germany with austria and czechoslovakia was chosen as a target region to install a noress type array the bf area as part of the bohemian massif represents the largest outcropping crystalline complex in central europe detailed noise measurements show average values for the power spectrum slightly lower than 1 nm 2 hz at 1 hz and a fairly smooth decay proportional to f 4 per decade up to 40 hz leading to a value of 10 4 nm 2 hz at 10 hz and 10 5 nm 2 hz at 20 hz diurnal variations due to industrial noise sources such as saw mills are primarily found in the 4 hz to 10 hz band compared to scandinavia the noise level in central europe is comparable or even lower for frequencies about 1 hz but it is about a decade higher at 10 hz and above the spatial correlation properties of noise and signals were investigated using data from a temporary 9 element array with a diameter of 3 km in the 1 to 2 hz band the noise coherence values drop to 0 25 at interstation distances of 800 m and in the 2 to 4 hz band at 400 m respectively there is no clear evidence for a negative noise correlation distance at these frequencies signal coherence in the same frequency bands proved to be excellent 0 9 for all regional phases over the 3 km aperture of the test array the final configuration of the new regional array in the bf area named geress has been selected as a slightly enlarged noress type ring geometry with an innermost radius of 200 m and with a large radius of about 2 000 m

finite difference modelling of lg blockage summary a p sv finite difference method is used to calculate seismic wave propagation in the crust and upper mantle the anelastic effect is excluded from the calculation and therefore any wavefield changes can be attributed to either geometrical or structural effects snapshots of displacement distrihutions within and synthetic seismograms at the free surface of different models revealed that the inclusion of a water column over an appropriate section of the crust is necessary to explain the severe lg attenuation widely observed in many parts of the world in particular for an oceanic propagation path they clearly show that the effect of a water column over the crust is an important factor in blocking lg piupagation a propagation path of more than 100 km over an oceanic crust can completely block the transmission of lg waves originating in a neighbouring continental crust the energy of the lg wavetrain is redistributed at continental margins most of the incoming energy is either converted to waves which propagate into the mantle or is backscattered to form waves which propagatc in the continental crust in the opposite direction very little energy is presented at the expected arrival times at the other side of the oceanic crust which is consistent with the lg blocking phenomena simplified 2 d models of the north sea central graben are used to simulate lg propagation in a laterally varying continental path the inclusion of a water column over the crust enhances the attenuation of lg the deeper the water column the greater the attenuation the undulation of sea bottom can further enhance the attenuation of lg

high resolution 3d seismic model of the crustal and uppermost mantle structure in poland abstract in the area of poland a contact between the precambrian and phanerozoic europe and the carpathians has a complicated structure and a complex p wave velocity of the sedimentary cover crystalline crust moho depth and the uppermost mantle the geometry of the uppermost several kilometers of sediments is relatively well recognized from over 100 000 boreholes the vertical seismic profiling vsp from 1188 boreholes provided detailed velocity data for regional tectonic units and for stratigraphic successions from permian to the tertiary and quaternary deposits these data however do not provide information about the velocity and basement depth in the central part of the trans european suture zone tesz and in the carpathians so the data set is supplemented by 2d velocity models from 32 deep seismic sounding refraction profiles which also provide information about the crust and uppermost mantle together with the results of other methods vertical seismic profiling magnetotelluric allow for the creation of a detailed high resolution 3d model for the entire earth s crust and the uppermost mantle down to a depth of 60 km the thinnest sedimentary cover in the mazury belarus anteclise is only 0 3 to 1 km thick which increases to 7 to 8 km along the east european craton eec margin and 9 to 12 km in the tesz the variscan domain is characterized by a 1 4 km thick sedimentary cover while the carpathians are characterized by very thick sedimentary layers up to about 20 km the crystalline crust is differentiated and has a layered structure the crust beneath the west european platform wep variscan domain is characterized by p wave velocities of 5 8 6 6 km s the upper and middle crusts beneath the eec are characterized by velocities of 6 1 6 6 km s and are underlain by a high velocity lower crust with a velocity of about 7 km s a general decrease in velocity is observed from the older to the younger tectonic domains the tesz is associated with a steep dip in the moho depth from 30 35 km in the paleozoic platform to 42 52 km in the precambrian craton the new model confirms the moho depth derived from previous compilations in the tesz the lower crust has a very high seismic velocity 7 0 km s which correlates to the high p wave velocity about 8 4 km s in the uppermost mantle beneath the polish basin the cratonic area is generally characterized by high p wave velocities 8 2 km s while the phanerozoic area is characterized by velocities of 8 0 km s in the tesz very high velocities of 8 3 8 4 km s are observed and the southwestern limitation of this area coincides with a high velocity lower crust and could be continued to the nw toward the elbe line the influence of the structure for teleseismic tomography time residuals of seismic waves traveling through the 3d seismic model was analyzed lithological candidates for the crust and uppermost mantle of the eec and wep were suggested by comparison to laboratory data the presented 3d seismic model may make more reliable studies on global dynamics and geotectonic correlations particularly for sedimentary basins in the polish lowlands the napped flysch sediment series in the carpathians the basement shape the southwestern edge of the eec a high velocity lower crust and the high velocity uppermost mantle in the tesz finally the new 3d velocity model of the crust shows a heterogeneous structure and offers a starting point for the numerical modeling of deeper structures by allowing for a correction of the crustal effects in studies of the mantle heterogeneities

blockage of regional seismic waves by the teisseyre tornquist zone summary during the group of scientific experts technical test gsett second experiment 22 april 2 june 1991 several hundred seismic events were located in europe associating these events with the detecting stations altogether 28 european stations including seven arrays participated in the gsett 2 experiment clearly shows that the teisseyre tornquist zone ttz influences the propagation of regional seismic phases large explosions in the bay of gdansk for example were observed by the wellestablished scandinavian arrays norsar a 830 km and arcess a z 1650 km but not by the polish station ksp a 470km nor by the new highly sensitive geress array a 750 km both situated south west of the ttz for events in central europe with comparable magnitudes we observe a similar increase of the detection threshold at stations located north east of the ttz in scandinavia to explain these observations the wave propagation of pn and pg perpendicular to the ttz was modelled for a profile from the estonian russian border region to geress with gaussian beam seismograms published crustal and uppermost mantle models for poland and for europe were used as a starting point for developing a model of the ttz the observations cannot be explained only by a graben like crustal structure with a jump in moho depth from 30 km to 50 km to defocus the seismic energy the ttz as a structural anomaly between eastern and western europe must reach down into the upper mantle to a depth of at least about 200 km the proposed model has such a deep reaching root of the ttz

the crustal structure of western europe a thorough understanding of the tectonic processes that formed the con tinental lithosphere under changing geometric and physical conditions through time requires detailed knowledge of the structure of the crust one of the best locations to study this fundamental problem is the northern and western part of europe because it is made up of a number of tectonic provinces ranging in succession from the oldest precambrian areas of fennoscandia to the currently active regions of the mediterranean sea the geology of europe a region extending from the northern tip of scandinavia north cape southward to north africa encompasses the pre 2500 ma archean craton in the northernmost part of the baltic or fennoscandian shield the proterozoic paleozoic and cenozoic pro vinces of northern and central europe that have been added on to this nucleus and the active transition zone between the eurasian and african plates in the mediterranean area cf figure 1 from a tectonic geologic point of view europe can be divided into four main units that cover the whole time span of the history of the continental crust

thermal properties of the crust and the lithosphere asthenosphere boundary in the area of poland from the heat flow variability and seismic data high resolution 3d seismic p wave velocity model of poland grad et al tectonophysics 666 188 210 2016 and corrected for paleoclimate heat flow map majorowicz and wybraniec int j earth sci 100 4 881 887 2011 gridded to a common mesh are used together with four independent thermal models of the crust and upper mantle to calculate heat flow variation with depth and geotherms heat flow at moho depth are calculated and mapped and both confirm large variability with an elevated mantle heat flow circa 30 40 mw m2 in the paleozoic platform which is some 10 20 mw m2 higher than moho heat flow in the north eastern and south eastern poland which belong to a variety of tectonic terranes the oldest precambrian craton younger cadomian trans european suture zone carpathians temperatures calculated for the crust show consistent pattern higher temperatures beneath the paleozoic platform and lower temperatures beneath the precambrian and cadomian units at 10 km depth this difference is about 150 c about 300 c at 20 km depth and about 400 c at 50 60 km assuming the calculated isotherm 580 c as curie temperature the magnetic crust thickness was determined as 5 10 km only beneath the polish basin circa 20 km in carpathians circa 30 km in sudetes and 35 40 km beneath the precambrian and cadomian units such a thick magnetic crust results from a great depth of curie temperature thick crystalline crust and thin sediments mantle heat flow variability is mainly correlating with measured surface heat flow and influences geotherms calculated thermal lab depth follows patterns of heat flow and moho heat flow variability through poland with thinnest lithosphere in the high surface heat flow and high mantle heat flow areas comparison of this thermal lab depth estimates with seismic data based lab depth shows general coincidences when precambrian craton vs paleozoic platform are considered along the p4 seismic experiment data model circa 190 km depth vs some 90 km depth respectively however significant differences exist in many areas and especially for the se poland when compared with map for the whole of poland compiled from other seismic reported data

crustal structure variation from the precambrian to palaeozoic platforms in europe imaged by the inversion of teleseismic receiver functions project tor the tor experiment teleseismic tomography tornquist carried out in winter 1996 97 across the trans european suture zone tesz in germany denmark and sweden has collected new data to investigate the transition zone between precambrian and palaeozoic europe in this study seismograms of teleseismic earthquakes recorded by the broad band tor stations have been used to calculate the receiver functions the time domain inversion method has been applied to the receiver functions to compute s wave velocities in the crust and uppermost mantle beneath each station the results of inversion down to 60 km depth provide new independent information about the distribution of s wave velocity in this area beneath the swedish stations on baltica the thickness of the crust varies from about 45 to 50 km with mostly gradually increasing s wave velocity and no sharp discontinuities while for danish and german stations the crust is thinner 29 38 km with a sharp moho discontinuity a very distinct s wave low velocity layer was found at depth of 8 16 km in the upper crust of baltica supported by the results of refraction deep seismic sounding experiments using both p and s waves the map of v p v s ratio beneath the c 1000 km long tor profile was obtained using the v p velocity model from previous investigations the values of v p v s 1 73 were found in the uppermost crust of baltica and upper avalonian crust the low velocity layer in the upper crust of baltica is characterized by high value of v p v s 1 85 relatively low s wave velocities are observed in the lower crust of variscides v p v s 1 79 baltica v p v s 1 83 and avalonia v p v s 1 91 in the uppermost mantle v p v s values are 1 77 1 79 and 1 82 respectively

sharp contrast in lithospheric structure across the sorgenfrei tornquist zone as inferred by rayleigh wave analysis of tor1 project data abstract this work is a part of the tor1 project 1996 1997 and is devoted to determining the lithospheric structure across the sorgenfrei tornquist zone in northern europe for the first time in europe a very dense seismic broadband array has offered the possibility of determining very sharp lateral variations in the structure of the lithosphere at small scales using surface wave analysis we measure phase velocities for rayleigh waves with periods ranging between 10 and 100 s both within arrays with apertures of 40 50 km small compared to the wavelength and along long profiles of at least 100 km dispersion curves are then inverted and shear wave velocity models down to the depth of 200 km are proposed we show that the sorgenfrei tornquist zone is a major tectonic feature within the whole lithosphere north east of this feature in sweden beneath the baltic shield no lithosphere asthenosphere boundary is observed to exist to depths of 200 km south west of the sorgenfrei tornquist zone beneath denmark we find a lithospheric thickness of 120 20 km the transition across the sorgenfrei tornquist zone is sharp and determined to be very steeply dipping to the south west we also demonstrate the existence of a sharp discontinuity between the lithospheres beneath denmark 120 20 km thick and beneath germany characterized by thicknesses of 50 10 km in the northernmost part and 100 20 km in the southwest this discontinuity is most likely related to the trans european fault at the surface

crustal structure of the trans european suture zone region along polonaise 97 seismic profile p4 1 the large scale polonaise 97 seismic experiment investigated the velocity structure of the crust and upper mantle in the trans european suture zone tesz region between the precambrian east european craton eec and paleozoic platform that comprises terranes added during the caledonian and variscan orogenies 530 370 and 370 225 ma respectively this experiment included 64 shots recorded by 613 seismic stations during two deployments very good quality data were recorded along five profiles and the longest and most important one p4 is the focus of this paper clear first arrivals and later phases of waves reflected refracted in the crust and moho were interpreted using two dimensional 2 d tomographic inversion and ray tracing techniques the crustal thickness along the profile varies from 30 35 km in the paleozoic platform area to 40 km below and due northeast of the tesz to 43 km in the polish part of the eec and to 50 km in lithuania the paleozoic platform and eec are divided by the polish basin so the upper crustal structure varies considerably in the area of the polish basin the p wave velocity is very low vp 6 1 km s down to depths of 15 20 km indicating that a very thick sedimentary sequence is present we suggest two possible tectonic interpretations of the velocity models 1 baltica indented avalonia obducting its upper crust and underthrusting its lower crust in a tectonic flake structure and 2 a rifted margin of baltica underlies the polish basin this model is similar to other interpretations of seismic profiles recorded in the baltic sea the second model implies that the paleozoic platform solely consists of avalonian lithosphere and the eec of baltica lithosphere it offers a simple explanation of the difference in crustal thickness of the two platforms it also implies that the caledonian and variscan orogenies in this area were relatively soft collisions that left this continental margin largely intact

deep structure of the earth s crust in the contact zone of the palaeozoic and precambrian platforms in poland tornquist teisseyre zone abstract one of the major tectonic problems in europe concerns the southwest margin of the east european platform in the region of the so called polish danish trough in general this margin is assumed to be the tornquist teisseyre t t line running approximately from northwest to southeast in this part of europe determination of deep crustal structure of the contact zone between the precambrian platform and the palaeozoic platform was the main aim of the deep seismic sounding dss programme in poland in 1965 1982 deep seismic soundings of the earth s crust have been made in the t t line zone along nine profiles with a total length of about 2600 km the results of deep seismic soundings have shown that the crust in the marginal zone of the east european platform has highly anomalous properties the width of this zone ranges from 50 km in northwest poland to about 90 km in southeast poland the crustal thickness of the palaeozoic platform in poland is 30 35 km and of the precambrian platform 42 47 km while in the t t tectonic zone it varies from 50 to 55 km above the moho boundary in the t t zone at a depth of 40 45 km there is a seismic discontinuity with p wave velocities of 7 5 7 7 km s boundary velocities mean velocities and stratification of the earth s crust vary distinctly along the t t zone there are also observed high gravimetric and magnetic anomalies in the t t zone the t t tectonic zone determined in this manner is a deep tectonic trough with rift properties the deep fractures delineating the t t tectonic zone are of fundamental importance for the localization of the plate edge of the precambrian platform of eastern europe in the light of dss results the northeastern margin of the t t tectonic zone is a former plate boundary of the east european platform