tomography study of the upper mantle around the tesz based on passeq experiment data abstract we present a detailed velocity perturbation model of the earth s upper mantle in the area around the trans european suture zone tesz imaged by the teleseismic tomography the model is based on 12473 p wave arrival times measured on recordings of 273 stations of the passive seismic experiment passeq which was active during 2006 and 2008 station and teleseismic event distribution is sufficient to resolve the structure below the passeq array down to a depth of 350 km the velocity perturbation model clearly shows a 250 km thick uniform layer of positive velocity perturbations north east of the teisseyre tornquist zone ttz and 150 km thick layer south west of the ttz characterized by relatively lower velocity perturbations the former we associate with the precambrian mantle lithosphere of the european plate while the latter represents the much younger phanerozoic lithosphere in the uppermost layer of the model 40 km the boundary between the two regions closely follows the crustal trace of the ttz in deeper layers the boundary shifts south westward at a depth of approximately 120 km the region with positive perturbations reaches the northern part of the bohemian massif bm the shift suggests that the phanerozoic part of the european plate thrusts over the precambrian lithosphere the upper mantle below a depth of 250 km lacks the pronounced division between the two regions around the tesz which allows us to associate these depths with asthenospheric part of the upper mantle

comments on nd sr isotopic compositions of lower crustal xenoliths evidence for the origin of mid tertiary felsic volcanics in mexico by j ruiz p j patchett and r j arculus

high resolution body wave tomography beneath the svekalapko array ii anomalous upper mantle structure beneath the central baltic shield high resolution body wave tomography beneath the svekalapko array ii anomalous upper mantle structure beneath the central baltic shield

the sorgenfrei tornquist zone as the mantle edge of baltica lithosphere new evidence from three dimensional seismic anisotropy joint analysis of shear wave splitting parameters and directional dependence of teleseismic p residuals based on data from the seismic experiment tor across the trans european suture zone suggest that the sorgenfrei tornquist zone stz in northern denmark forms the south western margin of baltica in the upper mantle different lithosphere thickness and different orientation of seismic anisotropy in the mantle lithosphere identify three domains separated by the stz between denmark and southern sweden and the thor suture between northern germany and denmark we suggest that the anisotropy reflects frozen in olivine fabrics most probably created during early stages of the evolution of the european continent the middle danish block might represent a microplate caught in between avalonia and baltica before the caledonian orogeny

novel anisotropic teleseismic body wave tomography code anitomo to illuminate heterogeneous anisotropic upper mantle part ii application to data of passive seismic experiment lapnet in northern fennoscandia seismic anisotropy provides a unique constraint on the past and present dynamics of the lithosphere and sublithospheric mantle to contribute to studies of large scale tectonic fabric we have developed code anitomo for regional anisotropic tomography anitomo allows us to invert simultaneously relative traveltime residuals of teleseismic p waves for 3 d distribution of isotropic velocity perturbations and velocity anisotropy in the upper mantle weak hexagonal anisotropy with the symmetry axis oriented generally in 3 d is considered the first application of novel code anitomo to data from passive seismic experiment lapnet results in a model of anisotropic velocities of the upper mantle beneath northern fennoscandia we have opted for northern fennoscandia for the first application because it is a tectonically stable precambrian region with a thick anisotropic mantle lithosphere without significant thermal heterogeneities we carefully analyse the distribution of the rays to limit the fully anisotropic inversion only to the volume with the sufficient directional ray coverage capability of the given inversion setup to reveal large scale anisotropic structures in the upper mantle is documented by a series of synthetic tests the strongest anisotropy and the largest velocity perturbations concentrate at depths corresponding to the mantle lithosphere while in deeper parts of the tomographic model the lateral variations are insignificant we delimit regions of laterally and vertically consistent anisotropy in the mantle lithospheric part of the model we attribute the retrieved domain like anisotropic structure of the mantle lithosphere in northern fennoscandia to preserved fossil fabrics of the archean microplates accreted during the precambrian orogenic processes

non linear body wave teleseismic tomography along the tor array summary the tor project investigates the lithosphere asthenosphere structure under the tornquist zone between denmark and sweden around 150 seismic stations 108 short period 28 broadband and 14 other permanent stations were employed in a rectangular array along a 900 km long by 100 km wide strip across the tornquist zone from july 1996 to august 1997 the results obtained based on a non linear teleseismic tomography algorithm reveal significant p velocity variations up to 5 per cent along the tor array from northern germany to southern sweden distinct lithospheric blocks are also recognized in the inversion results two inverse methods singular value decomposition and a quadratic programming method were implemented in order to investigate whether or not the lithospheric blocks and major boundaries in the inversion are required by the data or are artefacts of the inversion according to the results the lithosphere under northern germany is thin but reaches to intermediate thicknesses of about 120 km in the tornquist zone area farther north in the baltic shield more than 200 km of continental lithosphere is recognized in the model abrupt lateral p velocity changes maximum 5 per cent are seen at both the southern and northern sides of the tornquist zone

crustal structure below the polish basin is it composed of proximal terranes derived from baltica abstract the large scale seismic refraction and wide angle reflection experiment polonaise 97 together with lt 7 and ttz profiles carried out with the most modern techniques gave a high resolution of crustal structure of the trans european suture zone tesz in nw and central poland the results of seismic investigations show the presence of relatively low velocity rocks vp

cenozoic volcanism in the bohemian massif in the context of p and s velocity high resolution teleseismic tomography of the upper mantle

mapping seismic anisotropy of the lithospheric mantle beneath the northern and eastern bohemian massif central europe abstract we evaluate 3d body wave anisotropic parameters shear wave splitting fast s polarizations and delay times of the split slow shear waves and directional terms of relative p wave residuals from data of passive seismic experiment bohema ii 2004 2005 data from 34 temporary stations increased substantial density of observations in the bohemain massif bm and allowed us to scan in detail the upper mantle structure of its northern and eastern parts for the first time we delimit domains of the mantle lithosphere in this part of the bm and infer 3d self consistent models of their fabrics by a joint inversion of the body wave anisotropic parameters fabrics of the northern and north eastern parts of the bm are approximated best by peridotite aggregates with the a c foliations dipping approximately to the n and ne respectively whereas a model with the westerly dipping a lineation fits best the fabric of the south eastern domain the saxothuringian fabric nw of the eger rift extends to the east across the elbe fault zone and continues along this zone to the southeast beneath the cretaceous basin the south eastward continuation of the elbe fault zone seems to be related to the boundary between two different fabrics of the northern and southern brunovistulian domains below the moravo silesian zone this study shows an underthrusting of the brunovistulian micro plate beneath the eastern rim of the bm and indicates that its northern and southern fragments might have originally belonged to baltica and to gondwana respectively according to a zone of distinctly decreased anisotropic signals the brunovistulian micro plate extends at least about 100 km westward beneath the moldanubian with these new findings we update the domain like mantle structure of the bm and compare the results with inferences from the upper mantle velocity tomography and depth changes of the lithosphere asthenosphere boundary retrieved in a detailed model from relative residuals and from the receiver functions inferences on anisotropic structure beneath the permanent observatories included in different experiments are stable and are validated by the bohema ii experiment

nonlinear teleseismic tomography at long valley caldera using three dimensional minimum travel time ray tracing the authors explore the impact of three dimensional minimum travel time ray tracing on nonlinear teleseismic inversion this problem has particular significance when trying to image strongly contrasting low velocity bodies such as magma chambers because strongly refracted and or diffracted rays may precede the direct p wave arrival traditionally used in straight ray seismic tomography they use a simplex based ray tracer to compute the three dimensional minimum travel time ray paths and employ an interative technique to cope with nonlinearity results from synthetic data show that their algorithm results in better model reconstructions compared with traditional straight ray inversions the authors reexamine the teleseismic data collected at long valley caldera by the u s geological survey the most prominent feature of their result is a 25 30 low velocity zone centered at 11 5 km depth beneath the northwestern quandrant of the caldera beneath this at a depth of 24 5 km is a more diffuse 15 low velocity zone in general the low velocities tend to deepen to the south and east the authors interpret the shallow feature to be the residual long valley caldera magma chamber while the deeper feature may represent basaltic magmas ponded in the midcrust the deeper position of the prominent low velocity region in comparison to earliermore tomographic images is a result of using three dimensional rays rather than straight rays in the ray tracing the magnitude of the low velocity anomaly is a factor of approximately 3 times larger than earlier models from linear arrival time inversions and is consistent with models based on observations of ray bending at sites within the caldera these results imply the presence of anywhere from 7 to 100 partial melt beneath the caldera 40 refs 1 fig 1 tab less

palaeozoic terranes and their lithospheric boundaries within the trans european suture zone tesz a review the trans european suture zone tesz is a broad and complex zone of terrane accretion separating ancient lithosphere of the baltic shield and east european craton eec from the younger lithosphere of western and southern europe there is debate about the number of terranes involved and their origins the most significant terrane boundaries originally oceanic sutures are poorly exposed and are defined using faunal provinciality prominent geophysical lineaments may represent sub terrane boundaries within composite terranes the avalonia composite terrane was amalgamated to baltica in latest ician time the provenance of the malopolska and moravo silesian terranes whose neoproterozoic basement is suspect with respect to baltica but with which they nonetheless share faunal affinities is still debated the extent of the variscide rhenohercynian zone defines the southern limit of the early palaeozoic accreted terranes terranes within the bohemian massif exhibit hp metamorphism recording subduction driven collision prior to incorporation in the tesz collage itself associated with a hp event in romania the saxothuringian zone and rheic suture are directly juxtaposed with the eec and the crustal structure of the tesz has been much modified by post palaeozoic tectonism deep seismic reflection data where available show that the oceanic sutures are frequently associated with inclined reflectivity zones irz in the lithospheric mantle here inferred to mark relict subduction zones interpreting the age of subduction is complicated by offset of originally coplanar mantle and crustal segments of the irz resulting from early orogenic lithospheric delamination at the moho interface and or post orogenic reordering processes the mantle irz appear to indicate a n directed polarity for early palaeozoic subduction apparently incompatible with the geological evidence which indicates subduction of the tornquist sea beneath avalonia and a large amount of underthrusting of avalonia by baltica possible explanations for these apparently incompatible observations are evaluated

opening of a fault and resulting slip due to injection of fluid for the extraction of geothermal heat 2 further details further details of the behavior of a fault with a fluid filled region are presented an oblique fault is modeled by an interface across which two elastic bodies are in frictional contact and the tectonic stresses varying linearly with respect to depth are taken into account it is shown that a fault can keep fluid if there exists a spatially fluctuating tectonic stress field superimposed on the linear depth dependent stress field although the fluctuation amplitude must be larger than a lower limit when the fault is oblique it is also revealed that except for the case of a horizontal fault there is an upper limit for the size of the fluid filled region even if the fluctuating stress field is spatially periodic as the fluid filled region is created slip spreads simultaneously along the fault this resulting slip is also analyzed

seismic tomography of the upper mantle beneath the north eastern bohemian massif central europe abstract we present a 3 d velocity model of the upper mantle beneath the northern and eastern parts of the bohemian massif bm based on data from passive seismic experiment bohema ii may 2004 june 2005 consisted of 35 temporary stations complemented by data of permanent observatories the resulting tomographic model with a variance reduction of 84 shows relatively small velocity variations both in size and in amplitude a small size high velocity perturbation in the eastern part of the model can be related to the complex structure beneath the sudetes moravo silesian unit contact similarly to results from the bohema i experiment in the western bm the presented model from bohema ii data confirms the north southward thickening of the lithosphere though in the upper mantle the low perturbations prevail some inconsistencies among the isotropic velocity perturbation model sp receiver function inferences and anisotropic models of the mantle lithosphere domains indicate that both the topography of the lithosphere asthenosphere boundary and internal velocity structure of the upper mantle beneath the bm can be complex we tested two regularization techniques truncated singular value decomposition and damped least square method results of which lead us to prefer the damped least square method the truncated singular value decomposition seems to be more sensitive to uneven ray geometry

seismic anisotropy of the lithosphere around the trans european suture zone tesz based on teleseismic body wave data of the tor experiment abstract a passive teleseismic experiment tor traversing the northern part of the trans european suture zone tesz in germany denmark and sweden recorded data for tomography of the upper mantle with a lateral resolution of few tens of kilometers as well as for a detailed study of seismic anisotropy a joint inversion of teleseismic p residual spheres and shear wave splitting parameters allows us to retrieve the 3d orientation of dipping anisotropic structures in different domains of the sub crustal lithosphere we distinguish three major domains of different large scale fabric divided by first order sutures cutting the whole lithosphere thickness the baltic shield north of the sorgenfrei tornquist zone stz is characterised by lithosphere thickness around 175 km and the anisotropy is modelled by olivine aggregate of hexagonal symmetry with the high velocity ac foliation plane striking nw se and dipping to ne southward of the stz beneath the norwegian danish basin the lithosphere thins abruptly to about 75 km in this domain between the stz and the so called caledonian deformation front cdf the anisotropic structures strike ne sw and the high velocity ac foliation dips to nw to the south of the cdf beneath northern germany we observe a heterogeneous lithosphere with variable thickness and anisotropic structures with high velocity dipping predominantly to sw most of the anisotropy observed at tor stations can be explained by a preferred olivine orientation frozen in the sub crustal lithosphere beneath northern germany a part of the shear wave splitting is probably caused by a present day flow in the asthenosphere

crustal lithology vs thermal state and moho heat flow across the ne part of the european variscan orogen a case study from sw poland geotherms of four crustal profiles across the variscan orogen in sw poland have been constructed to better understand the variation in thermal state of the region seismic and drilling data as well as rock sequences in exposed parts of the orogen were used for wilcza gora sudetic block polkowice rudna middle odra horst wieciechowa wolsztyn leszno horst and wrze nia szczecin miechow synclinorium within tesz profiles the palaeoclimate corrected surface heat flow map and the heat production calculations based on literature data enabled the construction of geotherms and estimation of moho heat flow exception is the polkowice rudna profile where the surface heat flow was calculated using temperature measurements in underground copper mines and k u and th contents and density heat conductivity measurements in rocks drilled in the middle odra horst were used to calculate geotherm the basaltic lava migration through the lithospheric mantle and its effect on crustal geotherm in wilcza gora area of cenozoic alkaline volcanism at ca 30 18 ma was shown to increase slightly both current surface and current moho heat flow by ca 4 mw m2 the presented approach couples geological and geophysical information and thus differs from standard purely geophysical assessment of lithosphere thermal state it shows that surface heat flow is enlarged to 84 mw m2 by granitic plutons in the upper crust in the lubin polkowice site heat flow on the moho varies from 28 to 34 mw m2 in sites located in the sudetic fore sudetic blocks middle odra horst and wolsztyn leszno horst locally it may slightly increase because of extraneous heat input by cenozoic basaltic volcanism but the values close to 30 mw m2 are specific for mantle root of saxothuringian zone in sw poland mantle heat flow is 36 mw m2 in wrze nia site and supposedly is a manifestation of different nature of lithospheric mantle underlying tesz

shear wave splitting measurements problems and solutions abstract we compare sensitivity and reliability of three basic techniques of shear wave splitting analysis cross correlation of wave components minimization of covariance matrix eigenvalues and minimizing energy on the transverse component of both synthetic and real data point out some problems and propose solutions we discuss major difficulties of evaluating shear wave splitting parameters which are not always obvious in routine processing and can sometimes lead to false results and wrong interpretations we describe effects of pre processing of digital records of shear waves e g filtering and setting lengths of analyzed signals and discuss reliability of results to minimize outliers in evaluated splitting parameters for reliable evaluation of splitting of medium quality sks wave forms which are valuable mainly in temporary deployments of stations we recommend a careful band pass filtering of the signal using a window length not shorter than the dominant period inspecting the signal noise ratio on t component and the particle motion the transverse minimization method provides usually more robust and stable solutions than the other two methods in the conclusion we suggest how to proceed in evaluation of splitting parameters to ensure reliable solutions even for medium or low quality shear waveforms recorded frequently during temporary field measurements

the moho depth map of the european plate summary the european plate has a 4 5 gy long and complex tectonic history this is reflected in the present day large scale crustal structures a new digital moho depth map is compiled from more than 250 data sets of individual seismic profiles 3 d models obtained by body and surface waves receiver function results and maps of seismic and or gravity data compilations we have compiled the first digital high resolution map of the moho depth for the whole european plate extending from the mid atlantic ridge in the west to the ural mountains in the east and from the mediterranean sea in the south to the barents sea and spitsbergen in the arctic in the north in general three large domains within the european plate crust are visible the oldest archean and proterozoic crust has a thickness of 40 60 km the continental variscan and alpine crust has a thickness of 20 40 km and the youngest oceanic atlantic crust has a thickness of 10 20 km

lithospheric structure of the tornquist zone resolved by nonlinear p and s teleseismic tomography along the tor array lithospheric structure of the tornquist zone resolved by nonlinear p and s teleseismic tompgraphy along the tor array

opening of a fault and resulting slip due to injection of fluid for the extraction of geothermal heat the behavior of a fault with a fluid filled region is studied for the extraction of heat from hot dry rock masses a fault is viewed as a prefractured plane in the earth s crust and is modeled by an interface across which two elastic bodies contact with each other where frictional forces against the relative movement between two surfaces of the interface are taken into account once fluid is injected between the two surfaces the fault will be opened up over a region where the pressure acting on the fault plane before the injection is locally smaller than that on the neighboring regions the size of the fluid filled region is compared with that of a crack opened by a hydraulic pressure in a homogeneous medium to show that the fluid filled region could be used as a reservoir for the extraction of geothermal heat the resulting slip caused by the reduction of frictional forces due to the injection of fluid is analyzed by the use of two models i e an interface with frictional resistance only and an interface with both frictional resistance and fracture toughness it is shown that the two models do not exhibit any significant difference in the size of the slipped region when the fluid filled region is of dimensions of practical interest

shear wave splitting as a diagnostic of variable anisotropic structure of the upper mantle beneath central fennoscandia abstract we analyze splitting of shear waves recorded during the svekalapko passive seismic experiment in south central finland to study fabrics of the mantle lithosphere of the precambrian region and thus to bring information into a debate on existence of plate tectonics or its forms in the early stage of continent formation geographical variations of the splitting parameters and their distinct dependence on direction of wave propagation through the upper mantle allow us to identify six domains of the central fennoscandian mantle lithosphere including the proterozoic archean transition and to model their fabrics by joint inversion of body wave anisotropic parameters fabrics of the archean mantle lithosphere can be approximated by a peridotite aggregate with lineation a dipping to the ne on the other hand anisotropy of the proterozoic mantle lithosphere is weaker and we model its fabric by the a c foliations dipping to the se we present a 3d self consistent anisotropic model of the proterozoic and archean upper mantle along the sw ne profile in the south central finland boundaries of inter growing wedges of the proterozoic and archean mantle lithospheres explain the longitudinal and shear wave propagation and polarization mantle xenolith ages surface wave tomography and location of the upper mantle reflectors we interpret the six anisotropic domains as fragments of mantle lithosphere retaining an old fossil olivine fabric which was created before these micro continents assembled

upper mantle structure beneath the alpine orogen from high resolution teleseismic tomography 1 to understand the evolution of the alpine orogen knowledge of the actual structure of the lithosphere asthenosphere system is important we perform high resolution teleseismic tomography with manually picked p wave arrival times from seismograms recorded in the greater alpine region the resulting data set consists of 4199 relative p wave arrivals and 499 absolute p wave arrivals from 76 teleseismic events corrected for the contribution of the alpine crust to the travel times the three dimensional 3 d crustal model established from controlled source seismology data for that purpose represents the large scale alpine crustal structure absolute p wave arrival times are used to compute an initial reference model for the inversion tests with synthetic data document that the combination of nonlinear inversion high quality teleseismic data and usage of an a priori 3 d crustal model allows a reliable resolution of cells at 50 km 50 km 30 km hence structures as small as two cells can be resolved in the upper mantle our tomographic images illuminate the structure of the uppermost mantle to depth of 400 km along strike of the alps the inversion reveals a high velocity structure that dips toward the se beneath the adriatic microplate in the western and central alps in the eastern alps we observe a northeastward dipping feature subducting beneath the european plate we interpret this feature in the western and central alps as subducted mainly continental european lower lithosphere for the east we propose that parts of the vardar oceanic basin were subducted toward the ne forcing continental adriatic lower lithosphere to subduct northeastward beneath the european plate

three dimensional crustal structure beneath the tor array and effects on teleseismic wavefronts abstract the temporary seismic station array tor was designed to study the lithosphere asthenosphere system across the northwestern part of the trans european suture zone tesz by teleseismic tomography teleseismic wavefronts when propagating through complex crustal structure undergo severe distortion that may result in travel time residual anomalies of significant amplitude the inversion of teleseismic travel time residuals for deep structures without accounting for such crustal related anomalies may erroneously map these travel time anomalies into features at greater depth in this study we apply a three dimensional 3 d technique to estimate effects of a priori known 3 d crustal structure on travel times of teleseismic waves observed at the tor seismic array across the tesz to correct for these effects in future tomographic studies a uniform 3 d crustal model is developed by use of published two dimensional crustal models from previous active seismic surveys the parameterization of this 3 d crustal model is designed to adequately represent those crustal structures that mostly influence the propagation of teleseismic wavefronts the 3 d model includes lateral variation in velocity structure moho topography and large and deep sedimentary basins the teleseismic forward problem for this local 3 d model is solved by calculation of travel times to the base of the model using a standard whole earth model and by subsequent propagation of spherical wavefronts using finite difference methods travel time calculations for an event near japan reveal significant lateral variations in the range between 0 3 s and 0 5 s due to crustal structures being able to obtain the full travel time field at the surface of the model has the additional advantage of improving the identification and timing of seismic phases observed at the tor seismic array

polonaise 97 an international seismic experiment between precambrian and variscan europe in poland abstract the trans european suture zone tesz comprises a series of sutures that developed by palaeozoic amalgamation of the phanerozoic central europe onto the proterozoic baltica and east european plate during the formation of pangea within tesz the permian basin in poland forms the easternmost part of the permian central european basin which is bordered on the east by the east european craton eec and on the southwest by the bohemian massif the axis of the basin the mid polish trough parallels the edge of the eec the teisseyre tornquist zone ttz is a geological inversion zone in the polish trough a large seismic experiment the polonaise 97 project was conducted in poland during may of 1997 and targeted the deep structure of the tesz and the complex series of upper crustal features associated with it it included contributions from the geophysical communities in poland denmark the usa lithuania germany finland sweden and canada this large lithospheric seismic experiment deployed 613 instruments to record 64 shots along five profiles with a total length of about 2000 km moreover five multichannel seismic reflection stations 90 and 120 channels recorded all signals from shots two dimensional velocity models were derived by p wave tomographic inversion these models provide an initial interpretation of this massive data set and allow us to present a few significant seismic and tectonic observations one of the most important is a very distinct asymmetry between the maximum thickness of the sedimentary cover in the polish trough 16 20 km and the crustal root 50 km associated with tesz ttz

europe from the bottom up a statistical examination of the central and northern european lithosphere asthenosphere boundary from comparing seismological and electromagnetic observations abstract the lithosphere asthenosphere boundary lab is a fundamental boundary in the plate tectonic paradigm it is the most pervasive on the planet yet comparatively it is one we know little about defined initially on the basis of the mechanical response of the earth to loading its usage has become ubiquitous across the geosciences but the natural differences in its definition due to differences in thermal physical and chemical parameters cause confusion to advance this debate comparisons are made both qualitatively and quantitatively between the delineation of the lab for europe based on seismological and electromagnetic observations we examine statistically using robust methods the labs derived from independent datasets and methods essentially all definitions of the lab as an impedance contrast from receiver functions slabrf a seismic anisotropy change slaba and an increase in conductivity from magnetotellurics elab are consistent with a deeper lab beneath precambrian europe and a shallower lab beneath phanerozoic europe with some exceptionally deep regions in phanerozoic europe such as the alps all three labs increase in depth significantly and rapidly at a location consistent with the surface expression of the trans european suture zone tesz which separates precambrian europe to the north and east from phanerozoic europe in the centre two of the definitions slabrf and elab are consistent for phanerozoic europe with mean values of 90 100 km compared to an average slabrf of 135 km a different two slaba and slabrf are consistent for precambrian europe with mean values of 170 180 km compared to an elab mean of 250 km the deeper elab depths for precambrian europe are more consistent with body wave and surface wave tomography models than are the slaba and slabrf ones suggesting that the lower lithosphere beneath precambrian europe between 170 to 250 km is responding to shearing on the base of the lithosphere from plate driving forces taken together the definitions provide strong constraints on the nature of the lab for example the electrical elab beneath the tesz is anomalously thick to possibly the transition zone whereas slaba and slabrf seismological definitions would place it at far shallower depths given the sensitivity of electrical conductivity to partial melt and water content the thick elab beneath the tesz excludes interpretation of the seismic lab in that location in terms of a thermal structure that would induce partial melting or of hydration

upper mantle beneath the eger rift central europe plume or asthenosphere upwelling summary we present the first results of a high resolution teleseismic traveltime tomography and seismic anisotropy study of the lithosphere asthenosphere system beneath the western bohemian massif the initial high resolution tomography down to a depth of 250 km did not image any columnar low velocity anomaly which could be interpreted as a mantle plume anticipated beneath the eger rift similar to recent findings of small plumes beneath the french massif central and the eifel in germany alternatively we interpret the broad low velocity anomaly beneath the eger rift by an upwelling of the lithosphere asthenosphere transition we also map lateral variations of seismic anisotropy of the mantle lithosphere from spatial variations of p wave delay times and the shear wave splitting three major domains characterised by different orientations of seismic anisotropy correspond to the major tectonic units saxothuringian moldanubian and the tepla barrandian and their fabrics fit to those found in our previous studies of mantle anisotropy on large european scales

brunovistulian terrane bohemian massif central europe from late proterozoic to late paleozoic a review the brunovistulian terrane represents a microcontinent of enigmatic proterozoic provenance that was located at the southern margin of baltica in the early paleozoic during the variscan orogeny it represented the lower plate at the southern margin of laurussia involved in the collision with the armorican terrane assemblage in this respect it resembles the avalonian terrane in the west and the istanbul zone in the east there is a growing evidence about the presence of a devonian back arc at the margin of the brunovistulian terrane the early variscan phase was characterized by the formation of devonian extensional basins with the within plate volcanic activity and formation of narrow segments of oceanic crust the oldest visean flysch of the rheic rhenohercynian remnant basin protivanov andelska hora and horni benesov formations forms the highest allochthonous units and contains together with slices of silurian bohemian facies clastic micas from early paleozoic crystalline rocks that are presumably derived from terranes of armorican affinity although provenance from an active brunovistulian margin cannot be fully excluded either the development of the moravo silesian late paleozoic basin was terminated by coal bearing paralic and limnic sediments the progressive carboniferous stacking of nappes and their impingement on the laurussian foreland led to crustal thickening and shortening and a number of distinct deformational and folding events the postorogenic extension led to the formation of the terminal carboniferous early permian boskovice graben located in the eastern part of the brunovistulian terrane in front of the crystalline nappes the highest allochthonous westernmost flysch units locally with the basal slices of the devonian and silurian rocks thrusted over the silesicum in the nw part of the brunovistulian terrane may share a similar tectonic position with the giessen harz nappes the silesicum represents the outermost margin of the brunovistulian terrane with many features in common with the northern phyllite zone at the avalonia armorica interface in germany

novel anisotropic teleseismic body wave tomography code anitomo to illuminate heterogeneous anisotropic upper mantle part i theory and inversion tuning with realistic synthetic data

upper mantle structure of the baltic shield below the swedish national seismological network snsn resolved by teleseismic tomography summary upper mantle structure under the baltic shield is studied using non linear high resolution teleseismic p phase tomography observed relative arrival time residuals from 52 teleseismic earthquakes recorded by the swedish national seismological network snsn are inverted to delineate the structure of the upper mantle the network consists of 47 currently working three component broad band stations located in an area about 450 km wide and 1450 km long in order to reduce complications due to possible significant three dimensionality of earth structure events chosen for this study lay close to in line with the long axis of the array 30 results indicate p wave velocity perturbations of 3 per cent down to at least 470 km below the network the size of the array allows inversion for structures even at greater depths and lateral variations of velocity at depths of up to 680 km appear to be resolved below the central part of the array 60 64 n where ray coverage is best the data reveals a large region of relatively low velocity at depths of over about 300 km at depths less than about 250 300 km the models include a number of features including an apparent slab like structure dipping gently towards the north

p and s velocity anomalies in the upper mantle beneath europe from tomographic inversion of isc data we present a new tomographic model for p and s velocity anomalies beneath europe 30 n 55 n 5 w 40 e extending in depth up to 700 km and constrained by inversion of data from the international seismological center isc catalogue the algorithm uses the traveltimes from events located in the study area recorded by all available worldwide stations as well as times from teleseismic events recorded by european stations the events from the isc catalogue have been relocated and combined into composite events all the traveltimes were corrected for crustal structure using the reference model eucrust 07 the resulting velocity anomalies show similar large scale patterns as observed in previous studies but have a higher resolution which allows detection of some features in more detail for example it is now possible to assess the depth extension of the small slow velocity body beneath the eifel region and eger graben the p and the s model show a good consistency in the uppermost 200 km below most of the european area and in some parts even in the deeper layers e g beneath the apennines and the hellenic arc the new model provides clear images of some principal features which were previously detected in a limited number of studies while the comparison between p and s velocity anomalies provides novel constraints to address on their nature e g the gap in the adriatic plate subducted below the central southern apennines in this paper we pay special attention to testing the reliability of the results the random noise effect is evaluated using a test with independent inversion of two data subsets with odd even events the spatial resolution is estimated using different checkerboard tests furthermore we present a synthetic model with realistic patterns which reproduces after performing forward and inverse modelling the same shape and amplitudes of the anomalies as in the case of the real data inversion in this case the parameters of the model can be used to assess the amplitudes of p and s anomalies that is critical for evaluation of other petrophysical parameters temperature density composition etc in the upper mantle 2009 the authors journal compilation 2009 ras