dynamical interpolation and forecast of the evolution of mesoscale features off northern california abstract the series of cruises off northern california comprising optoma11 during two months in summer 1984 were specifically designed as an ocean prediction experiment in addition to a regional survey from cape mendocino to monterey six surveys were made of a 150 km 2 domain offshore of pt arena pt arena pt reyes during the initial phase over about ten days of optoma11 an intense speeds up to 50 cm s 1 relative to 450 m jet cyclone system propagated offshore at about 5 km day 1 the subsequent evolution over about 40 days of the streamfunction field was governed by the meandering of the jet and the associated changes in the intensity of the anticyclonic region to the north of the jet and the cyclonic region to the south from quasi geostrophic qg model hindcast experiments using the streamfunction data wind stress curl was an important forcing mechanism in the later phase of the experiment forecast in a domain extending over the continental slope were in agreement with objective anal

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

potential field imaging of palaeozoic orogenic structure in northern and central europe abstract the trans european suture zone tesz is the most fundamental lithospheric boundary in europe separating the ancient crust of the fennoscandian shield east european craton from the younger crust of central europe and extending deep into the mantle geophysical potential field images provide an overview of the entire palaeozoic orogenic system of northern and central europe for the first time the tesz is largely concealed by sedimentary basins of permian cenozoic age geological observations are largely restricted to local basement highs and deep boreholes and the coverage of deep seismic surveys is widely spaced despite experiments recently acquired within the europrobe programme by contrast the potential field data offer a relatively detailed coverage of standardised observations throughout the tesz while some features of the images may be sourced in the near surface particularly in the gravity image much of their content reflects the structure of the underlying palaeozoic basement at the scale presented the images highlight the most fundamental features of the crustal structure of the tesz these include the strong contrast between the highly magnetic crust of the east european craton and the less magnetic palaeozoic accreted terranes of central europe the lateral continuity of terranes and their internal structure particularly where arc magmatic complexes are involved and the location and geometry of the terrane boundaries oceanic sutures and strike slip zones that separate them

reflected diffracted waves in fracture zone models summary the paper presents the results of modelling of diffracted and reflected diffracted waves in fracture zones the berryhill method was used and the calculations were made for a profile perpendicular to the diffracting edge several homogeneous models of the earth s crust characterized by different values of crustal thickness velocity and horizontal distance between shot point and diffracting edge were considered a dependence of the relative amplitude of diffracted waves on the location of the diffracting edge is given the pattern of the seismic wavefield depends upon the dimensions of the fracture zone amplitude curves of reflected diffracted waves are presented for a series of models of fracture zones the possibility of applying the amplitudes of reflected diffracted wave trains to the interpretation of the structure of fracture zones in the earth s crust is andysed for different types of fracture zones

analysis of geomagnetic field along seismic profile p4 of the international project polonaise 97 abstract this paper presents relative secular variations of the total intensity of the geomagnetic field against a background of results of magnetic anomaly interpretation along seismic profile p4 profile p4 crosses a variscan folding zone in the paleozoic platform plz the trans european suture zone tesz and the polish part of the east european craton eec secular geomagnetic field variations t measured in 1966 2000 along a line adjacent to seismic profile p4 were analysed the study of secular variations reduced to the base recordings at the belsk magnetic observatory showed that the growth of geomagnetic field at the east european craton was slower than in the trans european suture zone and the paleozoic platform a 2d crustal magnetic model was interpreted as a result of magnetic modelling in which seismic geological and geothermal data were also used the modelling showed that there were significant differences in the magnetic model for geotectonic units which had been earlier determined based on deep seismic survey data it should be noted that a fundamental change of trend of the relative secular variations was observed at the slope of the precambrian platform after analysing the geomagnetic field observed along profile p4 the hypothesis that the contact between phanerozoic and precambrian europe lies in poland s territory can be proven

interpolating satellite derived wind field data using ordinary kriging with application to the nadir gap dual swath satellite wind sensors are unable to obtain measurements directly below the satellite creating a nadir gap centered on the subsatellite track this is true of active sensors such as the scatterometer as well as the microwave radiometers newly used for this purpose in addition sensor coverage in equatorial regions is incomplete using processed ers 1 wind field data it is shown that ordinary kriging is an appropriate technique to interpolate this nadir gap

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

3d lithosphere scale density model of the central european basin system and adjacent areas abstract to analyze the first order structural features characterizing the crust and the lithospheric mantle below the central european basin system and adjacent areas a new lithosphere scale 3d structural density model has been derived that integrates published knowledge with 3d gravity modeling with this study we aim to integrate previous results on sub domains of the study area and regional results of limited resolution in conjunction with 3d gravity analysis to derive the configuration of the lower crust and lithospheric mantle that is consistent with the known density distribution of the sediment fill and with observed deep seismic data as well as with observed gravity the derived 3d density model resolves the internal configuration of the crystalline crust below the central european basin system and adjacent areas at the regional scale and shows that the crystalline crust is characterized by a layered structure the upper to middle crystalline crust is characterized by relatively low seismic p wave velocities and densities it shows strong variations in thickness across the study area that partly correlate spatially with the inherited segmentation in response to crustal amalgamation this upper to middle crystalline crust is underlain by a continuous high density high velocity lower crustal layer locally more than 30 km thick beneath the east european craton and generally decreasing in thickness from the older to the younger tectonic domains though the thickness of this high density lower crust is generally small below the permo cenozoic central european basin system it can reach locally more than 18 km below the northeast german and the norwegian danish basins the derived depth to the lithosphere asthenosphere boundary confirms previously proposed geometries and is up to 230 km deep beneath the precambrian domain but less than 100 km deep beneath the phanerozoic domains implying that the average thermal gradient is higher in the phanerozoic lithosphere than in the precambrian part

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

tertiary tectonic evolution of the external east carpathians romania abstract paleostress calculation and analysis of mesoscopic structures are integrated with depth interpreted geological profiles based on seismic studies and well correlation to derive a tertiary tectonic model for the east carpathians following early miocene and older orogenic phases the first tectonic event that affected the studied area is characterised by a wsw ene oriented shortening of middle miocene late burdigalian in age resulting deformations induced ene ward thrusting of tarcau and marginal units as well as the internal part of the subcarpathian nappe a second shortening event with an e w to wsw ene contraction direction took place in the late miocene sarmatian characterised by further foreland thrusting of the subcarpathian nappe and out of sequence deformation in the tarcau and marginal folds nappes along strike differences in deformation mechanisms are controlled by the friction coefficients along the main detachment layers by the lateral variations in the wedge thickness and by the involvement in the northern part of the thrusting system of the thick competent east european platform tear faulting occurred in both tectonic events the main resulting structure being the triangle zone developed south of the trotus valley the latest miocene latest sarmatian early pliocene is characterised by a strike slip stress field with nne ssw compression and wnw ese tension axis left lateral faults being dominant the last deformation which affected the studied area is characterised by nnw sse shortening during the pliocene major deformations taking place mainly in the sw most bending zone

a modified objective mapping technique for scatterometer wind data an objective method to generate high resolution wind maps from the irregularly spaced scatterometer data was developed and tested on synthetic data for the northeast pacific ocean current assimilation methods for atmospheric global circulation models gcms reproduce only the large scale features 600 km of the wind field in contrast this method attempts to retain the high spatial resolution of the scatterometer where there are adequate measurements to estimate the covariance function and to compute realistic error estimates for the method a synthetic data set was constructed using wind fields from the european centre for medium range weather forecasts the wave number spectrum of the synthetic data was based on an analysis of seasat scatterometer data the patchiness of the scatterometer data caused discontinuities in the objective estimates which would give unacceptable wind stress curl fields thus the initial estimates were selectively smoothed using overdetermined biharmonic splines a constraint on the horizontal divergence of the wind applied only in regions of large estimated errors improved the estimates for the nasa scatterometer this method would produce a wind map every 12 hours with spatial resolution that preserves the small scale features of the original data over about half the mapped region and with somewhat decreased resolution and accuracy over the rest of the region

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

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

quaternary geochronology and distribution of mammuthus on the colorado plateau there are 41 known localities containing mammoth remains from the colorado plateau 24 in arizona 12 in utah 3 in new mexico and 2 in colorado of the 41 localities 13 32 arizona and utah only have yielded radiometric dates sup 14 c and u th 10 77 of these have been the result of the authors investigations the four youngest radiocarbon dates produce a weighted average date of approximately 11 270 plus minus 65 yr b p the youngest directly aged mammoth remains on the colorado plateau mammoth remains are recovered predominantly in alluvial regimes in addition to alcove cave and spring deposits no direct association of mammuthus and the clovis hunters has been reported from the colorado plateau dietary intake recorded in dung remains included predominantly graminoids in addition to various woody shrubs and trees that currently grow at higher elevations on the colorado plateau

geoarchaeological and paleohydrological evidence for a clovis age drought in north america and its bearing on extinction abstract at the murray springs clovis site in southeastern arizona stratigraphic and geomorphic evidence indicates that an abnormally low water table 10 900 yr b p was followed soon thereafter by a water table rise accompanied by the deposition of an algal mat the black mat that buried mammoth tracks clovis artifacts and a well this water table fluctuation correlates with pluvial lake fluctuations in the great basin during and immediately following clovis occupation of that region many elements of pleistocene megafauna in north america became extinct during the dry period oxygen isotope records show a marked decrease in 18o correlated with the younger dryas cold dry event of northern europe which ended 10 750 yr b p essentially the same time as the water table began to rise in southeastern arizona clovis hunters may have found large game animals easier prey when concentrated at water holes and under stress if so both climate and human predation contributed to pleistocene extinction in america

redistribution of recent collision push and ridge push in central europe insights from fem modelling summary 2 d elastic finite element models of the recent stress field of central europe are built to evaluate the loads exerted on the continental boundary and the magnitude of tectonic stresses within the continental part of the plate the models comprise 24 tectonic blocks their stiffness is either constant throughout the model or varies from block to block 16 fault zones and 12 geologically significant boundary segments we have obtained a relatively unique balance of external tectonic forces by 1 careful adjustment of calculated stress directions and regimes to complex pattern of stress from data and 2 by calibration with gravitational potential energy a high level of compression ca 9 10 12 nm 1 exerted to the short ionian side of the adriatic indenter is crucial for the stress field pattern in central europe the adria microplate rotates due to eccentricity between the africa push from the south and the alpine buttress to the north a free boundary of the apennines does not contribute significantly to this motion kinematics of this indenter is controlled by friction on the dinaric suture which in turn is decisive for strain energy distribution between the alpine and the pannonian domains the predicted pronounced extension in the greece aegean segment 2 5 10 12 nm 1 implies active pull transferred from the hellenic subduction zone this extension releases stress in the balkan pannonian region and enables the eastward escape of tectonic blocks in front of advancing adria significant changes of tectonic push trends are found along the black sea caucasus boundary segment and at the european passive margin from the north sea to the arctic ocean differential stresses in central europe are estimated in the range of 10 60 mpa when averaged over the 30 80 km thick mechanically heterogeneous lithosphere the maximum stiffness contrast across the model is predicted to be of one order of magnitude apparent friction coefficients of fault zones differ between the north european part of the plate 0 4 0 7 the pannonian region 0 15 0 25 and the dinaric suture 0 55

strike slip tectonics within the sw baltic sea and its relationship to the inversion of the mid polish trough evidence from high resolution seismic data abstract the sw baltic sea occupies an area where crustal scale regional tectonic zones of different age merge and overlap creating a complex tectonic pattern this pattern influenced the evolution of the mesozoic sedimentary basin in this area we present an interpretation of new high resolution seismic data from the sw baltic sea which provided new information both on modes of the late cretaceous inversion of this part of the danish polish mesozoic basin system as well as on relationship between tectonic processes and syn tectonic depositional systems within the bornholm darlowo fault zone located between the koszalin fault and christianso block both strike slip and reverse faulting took place during the inversion related activity the faulting was related to reactivation of extensional pre permian fault system syn tectonic sedimentary features include a prominent generally s and se directed progradational depositional system with the major source area provided by uplifted basement blocks in particular by the bornholm block sediment progradation was enhanced by downfaulting along a strike slip fault zone and related expansion of accommodation space closer to the christianso block some syn tectonic deposition also took place and resulted in subtle thickness changes within the hinge zones of inversion related growth folds lack of significant sediment supply from the inverted and uplifted offshore part of the mid polish trough suggests that in this area nw se located marginal trough parallel to the inversion axis of the mid polish trough did not form and that uplifted bornholm block played by far more prominent role for development of syn inversion depositional successions

approximating edges of source bodies from magnetic or gravity anomalies cordell and grauch 1982 1985 discussed a technique to estimate the location of abrupt lateral changes in magnetization or mass density of upper crustal rocks the final step of their procedure is to identify maxima on a contoured map of horizontal gradient magnitudes we attempt to automate their final step our method begins with gridded magnetic or gravity anomaly data and produces a plan view of inferred boundaries of magnetic or gravity sources the method applies to both local surveys and to continent wide compilations of magnetic and gravity data e g zietz 1982 simpson et al 1983a kane et al 1982

air blast produced by the meteor crater impact event and a reconstruction of the affected environment using scaling relationships determined from nuclear explosions the radial extent of the air blast produced by the meteor crater impact event is estimated the wind velocity at a distance of 5 crater radii 3 km from the point of impact should have exceeded 2000 km h hurricane force winds would have existed as far away as 20 to 40 km depending on the exact explosive energy of the impact event to determine how this event may have affected the environment surrounding the crater the topography vegetation and animal life that existed at the time of the impact are reconstructed for example if the coniferous woodlands were 100 m lower than they are presently and they had moved farther out onto the plains then the air blast would have flattened trees within a 16 to 22 km radius of the point of impact and damaged them over an area of 4100 to 8500 km2 the distance over which the damage occurred may have been up to 2 larger in some directions around the crater because of additional effects produced by the ballistic shock wave unfortunately since the trajectory of the projectile is not well known the direction of the ballistic shock wave effects cannot yet be determined

integrated seismic model of the crust and upper mantle of the trans european suture zone between the precambrian craton and phanerozoic terranes in central europe abstract the structure and evolution of the trans european suture zone tesz contact between precambrian europe to the northeast and phanerozoic terranes to the southwest is one of the main tectonic questions in europe the knowledge of the crustal structure lithosphere asthenosphere boundary and mantle transition zone between two seismic discontinuities at depths 410 and 660 km is one of the most important issues to understand the earth s dynamics to create a mantle model of the tesz and surroundings we used different seismic data collected along the 950 km long polonaise 97 profile p4 previous results of 2 d ray tracing and p wave travel time modelling and new results of p wave travel time residuals methods and receiver function sections provide facts about the seismic structure from the surface down to 900 km depth in the tesz a large basin about 125 km wide is filled with sedimentary strata vp 7 0 km s 1 along most of the p4 profile however lower values to the southwest may indicate the termination of baltica high velocity 8 35 km s 1 uppermost mantle lies beneath the avalonia variscan terranes and may be due to rifting and or subduction the seismic lithosphere thickness for the eec is about 200 km while it is only 90 km in the palaeozoic platform pp the mantle transition zone is shallower and about 30 km thicker under the eec which could be due to thermal conditions lower temperature and or the presence of water and feo the result of this paper is a new compiled and integrated seismic velocity model available in digital form down to 900 km depth http www igf fuw edu pl p4 mantle which can be used as a preliminary model of the crust and upper mantle in the tesz area in central europe

wavenumber spectra of pacific winds measured by the seasat scatterometer abstract vector winds measured by the seasat a satellite scatterometer sass are analyzed to determine the spatial structure of oceanic surface winds over wavelengths from 200 to 2200 km the analysis is performed in four latitudinal bands in the pacific ocean sampling characteristics of sass preclude the possibility of determining full two dimensional spectra the analysis is therefore limited to one dimensional along the satellite ground track spectra of vector wind components and kinetic energy the salient features of the results are summarized as follows i for each of the four geographic regions the spectra of meridional and zonal wind components and of kinetic energy are consistent with a power law dependence on wavenumber for midlatitude regions in both the northern and southern hemispheres the wave number dependence of kinetic energy is k 2 2 while for tropical regions in both hemisphere it is k 1 9 ii for each individual region the spectral dependence on wavenumber is nearly the same

devonian cretaceous repeated subsidence and uplift along the teisseyre tornquist zone in se poland insight from seismic data interpretation abstract the teisseyre tornquist zone that separates the east european craton from the palaeozoic platform forms one of the most fundamental lithospheric boundaries in europe devonian to cretaceous paleogene evolution of the se segment of this zone was analyzed using high quality seismic reflection data that provided detailed information regarding entire palaeozoic and mesozoic sedimentary cover with particular focus on problems of late carboniferous and late cretaceous paleogene basin inversion and uplift two previously proposed models of development and inversion of the devonian carboniferous lublin basin seem to only partly explain configuration of this sedimentary basin a new model includes late devonian early carboniferous reverse faulting within the cratonic area ne from the kock fault zone possibly first far field effect of the variscan orogeny this was followed by late carboniferous inversion of the lublin basin inversion tectonics was associated with strike slip movements along the ursynow kazimierz fault zone and thrusting along the kock fault zone possibly triggered by deeper strike slip movements late carboniferous inversion related deformations along the ne boundary of the lublin basin were associated with some degree of ductile quasi diapiric deformation facilitated by thick series of silurian shales during mesozoic extension and development of the mid polish trough major fault zones within the lublin basin remained mostly inactive and subsidence centre moved to the sw towards the nowe miasto zawichost fault zone and further to the sw into the present day holy cross mts area late cretaceous paleogene inversion of the mid polish trough and formation of the mid polish swell was associated with reactivation of inherited deeper fault zones and included also some strike slip faulting the study area provides well documented example of the foreland plate within which repeated basin inversion related to compressive transpressive deformations was triggered by active orogenic processes at the plate margin i e variscan or carpathian orogeny and involved important strike slip reactivation of crustal scale inherited fault zones belonging to the teisseyre tornquist zone

crustal structure at the trans european suture zone in northwest poland based on gravity data a new gravity model of the crustal structure of the trans european suture zone in the northwestern poland has been constructed the bouguer anomaly map obtained after stripping off the three dimensional gravity effect of the sedimentary cover down to the zechstein formations is characterized by a 50 mgal gravity anomaly we have assumed that the short wavelength components derive from upper crustal intrusions and the long wavelength components reflect crustal thickness and lateral heterogeneity which are strongly supported by the new seismic data along the lt 7 geotraverse quantitative modelling of gravity data along three profiles crossing the area indicate the presence of anomalous masses within the lower palaeozoic sequence mainly along the teisseyre tornquist zone two of the profiles crossing the long wavelength stripped gravity high suggest the existence of a zone of 35 km crust above a dense upper mantle along the teisseyre tornquist zone the extent of the zone can be determined based on the bouguer anomalies interpretation

a review of quaternary proboscideans from alberta canada here we present a summary of the largest museum collection of quaternary proboscideans known from alberta housed at the royal alberta museum the 378 specimens reported here come from localities across the province highlighting the broad distribution of proboscideans in southwestern canada during the late pleistocene despite the isolated nature of most individual specimen records the cumulative record provides a broad sense of the chronologic distribution of late pleistocene proboscideans in a large portion of southwestern canada new and summary radiocarbon data indicate that the sparse record of pre lgm mastodon mammut americanum is limited to 40 700 3000 yr bp suggesting a pattern of pre lgm extirpation previously observed at more northern latitudes mammoths mammuthus spp occur in greater numbers and have a more lengthy late pleistocene record characterized by a temporal gap related to the last glacial maximum lgm

crustal structure across the tesz along polonaise 97 seismic profile p2 in nw poland abstract the polonaise 97 po lish l ithospheric on set a n i nternational s eismic e xperiment 1997 seismic experiment in poland targeted the deep structure of the trans european suture zone tesz and the complex series of upper crustal features around the polish basin one of the seismic profiles was the 300 km long profile p2 in northwestern poland across the tesz results of 2d modelling show that the crustal thickness varies considerably along the profile 29 km below the palaeozoic platform 35 47 km at the crustal keel at the teisseyre tornquist zone ttz slightly displaced to the northeast of the geologic inversion zone and 42 km below the precambrian craton in the polish basin and further to the south the depth down to the consolidated basement is 6 14 km as characterised by a velocity of 5 8 5 9 km s the low basement velocities less than 6 0 km s extend to a depth of 16 22 km in the middle crust with a thickness of ca 4 14 km the velocity changes from 6 2 km s in the southwestern to 6 8 km s in the northeastern parts of the profile the lower crust also differs between the southwestern and northeastern parts of the profile from 8 km thickness with a velocity of 6 8 7 0 km s at a depth of 22 km to ca 12 km thickness with a velocity of 7 0 7 2 km s at a depth of 30 km in the lowermost crust a body with a velocity of 7 20 7 25 km s was found above moho at a depth of 33 45 km in the central part of the profile sub moho velocities are 8 2 8 3 km s beneath the palaeozoic platform and ttz and about 8 1 km s beneath the precambrian platform seismic reflectors in the upper mantle were interpreted at 45 km depth beneath the palaeozoic platform and 55 km depth beneath the ttz the polish basin is an up to 14 km thick asymmetric graben feature the basement beneath the palaeozoic platform in the southwest is similar to other areas that were subject to caledonian deformation avalonia such that the variscan basement has only been imaged at a shallow depth along the profile at northeastern end of the profile the velocity structure is comparable to the crustal structure found in other portions of the east european craton eec the crustal keel may be related to the geologic inversion processes or to magmatic underplating during the carboniferous permian extension and volcanic activity

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

the trans european fault a critical reassessment abstract new deep seismic pro les in the southern baltic region have failed to image the trans european fault evidence for this structure of suggested pre cadomian age is critically re examined localized geophysical anomalies are present but these cannot be correlated with known structuralfeatures of the region based on the inconclusive evidence for this structure we would therefore pro pose that the term trans european fault should not be used in the future and that to avoid confu sion authors use local names for local structures author for correspondence tmc gfz potsdam de stzcdftefdanishbasinrfh eugemi aelnorthgermanmassif nizu sebasin 9601pq2 9 1 4 13 25 berthelsen 1984eugeno s working group 1988horst flueh borngen 1994krauss 1994franke 1993 0 100 km 12345 i pq2 9pq2 9 3 3 loss 1 70h2 1 90k5 1 88g14 1 86pud 1 86rn 2 67gst 1 73rn 4 64 r u g enusedom 0 30 km figure 1 map showing the main structural features and thelocations of the deep seismic surveys in the region the vari ous trends of the trans european fault are also indicated 1 pozarski brochwicz lewinski tomczyk 1982 buttermed caledonian deformation front berthelsen 1984 babel working group 1993 mona lisa workinggroup 1997 2 eugeno s working group 1988 3 horst flueh borngen 1994 4 krauss 1994 5 franke 1993 inset map shows the locations of wells mentioned inthe text key cdf caledonian deformation front el elbe lineament rfh ringkobing fyn high stz sorgenfrei tornquist zone tef trans european fault