gravity above subduction zones and forces controlling plate motions 1 short and intermediate wavelength gravity and geoid anomalies are used to provide constraints on the mechanical structure of subduction zones and on the forces involved this study is based on 2d cartesian dynamically self consistent models with newtonian or power law rheologies we show that both strong decoupling of the two convergent plates shear stresses of the order of 107 pa and weakened bending lithosphere are necessary to reproduce the observed geoid and gravity data good fits are found for relatively low failure stresses 30 50 mpa for all models providing reasonable predictions of gravity only a small fraction of the downgoing slab weight is transmitted to the surface plates about 10 of the energy is dissipated in the contact zone between the two plates 10 to 20 in the bending region and more than 70 in the sublithospheric mantle the basal tractions on the order of 1 4 1012 n m induce a net motion of the plates with the subducting lithosphere moving faster than predicted by the no net motion principle a marked positive geoid anomaly is predicted above subduction zones at intermediate wavelength 2000 4000 km in the case of pure whole mantle convection such large geoid highs are not observed introducing partial layering i e mass anomalies hampering mantle flow through the transition zone is necessary to reconcile model predictions and observations for these wavelengths

rheological stratification of the lithosphere abstract the rheology of the lithosphere is estimated on the basis of pore pressure dependent frictional failure in the brittle regime and power law steady state creep in the ductile regime different petrological models of the continental and oceanic lithosphere combined with different geotherms and thicknesses are used to generate models covering a variety of geodynamic situations results show that the depth dependence of lithospheric rheology varies with the tectonic province and that in many instances the continental lithosphere has one at the bottom of the crust or two the previous one plus another at mid crustal levels soft ductile layers sandwiched between brittle layers the depth distribution of geophysical parameters seismicity seismic wave velocity and electrical conductivity matches the theological predictions well the lithospheric rheological profiles are used to analyze observed variations in the structural style of deformed continental margin and oceanic terranes in the southeastern canadian cordillera the large scale characteristics of the system show a satisfactory agreement with the inferred rheological structure sub horizontal decollements should be the rule rather than the exception where the lithospheric rheology is strongly stratified

constraining odd degree earth structure with coupled free oscillations several pairs of normal mode multiplets sensitive to long wavelength mantle structure are potential coupling partners geometric selection rules render such coupling the only means by which normal modes sample odd degree mantle structure that overtone coupling can be strong and can significantly impact normal mode spectra is illustrated using synthetic seismograms for a realistic earth model these observations motivate the generalization of normal mode spectral fitting to permit simultaneous estimation of even and odd degree structural constraints when generalized spectral fitting is applied to a data set of approximately 150 high signal to noise vertical records dominated by data from the northern bolivian event 6 9 1994 it is found to reduce misfits appreciably for coupled multiplets 1 s 5 2 s 4 and 2 s 5 1 s 6 to yield odd degree constraints generally consistent with recent mantle models and to improve agreement between estimated and predicted even degree constraints

cd ca changes in a deep cape basin core over the past 730 000 years response of circumpolar deepwater variability to northern hemisphere ice sheet melting a comparison of cadmium calcium cd ca records of benthic foraminifera from a deep cape basin and a deep eastern equatorial pacific core suggests that over the past 400 000 years the nutrient concentration of circumpolar deep water cpdw has always been lower than that of the deep pacific the data further suggest that at the 100 000 and 23 000 year orbital periods the contribution of north atlantic deep water to cpdw is at a maximum during periods of ice growth and at a minimum during periods of ice decay these results are not in agreement with results based on carbon isotope records of benthic foraminifera which suggest intervals of cpdw nutrient enrichment relative to the deep pacific and an approximately in phase relationship between cpdw nutrient concentration and ice volume resolution of the apparent conflict between 13c and cd ca data may provide important constraints on past deep ocean circulation and nutrient variability

the evolution of the carpathians pannonian system interaction between neotectonics deep structure polyphase orogeny and sedimentary basins in a source to sink natural laboratory abstract the carpathians pannonian basin system provides a natural laboratory for analysing lithospheric to surface controls on tectonic topography development in a coupled source to sink environment to link processes taking place at depth and at the surface recent research focused on the interplay between basin evolution active tectonics topography evolution and intraplate folding mechanisms neotectonic processes control landscape development and natural hazards in particular the seismicity during the late stage late neogene quaternary evolution of both the carpathians pannonian basin system and its interaction with the adjacent dinarides and balkans the deep structure of the se carpathians exerts a strong control on the post collisional evolution of the system new constraints are available from seismic tomography deep seismic reflection and refraction profiling and detailed studies of the vreancea seismicity inherited orogenic fabric and structure of the active black sea sink has a strong influence on the localisation of the neogene sediment pathways a close relationship has been established between the timing and mechanisms of stress changes in the pannonian and transylvania basins and structural episodes in the surrounding thrust belts pointing to an intrinsic mechanical coupling with these basins the orogen and its foredeep basin inversion taking place during the pliocene quaternary times in the entire carpathians pannonian system is related to changes in the regional stress field leading to differential vertical movements associated with a laterally variable folding mechanism active in the entire system short crustal folding patterns alternate with lithospheric wavelengths in the se carpathians foreland east and south carpathians transylvania and pannonian basins the lateral variability is the result of a marked contrast in rheology between these areas directly related to the crustal configuration thermal properties and late stage collision kinematics with the carpathians foreland lateral variations in the properties of the downgoing plates largely control the collision mode in the carpathians and the post collisional evolution of the entire system

the strength of the continental crust detachment zones and the development of plastic instabilities abstract the maximum strength of the continental crust is constrained by the geothermal gradient the lithological make up of the crust and whether or not the byerlee relation holds to the base of the continental crust if this linear byerlee relation holds then maximum shear stress levels sustained at low geothermal gradients 10 20 c km 1 could be as high as 300 mpa in the upper part of the mantle for strike slip regimes and up to 700 mpa in thrust regimes towards the base of the crust however if byerlee s relation breaks down at moderate temperatures and pressures and if such breakdown is associated with the transition from unstable to stable sliding on pre existing faults then the maximum stress levels in the crust being set by the shear stress at the breakdown depth are much lower ca 300 mpa for low geothermal gradients and thrust regimes the lithosphere is quite weak below the crust for geothermal gradients greater than 20 c km 1 so attempts to treat the lithosphere as an elastic slab for time scales for which plastic flow contributes significantly to the deformation should be questioned for a geothermal gradient of 10 c km 1 the entire continental crust and part of the upper mantle behave as an elastic brittle slab at higher geothermal gradients the distribution of strength is variable vertically according to the magnitude of the geothermal gradient and the lithological make up large contrasts in strength occur across rheologically defined boundaries as well as across lithological boundaries at these higher geothermal gradients such contrasts in strength could act as nuclei for detachment zones within the continental crust and upper mantle detachment at or near the moho is to be expected only for low geothermal gradients lateral variations in the geothermal gradient produce shallowly dipping zones of highly contrasting strength throughout the continental crust and uppermost mantle possibly resulting in flat lying thrusts and normal faults which may ramp upwards through the crust instabilities leading to seismic events which occur solely during plastic shearing should be common in thrust terranes where the stresses are relatively high ca 100 200 mpa for geothermal gradients ranging from 10 to 50 c km 1 and for quartz rich felsic mafic and peridotitic rock types thrust terranes are therefore predicted to be characterized by coseismic plastic instabilities on all detachment zones throughout the crust and into the uppermost mantle but embryonic rift zones should be aseismic at depth ca 10 km

buckling of the lithosphere in western himalaya constraints from gravity and topography data the deformation of the lithosphere in western himalaya and karakoram is analyzed by correlating bouguer gravity anomalies and topographic heights sampled along profiles in the direction of the indo asian collision the spectral features of the coherence linear admittance and correlation coefficients between topography and deformation at depth support the hypothesis that the flexural mode of lithospheric deformation is complemented by a folding mode with typical wavelengths concentrated in bands centered at 250 and 120 km when combined with realistic models of a rheologically stratified lithosphere with two strong layers upper crust and upper mantle sandwiching a weak very ductile layer the lower crust the data are consistent with a model of response to horizontal deformation in which a coupled biharmonic folding instability develops the lithosphere as a whole warps with the longer wavelengths and the upper layer alone also with the shorter wavelengths major faults such as the main boundary thrust or the main karakoram thrust and the computed folds of the upper layer are phased as if there were a causal relationship between the position of the faults and the zones of highest strain in the crust

slab break off abrupt cut or gradual detachment new insights from the vrancea region se carpathians romania slab break off is a plate tectonic process which does not only return lithospheric material into the deeper mantle but also has severe effects on surface movements and seismic hazard slab pull induced seismicity is reduced when the subducted slab decouples from the overlying crust in the vrancea region se carpathians strong earthquakes frequently occur at intermediate depths 70 180 km in a laterally small volume while the crust shows low but distributed seismicity the stress pattern shows similar partitioning with vertical extension in the slab and no preferred orientation in the overlying crust both features indicate a decoupling between slab and overlying crust either by slab break off or delamination however the strong vertical elongation of the slab requires that the upper end of the slab is fixed vertically thus a soft coupling is assumed that is strong enough to enable elongation of the slab but weak enough to inhibit quasi static stress transfer to the overlying crust

high resolution teleseismic body wave tomography beneath se romania ii imaging of a slab detachment scenario summary non linear teleseismic bodywave tomography with data of the 1999 calixto field experiment carpathian arc lithosphere x tomography in romania provides high resolution imaging of the upper mantle structure in this paper we present the relative p wave velocity distribution of the lithosphere asthenosphere system smearing from strong crustal velocity anomalies into the upper mantle is successfully suppressed by traveltime corrections with an a priori 3 d regional crustal velocity model see martin et al 2005 herein referenced as paper 1 our high resolution image shows a high velocity body beneath vrancea and the moesian platform with a ne sw orientation between 70 and 200 km depth beneath 200 km a change in the orientation from ne sw to n s can be observed the body reaches a maximum depth of about 350 370 km the velocity perturbation is maximal between 110 and 150 km depth 5 2 5 8 per cent and almost constant for depths beneath 200 km 3 2 3 8 per cent as most authors of previous studies agree on miocene subduction along the arc followed by soft continental collision we interpret the high velocity body as the subducted yet not fully detached slab the ne part of the slab appears to be mechanically coupled to the moesian lithosphere and hosts the intermediate depth seismicity in contrast the aseismic sw part is interpreted as decoupled from the overlying lithosphere and torn off from the underlying lithospheric material beneath 200 km depth low velocity anomalies nw of the slab above 110 km depth are interpreted as a shallow asthenospheric upwelling further low velocity anomalies are in agreement with a lithosphere asthenosphere boundary at 110 150 km depth below the moesian platform and deeper than 200 km under the east european platform eep the tomographic images support models proposing slab rollback during subduction collision followed by slab steepening and lithospheric delamination the different degrees of mechanical coupling of the slab to the overlying lithosphere allow to understand the loci of seismicity as volumes of stress concentration independent on the specifics of data interpretation our high resolution image is a novel contribution to understand the process of ongoing lithospheric detachment associated with strong intermediate depth seismicity in se romania

surface kinematics in the alpine carpathian dinaric and balkan region inferred from a new multi network gps combination solution abstract the understanding of the intraplate tectonics of central europe requires a detailed picture of how stress is transferred from the interaction of the eurasian nubian and anatolian plates to the alpine carpathian pannonian and dinaric regions recent strain distribution is controlled by the adria horizontal push by the vrancea vertical slab pull and associated horizontal displacements and by the aegean anatolia extension and slab roll back we present a horizontal velocity field for the alpine carpathian pannonic dinaric and balkan regions resulting from a new combination of seven different gps networks formed from permanent and campaign stations dedicated velocity profiles in two specific regions are studied in detail one is the alpine pannonian region with a detailed picture of the ns indentation of the adria microplate into the southern alps in ne italy the deformation in the tauern window and the eastwards kinematics of a pannonian plate fragment the second study region includes transylvania the southern carpathians up to the aegean sea and albania where a major right lateral shear deformation exists as a consequence of the ne convergence of the apulia platform towards the dinarids and the ssw motion of macedonia western bulgaria and rumania related to the hellenic arc dynamics in the eastern mediterranean the profiles in the alpine pannonian area indicate that a velocity drop of 2 5 0 4 mm yr associated with the adria indentation concentrates on a segment of some 50 km south of the periadriatic fault the deformation becomes extensional by a similar amount just north of the periadriatic fault in the tauern window where the updoming of the tauern window implies vertical motion which could well be associated with surface extension in the ew profile we observe a sudden velocity change of 1 5 0 2 mm yr in 20 km corresponding to the right lateral lavant fault which seems to mark the border between dominant indentation kinematics to the west and dominant extrusion kinematics to the east three profiles are considered in southern and eastern europe one across the lower adriatic sea from apulia in italy to the southern dinarides which enables it to constrain the velocity drop associated with the subduction of the adria microplate into the dinarides to 3 2 0 5 mm yr in 140 km the second profile is longitudinal and constrains the velocity inversion of 7 4 1 0 mm yr in 350 km associated with right lateral shear faults in albania the third profile crosses the transylvania region with a shortening of 2 3 1 0 mm yr in 220 km and the wallachian moesian region up to the chalcidic peninsula in n greece this lower part of the profile implies an extensional stretch of the upper crust of 3 2 0 9 mm yr in 440 km culminating in the hellenic arc strain rate maps are presented in this regional scale showing the excellent agreement between fault plane solutions of crustal earthquakes and the eigenvectors of the gps derived two dimensional strain rate tensor three profiles are considered in the balkan and se carpathians one across the lower adriatic sea from apulia in italy to the southern dinarides which enables to constrain the velocity drop associated to the subduction of the adria microplate into the dinarides to 3 2 0 5 mm yr in 140 km the second profile is longitudinal and constrains the velocity inversion of 7 4 1 0 mm yr in 350 km associated to right lateral shear faults in macedonia a highly seismic region the third profile crosses the transylvania with a shortening2 3 1 0 mm yr in 220 km and the wallachian moesian region up to the chalcidic peninsula in n greece this lower part of the profile implies an extensional stretch of the upper crust of 3 2 0 9 mm yr in 440 km culminating in the hellenic arc

carpathian foreland fold and thrust belt and its relation to pannonian and other basins the foreland fold and thrust belt of the carpathians can be traced from austria through the western and eastern carpathians to the south carpathian bend in romania where most of its structural units plunge beneath younger pliocene pleistocene cover folds in the youngest rocks at the south carpathian bend continue westward until all surface expression disappears before reaching the danube river the fold and thrust belt is flanked by elements of the european russian and moesian cratonal areas which are overlain by a variable width and thickness of foredeep deposits that are partly involved within the external fold and thrust belt internal to the fold and thrust belt are older parts of the carpathian orogene formed mainly on continental crust these older structures have significant differences in evolution between the western and eastern carpathians the foreland fold and thrust belt consists predominantly of flysch in its inner parts and molasse in its outer parts these sedimentary rocks are cut into a series of thrust sheets that have moved relatively toward the craton oldest flysch units are late jurassic and the youngest units are miocene some of the flysch units of the inner part of the belt may have been underlain by oceanic crust whereas the younger more external molasse units were underlain by continental crust timing of thrusting is only well constrained locally but suggests that deformation in the western carpathians developed during oligocene to miocene time in the eastern carpathians structural activity continued into the pliocene and deep earthquake activity at vrancea suggests subduction deformation is sti l locally active a volcanic arc of miocene to holocene age lies internal to the fold and thrust belt magmatic activity appears to have migrated externally and eastward in time contemporaneous with thrusting was the development of neogene basins in the intra carpathian region these basins exhibit a two phase subsidence history except for the pannonian and transylvanian basins fast initial subsidence followed by a period of slower linear subsidence the pannonian basin shows only a reasonably fast linear subsidence structural and thermal models indicate the basins were formed by about 100 stretching the convex east loop of the carpathian foreland fold and thrust belt is a result of the collision of continental fragments against a recess in the combined european moesian plate in this region subduction or downbending of the subducted slab results in an extensional stress field suggesting that thrusting and apparent compression along the mountain belt are only thin skinned superficial effects due to the inability to subduct light upper crustal material and detachment of the crust from the underlying lithosphere the dominant forces seem to be those acting on the downgoing slab which produce shortening along the plate boundary and plate geometry that inhibits rigid plate convergence

topo europe studying continental topography and deep earth surface processes in 4d abstract topo europe is a multidisciplinary international research program that addresses the interaction of processes inherent to the deep earth lithosphere mantle with surface processes erosion climate sea level which together shaped the topography of europe the objective of this programme is to assess neotectonic deformation rates and to quantify related geo risks such as earthquakes flooding landslides rock falls and volcanism research incorporating data interactive modeling focuses on the lithosphere memory and neotectonics with special attention on the thermo mechanical structure of the lithosphere mechanisms controlling large scale plate boundary and intraplate deformations anomalous subsidence and uplift and links with surface processes and topography evolution the topo europe natural laboratories in which these processes are analyzed cover a wide range of geodynamic settings these include the post collisional alpine carpathian pannonian basin system the very active aegean anatolian and apennines tyrrhenian orogens and back arc basins the caucasus levant area in the arabia europe collision zone the iberian peninsula caught up between alpine orogens the meta stable west and central european platform the stable east european platform and the seismically active and elevated scandinavian continental margin the topo europe project is a component of the international lithosphere program a european science foundation eurocores project provides funding for part of the research for a total amount of 13 5 m euro creating new research positions for 60 young researchers

age and significance of core complex formation in a very curved orogen evidence from fission track studies in the south carpathians romania abstract twenty four new zircon and apatite fission track ages from the getic and danubian nappes in the south carpathians are discussed in the light of a compilation of published fission track data a total of 101 fission track ages indicates that the getic nappes are generally characterized by cretaceous zircon and apatite fission track ages indicating cooling to near surface temperatures of these units immediately following late cretaceous orogeny the age distribution of the danubian nappes presently outcropping in the danubian window below the getic nappes depends on the position with respect to the cerna jiu fault eocene and oligocene zircon and apatite central ages from the part of the danubian core complex situated southeast of this fault monitor mid tertiary tectonic exhumation in the footwall of the getic detachment while zircon fission track data from northwest of this fault indicate that slow cooling started during the latest cretaceous the change from extension getic detachment to strike slip dominated tectonics along the curved cerna jiu fault allowed for further exhumation on the concave side of this strike slip fault while exhumation ceased on the convex side the available fission track data consistently indicate that the change to fast cooling associated with tectonic denudation by core complex formation did not occur before late eocene times i e long after the cessation of late cretaceous thrusting core complex formation in the danubian window is related to a larger scale scenario that is characterized by the nnw directed translation followed by a 90 clockwise rotation of the tisza dacia block due to roll back of the carpathian embayment this led to a complex pattern of strain partitioning within the tisza dacia block adjacent to the western tip of the rigid moesian platform our results suggest that the invasion of these southernmost parts of tisza dacia started before the late eocene i e significantly before the onset of miocene age rollback and associated extension in the pannonian basin

normal mode and free air gravity constraints on lateral variations in velocity and density of earth s mantle with the use of a large collection of free oscillation data and additional constraints imposed by the free air gravity anomaly lateral variations in shear velocity compressional velocity and density within the mantle dynamic topography on the free surface and topography on the 660 km discontinuity and the core mantle boundary were determined the velocity models are consistent with existing models based on travel time and waveform inversions in the lowermost mantle near the core mantle boundary denser than average material is found beneath regions of upwellings centered on the pacific ocean and africa that are characterized by slow shear velocities these anomalies suggest the existence of compositional heterogeneity near the core mantle boundary

tertiary evolution of the intra carpathian area a model abstract the outer carpathian flysch nappes encircle an intra carpathian domain which can be divided into two megatectonic units north pannonian and tisza mostly on the basis of contrasting mesozoic and palaeogene facies development we see two major kinematic problems to be solved 1 1 the present distribution of the mesozoic and palaeogene facies is mosaic like and some belts form exotic bodies within realms of austroalpine affinity 2 2 late eocene palinspastic reconstruction of the outer carpathian flysch nappes suggest that the entire intra carpathian area must have been located several hundreds of kilometres to the south and to the west of its present position neogene extension can account for shortening in the external carpathian nappes but is unable to explain mesozoic facies anomalies and offsets of palaeogene formations we suggest that evolution of the intra carpathian area involved first late palaeogene early miocene juxtaposition of the north pannonian and tisza megatectonic units accompanied by the closure of the external carpathian flysch troughs thereafter extension of this amalgamated unit occurred which was compensated by thrusting of flysch nappes onto the european foreland and formation of molasse foredeeps eastward escape of the north pannonian unit from the alpine collisional belt involved left lateral shear along the pieniny klippen belt and right lateral shear along the mid hungarian zone parts of the late palaeogene basin and an early miocene volcanic edifice were dissected offset and elongated by several 100 kms the driving mechanism of the eastward escape of the intra carpathian area can be related to the collision of apulia and europe and the subduction of the external carpathian crust under the pannonian units the escape ceased gradually in the early miocene when oblique collision between the north pannonian unit and european continent occurred neogene extension of the pannonian region was an areal deformation the extension at locally variable rate resulted in the break up of the heterogenous floor of the neogene basin the driving mechanism of basin extension and contemporaneous compressional deformation of the external carpathians is thought to be related to ongoing subduction involving the marginal part of the attenuated european continental crust tectonic activity in the carpathians and basin subsidence and volcanism shifted in time and in unison from the west toward the east southeast

neotectonics and intraplate continental topography of the northern alpine foreland research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues the accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years which on geological time scales is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity more reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling on going intraplate deformation the alpine orogen and the intraplate sedimentary basins and rifts in its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed seismicity and stress indicator data combined with geodetic and geomorphologic observations demonstrate that deformation of the northern alpine foreland is still on going and will continue in the future this has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area we examine relationships between deeper lithospheric processes neotectonics and surface processes in the northern alpine foreland and their implications for tectonically induced topography for the environmental tectonics project entec the upper and lower rhine graben urg and lrg and the vienna basin vb were selected as natural laboratories the vienna basin developed during the middle miocene as a sinistral pull apart structure on top of the east alpine nappe stack whereas the upper and lower rhine grabens are typical intracontinental rifts the upper rhine graben opened during its late eocene and oligocene initial rifting phase by nearly orthogonal crustal extension whereas its neogene evolution was controlled by oblique extension seismic tomography suggests that during extension the mantle lithosphere was partially decoupled from the upper crust at the level of the lower crust however whole lithospheric folding controlled the mid miocene to pliocene uplift of the vosges black forest arch whereas thermal thinning of the mantle lithosphere above a mantle plume contributed substantially to the past and present uplift of the rhenish massif by contrast oblique crustal extension controlling the late oligocene initial subsidence stage of the lower rhine graben gave way to orthogonal extension at the transition to the neogene the entec project integrated geological geophysical geomorphologic geodetic and seismological data and developed dynamic models to quantify the societal impact of neotectonics in areas hosting major urban and industrial activity concentrations the response of europe s intraplate lithosphere to late neogene compressional stresses depends largely on its thermo mechanical structure which in turn controls vertical motions topography evolution and related surface processes

thermal evolution and geometry of the descending lithosphere beneath the se carpathians an insight from the past abstract mantle heterogeneities imaged by seismic tomography in the se carpathians contain information on the present thermal state of the mantle based on p wave seismic velocity anomalies we develop a model of the present mantle temperature beneath the region and combine the model with a model of crustal temperature constrained by heat flow data the modeled temperatures are assimilated into the geological past using the information on the regional movement in the early and middle miocene prominent thermal states of the lithospheric slab descending in the region are restored from its diffuse present state in miocene times the slab geometry clearly shows two portions of the sinking body the northwest southeast oriented portion of the body is located in the vicinity of the boundary between the east european and scythian platforms and this portion of the sinking body may be a relic of cold lithosphere that has traveled eastward another portion has a northeast southwest orientation and is related to the present descending slab above a depth of 60 km the slab had a concave thermal shape confirming the curvature of the carpathian arc and a convex surface below that depth the slab maintained its convex shape until it split into two parts at a depth of about 220 km we propose that this change in the slab geometry which is likely to be preserved until the present can cause stress localization due to the slab bending and subsequent stress release resulting in large mantle earthquakes in the region also we hypothesize that either the processes of dehydration and partial melting of the descending lithospheric slab or dragging down of hotter rocks from the adjacent uppermost mantle by the slab are possible causes of the reduction in seismic velocities beneath the transylvanian basin

structural evolution of the transylvanian basin romania a sedimentary basin in the bend zone of the carpathians abstract the transylvanian basin with its up to 10 km thick upper cretaceous to pliocene fill is one of the most important sedimentary basins of southeastern europe upper cretaceous coarse grained clastics lie unconformably on basement strongly tectonized during early cretaceous and older stages upper cretaceous sediments were mainly deposited along roughly n s trending grabens and were subsequently folded before the end of the paleocene eocene to middle oligocene rocks record mostly quiet sedimentation n s tension and extension took place in the oligocene and was followed by widespread nw se compression and contraction important thrusts are associated with this phase in the northwestern and southeastern parts of the basin widespread n s contraction followed during the early miocene in association with s vergent thrusting in the northern part of the basin a southward thinning clastic wedge developed during this stage the badenian basal unconformity marked a major change in the sedimentary and tectonic pattern of the transylvanian basin with new depocenters developing in the central parts of the present day basin late miocene e w extension affected vast areas and caused some important normal faulting in the southeast the youngest deformation recorded is associated with e w contraction and is of pliocene or younger age

rheology predictions across the western carpathians bohemian massif and the pannonian basin implications for tectonic scenarios on the basis of extrapolation of failure criteria lithology and temperature models we predict the rheology of the lithosphere for several sections through the carpathians and surrounding regions our models show significant lateral variations in rheology for the different tectonic units with important implications for the tectonic evolution the theologically strong lithosphere of the polish platform area contrasts with the weak lithosphere of the pannonian basin indicating that the arcuate shape of the carpathian orogen is primarily caused by an inherited curvature of an ancient embayment in the foreland with the pannonian units passively filling the space the polish platform and the moesian platform exhibit a similar rheological anisotropy caused by nw se trending weakness zones paralleling the tornquist teisseyre zone this anisotropy was the main controlling factor on the behavior of the lithosphere in this area since cadomian times as documented by the geological evolution of the sudety mountains and the mesozoic polish trough including the late cretaceous alpine inversion and the neogene development of the carpathian foreland this rheological anisotropy appears to have a major controlling impact on the development of at least the eastern part of the european lithosphere rheology predictions for the bohemian massif support the idea that the rigid lithosphere of the bohemian massif governed the bending of the alpine carpathian transition zone expressed in the large scale wrench movements opening the vienna basin in the foreland area detachment levels are predicted for upper and lower crustal levels leading to a decoupling of crustal and subcrustal flexure in most areas comparison with basin formation models indicates that our predictions for effective elastic thickness eet are similar to those derived from flexural models for the foreland area also eet predictions from extensional basin models in the pannonian region yield values close to our findings

observation of present day tectonic motions in the southeastern carpathians results of the ises crc 461 gps measurements results are presented from gps measurements performed in the southeastern carpathians between 1997 and 2004 data from 25 stations observed during 13 campaigns were analyzed by the department of earth observation and space systems deos of delft university of technology the repeatabilities of the solutions are on the order of 1 4 mm for the horizontal and 4 8 mm for the vertical component the resulting velocity estimates have an uncertainty of b1 mm yr and b3 mm yr respectively the region southeast of the carpathian bend zone shows a horizontal movement towards sse of 2 5 mm yr while the transylvanian basin shows very small motions with respect to eurasia the vertical velocity field indicates the existence of uplift and subsidence domains in the se carpathians in good agreement with pliocene quaternary orogen and basin studies another 29 gps stations installed in the last 3 yr will generate a denser velocity field in the coming years for this region d 2005 elsevier b v all rights reserved

lithospheric flexure uplift and expected horizontal strain rate in the pannonian carpathian region abstract the apuseni mountains are located between the pannonian basin and the transylvanian basin along a direction of se convergence with the carpathian belt a flexural model based on the cylindrical bending of a semi infinite isostatically supported thin elastic plate is here examined with the apuseni playing the role of flexural bulge and under the assumption that the plate is deforming under the action of a vertical shear force and a bending moment applied at the end of the plate beneath the carpathians the model yields estimates of the plate thickness ranging between 13 and 14 5 km depending on the assumed density contrast between crust sediments and mantle providing buoyancy the vertical shear force which is necessary to bend the plate is in the range between 60 and 300 10 11 n m 1 depending on the assumed density contrast this force is shown to be modelled by a gravitational slab pull force using model parameters derived from seismic tomography if the height of the flexural bulge after correction for erosion is allowed to increase the model yields an estimate of the horizontal strain rate at the top of the bulge for example 5 mm yr vertical change of the flexural bulge of a 14 km thick plate results in a horizontal deformation rate of approximately 7 nanostrain yr at the top of the bulge a value which is at the threshold of sensitivity of continuous gps measurements different vertical rates will change the horizontal strain rate almost proportionally

vertical movements in and around the south east carpathian foredeep lithospheric memory and stress field control a 10 km thick basin formed in tertiary to quaternary times in front and overlapping with the south east carpathians the focs depression is part of this system and overlies the vrancea seismogenetic volume thought to correspond to the remnants of the continental slab subducted beneath the carpathians slab detachment and its lateral migration are considered to control vertical movements in the area we present the first complete analysis of subsidence patterns in the depression and derive a substantially different picture the strongest subsidence is sarmatian in age coeval with the main nappe emplacement events subsequently subsidence did not stop and persisted until present times despite cessation of thrusting the main depocen

models for relative motion of crustal blocks within the carpathian region based on restorations of the outer carpathian thrust sheets details of the oligocene present day motion of the adriatic block with respect to europe can be determined by palinspastic restorations of the outer carpathians thrust sheets the arcuate nature of the carpathians poses problems for simple restorations of sections because they create converging restoration paths which require large amounts of strike parallel extension 40 50 such large amounts of extension are not seen on maps or in the field a combination of thrust transport directions changing with time between and within thrust sheets and divergent transport directions helps minimise the arc parallel extension necessary 18 25 the pannonian basin can be treated either as an area dominated by strike slip motion rigid block movements or as an area of back arc extension the differences in restoration geometry produced by these two scenarios help to indicate which of the two mechanisms was dominant the consequences of the rigid block restoration indicate the model is inappropriate because it requires approximately 20 clockwise rotation of the adriatic block during the late tertiary it also indicates at least 300 km strike slip motion distributed among the late tertiary faults of the dinaride balkanide and hellenide mountain belts the back arc extension model alleviates the the 20 clockwise rotation of the adriatic block and requires about 200 km distributed strike slip motion in yugoslavia and bulgaria

volcano basement interaction in the eastern carpathians explaining unusual tectonic features in the eastern transylvanian basin romania abstract evidence of volcano basement interaction related to the neogene quaternary c limani gurghiu harghita volcanic chain cgh in the eastern carpathians romania includes both structural and morphological features the cgh is located roughly between the carpathian thrust and fold arc to the east and the transylvanian basin to the west geological and geophysical data demonstrate basement subsidence along most of the axial part of the volcanic chain the wide volcaniclastic plateau developed preferentially westward by adjoining composite volcanoes extends deep into the transylvanian basin and its surface is tilted toward the chain axis especially in the gurghiu mountains these features strongly suggest late stage or post volcanic basement sagging beneath the volcanoes and related peripheral uplift interpretation of 2d seismic profiles acquired in the transylvanian basin indicates strong influence of the salt related tectonics on the entire post salt sequence the middle to late miocene succession including the volcanic edifices are tilted toward the basin margins the pre salt deposits together with the metamorphic basement are not tilted instead they are progressively uplifted we suggest that the salt related tectonics enhanced by volcano induced compressive tectonics is the main triggering factor the neogene salt tectonics developed under an overall regional compressive stress field the salt withdrawal beneath the upper miocene siliciclastites was amplified by the influence of the weight of the volcanic edifices the post salt succession including the volcanics tilting is related to salt withdrawal processes and rotation of the whole post salt sedimentary succession along the salt layer acting as a detachment surface swarms of small scale west verging reverse faults developed near the cgh volcanic range represent small scale thrust structures accommodating the rotation induced compression in the post salt brittle lithologies the observed tectonic features are characteristic only for the eastern part of the transylvanian basin no such features have been identified along the western margin or elsewhere in the basin the peripheral deformation of the pre volcanic shallow sedimentary basement induced sagging and spreading of the nearby large volcanic edifices this process combined with the effect of increased heat flux may have strongly enhanced salt diapirism as well volcano spreading was asymmetric because the basement at the eastern margin of the volcanic chain consists of brittle mesozoic sedimentary and precambrian metamorphic rocks of the eastern carpathian thrust and fold belt the buttressing effect to the east favored spreading toward the west tectonic features resulted from volcano basement interaction are combined with those related to regional tectonic processes involved in the evolution of the transylvanian basin and the eastern carpathians interplay between regional stress fields and local volcano induced stress may best account for the complexity of tectonic features recorded in the eastern transylvanian basin