present day kinematics of the mediterranean a comprehensive overview of gps results i combine recently published gps results to derive a geodetic horizontal velocity field consistent at the scale of the mediterranean and the surrounding alpine belts the velocity field is then used to discuss the boundary conditions around each major deforming area in the mediterranean to describe the main patterns of motion and deformation to critically review the existing kinematics models and to finally point out the main unresolved kinematics questions strain rate in europe north of the alpines belt is dominated by the signature of the glacial isostatic adjustment and tectonic strain remains below the current accuracy of gps results in the western mediterranean deformation is restricted to the betics the alboran and the morrocan rif with west to southwestward motion with respect to iberia which is part of stable europe shortening consistent with the relative nubia eurasia plate motion is found throughout the maghrebides but the distribution of deformation in northern africa remains largely unknown the central mediterranean is dominated by the counter clockwise rotation of the adriatic the junction between the southern adriatic domain and nubia has yet to be firmly established the deformation over a wide area east of the maghrebides in tunisia and the gulf of sirte in libya still remains to be quantified in the eastern mediterranean the velocity field is dominated by a general anti clockwise rotation and a general trend towards the hellenic trench with velocity magnitude increasing with decreasing distances from the trench this trend is observed not only in the aegean and anatolia but also in the southern balkans geodetic results emphasize that the convergence of the nubia and arabia plates towards eurasia directly controls the deformation across only very few segments along the plate boundary zone additional processes are therefore required to explain the observed velocity field and deformation pattern

geophysical geological transect and tectonic evolution of the swiss italian alps a complete alpine cross section integrates numerous seismic reflection and refraction profiles across and along strike with published and new field data the deepest parts of the profile are constrained by geophysical data only while structural features at intermediate levels are largely depicted according to the results of three dimensional models making use of seismic and field geological data the geometry of the highest structural levels is constrained by classical along strike projections of field data parallel to the pronounced easterly axial dip of all tectonic units because the transect is placed close to the western erosional margin of the austroalpine nappes of the eastern alps it contains all the major tectonic units of the alps a model for the tectonic evolution along the transect is proposed in the form of scaled and area balanced profile sketches shortening within the austroalpine nappes is testimony of a separate cretaceous age orogenic event west directed thrusting in these units is related to westward propagation of a thrust wedge resulting from continental collision along the meliata hallstatt ocean further to the east considerable amounts of oceanic and continental crustal material were subducted during tertiary orogeny which involved some 500 km of n s convergence between europe and apulia consequently only a very small percentage of this crustal material is preserved within the nappes depicted in the transect postcollisional shortening is characterized by the simultaneous activity of gently dipping north directed detachments and steeply inclined south directed detachments both detachments nucleating at the interface between lower and upper crust large scale wedging of the adriatic or apulian lower crust into a gap opening between the subduced european lower crust and the pile of thin upper crustal flakes alpine nappes indicates a relatively strong lower crust and detachment between upper and lower crust

palinspastic reconstruction and topographic evolution of the eastern alps during late tertiary tectonic extrusion this paper presents a new palinspastic restoration of the eastern alps for neogene time and an attempt to reconstruct the neogene palaeogeology palaeotopography and palaeohydrography in connection with the structural evolution the eastern alps underwent radical horizontal displacement during the neogene due to large strike slip systems and formation of structural windows our palinspastic reconstruction considers a the rearrangement of tectonic units dismembered during tectonic extrusion b the tectonic denudation driven by displacement of the crystalline blocks c geochronological arguments and d the sedimentary record of the syn extrusion basins the rearrangement of tectonic blocks results in a remarkably good fit of highly dismembered zones both in crystalline and sedimentary areas and shows the pre miocene unstretched pattern of the eastern alps reduced to 65 of its present day e w elongation using this structural frame and considering the sedimentary record a set of palaeogeologic and palaeotopographic sketch maps with the palaeo river systems is presented for three time slices pre syn and post extension situation in late oligocene and early miocene times the western eastern alps were already mountainous whereas the eastern part of the orogen formed lowlands or hilly areas enhanced block movement in the course of the extrusion process around the early middle miocene boundary led to the formation of intramontane sedimentary basins and a fault induced reorientation of the drainage pattern which forms the basis of the modern river system in the area east of the tauern window this region where pre miocene land surfaces are preserved probably became a mountainous area not before late miocene time and never reached the elevations of the areas further west

orogen parallel strike slip faults bordering metamorphic core complexes the salzach enns fault zone in the eastern alps austria abstract the approximately ene trending salzach enns fault eastern alps contributed to late stage exhumation of the tauern metamorphic core complex in response to oblique convergence of european and adriatic plates six stages of kinematic evolution with early ductile and later brittle deformational structures were recognized as follows 1 initial ductile deformation is represented by a combination of sinistral shear dominated noncoaxial strain and coaxial strain 2 early brittle sinistral strike slip is combined with a pure shear deformation and represents roughly n s contraction it is followed by 3 sinistral strike slip and 4 ca n s extension due to normal slip striations 5 subsequent n s compression resulted in counterclockwise rotation of the maximum principal stress from ne to nw and led to final dextral strike slip displacements along the salzach enns fault the exhumation of the tauern window was accommodated by dip slip on the fault plane at shallow levels and coaxial flattening at deeper structural levels brittle sinistral faults at shallow structural levels produced a larger amount of strike slip displacement than ductile shear zones at the deeper structural levels which is explained as a scissors like movement and which resulted in the eastward tilting of the tauern window

igneous garnet and amphibole fractionation in the roots of island arcs experimental constraints on andesitic liquids to evaluate the role of garnet and amphibole fractionation at conditions relevant for the crystallization of magmas in the roots of island arcs a series of experiments were performed on a synthetic andesite at conditions ranging from 0 8 to 1 2 gpa 800 1 000 c and variable h2o contents at water undersaturated conditions and fo2 established around qfm garnet has a wide stability field at 1 2 gpa garnet amphibole are the high temperature liquidus phases followed by plagioclase at lower temperature clinopyroxene reaches its maximal stability at h2o contents 9 wt at 950 c and is replaced by amphibole at lower temperature the slopes of the plagioclase in boundaries are moderately negative in text t text x text h 2 text o space at 0 8 gpa garnet is stable at magmatic h2o contents exceeding 8 wt and is replaced by spinel at decreasing dissolved h2o the liquids formed by crystallization evolve through continuous silica increase from andesite to dacite and rhyolite for the 1 2 gpa series but show substantial enrichment in feo mgo for the 0 8 gpa series related to the contrasting roles of garnet and amphibole in fractionating fe mg in derivative liquids our experiments indicate that the stability of igneous garnet increases with increasing dissolved h2o in silicate liquids and is thus likely to affect trace element compositions of h2o rich derivative arc volcanic rocks by fractionation garnet controlled trace element ratios cannot be used as a proxy for slab melting or dehydration melting in the deep arc garnet fractionation either in the deep crust via formation of garnet gabbros or in the upper mantle via formation of garnet pyroxenites remains an important alternative despite the rare occurrence of magmatic garnet in volcanic rocks

lateral extrusion in the eastern alps part 1 boundary conditions and experiments scaled for gravity lateral extrusion encompasses extensional collapse gravitational spreading away from a topographic high in an orogenic belt and tectonic escape plane strain horizontal motion of wedges driven by forces applied to their boundaries in the eastern alps it resulted from 1 an overall northerly compression apulia against eurasia 2 a strong foreland bohemian massif 3 lack of constraint along a lateral boundary carpathian region and 4 a previously thickened gravitationally unstable thermally weakened crust eastern alpine orogenic belt six indentation experiments reproduce lateral extrusion at lithospheric scale the models have two to four lithospheric layers with a mohr coulomb rheology for the upper and a viscous rheology for the lower crust the lithosphere rests upon a low viscosity asthenosphere a broad indenter a narrow deformable area and a weakly constrained eastern margin fullfill as closely as possible conditions in the eastern alps indentation produces both thickening in front of the indenter and escape of triangular wedges lateral variations in crustal thickness become attenuated by gravitational spreading the overall fault pattern includes domains of reverse strike slip oblique normal and pure normal faults strike slip faults in conjugate sets develop serially the narrow width of the deformable area and the strength of the foreland determine the angles between the sets gravitational spreading produces a rhombohedral pattern of oblique and pure normal faults along the unconstrained margin opposite the unconstrained margin the indenter front shows thrusts and folds intersecting with the conjugate strike slip sets a triangular indenter favors spreading high velocity of indentation favors escape high confinement limits lateral motion inhibits spreading and favors thickening lateral extrusion in the eastern alps is best modeled by 1 a weak lateral confinement 2 a broad and straight indenter 3 a narrow width of the deformable area and 4 a rigid foreland crustal thickening lateral escape and gravitational spreading all contribute to the overall deformation

extension in compressional orogenic belts the eastern alps extension in the eastern alps encompasses the following 1 extension accompanying simple shear crustal stacking subhorizontal stretching occurs along flat lying foliations and regionally consistent stretching lineations with associated high strains on a local scale stretching results from extrusion of ductile sediments squeezed between rigid basement blocks basement blocks during thrust sheet imbrication the overall geometric effect is crustal thickening 2 classical extensional tectonics extension first occurs as a consequence of accretion and underthrusting of continental and oceanic material and represents gravitational adjustment of an unstable orogenic wedge extension then occurs as a consequence of terminal continental collision and is accommodated by lateral extrusion of crustal of crustal blocks the overall geometric effect is crustal thinning extension is generally oriented subparallel to the strike of the orogen

cooling and exhumation of the rieserferner pluton eastern alps italy austria the defereggen antholz vals dav line marks the southern border of alpine greenschist facies metamorphism within the austroalpine basement to the south of the western tauern window during the oligocene sinistral strike slip coeval with vertical displacement was accompanied by the syntectonic emplacement of the rieserferner pluton along the north side of the fault to the north of the dav line rb sr as well as k ar biotite cooling ages continuously increase from 16 ma at the rensen pluton in the west to 30 ma at the eastern end of the rieserferner pluton similar trends are apparent from zircon and apatite fission track data which increase eastward from 19 to 29 ma and 13 to 16 ma respectively low cooling rates allow a direct transformation into exhumation rates assuming an average geothermal gradient of 28 c km 1 the resulting exhumation rates of less than 1 mm year 1 do not affect the depth of isotherms in a geologically significant manner hence variable cooling rates within the basement north of the dav line are a result of differential exhumation of individual blocks high exhumation rates bracketed between the intrusion age of the rieserferner pluton at 31 3 ma and the apatite partial annealing zone paz range between 0 4 and 0 6 mm year 1 whereas final exposure takes place at reduced exhumation rates of 0 2 mm year 1 east side down tilting of the block north of the dav line as indicated by variations in exhumation rates strongly affects the western part of the area studied between the rensen and the central rieserferner pluton whereas further east block rotation becomes less important a total difference in exhumation of about 2 2 km corresponding to 5 tilting between the western and eastern rieserferner as indicated by k ar biotite and zircon fission track data occurred before going through the paz for apatite fission tracks furthermore the significance of the cooling ages especially for biotite is tested by calculating a finite element approximation different numerical models indicate fast cooling of the intrusive melts prior to approaching the closure temperature of the k ar system in biotite

diagnostic study of a narrow cold frontal rainband and severe winds associated with a stratospheric intrusion a diagnostic study of a severe wind event associated with a cold front is presented based on output from an operational numerical weather prediction model together with radar and satellite imagery and detailed surface observations an intrusion of stratospheric air initially with a potential vorticity of 2 pv units is shown as part of a backward tilted filament to have plunged down to the lower troposphere where it was associated with a narrow cold frontal rainband at its leading edge and produced severe wind gusts up to 70 knots a close correspondence in time and space is revealed between these surface events and the appearance in the model of a pocket of diluted stratospheric air with pv 1 at the 2 km level the stratospheric intrusion produced two distinguishable wind surges one behind the narrow cold frontal rainband and another mainly dry about 200 km farther behind the strength of the winds was attributable to the downward transport of momentum as part of the large scale dynamics local moist processes played only a minor role at coarse resolution the radar echo from the narrow cold frontal rainband resembled line convection but it is shown that there were significant differences between this event and the archetypal form of line convection often seen in the british isles

present day stress field and deformation in eastern austria we analysed fault plane solutions and borehole breakouts in the eastern part of the eastern alps and found a heterogeneous stress field which we interpret as a transition zone of three different stress provinces the western european stress province with nw to nnw sh orientation and mainly strike slip faulting regime the adriatic stress province with a radial stress pattern and thrust faulting to strike slip faulting regime and the dinaric pannonian stress province with ne sh orientation and strike slip faulting regime the western pannonian basin seems to be a part of the transition zone with wnw to nw sh orientation a stress regime stimulating strike slip faulting prevails in the eastern alps the south bohemian basement spur as a major tectonic structure with a high rheological contrast to surrounding units has a strong influence on the stress field and exhibits the highest seismicity at its tip due to stress concentration from a constructed vertical stress orientation profile we found stress decoupling of the northern calcareous alps from the underlying european foreland both the molasse and the flysch helvetic zone are considered as candidates for decoupling horizons due to stress orientation observations and due to their rheological behaviour from seismological and rheological data we suggest a horizontal stress decoupling across the eastern alps caused by a weakened central alpine lithosphere

geomorphic expression of midcrustal extension in convergent orogens 1 channel orientation gradient drainage basin spacing drainage patterns and alluvial fan sedimentology define a set of geomorphic observables for fingerprinting modes of extensional tectonism in convergent settings anomalous finely textured trellis drainage patterns in the alps are spatially coincident with the low angle simplon and brenner detachments the detachment footwalls are characterized by numerous high angle brittle faults which are etched out by low order stream gullies and channels we quantify the relationship between these faults and watershed scale geomorphology using high resolution digital topography to extract channel and basin metrics topographic data are complemented by a field data set of channel gradients and the integrated erosional response of the watersheds preserved in valley bottom alluvial fans in footwall regions adjacent to the detachments channels are steeper more closely spaced have statistically coherent orientations and feed coarse steep alluvial fans drainage spacing increases in the footwall away from the detachment and the trellis pattern diminishes in the detachment hanging walls which typically lack high angle brittle faults there is a poor correlation between channel steepness density or orientation and hanging wall alluvial fans tend to be relatively larger gentler and debris flow dominated comparisons are made to the ticino dome region of the alps as well as to the pioneer core complex of central idaho in both cases our analysis suggests high angle brittle faulting of the footwall is particularly well preserved in the region adjacent to a detachment these results are consistent with a subvertical simple shear model for footwall extrusion as well as annealing or a lack of reactivation of brittle structures in the footwall distal to the rolling hinge

vertical gps ground motion rates in the euro mediterranean region new evidence of velocity gradients at different spatial scales along the nubia eurasia plate boundary we use 2 5 to 14 years long position time series from 800 continuous global positioning system gps stations to study vertical deformation rates in the euro mediterranean region we estimate and remove common mode errors in position time series using a principal component analysis obtaining a significant gain in the signal to noise ratio of the displacements data following the results of a maximum likelihood estimation analysis which gives a mean spectral index 0 7 we adopt a power law white noise stochastic model in estimating the final vertical rates and find 95 of the velocities within 2 mm yr with uncertainties from filtered time series 40 smaller than from the unfiltered ones we highlight the presence of statistically significant velocity gradients where the stations density is higher we find undulations of the vertical velocity field at different spatial scales both in tectonically active regions like eastern alps apennines and eastern mediterranean and in regions characterized by a low or negligible tectonic activity like central iberia and western alps a correlation between smooth vertical velocities and topographic features is apparent in many sectors of the study area glacial isostatic adjustment and weathering processes do not completely explain the measured rates and a combination of active tectonics and deep seated geodynamic processes must be invoked excluding areas where localized processes are likely or where subduction processes may be active mantle dynamics is the most likely process but regional mantle modeling is required for a better understanding

coeval high pressure metamorphism thrusting strike slip and extensional shearing in the tauern window eastern alps 1 recent findings for a young 31 5 0 7 ma age of high pressure metamorphism at 90 km depths in the eclogite zone of the tauern window eastern alps prompt the question about the timing of the structural development of the tauern window and its relation to high pressure metamorphism we show that all major structures in the tauern window resulting from strong n s lithospheric shortening and simultaneous minor e w extension began developing coevally with high pressure metamorphism in the eclogite zone large scale strike slip shear zones started to form at 32 30 ma and facilitated the spatial accommodation of simultaneous shortening and extension at least some of the strike slip and extensional shear zones operated into the middle miocene either continuously or intermittently with pronounced activity at 21 15 ma the considerable exhumation of the eclogite zone from 90 km depths into the middle crust and the tectonic development of its framework occurred within only 1 2 ma after eclogitization this is evidenced by almost identical ages for eclogite facies metamorphism and for the development of the major structures that bound the eclogite zone under blueschist and greenschist facies metamorphic conditions we discuss a tectonic model in which considerable transpressional shortening and thickening took place in the present central southern part of the tauern window we propose that the tauern window nucleated here and that most of the regional deformation at 32 30 ma is today found at the periphery of the window and in the adjacent austroalpine units afterward transpression continued the window grew to the e w and n and deformation progressed to those parts of the window ductile deformation in the present day surface level ceased at 15 ma

late oligocene to early miocene lateral extrusion at the eastern border of the lepontine dome of the central alps bergell and insubric areas eastern central alps 1 how the internal domain of the central alps deformed during late stages of the continental collision remains poorly understood to fill this gap in knowledge we present new data constraining the late alpine brittle and brittle ductile tectonics in oligocene intrusions of the bergell alps eastern central alps syncollisional late normal faulting is widespread at all investigated scales but part of the deformation observed is also associated with oblique slip and transcurrent displacements the faults are explained by stress permutations in space and time implying the three principal stress axes and correspond to different homoaxial states of stress of one single transtensive tectonic event motion on these faults accommodated coeval orogen parallel extension and orogen perpendicular contraction during oblique indentation by the southern alpine crust extensional and transcurrent structures likely formed by lateral extrusion of the bergell alps via distributed eastward extrusion of imbricated wedge shaped crustal blocks during the late oligocene and lower miocene a first order wedge shaped crustal block in the bergell alps is represented by three coeval segments of the periadriatic fault system namely the tonale engadine and forcola faults the eastern central segment of the alpine belt appears to have deformed during the late oligocene and lower miocene in a similar way to its extremities where lateral escape tectonics occurred at least until the upper miocene according to free boundary availabilities

widespread extension in the core of the western alps revealed by earthquake analysis the western alps are an active collision belt whose current stress field is inhomogeneous muller et al 1992 we report new seismological data which significantly improve our knowledge of this stress field about 1600 earthquakes which occurred in the western alps during the last 10 years were precisely located and 79 new focal solutions were computed the analysis of this database shows that widespread extension affects all the internal zones of the belt to better constrain the associated stress regime six stress tensors were computed using the gephart and forsyth 1984 method they show that the current tectonics of the western alps are contrasted with close variation in the stress regime transpression to the front of the belt contrasting with extension in the core of the belt the extensional direction is radial to the arcuate geometry of the belt and bounded outboard by the former thrust of the internal zones onto the external zone suggesting extensional reactivation of this inherited crustal discontinuity such widespread extension within the inner part of an actually ongoing collision belt cannot be explained by simple collision related tectonics we propose that intrabelt buoyancy forces such as those produced by a slab retreat or slab break off interfere with the boundary forces driven by the ongoing europe africa convergence

extensional neotectonics around the bend of the western central alps an overview the western alps active tectonics is characterized by ongoing widespread extension in the highest parts of the belt and transpressive compressive tectonics along its borders we examine these contrasting tectonic regimes using a multidisciplinary approach including seismotectonics numerical modeling gps morphotectonics fieldwork and brittle deformation analysis extension appears to be the dominant process in the present day tectonic activity in the western alps affecting its internal areas all along the arc shortening in contrast is limited to small areas located along at the outer borders of the chain strike slip is observed throughout the alpine realm and in the foreland the stress orientation pattern is radial for 3 in the inner extensional zones and for 1 in the outer transcurrent tranpressional ones extensional areas can be correlated with the parts of the belt with the thickest crust quantification of seismic strain in tectonically homogeneous areas shows that only 10 20 of the geodesy documented deformation can be explained by the alpine seismicity we propose that alpine active tectonics are ruled by isostasy buoyancy forces rather than the ongoing shortening along the alpine europe adria collision zone this interpretation is corroborated by numerical modeling the neogene extensional structures in the alps formed under increasingly brittle conditions a synthesis of paleostress tensors for the internal parts of the west alpine arc documents major orogen parallel extension with a continuous change in 3 directions from ene wsw in the simplon area to n s in the vanoise area and to nnw sse in the briancon area minor orogen perpendicular extension increases from n to s this second signal correlates with the present day geodynamics as revealed by focal plane mechanisms analysis the orogen parallel extension could be related to the opening of the ligurian sea during the early middle miocene and to compression rotation of the adriatic indenter inducing lateral extrusion

the problem of the moho in the alps abstract the tertiary alps are the product of continental collision and material balance estimates require the subduction of continental crust and the underlying moho the present moho in the alpine region consists of three parts that of the european plate me that of the adriatic african plate ma and a new moho m2 believed to have developed in the subducted continental crust by high pressure metamorphism at 40 60 km depth the fate of m2 however is uncertain some of it is apparently destroyed subsequently as some eclogite facies and even highest p coesite bearing rocks somehow find their way to the surface where they form exotic bodies from microscopic to nappe size on the other hand the continental moho exposed in the ivrea body tells a different story here continental granulite facies rocks are intruded by ultramafic and mafic masses this suggests an origin in an extensional environment possibly in subduction related gravitational collapse basins such successor basins succeed the basins of the original tethys that had been largely consumed by the late cretaceous they puncture the 1000 2000 km wide belt of africa europa collisional interaction e g the aegean the tyrrhenian and the pannonian basins although in some ways similar to the back arc basins of the pacific these mostly intracontinental basins differ in important aspects such as their small size in these basins asthenospheric upwelling replaces m2 by a new moho m3 and the eclogitic rocks underlying m2 by the ultramafic mafic intrusions of the ivrea type material balance considerations suggest that most of the eclogues remain part of the mantle for some time on the other hand recent deep reflection seismic surveys in several places indicate delamination of a part of the lower crust and the uppermost mantle with the formation of imbrications and duplexes some of which are wedged into the middle crust of the opposite plate they may be the first stage in the formation of granulite and eclogite nappes

on the causes and modes of exhumation and lateral growth of the alps 1 a compilation of the apatite and zircon fission track ages of the alpine chain points to markedly different patterns of cooling and exhumation of the eastern alps compared to the central and western alps the site of exhumation and shortening in the western alps migrated outward whereas it was more stationary in the eastern alps where it created a narrower metamorphic belt a correlation of these observations to the deep structure of the orogen suggests that north directed lower crustal wedging induces northward propagation of the deformation and exhumation front in the middle and upper crust of the central and western alps the absence of such lower crustal wedges in the eastern alps does not induce a similar shift of deformation but rather a long term localization of shortening and exhumation in one and the same area namely the axial zone of the orogen a critical review of the temporal correlations between inferred changes in the erosional efficiency of the alps and tectonic phases points to a negative correlation and hence no erosional control on the shifts of the deformation front of the alps therefore we conclude that changes in the deep structure and rheology of the orogen instead of changes in its erosional efficiency exerted the prime control on the lateral growth of the alps

comment on rosenberg and garcia estimating displacement along the brenner fault and orogen parallel extension in the eastern alps int j earth sci geol rundsch 2011 100 1129 1145 the western end of the tauern window is marked by what we refer to as the brenner normal fault zone the brenner fault since the late eighties is known as a textbook example of a normal fault already in 1934 dunner proposed west directed normal faulting related to updoming of the footwall i e the tauern window these earlier publications e g schmidegg 1953 mainly focussed on a brittle normal fault known as silltal fault that represents a northern segment of the brenner normal fault zone behrmann 1988 and selverstone 1988 were the first to also describe ductile components of normal faulting in an area further south referred to as sterzing steinach mylonite zone behrmann or brenner line selverstone in 1997 fugenschuh et al presented a two stage model for the evolution of the brenner normal fault zone thereby ductile normal faulting was restricted to an area between sterzing and matrei during stage 1 referred to as brenner normal fault s str in this contribution while brittle faulting during stage 2 not only overprinted the earlier mylonites of the brenner line s str but extended further north into the entirely brittle silltal fault this model involved coeval n s compression and e w extension during stage 1 the published calculated total amounts of related e w extension derived from metamorphic data and distinct exhumation histories in footwall and hanging wall and from the estimated dip of the overall fault zone varied significantly between 10 and 20 km e g behrmann 1988 and up to 70 km e g fugenschuh et al 1997 the contribution of exhumation by erosion as a consequence of coeval n s compression has never been explicitly considered and calculated so far

indentation model of the eastern alps and the origin of the tauern window a lithospheric model scaled for density and viscosity was shortened obliquely in front of an indenter whose shape and orientation match those of the south alpine indenter deformation was initially localized into subparallel sets of conjugate transpressive thrusts these structures evolved into folds which were strongly amplified and converged closer together during ongoing shortening finally forming a series of tight antiforms at the same time this tightly folded structure locally accommodated significant orogen parallel extension attaining 100 in front of the leading edge of the indenter but only 15 on the scale of the entire model the internal architecture and fault pattern of the model in map view are very similar to those of the tauern window in the eastern alps emphasizing the importance of localization of folding and shortening rather than orogen parallel extension for its formation

thrust regime and transpression regime tectonics in the tauern window eastern alps below the penninic nappes of the tauern window the deepest level of the alpine thrust system is exposed in the parautochthonous sedimentary sequence of helvetic facies

tectonic analysis of fault slip data sets using data that include the direction and the sense of motion on individual fault surfaces determined by slickenside lineations it is possible to reconstruct reduced stress tensors that correspond to the orientation of stress axes and to the ratio 2 3 1 3 between principal stress values 1 2 3 compression being positive no assumption is made concerning the orientation of fault planes relative to stress axes so that reactived faults are taken into account as well as newly created ones qualitative and quantitative methods for analysis of fault slip data were developed during the last 10 years the practical limitation of the methods and the necessity for critical field observations are emphasized these methods can be applied to focal mechanisms of earthquakes a more complex analysis of heterogeneous data sets involving an iterative separation of different stress systems is also discussed this analysis enables one to distinguish successive faulting events careful qualitative study in the field is in all cases essential

present crustal movement and strain distribution in central europe inferred from gps measurements in 1992 an international collaboration was initiated to study the present day geodynamics of central europe the primary tool of this research is the global positioning system gps therefore the central european gps geodynamic reference network was established in 1994 the network extends from the south in the eurasian african plate boundary zone to the east european pre cambrian platform in the northeast during the first phase of the project four gps campaigns were organized between 1994 and 1997 analysis of gps data provided rms repeatabilities around 2 mm in the horizontal and 5 6 mm in the vertical component for each campaign the velocities of gps sites situated on the eurasian plate were compared with those predicted by the nnr nuvel 1a plate velocity model the intraplate velocity field shows that the northern part of central europe seems generally stable with velocities under 2 mm yr however the southern sites close to the plate boundary zone show higher values and abrupt changes of velocities indicating the existence of narrow deformation zones the primary feature revealed by the strain calculation in the alpine pannonian dinaric system is the dominant north south contraction resulting from the collision of the african and eurasian plates transmitted by the adriatic microplate however the direction of contraction in the alpine pannonian dinaric junction zone changes from nw se at the northeastern boundary of the adriatic microplate to ne sw toward the bohemian massif the magnitudes of these strain rates are similar 8 0 5 3 ppb yr and 8 6 2 5 ppb yr respectively over 200 350 km subnetworks we observe e w oriented 93 13 right lateral shear 12 5 ppb yr between the alpine north pannonian unit and the southernmost sites in the dinarides and southern alps along with left lateral shear 97 7 10 2 ppb yr relative to the stable bohemian massif in the north both the strain field and the intraplate velocities presented show that the alpine north pannonian unit is presently crushed out to the east with 2 mm yr velocity on average along two main fault zones as a consequence of the compression caused by the adria alpine collision

fault slip analysis and late exhumation of the tauern window eastern alps exhumation of the eastern alps from the early tertiary to the late miocene was localized mainly in the tauern window a thermal and structural dome located in front of the dolomites indenter stress inversions based on new structural investigations over the entire tauern window indicate a regional zoning of the paleostress field with a predominance of strike slip states of stress in the core of the investigated area and dominant extensional regimes in the eastern and western borders of the dome few inverse fault structures have been highlighted we propose a two stage deformation history in order to explain the different types of structures that characterise the ductile and the brittle domains during the first stage of exhumation of the tauern window corresponding to the folding event the brittle crust was probably dominated by n s shortening and compression the second stage of exhumation was marked by normal faulting at the borders of the dome and strike slip faulting in the core during the second stage the brittle part of the crust that was previously affected by compressive structures belonging to the first stage was eroded normal faulting associated to e w extension along the eastern and western borders of the tauern window was accommodated by strike slip faulting located in the core of the tauern window yielding e w extension and n s shortening the orientation of the extensional axes and the nature of the stress tensors are similar to the ones inferred for the late stage brittle overprint of the internal basement massifs of the central alps pointing to a possible common large scale state of stress acting well beyond the area of the eastern alps

modeling surface gps velocities in the southern and eastern alps by finite dislocations at crustal depths abstract the indentation of the adria plate into the southern and eastern alps is an ongoing collisional process accompanied by seismicity surface and rock uplift and lateral escape we present a 3d quantitative description of the process by combining gps and structural data with an elastic dislocation model horizontal velocities of 70 austrian and italian permanent gps stations in the eastern and southern alps serve as boundary condition on the free surface of an elastic half space containing six rectangular faults each with a uniform slip rate the geometry of the rectangular faults and the slip rate vector are constrained by least squares taking into account the structural setting of the area and the geographic distribution of the velocity data we find that the surface velocities of the order of some mm yr require reverse north side of the tauern window transpressional giudicarie north alpine wrench corridor pustertal dinarides and normal brenner fault slips ranging from 10 to 30 mm yr at crustal depths the regional stress pattern computed from fault plane solutions agrees with the principal directions of our rectangular fault planes the model although constrained by horizontal velocities only predicts a pattern of vertical motion which qualitatively agrees with known phenomena such as the surface uplift in the tauern window area of the order of up to few mm yr if the heat on the shearing fault planes is removed mostly by upwards diffusion the absence of large heat anomalies on the earth s surface suggests for nominal geotherms shear stresses and concentration of subcrustal radiogenic elements that the time of initiation of the slip dates to pliocene hence more recent than late oligocene miocene time of collision of the adria indenter