active tectonics and quaternary basin formation along the vienna basin transform fault abstract the vienna basin transform fault is an active fault system extending over a distance of some 300 km from the eastern alps through the vienna basin into the west carpathians active sinistral movement is indicated by moderate seismic activity in a ne striking zone paralleling the fault focal plane solutions and recent stress measurements by analogy to the miocene kinematics we propose that the sinistral strike slip fault terminates in the carpathians where horizontal offset is transformed into thin skinned thrust type deformation hypocenter depths mostly well above 12 km are in line with the inferred thin skinned style of deformation with active faults restricted to the overthrust alpine carpathian units mapping of active fault segments in the vienna basin using subcrop data thickness maps of quaternary deposits seismological data and geomorphological features seen in the digital elevation model shows that virtually all active faults are reactivated miocene structures in the southern part of the basin active faulting defines a small scale pull apart structure with an actively subsiding quaternary basin which is filled with up to 140 m fluvial gravel sand and paleosoils for this basin quaternary sinistral displacement was quantified by adopting a geometrical model for thin skinned extensional strike slip duplexes accordingly 1 5 2 km sinistral slip accumulated during deposition of the basin fill in the last 400 ky corresponding to a slip rate of 1 6 2 5 mm y results are in good agreement with published gps data indicating 2 mm slip per year a second group of quaternary basins is related to listric normal faulting rollover and crestal collapse of the reactivated normal faults at the nw basin margin rollover also resulted in tilting and dissecting late pleistocene river terraces of the danube

an interannual link between arctic sea ice cover and the north atlantic oscillation this work investigates links between arctic surface variability and the phases of the winter djf north atlantic oscillation nao on interannual time scales the analysis is based on era reanalysis and model data from the ec earth global climate model our study emphasizes a mode of sea ice cover variability that leads the nao index by 1 year the mechanism of this leading is based on persistent surface forcing by quasi stationary meridional thermal gradients associated thermal winds lead a slow adjustment of the pressure in the following winter which in turn feeds back on the propagation of sea ice anomalies the pattern of the sea ice mode leading nao has positive anomalies over key areas of south davis strait labrador sea the barents sea and the laptev ohkostsk seas associated to a high pressure anomaly over the canadian archipelago baffin bay and the laptev east siberian seas these anomalies create a quasi annular quasi steady positive gradient of sea ice anomalies about coastal line when leading the positive nao phase and force a cyclonic vorticity anomaly over the arctic in the following winter during recent decades in spite of slight shifts in the modes spectral properties the same leading mechanism remains valid encouraging actual models appear to reproduce the same mechanism leading model s nao relative to model areas of persistent surface forcing this indicates that the link between sea ice and nao could be exploited as a potential skill source for multi year prediction by addressing the key problem of initializing the phase of the nao ao arctic oscillation

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

a new detrital mica 40ar 39ar dating approach for provenance and exhumation of the eastern alps detrital thermochronology can be used as a tool to quantitatively constrain exhumation rates and its spatial variability from active mountain belts commonly used methods for this purpose assume a steady state relationship between tectonic uplift and erosion however this assumption does not account for the transitory response of a dynamic orogenic system to changes in the boundary conditions we propose a different approach that uses the observed detrital age distributions as markers of the past exhumation and of the present day erosion and mixing occurring in a river system in this paper we present new 40ar 39ar biotite and white mica age distributions for 19 modern river sands from the eastern alps north of the periadriatic line the results present three main clusters of ages at 0 5 50 60 120 and 250 350 ma that record the main orogenic phases in this sector of the alps we have applied two numerical methods to the cooling ages to a linearly compute the spatial variability of the relative present day erosion of a set of four detrital mineral samples from drainage basins along the inn river and b quantify the rates of the cooling and erosion in the tauern window during paleocene miocene time of the alpine orogeny our results suggest a 0 34 0 84 mm yr range of exhumation rates for the tauern window since the miocene our estimates of exhumation rates of the western tauern window are higher than those for the eastern tauern window which is consistent with the previous studies

role of topography induced gravitational stresses in basin inversion the case study of the pannonian basin numerical stress models suggest that gravitational body forces associated with elevated topography around sedimentary basins can significantly influence the stress and strain pattern in basin interiors in the absence of tectonic forces basins surrounded by high altitude mountain ranges experience net horizontal compression owing to gravitational forces pointing from areas of high gravitational potential energy to subsided basin areas further lithospheric extension can eventually terminate leading to a gradual late stage inversion of the entire basin system modeling results suggest that the state of recent stress in the pannonian basin particularly in its western part is controlled by the interplay of plate boundary forces i e the counterclockwise rotation and northward indentation of the adriatic microplate against the alpine dinaric belt and buoyancy forces associated with the elevated topography and related crustal thickness variation of the alpine dinaric belt model calculations show that uplifted regions surrounding the basin system can exert compression on the thinned pannonian lithosphere of 40 60 mpa that is of the order of the assumed far field tectonic stress magnitudes the combined analysis of stress sources of tectonic and gravitational origin helps estimating the magnitude of maximum horizontal compression high levels of compressional stresses up to 100 mpa are concentrated in the elastic core of the lithosphere consistent with the ongoing structural inversion of the pannonian basin system

determining the effect of topography on isotherms in the shallow crust using low temperature thermochronometry in tunnels apatite u th he and fission track age determinations of samples from a 20 km long near horizontal tunnel in the hochalm ankogel dome eastern tauem window austria are presented in order to determine the role of paleo topography in perturbing isotherms in the shallow crust apatite fission track ages 26 8 ma show no systematic correlation with distance along the tunnel or elevation two age components in the fission track data indicate cooling through 120 c at approximately 20 ma and 80 c at approximately 6 ma surface and tunnel u th he ages 17 9 ma and 13 5 ma respectively are consistently younger than the equivalent fission track ages u th he ages vary systematically along the tunnel with older ages at the northern and southern tunnel portals and younger ages in the central section geological factors faulting lithology appear to have had little effect on this age distribution the u th he age pattern is inconsistent with rock cooling underneath the present day hochalm ankogel dome topography the age minimum is interpreted to coincide with a paleotopographic maximum in the hochalm ankogel dome and suggests that the 40 60 c isotherms were warped sufficiently to affect apatite u th he ages the tunnel apatite u th he ages match synthetic he ages derived from a two dimensional numerical model of landscape evolution integrating the thermal model results with the data allows the relief development to be constrained and we calculate that the present day hochalm ankogel dome topography was formed at 7 to 10 ma copyright 2007 by the american geophysical union

dating of fault zone activity by apatite fission track and apatite u th he thermochronometry a case study from the lavanttal fault system eastern alps introductionfaulting in the upper crust may leadto thermal anomalies caused by fric tional heating e g maddock 1983 dalessio et al 2003 and or in ltra tion of hydrothermal uids yamadaet al 2007 heating e ects are ex pected to be localised along faultzones and restricted to zones a fewcentimetres adjacent to the main faultsurface dalessio et al 2003 in this study we attempted to datethermal anomalies within fault zonesby comparison of cooling ages at thetransition from fault related rocks tothe undeformed host rocks for thispurpose we chose the lavanttal faultsystem due to underground excava tion and cored drillings related togeological site investigations for amajor railway project in austria it isone of the best exposed fault zones inthe eastern alps we used a combi nation of ssion track aft and u th he analysis on apatites thesensitivity intervals of these thermo chronometers are often referred to aspartial annealing and retention zones apaz heprz and range from 120to 60 c and 80 to 40 c respectively green et al 1986 wolf et al 1996 assuming holding times over geo logical time scales wagner 1979 ketcham et al 1999 the low temperature sensitivity of these ther mochronometers allows thermalanomalies along surfaces of fault slipor uid pathways to be detected forsuch applications however annealingand retention depend not only onheating temperature but also on heat ing duration laslett et al 1987 murakami et al 2006 a combina tion of forward and inverse modellingon apatite age track length and hedata allows quantitative analysis ofthe cooling behaviour of the hostrocks our new results underline theimportance of using multiple low temperature thermochronometersin elucidating details of the thermalhistory of a fault zone geological outlinethe nnw trending lavanttal faultsystem one of the major strike slipfaults in the eastern alps fig 1 separates the basement complexes ofthe kor and saualm by dextral o setof approximately 10 km reinecker 2000 it is assumed to have beenactive since early miocene times withpeaks in activity between 18 16 and14 12 ma reinecker 2000 as indi cated by the evolution of adjacentsedimentary basins and the regionalstructural framework e g pischingeret al 2008 near its southern termi nation the lavanttal fault o sets theperiadriatic fault by about 20 km despite some models at the scale ofthe eastern alps describing the gen eral evolution of con ning fault zonesduring miocene times e g peressonand decker 1997 frisch et al 1998 2000 neubauer et al 2000 littleremains known about the evolutionof the lavanttal fault system how ever these models include a relation ship between the lavanttal faultsystem and the uplift of the koralmcomplex neubauer and genser 1990 previous thermochronologicalstudies documented that the koralmcomplex was already near the surfaceduring the whole cenozoic period hejl 1997 the timing of its naluplift however is less constrained sample descriptionparts of the lavanttal fault system arecharacterised by cataclasites and faultgouges up to several tens of metresthick thermochronological analyseswere carried out on drill core samples diameter 10 cm taken during thegeological investigations for thekoralm railway tunnel drillingabstract

continental collision with finite indenter strength 2 european eastern alps 1 comparison of the results of a thin viscous sheet model with the velocity field determined by gps stations in the alpine pannonian realm shows that the adriatic plate is only slightly stronger than the eastern alps the observed velocity field is best approximated with a newtonian fluid however this scenario must be fairly recent as the overall geometry of the orogen can only be reproduced if the rheology contrast was about 1 10 before the late miocene the boundary conditions for this model are tested against the orientation of the intraplate stress field and are robust for argand numbers between 1 and 5 we conclude that the convergence rate between the adriatic and european plates must have slowed since the miocene and that the present day eastward extrusion of the eastern alps is largely due to lateral escape and only to a minor degree due to gravitational collapse scaled viscosities of the eastern alps are on the order of 1023 pa s

morphological analysis of the drainage system in the eastern alps abstract we study the morphology of the major rivers draining the eastern alps to test whether the active tectonics of this part of the orogen is reflected in the shape of channel profiles of the river network in our approach we compare channel profiles measured from digital elevation models with numerically modelled channel profiles using a stream power approach it is shown that regions of high stream power coincide largely with regions of highest topography and largest uplift rates while the forelands and the pannonian basin are characterised by a significantly lower stream power from stream power modelling we conclude that there is young uplift at the very east of the eastern alps in the bohemian massif and in the pohorje range the impact of the pleistocene glaciations is explored by comparing properties of rivers that drain in proximal and distal positions relative to the ice sheet during the last glacial maximum our analysis shows that most knick points wind gaps and other non equilibrium features of catchments covered by ice during the last glaciations salzach enns can be correlated with glacial processes in contrast the ice free catchments of the mur and drava are characterized by channels in morphological equilibrium at the first approximation and are showing only weak evidence of the strong tectonic activity within these catchments finally the channel profiles of the adige and the divide between the upper rhine and danube catchments differ significantly from the other catchments we relate this to the fact that the adige and the rhine respond to different base levels from the remainder of the eastern alps the adige may preserve a record from the messininan base level change and the rhine is subject to the base level lowering in the rhine graben

arctic sea ice variability on a timescale of weeks and its relation to atmospheric forcing abstract northern hemisphere sea ice concentration 500 hpa height sea level pressure and 1000 500 hpa thickness at 7 day intervals are examined for the period 1972 1989 with emphasis on the winter season the temporal variability of sea ice concentration is largest along the climatological mean ice edge where its frequency distribution is strongly bimodal with ice free and ice covered conditions being observed much more frequently than partial ice cover these results confirm impressions based on visual inspection of satellite imagery that most of the variability in these regions is associated with the advance and retreat of the ice edge relationships between large scale patterns of atmospheric variability and sea ice variability are investigated making use of singular value decomposition of the temporal covariance matrix the analysis is conducted separately for the atlantic and pacific sectors in agreement with earlier studies based upon monthly mean data on sea ice concentration the strongest

exhumation in a convergent orogen the western tauern window unroofing of the western tauern window involved both low angle detachment faulting brenner fault and enhanced footwall erosion contemporaneous with upright antiformal folding this combination reflects orogen parallel e w extension during continued n s alpine convergence new fission track ages establish the relative chronology of folding and faulting and demonstrate that displacement was not always accommodated on the same surface during exhumation some units migrated from the footwall to the hanging wall of the main detachment fault due to the interplay between folding and faulting the region can effectively be divided into 3 distinct domains 1 the penninic units of the western tauern window were always in the footwall to the fault with maximum exhumation in the core of the dome due to folding and erosion 2 the lower austroalpine unit north of the tauern window was first part of the hanging wall to the brenner fault at a later stage this unit was exhumed by a further 4 5 km as part of the footwall to a more discrete through going fault the silltal fault 3 the middle and upper austroalpine units west of the tauern window were always within the hanging wall exhumation of the footwall from an initial depth of 25 km led to a transition in mechanical behaviour the curviplanar folded ductile shear zone marking the boundary to the tauern window was eventually transected by a more planar discrete brittle fault silltal fault with unit 2 now in the footwall along which the pre existing mylonites were passively exhumed to the surface

incised relict landscapes in the eastern alps abstract we investigate landscape evolution in a region of the alps that has escaped glacial erosion during periodic glaciations of the last million years the research is thus suited to investigate landscaping processes on a longer time scale at the eastern end of the alps morphometric analysis reveals the presence of incised relict landscapes in several regions in the koralpe range topographic analysis is interpreted in terms of the relict landscape being present on both sides of the eastward tilted koralpe block this suggests that the relict landscape is younger than the tilting of the range which is inferred to have taken place between 18 and 16 ma in the pohorje region a relict landscape is developed across the contacts of a 19 ma pluton we use apatite u th he thermochronology to constrain the possible age of the koralpe and pohorje relict landscapes the results indicate that the pohorje massif had cooled below 70 c by about 15 ma suggesting that the relict landscape must be younger consistent with the interpretation of the koralpe range these results suggest that many relict landscapes of the eastern alps may have formed after 15 ma in a period of tectonic quiescence and erosion however in both ranges channel profile projections show that about 387 105 m uplift and incision occurred subsequently this incision is likely to have occurred during the last 6 5 ma in response to the uplift of the whole region it testifies to a renewed and ongoing uplift event that is earlier than the glaciation periods but might easily be confused with impact of glacial erosion elsewhere in the eastern alps

estimating displacement along the brenner fault and orogen parallel extension in the eastern alps the major structure accommodating orogen parallel extension in the eastern alps is inferred to be the brenner fault which forms the western boundary of the tauern window the estimated amount of extension along this fault varies from a minimum of 10 20 km to a maximum of 70 km all investigations that have attempted to constrain this amount of extension have calculated the fault plane parallel displacement required to restore the difference in structural level between footwall and hanging wall as constrained by geobarometry however these calculations neglected the component of exhumation of the footwall resulting from folding and erosion therefore the total amount of extensional displacement was systematically overestimated in the present study we project a tectonic marker surface from the footwall and hanging wall of the brenner fault onto a n s striking cross section this marker surface which is the base of the patscherkofel unit in the footwall and the base of the otztal basement in the hanging wall is inferred to have occupied the same structural level in the hanging wall and footwall of the brenner fault before its activity therefore the difference in height between the marker projected from the footwall and from the hanging wall is a measure of the vertical offset across the brenner fault this construction shows that the vertical offset of the marker horizon on both sides of the brenner fault varies strongly and continuously along strike of the brenner fault attaining a maximum value of 15 km at the hinge of the folded footwall tauern dome the along strike change of vertical offset is explained by large scale upright folding of the footwall that did not affect the hanging wall of the brenner fault therefore the difference in vertical offset of 10 km between the area of the brenner pass and the area immediately south of innsbruck corresponds to the shortening upright folding component of exhumation of the footwall the remaining 5 km of vertical offset must be attributed to extensional deformation the brenner fault itself is barely folded its dip varies between 20 and 70 and it crosscuts the upright folds of the western tauern window given the offset of 5 km the dip of the fault constrains the extensional displacement to be between 2 and 14 km we conclude that the tauern window was exhumed primarily by folding and erosion not by extensional unroofing

dynamic and thermodynamic characteristics of atmospheric response to anomalous sea ice extent in the sea of okhotsk abstract influence of sea ice extent anomalies within the sea of okhotsk on the large scale atmospheric circulation is investigated through an analysis of the dynamic and thermodynamic characteristics of the response in an atmospheric general circulation model to specified anomalous sea ice cover significant response appears not only around the sea of okhotsk but also downstream over the bering sea alaska and north america in the form of a stationary wave train in the troposphere this remote response associated with wave activity flux emanating from the okhotsk area to the downstream is regarded as a stationary rossby wave generated thermally by the anomalous turbulent heat fluxes from the ocean surface as a result of the anomalous sea ice cover the pacific storm track in the model that extends zonally at 35 n is located too far south of the sea of okhotsk to exert substantial feedback forcing on the local and remote response since a similar stationary wave train is identified in the composite di

on the relationship between winter sea ice and summer atmospheric circulation over eurasia abstractusing ncep ncar reanalysis and japanese 25 yr reanalysis jra 25 data this paper investigates the association between winter sea ice concentration sic in baffin bay southward to the eastern coast of newfoundland and the ensuing summer atmospheric circulation over the mid to high latitudes of eurasia it is found that winter sic anomalies are significantly correlated with the ensuing summer 500 hpa height anomalies that dynamically correspond to the eurasian pattern of 850 hpa wind variability and significantly influence summer rainfall variability over northern eurasia spring atmospheric circulation anomalies south of newfoundland associated with persistent winter spring sic and a horseshoe like pattern of sea surface temperature sst anomalies in the north atlantic act as a bridge linking winter sic and the ensuing summer atmospheric circulation anomalies over northern eurasia indeed this study only reveals the association based on observations and simple simulation experiments with s

the modeled atmospheric response to midlatitude sst anomalies and its dependence on background circulation states abstract the atmospheric response to a midlatitude sst anomaly in the north pacific and its dependence on background flow are examined in a gcm experiments are conducted using the same warm sst anomalies but two different model states perpetual january and perpetual february the atmospheric responses to the sst anomalies are statistically significant in both january and february but are completely different the anomalous circulation in january is characterized by a trough decaying with height immediately downstream of the sst anomalies in february the anomalous circulation is dominated by a downstream ridge growing with height the patterns of the anomalous heights in the two months are nearly orthogonal vorticity and thermodynamic budgets are diagnosed to illustrate how the anomalous circulations are maintained over the sst anomalies low level convergence and ascent are observed in both months in january the anomalous convergence is balanced by a residual due primarily to the forcing by submont

intra seasonal relationship between the northern hemisphere sea ice variability and the north atlantic oscillation 1 an intra seasonal relationship including a possible feedback is investigated between the north atlantic oscillation nao and a hemispheric scale seesaw like pattern dominant in sea ice variability over the wintertime northern hemisphere with one polarity in the bering and labrador seas and the other in the okhotsk and greenland barents seas statistical analysis using observational data suggests that a particular phase of nao and anomalous atmospheric circulation in the pacific during early winter contribute toward the development of the midwinter hemispheric sea ice seesaw in contrast the ice seesaw tends to damp the preexisting nao signal during late winter indicating a reversal of the phase relation between them this nao damping may be triggered by the pacific sea ice anomalies results from numerical experiments generally support this notion and further suggests a stationary rossby wave train emanated from the north pacific as a dynamical mechanism for damping the nao signal

on the relationship between atmospheric circulation and the fluctuations in the sea ice extents of the bering and okhotsk seas monthly and 3 day averaged nimbus 5 electrically scanning microwave radiometer sea ice data have been analyzed to document the fluctuations of the bering sea and sea of okhotsk ice covers for the four winters 1972 1973 through 1975 1976 on the short term seasonal and interannual time scales and to define those periods for which there is an out of phase relationship between the fluctuations of the two sea ice covers the sea ice fluctuations are shown to be related to changes in the position and intensity of quasi stationary high and low pressure systems associated with large scale standing wave patterns in the atmosphere through a comparison of the areal changes in ice cover with changes in the amplitude and phase of zonal harmonics 1 2 and 3 of the sea level pressure field on the seasonal time scale the sea level pressure for december the month of most rapid seasonal sea ice growth for both the bering and okhotsk seas is dominated by harmonic 2 which explains almost 60 of the total sea level pressure variance on average over the four winters the phase of harmonic 2 which is associated with the position of the aleutian low shifts from 156 e in 1972 1973 to 190 e in 1975 1976 thus providing a connection between the increasingly heavy bering sea ice cover over these four winters and the general circulation of the atmosphere on the short term episodes of midwinter bering sea ice retreat are generally preceded by or coincident with the breakdown of harmonic 1 and the intensification of harmonics 2 and 3 these episodes are also related to the coincidence of the phases of harmonics 2 and 3 with a mean position of 165 e this result is in excellent agreement with a study of the north pacific oscillation showing that the two modes of the oscillation are associated with the longitudinal position of the aleutian low it is suggested here that these two modes result from changes in the amplitudes and phases of atmospheric long waves 1 2 and 3 evidence is also presented indicating that the interaction of standing and transient components of wave 1 may play an important role in these fluctuations finally these results establish an observational connection relating climate dynamics to changes in ice covers in seasonal sea ice zones

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

post collisional orogen parallel large scale extension in the eastern alps abstract large scale extension affected the eastern alps during post collisional lateral tectonic extrusion in early and middle miocene times the tauern window was mainly tectonically exhumed by the 160 km pullapart of the rigidly behaving austroalpine basement blocks forming the tectonic lid of the penninic contents of the window an evaluation of the syn extrusion fault pattern reveals displacements of several tens of kilometers along the low angle extensional shear zones at the western and eastern margins of the window and along the important strike slip fault zones north and south of the window large scale shear is reflected by discontinuities in mineral cooling patterns across important shear zones the cooling histories of the tectonic blocks show that the window boundaries during exhumation coincide only partly with the classical boundaries of the window defined by thrust units reconstruction of the exhumation history shows an asymmetric evolution of the tauern window we argue that the eastern and western low angle extensional shear zones formed in sequence which is reflected by different evolutions of the fragmentation and uplift history of the austraolpine tectonic blocks to the east and west of the window in the central and eastern alps three structural domes the lepontin dome in the central alps and the tauern and rechnitz domes in the eastern alps were formed by large scale extension in miocene times total e w stretch amounts to more than 300 km and results in 70 extension we propose that the central and eastern alps are part of an extensional province that also includes the pannonian basin and has a counterpart separated by the moesian indenter in the rhodope mountains the aegean sea and the menderes massif in asia minor in these regions a number of mainly tectonically exhumed domes or deep sedimentary basins formed by miocene large scale extension

month to month variability of winter temperature over northeast china linked to sea ice over the davis strait baffin bay and the barents kara sea abstractthis study focuses on the month to month variability of winter temperature anomalies over northeast china necta especially the out of phase change between december and january february

post collisional sediment budget history of the alps tectonic versus climatic control based on the sediment budget of the eastern swiss and western alps since the oligocene the regional tectonic evolution has been identified as the dominant factor it is superimposed on the influence of both regional and global climate change and global sea level change during late pliocene and pleistocene times climate became the dominant factor because of cyclic glaciations the early post collisional history of the alps is characterized by a doubling of sediment discharge rates around the rupelian chattian boundary this increase is attributed to isostatic re adjustment either after large scale thermal reorganization of the lithosphere related to slab break off or to crustal thickening as continental crust became subducted from middle oligocene to late miocene times the overall trend of sediment discharge rates in the entire alps was modified only during relatively short lived phases these are characterized by an increase in aquitanian ca 23 21 ma and late burdigalian times ca 18 16 4 ma and a decrease in early to middle burdigalian 21 19 ma and langhian to serravalian times 16 4 12 ma an important still ongoing period of uplift reflected by rapidly increasing sediment discharge rates started in latest miocene times in the swiss and western alps and affected the eastern alps some 2 million years later the reason for this uplift is not clear but deep seated lithospheric processes appear to be likely

the effect of long term low temperature exposure on apatite fission track stability a natural annealing experiment in the deep ocean abstract since studies on deep sea cores were carried out in the early 1990s it has been known that ambient temperature may have a marked affect on apatite fission track annealing due to sluggish annealing kinetics this effect cannot be quantified by laboratory annealing experiments the unknown amount of low temperature annealing remains one of the main uncertainties for extracting thermal histories from fission track data particularly for samples which experienced slow cooling in shallow crustal levels to further elucidate these uncertainties we studied volcanogenic sediments from five deep sea drill cores that were exposed to maximum temperatures between 10 and 70 c over geological time scales of 15 120 ma mean track lengths mtl and etch pit diameters dpar of all samples were measured and the chemical composition of each grain analysed for age and track length measurements was determined by electron microprobe analysis thermal histories of the sampled sites were independently reconstructed based on vitrinite reflectance measurements and or 1d numerical modelling these reconstructions were used to test the most widely used annealing models for their ability to predict low temperature annealing our results show that long term exposure to temperatures below the temperature range of the nominal apatite fission track partial annealing zone results in track shortening ranging between 4 and 11 both chlorine content and dpar values explain the downhole annealing patterns equally well low chlorine apatite from one drill core revealed a systematic relation between si content and dpar value the question whether si substitution in apatite has direct and systematic effects on annealing properties however cannot be addressed by our data for samples which remained at temperatures 30 c the predictions of the laslett et al 1987 model agree with the measured mtl data within error levels with few exceptions predictions by the ketcham et al ketcham r donelick r and carlson w 1999 variability of apatite fission track annealing kinetics iii extrapolation to geological time scales am mineral 84 9 1235 1255 annealing model are consistent with the measured data for samples which remained at temperatures below 30 c for samples which experienced maximum temperatures between 30 and 70 c and which are rich in chlorine the ketcham et al 1999 model overestimates track annealing

gas sources of the yn2 gas pool in the tarim basin evidence from gas generation and methane carbon isotope fractionation kinetics of source rocks and crude oils abstract the yn2 gas pool in the eastern tarim basin has been believed to be an accumulation of gases resulting from oil cracking however this gas source model cannot explain such geochemical characteristics of the natural gases as heavier carbon isotope values 13 c 1 37 5 to 36 2 13 c 2 34 7 to 30 9 and high content of nitrogen gas 15 5 on average in this study we performed pyrolysis experiments on typical source rock and crude oil samples selected from the basin evaluated their kinetic parameters of gas generation and methane carbon isotopic fractionation and extrapolated them to geological conditions the results show that neither kerogen cracking gas nor oil cracking gas can act as the single gas source of the yn2 gas pool by contrast a mixing model of 55 kerogen cracking gas and 45 oil cracking gas results in an excellent match with the geochemical characteristics of the gas pool the gas condensate from the yn2 gas pool originated from the cracking of oils in mid upper ordovician strata and the nitrogen gas was mainly derived from the cracking of kerogen in cambrian lower ordovician mudstones in the yingjisu depression center during the very high level of maturation the yn2 gas pool went through three stages of formation 1 oils from cambrian lower ordovician source rocks accumulated in cambrian and ordovician reservoirs during the middle ordovician and gases were generated from both kerogen and paleo oil pools in the cambrian lower ordovician strata during late ordovician to early devonian 2 gases leaked during either late devonian to triassic due to uplifting or late jurassic due to intense faulting activity in this area 3 gases were regenerated from the late cracking of kerogen in the cambrian lower ordovician strata as well as from oil cracking in mid upper ordovician reservoirs with rapid subsidence after the cretaceous the two types of gas mixed and accumulated in the jurassic traps to form the present wet gas pool with high nitrogen content and a heavier methane carbon isotopic value

a preliminary assessment of the regional dispersivity of selected basalt flows at the hanford site washington u s a abstract dispersivity is one of the hydraulic parameters that controls the distribution in groundwater of chemical constituents migrating from a source region therefore knowledge of the range of dispersivity values along likely flow paths from proposed high level nuclear waste repositories is important for assessing how well a site will perform in limiting releases of radionuclides to the environment a primary reason why dispersivity has not been analyzed with regional scale data is the general lack of suitable environmental tracers that have been in the hydrologic environment for long periods of time such tracers could normally result from some natural event perhaps disruptive that may have transpired in the geologic past such an event may have occurred at the u s department of energy hanford site in the state of washington resulting in a chemical enclave of regional proportions a preliminary interpretation is that the enclave occurs immediately down gradient from a hydraulic barrier possibly a fault which may have placed deeper formations in hydraulic connection with the upper basalts with this hypothesized source for constituents making up the enclave the observed concentrations are employed in a preliminary attempt to assess the regional dispersivity this is the single conceptual model being tested in this paper the mathematical method employed assumes that the concentration data conform to what would be expected of a perfectly symmetrical enclave and part of the problem deals with identifying that symmetry the results obtained are quite reasonable when compared to the range in dispersivities determined in laboratory tracer and model scale studies

lateral extrusion in the eastern alps revisited refining the model by thermochronological sedimentary and seismic data 1 this study comprises a reassessment of the classical model of lateral extrusion in the eastern alps by using recently published geochronological data sedimentary ages from intramontane basins ages and distribution of magmatic rocks and information from seismic profiles extrusion related faulting continuously propagated from the western toward the central eastern part of the eastern alps during oligocene to middle miocene times this is confined by oblique convergence between the adriatic and european plates during middle miocene times extrusion became not only lateral in terms of parallel to the trend of the eastern alps but was characterized by a displacement vector at a high angle to the strike of the orogen this resulted in the exhumation of the schladming and pohorje blocks that were exhumed within extensional bridges at the northern and southern terminations of the pols lavanttal fault system respectively from middle miocene to recent times extrusion was controlled by overall extension between the dinaric and carpathian subduction zones the influence of north directed compression triggered by the northward moving adriatic plate diminished and the influence of the retreating carpathian subduction zone increased this gave rise to miocene volcanism that is exclusively found east of the dinaric subduction zone we therefore consider that lateral extrusion in the eastern alps can be subdivided into distinct tectonic phases with less pronounced eastward extension related displacement between late oligocene and middle miocene times as soon as the eastern alps passed the dinaric subduction zone the entire domain became highly extensive

mechanisms determining the atmospheric response to midlatitude sst anomalies abstract previous gcm experiments demonstrated that a model atmosphere produces two different responses to a midlatitude warm sst anomaly over the pacific under perpetual january and february conditions to elucidate the mechanisms responsible for the different gcm responses and their dependence on the background flow experiments with two idealized models are conducted experiments with a linear baroclinic model reveal that the gcm responses at equilibrium are primarily maintained by the anomalous eddy forcing the anomalous flow induced directly by an idealized initial heat source exhibits little sensitivity to the background flow eddy feedbacks on the heating induced anomalous flow are examined using a linear storm track model the anomalous eddy forcing produced by the storm track model is sensitive to the basic state the eddy forcing in january acts to shift the heating induced upper level ridge toward the northeast of the gulf of alaska while in february it acts to reinforce the ridge this sugge

the impact of the siberian high and aleutian low on the sea ice cover of the sea of okhotsk comparison of monthly averaged sea ice distributions in the sea of okhotsk with atmospheric pressure data during the four winters having passive microwave sea ice coverage from the nimbus 5 satellite 1973 76 revealed a strong apparent relationship between the extent of the sea ice cover and the influence of the siberian high atmospheric pressure system examination of data for the years 1978 86 having passive microwave coverage from the nimbus 7 satellite reveals that the strong correspondence found for 1973 76 between okhotsk sea ice extents and the siberian high was not maintained in the 1978 86 period a weaker correspondence continued however between the sea ice and the combined siberian high aleutian low system a siberian high aleutian low index was created and the correlation coefficient between that index and sea ice extents in the midwinter month of february is 0 97 for the 1973 76 period and 0 52 for the 1978 86 period primary reasons for the lack of a consistently strong monthly averaged ice atmosphere correspondence are the various oceanographic influences on the sea ice cover the failure of monthly averages to reflect fully the important shorter term interactions between the ice and the atmosphere and the fact that ice conditions in one month are influenced by ice conditions in previous months

modes of orogen parallel stretching and extensional exhumation in response to microplate indentation and roll back subduction tauern window eastern alps the tauern window exposes a paleogene nappe stack consisting of highly metamorphosed oceanic alpine tethys and continental distal european margin thrust sheets in the eastern part of this window this nappe stack eastern tauern subdome etd is bounded by a neogene system of shear the katschberg shear zone system kszs that accommodated orogen parallel stretching orogen normal shortening and exhumation with respect to the structurally overlying austroalpine units adriatic margin the kszs comprises a 5 km thick belt of retrograde mylonite the central segment of which is a southeast dipping low angle extensional shear zone with a brittle overprint katschberg normal fault knf at the northern and southern ends of this central segment the kszs loses its brittle overprint and swings around both corners of the etd to become subvertical dextral and sinistral strike slip faults the latter represent stretching faults whose displacements decrease westward to near zero the kinematic continuity of top east to top southeast ductile shearing along the central low angle extensional part of the kszs with strike slip shearing along its steep ends combined with maximum tectonic omission of nappes of the etd in the footwall of the knf indicates that north south shortening orogen parallel stretching and normal faulting were coeval stratigraphic and radiometric ages constrain exhumation of the folded nappe complex in the footwall of the kszs to have begun at 23 21 ma leading to rapid cooling between 21 and 16 ma this exhumation involved a combination of tectonic unroofing by extensional shearing upright folding and erosional denudation the contribution of tectonic unroofing is greatest along the central segment of the kszs and decreases westward to the central part of the tauern window the kszs formed in response to the indentation of wedge shaped blocks of semi rigid austroalpine basement located in front of the south alpine indenter that was part of the adriatic microplate northward motion of this indenter along the sinistral giudicarie belt offsets the periadriatic fault and triggered rapid exhumation of orogenic crust within the entire tauern window exhumation involved strike slip and normal faulting that accommodated about 100 km of orogen parallel extension and was contemporaneous with about 30 km of orogen perpendicular north south shortening of the etd extension of the pannonian basin related to roll back subduction in the carpathians began at 20 ma but did not affect the eastern alps before about 17 ma the effect of this extension was to reduce the lateral resistance to eastward crustal flow away from the zone of greatest thickening in the tauern window area therefore we propose that roll back subduction temporarily enhanced rather than triggered exhumation and orogen parallel motion in the eastern alps lateral extrusion and orogen parallel extension in the eastern alps have continued from 12 to 10 ma to the present and are driven by northward push of adria

ocean tidal cooling effect on summer sea fog over the okhotsk sea 1 ocean tide is a periodic phenomenon of the rise and fall of the sea level that depends on the bathymetry and positions of the moon and sun relative to the earth in the okhotsk sea the ocean tide causes strong vertical mixing in the upper ocean generating rich structures in summer sst with extraordinarily cold patches on kashevarov bank along the kuril islands northeast of the terpeniya peninsula and inside shelikhov bay the present study analyzes and synthesizes a suite of ship board and satellite observations and numerical simulations to investigate the ocean tidal cooling effect on summer sea fog over the okhotsk sea over the tide induced cold patches atmospheric stability increases and surface wind weakens markedly possibly through suppressed atmospheric vertical mixing our analysis of ship board observations reveals frequent sea fog occurrence over the cold patches with a maximum exceeding 70 along the kuril islands in july august numerical simulations with the weather research and forecasting wrf model support that the cold patches cool air temperature decelerate surface wind and form a strong surface inversion layer up to 0 5 km high creating favorable conditions for sea fog occurrence the wrf simulation without the tidal cooling effect reduces sea fog occurrence by more than 20 over cold patches illustrating the importance of sst products for climate models

cold spots during the cenozoic evolution of the eastern alps thermochronological interpretation of apatite fission track data abstract the tectonical and morphological evolution of the eastern alps during the cenozoic is discussed in the light of sedimentary record and thermochronological data of crystalline basement rocks the regional distribution of apatite fission track data in the central eastern alps reveals the differential cenozoic exhumation in contrast to the penninic of the tauern window which has been strongly uplifted and eroded since the early miocene the amount of neogene denudation was much smaller in most areas east of the hohe tauern a sudden change in the regional cooling behaviour is observed at the katschberg fault system which must have been active in post oligocene times within the austroalpine only the schladming tauern have experienced a rather strong denudation the seckau core complex east of the pols line and the area of the northern koralpe cooled to below 100 c at the end of the cretaceous and in the early eocene respectively and have never been heated again during the cenozoic these parts of the austroalpine nappe pile were always near to the surface and therefore may be summarized under the term cold spots a major post cretaceous thickening of the austroalpine can be excluded because it would have produced more uplift and erosion any remnants of miocene or older landforms are certainly not preserved in the area of the tauern window the uppermost planation surfaces in the crystalline basement at the western border of the styrian basin koralpe probably developed in the late miocene

the messinian diatomite deposition in the mediterranean region and its relationships to the global silica cycle abstract diatomites constitute a widely represented lithology in the messinian sections of the circum mediterranean neogene marginal basins although traditionally interpreted as genuine evidence of the gradually restricted conditions that characterized the mediterranean just before the messinian salinity crisis their coeval occurrence with a global intensification of the opaline production in the world oceans late miocene early pliocene biogenic bloom suggests that an integrative analysis of the origins of these sediments is necessary a comprehensive analysis of the geological and paleontological records suggests that the synergistic intervention of abiotic tectonic and climate reconfigurations and biotic expansion of grass dominated opal rich biomes controlling factors may have promoted a remarkable enhancement of silica flux from continents to oceans which in turn can explain the opaline burst that occurred during the late miocene at both the global and mediterranean scale the finely laminated pattern and the rich fossil content of diatomaceous deposits that are usually considered to be byproducts of anoxic conditions are briefly discussed some studies seem to indicate that instead of anoxia the aggregation and sedimentation of diatom tests may play a critical role in these processes the lower messinian diatomites of the mediterranean region are generally interbedded with organic rich sediments sapropels clearly attesting prolonged precessionally controlled periods of basin stratification and bottom water anoxia or hypoxia a causal relationship between sapropel and diatomite deposition in the mediterranean is proposed considering the possible interplay between stratification adapted diatoms and anaerobic bacteria and their respective role in influencing the marine silica cycle

monthly and seasonal variability in the ocean ice atmosphere systems of the north pacific and the north atlantic four regional indices of sea ice variability and thirty years of monthly sea surface temperature sst and sea level pressure slp data are used to evaluate the large scale interactions within the ocean ice atmosphere systems of the north pacific and the north atlantic a direct association between positive negative sst anomalies and light heavy ice in the bering sea is indicated the sst ice coupling in the northern alaskan waters is also statistically significant the sst anomalies in both the north pacific and the north atlantic appear as persistent responses to atmospheric forcing the slp distributions over both oceans correlate significantly with the arctic slp distribution although the midlatitude atmospheric circulation shows no systematic tendency to lead or lag the arctic circulation sea ice fluctuations correlate most highly with the atmospheric forcing over antecedent periods of approximately 9 months in the northern alaskan waters 3 4 months in the bering sea and 5 7 months in the east greenland sea the strength of the 9 month mean onshore air flow component describes over 70 of the northern alaskan ice variance

constraining long term fault activity in the brittle domain through in situ dating of hydrothermal monazite sims th pb dating of hydrothermal fissure vein monazite ce has the unique potential to date multiple tectonic events under low grade metamorphic brittle ductile conditions over large time frames monazites ce from brittle fault systems in the eastern alps allow us to constrain their cretaceous activity over 20 ma within single crystals recording all major tectonic events eo alpine formation of the fluid filled fissure veins occurred 90 ma ago at 352 19 c and 342 42 mpa this corresponds to peak conditions during regional metamorphism of the cretaceous collisional nappe stacking several stages of dissolution reprecipitation recrystallization record fault activity between 84 and 70 ma corresponding fluid inclusions indicate conditions of 229 10 c and 143 20 mpa this correlates with the formation of sedimentary basins during post orogenic extension associated with strike slip movements the results strengthen the hypothesis that many large fault systems in the eastern alps developed during the cretaceous orogeny and became reactivated during neogene alpine tectonics

the occurrence and origin of methane in some groundwater flow systems the origin of methane in selected groundwater flow systems is investigated through carbon isotope geochemical studies combined with hydrogeological and hydrogeochemical information methane is a common trace constituent in these groundwaters and occasionally constitutes a major carbon pool two modes of origin for methane are commonly recognized microbial production biogenic methane and non biological chemical production thermocatalytic methane in the groundwaters sampled the few thermocatalytic methanes encountered have 13c values greater than about 45 whereas the more common normal biogenic methanes have 13c values less than about 60 biogenic methanes from sanitary landfill sites have intermediate 13c values of about 38 to 56 and so can easily be distinguished from normal biogenic methane the carbon source for biogenic methane is usually organic matter present in the aquifer materials the carbon isotope ratios of dissolved methane and total inorganic carbon in sampled groundwaters ar

neotectonic extrusion of the eastern alps constraints from u th dating of tectonically damaged speleothems we suggest that the salzachtal ennstal mariazell puchberg semp fault a major strike slip system in the european alps is active it has accommodated lateral extrusion of the central part of the eastern alps toward the pannonian basin the main tectonic activity of this fault dates back to oligocene and miocene time but until now it was largely unknown whether the fault was still active we present here the first field evidence of neotectonic activity from a cave in the hochschwab karst massif styria austria that intersects a segment of the semp fault zone damaged speleothems in this cave include scratched flowstone a hitherto undescribed feature massive flowstone disrupted by a fault and ruptured flowstone the superposition of younger flowstone layers allows constraining the time frame of the tectonic events using u th dating the youngest flowstone of the pre damage generation is ca 118 ka end of the last interglacial and the oldest post event layer is ca 9 ka early holocene the tectonic event bracketed by these layers coincided with a growth hiatus during the last glacial period consistent with the high alpine setting of the cave geologic evidence precludes deformation mechanisms other than tectonic these new data are consistent with vectors of continuous global positioning system measurements as well as instrumental seismicity data and collectively suggest that the semp is an active fault and that lateral extrusion of the eastern alps is ongoing

influence of okhotsk sea ice extent on atmospheric circulation an atmospheric general circulation model was used to investigate the influence of okhotsk sea ice on large scale atmospheric circulation significant differences in the model responses between heavy and light ice cover are evident not only around the sea of okhotsk but also downstream towards north america in the form of a stationary wavetrain in the troposphere because the wave activity flux associated with the wavetrain emanates downstream from the sea of okhotsk this remote response is regarded as a stationary rossby wave excited thermally through an anomalous surface heat flux over the sea of okhotsk the wavetrain is thermally reinforced downstream by the anomalous heat flux associated with wind anomalies over the ocean surface which are induced by the wavetrain itself

late stage differential exhumation of crustal blocks in the central eastern alps evidence from fission track and u th he thermochronology thermal history modelling based on zircon and apatite fission track and apatite u th he data constrain and refine the near surface exhumation of the south eastern tauern window penninic units and neighbouring austroalpine basement units in the eastern alps fast exhumation on both sides of the penninic austroalpine boundary coincides with a period of lateral extrusion and tectonic denudation of the penninic units in miocene time 22 12 ma the jump to older ages occurs within the austroalpine unit along the polinik fault which therefore defines the boundary between the tectonically denuded units and the hangingwall at that time according to the different u th he ages between the penninic hochalm and sonnblick domes we demonstrate a differential cooling history of these two domes in the latest miocene and early pliocene

on the three dimensional propagation of stationary waves abstract a locally applicable nonzonally averaged conservation relation is derived for quasi geostrophic stationary waves on a zonal flow a generalization of the eliassen palm relation the flux which appears in this relation constitutes it is argued a useful diagnostic of the three dimensional propagation of stationary wave activity this is illustrated by application to a simple theoretical model of a forced rossby wave train and to a northern hemisphere winter climatology results of the latter procedure suggest that the major forcing of the stationary wave field derives from the orographic effects of the tibetan plateau and from nonorographic effects diabatic heating and or interaction with transient eddies in the western north atlantic and north pacific oceans and siberia no evidence is found in the data for wave trains of tropical origin forcing by the orographic effects of the rocky mountains seems to be of secondary importance

relation between rock uplift and denudation from cosmogenic nuclides in river sediment in the central alps of switzerland 1 a north south traverse through the swiss central alps reveals that denudation rates correlate with recent rock uplift rates in both magnitude and spatial distribution this result emerges from a study of in situ produced cosmogenic 10be in riverborne quartz in central alpine catchments as a prerequisite we took care to investigate the potential influence of shielding from cosmic rays due to snow glaciers and topographic obstructions to calculate a possible memory from last glacial maximum lgm glaciation and to identify a watershed size that is appropriate for systematic sampling mean denudation rates are 0 27 0 14 mm a for the alpine foreland and 0 9 0 3 mm a for the crystalline central alps the measured cosmogenic nuclide derived denudation rates are in good agreement with post lgm lake infill rates and are about twice as high as denudation rates from apatite fission track ages that record denudation from 9 to 5 ma in general denudation rates are high in areas of high topography and high crustal thickness the similarity in the spatial distribution and magnitude of denudation rates and those of rock uplift rates can be interpreted in several ways 1 postglacial rebound or climate change has introduced a transient change in which both uplift and denudation follow each other with a short lag time 2 the amplitude of glacial to interglacial changes in both is small and is contained in the scatter of the data 3 both are driven by ongoing convergence where their similarity might hint at some form of long term quasi steady state or 4 enhanced continuous quaternary erosion and isostatic compensation of the mass removed accounts for the distribution of present day rock uplift

stratigraphy and petrogenesis of the grande ronde basalt from the deep canyon country of washington oregon and idaho deep canyons cut by the snake salmon grande ronde and imnaha rivers near the point where washington oregon and idaho join expose 800 m of grande ronde basalt flows the grande ronde basalt erupted 16 5 to 14 5 m y b p makes up 85 vol of the columbia river basalt group an area enclosing 1 000 km 2 of the deep canyon country dominated by this basalt was mapped and samples from 16 measured sections in the grande ronde basalt were analyzed for major minor and trace elements three magnetostratigraphic units r 1 n 1 and r 2 were helpful in mapping the area using physically distinct flows the magnetostratigraphic units and certain chemical variations a detailed flow by flow stratigraphy was developed and the lateral extent of many individual flows was traced the number of flows and thickness of each stratigraphic unit decrease from west to east these tholeiitic flows are fine grained and aphyric clinopyroxene and plagioclase are the predominant minerals but olivine orthopyroxene pigeonite and accessory minerals are minor but important phases the flows are primarily of the low mg chemical type with lesser amounts of the high mg chemical type a cyclical trend in the over all major and trace element chemistry through the stratigraphic section is dominated by a ca rich clinopyroxene chemistry rare earth elements show significant light over heavy enrichment but overall patterns remain similar from flow to flow a small negative eu anomaly is present in many flows three models employing fractional crystallization schemes and one combining fractional crystallization and partial melting were tested using least squares modeling a petrogenetic model is proposed wherein partial melting of a heterogeneous clinopyroxene dominated mantle supplied magma that ascended to the crust was temporarily stored and recurrently erupted during storage new basaltic melt with slightly different isotopic and trace element abundances was added and mixed into the liquid that remained after previous eruptions orthopyroxene plagioclase and to a lesser extent olivine fractionated from these temporarily stored liquids upon eruption clinopyroxene and plagioclase with accessory minerals crystallized at the surface

stress induced late stage subsidence anomalies in the pannonian basin abstract subsidence sedimentation and tectonic quiescence of the pannonian basin was interrupted a few million years ago by tectonic reactivation this recent activity has manifested itself in uplift of the western and eastern flanks and continuing subsidence of the central part of the pannonian basin low to medium magnitude earthquakes of the carpathian pannonian region are generated mostly in the upper crust by reverse and wrench fault mechanisms there is no evidence for earthquakes of extensional origin 2 d model calculation of the subsidence history shows that a recent increase in magnitude of horizontal compressional intraplate stress can explain fairly well the observed quaternary uplift and subsidence pattern we propose that this stress increase is caused by the overall europe africa convergence in late pliocene consumption of subductible lithosphere at the eastern margin of the pannonian basin was completed and the lithosphere underlying the pannonian basin became locked in a stable continental frame consequently extensional basin formation has come to an end and compressional inversion of the pannonian basin is in progress

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

the klagenfurt basin in the eastern alps an intra orogenic decoupled flexural basin abstract the klagenfurt basin is an e w trending narrow sarmation to quaternary flexural basin formed by flexure of the austro alpine lithosphere by loading through the southerly adjacent karawanken mountains in the eastern alps austria the tectonic evolution of the basin is kinematically connected to miocene brittle transpressive dextral strike slip deformation along the periadriatic fault which separates the south alpine unit from the austro alpine unit in the eastern alps the final nw directed overthrust of the karawanken mountains onto the foreland is characterised by a positive flower structure which is kinematically linked to dextral transpressive shearing along the periadriatic fault only a small part of the lithosphere appears to support the regional isostatic response to the load by the karawanken mountains the area is characterised by a crustal thickness between 40 and 45 km elevated heat flow and a strength distribution which suggests that only the upper crust elastically supports the topographic load ductile flow of the lower crust is also supported by the absence of a crustal root beneath the karawanken chain rheologic models for this lithospheric configuration indicate a mechanical decoupling of upper crust lower crust and mantle and generally low strengths for the lower crust and mantle

quantifying tectonic versus erosive denudation by the sediment budget the miocene core complexes of the alps abstract the denudation budget of the alps is quantified for the main period of lateral extrusion between 22 and 12 ma the relative importance of tectonic denudation increases from w to e from 70 in the lepontine window in the swiss alps to 80 in the tauern window and to more than 95 in the rechnitz window the driving mechanism of tectonic denudation was eastward extrusion due to an unconstrained orogenic margin in the pannonian basin tectonic denudation in the alps was responsible for about 30 of the total exhumation between 22 and 12 ma

role of the indochina peninsula narrow mountains in modulating the east asian western north pacific summer monsoon abstractunrealistic topographic effects are generally incorporated in global climate simulations and may contribute significantly to model biases in the asian monsoon region by artificially implementing the arakan yoma and annamese cordillera two south north oriented high mountain ranges on the coasts of the indochina peninsula in a 1 global climate model it is demonstrated that the proper representation of mesoscale topography over the indochina peninsula is crucial for realistically simulating the seasonality of the east asian western north pacific eawnp summer monsoon presence of the arakan yoma and annamese cordillera helps simulate the vertical coupling of atmospheric circulation over the mountain regions in late may the existence of the arakan yoma enhances the vertically deep southwesterly flow originating from the trough over the bay of bengal the ascending southwesterly flow converges with the midlatitude jet stream downstream in the southeast of the tibetan plateau and transports moistur

young uplift in the non glaciated parts of the eastern alps abstract we report the first incision rates derived from burial ages of cave sediments from the mur river catchment at the eastern margin of the eastern alps at the transition zone between the alpine orogen and the pannonian basin this river passes through the paleozoic of graz a region of karstifiable rocks called the central styrian karst this river dissects the study area in a north south direction and has left behind an abundance of caves these caves can be grouped into several distinct levels according to their elevation above the present fluvial base level age estimates of abandoned cave levels are constrained by dating fluvial sediments washed into caves during the waning stages of speleogenesis with the terrestrial cosmogenic nuclide method these ages and the elevations of the cave levels relative to the current valley floor are used to infer a very complex history of 4 million years of water table position influenced by the entrenchment and aggradation of the mur river we observe rather low rates of bedrock incision over the last 4 ma in the order of 0 1 mm y with an e folding decrease in this trend to lower rates at younger times we relate this incision history to a tectonic setting where an increase of drainage area of the mur river due to stream piracy in late miocene to pliocene times is linked to surface uplift the later decrease in valley lowering rates is attributed to the rise of the base level related to aggradation of sediments within the valley sediment transport through the valley from the upstream section of the mur river limited the erosional potential of the river to a transport limited state at the later stages of the incision history

basin formation during the post collisional evolution of the eastern alps the example of the lavanttal basin the miocene lavanttal basin formed in the eastern alps during extrusion of crustal blocks towards the east in contrast to basins which formed contemporaneously along the strike slip faults of the noric depression and on top of the moving blocks styrian basin little is known about the lavanttal basin in this paper geophysical sedimentological and structural data are used to study structure and evolution of the lavanttal basin the eastern margin of the 2 km deep basin is formed by the wnw trending koralm fault the geometry of the gently dipping western basin flank shows that the present day basin is only a remnant of a former significantly larger basin late early karpatian and early middle miocene badenian pull apart phases initiated basin formation and deposition of thick fluvial granitztal beds lacustrine and marine muhldorf fm sediments the muhldorf fm represents the lower badenian cycle tb2 4 another flooding event caused brackish environments in late middle miocene early sarmatian time whereas freshwater environments existed in late sarmatian time the coal bearing sarmatian succession is subdivided into four fourth order sequences the number of sequences suggests that the effect of tectonic subsidence was overruled by sea level fluctuations during sarmatian time increased relief energy caused by early pannonian pull apart activity initiated deposition of thick fluvial sediments the present day shape of the basin is a result of young plio pleistocene basin inversion in contrast to the multi stage lavanttal basin basins along the noric depression show a single stage history similarities between the lavanttal and styrian basins exist in early badenian and early sarmatian times

eruption and emplacement of flood basalt an example from the large volume teepee butte member columbia river basalt group flows of the teepee butte member grande ronde basalt issued from a vent system in southeastern washington northeastern oregon and western idaho three distinct basalt flows were erupted the limekiln rapids flow the joseph creek flow and the pruitt draw flow together these mappable flows cover more than 52 000 km sup 2 and have a volume exceeding 5 000 km sup 3 a portion of the vent system for the joseph creek flow is exposed in cross section in joseph canyon washington it is one of the best preserved columbia river basalt group vent complexes known the vent complex is about 1 km in cross section 30 m high and composed of deposits characteristic of hawaiian type volcanism the vent is asymmetrical the eastern rampart consists of intercalated pyroclastic deposits and thin pahoehoe flows the western rampart is composed wholly of pahoehoe flows flows of the teepee butte member are compositionally homogeneous and were emplaced as sheet flows each having several local flow units our study supports the importance of linear vent systems and the westward palouse slope along with the large volume lava flows in controlling the distribution of columbia river basalt group flows other factors including the number of active fissure segments andmore topography modified the shape of the flows and the number of flow units 45 refs 19 figs 2 tabs less

late neogene erosion of the alps a climate driver as with many mountain belts globally the alps have seen a large increase in sediment yield in the late neogene the hypothesis that this increase results from climate change impacts on erosion rate over the past 5 ma is testable given the extensive work completed in the alps sediment budgets thermochronology based cooling rates and estimates of modern rock uplift and erosion in the western alps are reviewed to search for correlation in space and time that might fingerprint climatic events major increases in sediment yield are apparent starting in the late messinian 5 5 mya and accelerating toward the present day this suggests the occurrence of a series of climatic changes that increased erosion rates even as tectonic processes appear to have slowed or stopped at present tight correlations in time are difficult to establish and there remain open questions about the role of tectonics in the coupled system

deformation partitioning during polyphase oblique convergence in the karawanken mountains southeastern alps abstract the karawanken mountains of southeastern austria straddle the insubric line a major fault zone that corresponds to the austroalpine south alpine border of the eastern alps they display polyphase structural patterns that resulted from deformation partitioning at shallow crustal levels following a poorly constrained late cretaceous deformation history paleogene contraction produced nw se trending fold thrust structures and possibly related sinistral cross faults miocene deformation produced both nw and se directed thrust faults and nw striking high angle dextral cross faults which merged with or displaced the w striking insubric line distributed dextral strike slip displacements of the order of 30 40 km and thrust displacement of 4 5 km along the northern karawanken front initiated subsidence of a small foreland basin north of the karawanken mountains recent regional deformation seems to be concentrated along cross cutting nnw striking dextral faults within a shifting system of seismogenic transfer faults that probably merge with the convergent south alpine thrust front to the west there are conspicuous parallels in the style of deformation along the karawanken mountains with that found along other seismogenic convergent strike slip faults such as those of southern california new zealand and anatolia

possible controls of hydrogeological and stress regimes on the producibility of coalbed methane in upper cretaceous tertiary strata of the alberta basin canada the coalbed methane potential and producibility of any coal bearing strata are strongly affected by the hydrogeological regime of formation waters and by coal permeability which in turn depends on the effective stress regime of the coals peat that accumulated in the alberta basin during the late cretaceous and early tertiary led to the formation of coal deposits that may contain significant coalbed methane resources the flow of formation waters plays an important role in the maintenance and producibility of this resource the present day flow is driven by gravity topography and erosional rebound and is controlled by rock permeability and the presence of gas saturated sandstones the estimated gas in place in the tertiary upper cretaceous coals decreases significantly with stratigraphic age ranging between less than 2 bcf mi2 in the lower coal zones and 12 bcf mi2 in the uppermost coals the gas content especially of the deeper coals is lower than would be expected for the corresponding coal rank and burial depth most likely because the underpressuring has caused the release of gas from the coals and accumulation in adjacent sands the shallow coals although of low rank may contain important amounts of late stage biogenic methane the salinity of formation water in shallow coal seams where the flow is driven by topography is low generally less than 1500 mg l although in places it reaches 3000 5000 mg l the salinity of formation water in the deeper underpressured strata in the west central part of the basin is significantly higher reaching 18 000 mg l this affects treatment and or disposal strategies with regard to the water produced concurrent to coalbed methane the producibility of this resource depends on coal permeability which decreases west southwestward with increasing burial depth from the order of several darcys in the shallow zones to millidarcys in the deep zones the minimum effective stress which affects coal permeability by closing fractures increases west southwestward from zero at the erosional edge of these strata to approximately 20 mpa near the rocky mountain deformation front fractures including those in coal seams will generally be vertical and will propagate on a southwest northeast axis along the direction of the maximum horizontal stress in a direction generally perpendicular to the rocky mountain deformation front considering the hydrogeological and stress regimes in conjunction with estimations of the gas content in coals the region with probably good coalbed methane potential and producibility are the ardley coal zone in the scollard formation and maybe to a lesser extent the coal zones of the stratigraphically deeper edmonton and belly river groups along their respective subcrop in central and southern alberta the deep edmonton and belly river strata in western and central alberta have most likely a reduced coalbed methane potential as a result of lower gas content and of low permeability these regional considerations need to be applied against local studies of coal thickness rank permeability and gas content to identify the best targets for coalbed methane exploration and production

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

cooling and vertical motions of crustal wedges prior to during and after lateral extrusion in the eastern alps new field kinematic and fission track data from the mur murz fault system new structural and thermochronological zircon and apatite fission track data from the eastern most alps highlight distinct deformation phases affecting the austroalpine unit along a major sinistral strike slip fault system the mur murz fault mmf the data link deformation to vertical motions prior to during and after the main phase of lateral extrusion of the orogen zircon fission track ages document rapid ca 15 c myr and diachronous eastward younging cooling and rock exhumation during the latest cretaceous to paleocene subsequent regional eocene to early miocene cooling below the closure temperature of the apatite fission track system occurred at slow rates ca 2 c myr suggesting that the region was not subject to major surface uplift and erosion during that period fault kinematic analysis along the mmf document pre extrusion nnw sse contraction middle miocene syn extrusion ne sw to nne ssw directed shortening and late miocene e w contraction all phases are characterized by strike slip fault regimes formation of the complex mmf zone triggered the exhumation of small fault bound crustal blocks within the fault zone as documented by middle miocene apatite fission track ages overall ages are similar on both sides of the fault suggesting that lateral extrusion along the mmf was not associated with significant differential vertical motions local pliocene rock cooling and exhumation was probably related to the buttressing effect of the underthrust bohemian basement spur whereas large scale post extrusion surface uplift of the extruding crustal wedges such as the styrian block must have been related to long wavelength deformation processes affecting the easternmost alps

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

is climate variability over the north pacific a linear response to enso abstract indices of the dominant spatial patterns of wintertime northern hemisphere 500 mb height and north pacific sea surface temperature are strongly correlated with one another on interannual and interdecadal timescales and both am correlated with indices of the el nin southern oscillation one possible interpretation of these relationships is that the tropical sst anomalies associated with enso force the atmospheric circulation over the north pacific and these atmospheric anomalies in turn give rise to the observed sst anomalies over the extratropical north pacific in this study linear relationships between enso and extratropical variables are examined in two different ways first the component of the observed extratropical variability that is linearly dependent upon enso is removed the dominant spatial patterns in the residual variability of 500 mb height and sst anomalies over the north pacific are shown to be similar to their counterparts in the total fields and remain strongly coupled on

methane in columbia river basalt aquifers isotopic and geohydrologic evidence for a deep coal bed gas source in the columbia basin washington methane occurs as a dissolved constituent in groundwater from confined aquifers in the columbia river basalt group columbia basin washington isotopic compositions of methane in groundwater indicate that the methane is a mixture of biogenic dgr13c ch4 to 88 pmil and dgr2h ch4 to 265 pmil and thermogenic dgr13c ch4 to 35 pmil and dgr2h ch4 to 134 pmil components chemical and isotopic data are consistent with entrainment of deep coal bed generated methane in upwelling groundwater from below the columbia river basalt group 4 km that mixes with near surface groundwater the areal distribution pattern of methane suggests that fault intersections are necessary for vert cal migration of deep methane through the basalt this study suggests that deep subbasalt coal bed methane in the columbia basin has infiltrated the shallow basalt groundwater system and isotopic analyses of methane in groundwater from structurally favorable locations can be used to identify potential exploration targets the wide areal distribution of methane in this large relatively unexplored frontier province suggests economic gas reserves

the saddle mountains the evolution of an anticline in the yakima fold belt the saddle mountains uplift is an asymmetrical north vergent anticline with a length of about 110 km it varies from an open to tight fold and is divided into six segments based upon differences in geometry flows of the columbia river basalt group intercalated sedimentary deposits of the ellensburg formation and suprabasalt sediments thin over the uplift and thicken into the synclines variations in thickness are used to determine the timing of deformation and age of major and minor structures the close correlation of growth rate of the folds with rate of magma supply of the columbia river basalt group suggests that the yakima fold belt resulted from the same tectonic processes that produced eruption of the columbia river basalt modified journal abstract

neogene quaternary tectonic stratigraphy of the eastern southern alps ne italy abstract in order to reconstruct the neogene quaternary tectonic stratigraphy of the eastern southern alps the late tortonian lower pleistocene foredeep clastic sequences cropping out in the veneto and friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers pitted pebbles the eastern southern alps is the result of a typical polyphase tectonic activity initiated in late oligocene characterised by the occurrence of several non coaxial stress regimes based on careful analyses of the pebbles surfaces shape and orientation of the indented features and following a systematic and statistical approach the mean orientation of the maximum compressive stress axis 1 has been obtained for more than 30 sites of measurements along the ca 120 km long investigated piedmont area the affected lithostratigraphic units and the orientation pre versus post tilting of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean 1 direction and timing late tortonian 1 313 00 late messinian early pliocene 338 04 late pliocene 314 03 and early middle pleistocene 160 03 the tectonic stratigraphy of the eastern southern alps during the last ca 10 ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the 1 axis between an nnw sse and nw se directions twist tectonics taking also into account literature data about older deformational events chattian burdigalian and serravallian tortonian we analyse the neogene quaternary tectonic evolution in the frame of the central mediterranean realm and compare it with the convergence direction between the adria africa and europe lithospheric plates we show that compressional directions within the eastern southern alps are basically governed by the remote plate convergence though since late messinian the approaching northern apennines started to play a crucial role within the investigated area alternating short lived phases 1 2 ma of coupling and decoupling along the basal detachment of the apennines accretionary wedge probably caused temporary perturbations of the local stress field and complex accommodation structures in this region of ongoing crustal collision

climate induced rebound and exhumation of the european alps foreland basins record the regional isostatic compensation of mountain belts during periods of crustal thickening they subside and when erosion unloads the mass of the mountains the basins rebound and are eroded in order to evaluate this mechanism for rebound it is critical that the timing and magnitude of erosion are documented we present data estimating the timing and magnitude of late orogenic or postorogenic erosion in the north alpine foreland basin of switzerland mineral cooling ages demonstrate that the basin underwent 1 3 km of erosion soon after 5 ma this erosion coincided with a decline in structural deformation in the swiss alps and a doubling of sediment accu mulation rates in surrounding depocenters we propose that accelerated erosional un roofing of the swiss alps triggered isostatic rebound and erosion of the foreland basin after 5 ma a projection of the isostatic rebound of the basin into the mountains suggests that at least 6 5 km of erosion should have occurred in the high topography of the aar massif accelerated erosion in the swiss alps at that time is explained by an increase in atmospheric moisture driven by an intensification of the atlantic gulf stream at 4 6 ma consequently we propose that the changing erosional capacity of the climate triggered late orogenic to postorogenic mass reduction and isostatic rebound of the swiss alps and their neighboring foreland basin

the atmospheric response to realistic arctic sea ice anomalies in an agcm during winter abstract the influence of realistic arctic sea ice anomalies on the atmosphere during winter is investigated with version 3 6 of the community climate model ccm3 6 model experiments are performed for the winters with the most 1982 83 and least 1995 96 arctic ice coverage during 1979 99 when ice concentration estimates were available from satellites the experiments consist of 50 member ensembles using large ensembles proved critical to distinguish the signal from noise the local response to ice anomalies over the subpolar seas of both the atlantic and pacific is robust and generally shallow with large upward surface heat fluxes 100 w m 2 near surface warming enhanced precipitation and below normal sea level pressure where sea ice receded and the reverse where the ice expanded the large scale response to reduced enhanced ice extent to the east west of greenland during 1982 83 resembles the negative phase of the arctic oscillation north atlantic oscillation ao nao with a ridge over t

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

generation accumulation and resource potential of biogenic gas biogenic gas is generated at low temperatures by decomposition of organic matter by anaerobic microorganisms more than 20 of the world s discovered gas reserves are of biogenic origin a higher percentage of gases of predominantly biogenic origin will be discovered in the future biogenic gas is an important target for exploration because it occurs in geologically predictable circumstances and in areally widespread large quantities at shallow depths in rapidly accumulating marine sediments a succession of microbial ecosystems leads to the generation of biogenic gas after oxygen is consumed by aerobic respiration sulfate reduction becomes the dominant form of respiration methane generation and accumulation become dominant only after sulfate in sediment pore water is depleted the most important mechanism of methane generation in marine sediments is the reduction of co2 by hydrogen electrons produced by the anaerobic oxidation of organic matter co2 is the product of either metabolic decarboxylation or chemical decarboxylation at slightly higher temperatures the factors that control the level of methane production after sediment burial are anoxic environment sulfate deficient environment low temperatu e availability of organic matter and sufficient space the timing of these factors is such that most biogenic gas is generated prior to burial depths of 1 000 m in marine sediments most of the biogenic gas formed can be retained in solution in the interstitial pore waters because of higher methane solubility at the higher hydrostatic pressures due to the weight of the overlying water column under certain conditions of high pressures and or low temperatures biogenic methane combines with water to form gas hydrates biogenic gas usually can be distinguished from thermogenic gas by chemical and isotopic analyses the hydrocarbon fraction of biogenic gas consists predominantly of methane the presence of as much as 2 of heavier hydrocarbons can be attributed to admixture of minor thermogenic gas due to low temperature degradation of organic matter the amounts of hydrocarbon components other than methane generally are proportional to temperature age and organic matter content of the sediments biogenic methane is enriched in the light isotope 12c dgr13c1 lighter than 55 ppt owing to kinetic isotope fractionation by methanogens the variations in isotopic composition of biogenic methane are controlled primarily by dgr13c of the original co2 substrate which reflects the net isotopic effect of both addition and removal of co2 the methane isotopic composition also can be affected by mixing of isotopically heavier thermogenic gas the possible complicating factors require that geologic chemical and isotopic evidence be considered in attempts to interpret the origin of gas accumulations accumulations of biogenic gas have been discovered in canada germany italy japan trinidad the united states and ussr in cretaceous and younger rocks at less than 3 350 m of burial and in marine and nonmarine rocks other gas accumulations of biogenic origin have undoubtedly been discovered however data that permit their recognition are not available

the dachstein paleosurface and the augenstein formation in the northern calcareous alps a mosaic stone in the geomorphological evolution of the eastern alps the central and eastern areas of the northern calcareous alps nca are characterized by remnants of the dachstein paleosurface which formed in late eocene to early oligocene time and is preserved with limited modification on elevated karst plateaus in oligocene time the dachstein paleosurface subsided and was sealed by the augenstein formation a terrestrial succession of conglomerates and sandstones which are only preserved in small remnants on the plateaus some in an autochthonous position thermochronological data suggest a maximum thickness of the augenstein formation of 1 3 km possibly 2 km the age of the augenstein formation is constrained by the overall geological situation as early oligocene to earliest miocene fission track age data support an early oligocene age of the basal parts of the formation the source area of the augenstein formation consisted predominantly of weakly metamorphic paleozoic terrains greywacke zone and equivalents as well as the late carboniferous to scythian siliciclastic base of the nca to the south of the depositional area to the west the augenstein formation interfingered with the tertiary deposits of the inntal sedimentation of the augenstein formation was terminated in early miocene time in the course of the orogenic collapse of the eastern alps the augenstein sediments were eroded and redeposited in the foreland molasse zone from pannonian times 10 ma on the nca and the denuded dachstein surface experienced uplift in several pulses the dachstein paleosurface has been preserved in areas in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion

transition from orogen perpendicular to orogen parallel exhumation and cooling during crustal indentation key constraints from 147sm 144nd and 87rb 87sr geochronology tauern window alps abstract the core of the alpine orogen in the eastern alps tauern window experienced a change from orogen normal shortening and post nappe doming to predominantly orogen parallel extension and tectonic unroofing during late oligocene to miocene northward indentation of the adriatic microplate a new 147 sm 144 nd isochron age of 25 7 0 9 ma on a garnet bearing assemblage from the lowest nappe complex forming a dome in the eastern part of the tauern window indicates that high temperatures related to post nappe barrovian type metamorphism overlapped in time with the onset of doming new 87 rb 87 sr biotite ages from this same complex combined with previously published 87 rb 87 sr white mica ages suggest that doming and exhumation began no later than 28 ma immediately in front of indenting austroalpine crustal blocks then migrated laterally to the ese during rapid exhumation and orogen parallel stretching beginning at about 23 ma rapid cooling ended at approximately 17 ma in the footwall of the katschberg normal fault which delimits the eastern margin of the tauern window a similar pattern of migrating doming orogen parallel extension and cooling is recognized in the western part of the tauern window where rapid exhumation began at about 20 ma some 2 3 ma later than in the eastern part this difference in the onset of rapid exhumation as well as the overall migration of doming from the center to the ends of the tauern window are attributed to fragmentation of the aforementioned austroalpine blocks along the leading edge of the main adriatic indenter southern alps as this indenter advanced to the north

balancing lateral orogenic float of the eastern alps abstract oligocene to miocene post collisional shortening between the adriatic and european plates was compensated by frontal thrusting onto the molasse foreland basin and by contemporaneous lateral wedging of the austroalpine upper plate balancing of the upper plate shortening by horizontal retrodeformation of lateral escaping and extruding wedges of the austroalpine lid enables an evaluation of the total post collisional deformation of the hangingwall plate quantification of the north south shortening and east west extension of the upper plate is derived from displacement data of major faults that dissect the austroalpine wedges indentation of the south alpine unit corresponds to 64 km north south shortening and a minimum of 120 km of east west extension lateral wedging affected the eastern alps east of the giudicarie fault west of the giudicarie fault north south shortening was compensated by 50 to 80 km of backthrusting in the lombardian thrust system of the southern alps the main structures that bound the escaping wedges to the north are the inntal fault system ca 50 km sinistral offset the konigsee lammertal traunsee klt fault 10 km and the salzach ennstal mariazell puchberg semp fault system 60 km these faults as well as a number of minor faults with displacements less than 10 km root in the basal detachment of the alps the thin skinned nature of lateral escape related structures north of the semp line is documented by industry reflection seismic lines crossing the northern calcareous alps nca and the frontal thrust of the eastern alps complex triangle zones with passive roof backthrusts of middle miocene molasse sediments formed in front of the laterally escaping wedges of the northern eastern alps the aim of this paper is a semiquantitative reconstruction of the upper plate of the eastern alps most of the data is published elsewhere

role of topography in isotherm perturbation apatite u th he and fission track results from the malta tunnel tauern window austria 1 apatite u th he and fission track age determinations of samples from a 20 km long near horizontal tunnel in the hochalm ankogel dome eastern tauern window austria are presented in order to determine the role of paleo topography in perturbing isotherms in the shallow crust apatite fission track ages 26 8 ma show no systematic correlation with distance along the tunnel or elevation two age components in the fission track data indicate cooling through 120 c at approximately 20 ma and 80 c at approximately 6 ma surface and tunnel u th he ages 17 9 ma and 13 5 ma respectively are consistently younger than the equivalent fission track ages u th he ages vary systematically along the tunnel with older ages at the northern and southern tunnel portals and younger ages in the central section geological factors faulting lithology appear to have had little effect on this age distribution the u th he age pattern is inconsistent with rock cooling underneath the present day hochalm ankogel dome topography the age minimum is interpreted to coincide with a paleotopographic maximum in the hochalm ankogel dome and suggests that the 40 60 c isotherms were warped sufficiently to affect apatite u th he ages the tunnel apatite u th he ages match synthetic he ages derived from a two dimensional numerical model of landscape evolution integrating the thermal model results with the data allows the relief development to be constrained and we calculate that the present day hochalm ankogel dome topography was formed at 7 to 10 ma

increase in late neogene denudation of the european alps confirmed by analysis of a fission track thermochronology database abstract a sharp increase in deposited sediment volume since pliocene times has been observed worldwide and in particular around the european alps this phenomenon has been linked to a rise in denudation rates controlled by an increase of either climatic or tectonic forcing observation of in situ cooling histories for orogens is critical to assess the reality of the inferred increase in denudation rates and to determine whether this phenomenon is widespread or localized at active tectonic structures we exploit the unique density of fission track ages in the western european alps to reconstruct cooling isoage surfaces and to estimate exhumation rates on the orogen scale between 13 5 and 2 5 ma our novel technique is based on the association of isoage contours with age elevation relationships it uses map view interpolation enabling a spatio temporal analysis of exhumation rates over the entire western alps the resulting exhumation histories reconstructed for eight areas of the western alps display strong similarities in timing and rates with orogen wide average denudation rates inferred from sediment volumes this consistency validates the use of both techniques for the study of an orogen characterized by strong relief and high recent exhumation rates we conclude that exhumation rates in the western alps have increased more than twofold since late miocene times this increase may have been locally modulated by the distinct response of different tectonic units

a modelling and observational study of the relationship between sea surface temperature in the north west atlantic and the atmospheric general circulation results from four pairs of 50 day wintertime integrations of the meteorological office s 5 level general circulation model with warm and cold sea surface temperature s s t anomalies of about 3 k in the northwest atlantic are described difference fields between the warm and cold integrations are statistically significant at the 1 level with positive geopotential height over the central north atlantic and weaker negative height over europe the storm track over the atlantic is displaced from its normal position results from four further pairs of integrations with halved s s t anomalies are also described the response is approximately linear with systematic differences in 500 mb geopotential height over the atlantic parts of which are just significant at the 10 level with half the full s s t anomaly overall however the model s response is weaker than could be obtained with tropical s s t anomalies of the same magnitude results from the model integrations are compared with results from an observational study of the relationship between wintertime s s t in the north west atlantic and mean sea level pressure and 500mb height two independent 30 year periods were chosen for study thus minimizing the influence of long term trends in s s t over the atlantic and europe the model results compared well with the observations with s s t data lagging the atmosphere by one month the observational study appears to show that the s s t anomalies are initially forced by perturbations in the atmospheric circulation with s s t data leading the atmosphere by one month results show that atmospheric and s s t anomalies are most persistent in the period october to december throughout the winter these lagged relationships are much weaker and not statistically significant diagnostics of e vector divergence from the gcm experiments are used to suggest that anomalous baroclinic wave activity over the atlantic is important as a momentum forcing for the anomalous time mean flow pattern on the other hand the role of thermal forcing provided by anomalous diabatic heating and transient eddy heat flux convergence may be important to substantiate this statement a simple linear steadystate two layer model of the response to extratropical thermal forcing is described with a suitable basic state flow and a mid tropospheric heat source given mainly by the transient eddy heat flux convergence the response is shown to be equivalent barotropic with a downstream ridge and ascent over the thermal source conversely results from an ocean mixed layer model are discussed which suggest that warm s s t anomalies could be maintained by a positive surface pressure perturbation positioned downstream of the anomaly through anomalous northward advection of warm ocean water by ekman drift currents this northward advection would balance the sensible and latent heat loss into the atmosphere over the s s t anomaly hence it is possible that some positive ocean atmosphere feedback may account for the persistence of such atmospheric and oceanic anomalies