peculiar phenomena regarding climatic and glacial variations on the tibetan plateau in contrast to the worldwide intensive warming and consequent glacier shrinkage during the last 30 years two peculiar phenomena have been observed on the tibetan plateau 1 the temperature has decreased about 0 68c on the northern tibetan plateau with smaller than average glacier retreat and meltwater discharge and 2 a number of glaciers have been advancing on the southeast tibetan plateau in response to increased precipitation these observations indicate the complex nature of the response of glaciers to climate changes the main part of the northern tibetan plateau includes the western and central kunlun shan and the northern qiangtang plateau roughly 32 378 n 75 958 e fig 1 the kunlun shan are known as the backbone of asia extending from west to east with wide mountain ranges mostly higher than 6000 m a s l and the highest peak at 7167 m a s l the high and broad mountains and prevailing climate provide favorable conditions for glacier develop ment at present according to the china glacier inventory cgi glaciers in the western and central kunlun shan cover 12 136 km 2 and the equilibrium line altitude ela ranges between 480 and 6200 m there are several isolated mountains in the northern qiangtang plateau with eroded surfaces above 6000 m a s l and some isolated interior lake basins in this region glaciers cover an area of about 1500 km 2 with the ela ranging from 5300 to 6100 m

late miocene to pliocene palaeogeography of the paratethys and its relation to the mediterranean abstract the palaeogeographic evolution of the paratethyan and mediterranean realms are reconstructed with three maps ranging from the late miocene to the middle late pliocene the maps are based on the facial analysis of selected deposits clastic input slope slide process analyses as well as biogeographic data of the planktic benthic and terrestrial biota characteristic fossil assemblages are used for palaeobathymetric and palaeohydrologic interpretations restoration of palaeogeographic connections the palaeogeographic reconstructions are palinspastically restored after dercourt j ricou l e vrielynck b eds 1993 atlas tethys palaeoenvironmental maps gauthier villars paris pp 1 307 14 maps the paleogeographic atlas of northern eurasia 1997 inst tectonics lithospheric plates moscow 26 maps with modifications maps have been prepared for the terminal tortonian early messinian late pannonian early maeotian late messinian pontian salinity crisis time and piacenzian gelasian akchagilian they illustrate the neogene palaeogeographic evolution during and after the attic orogenesis though the emerging mountain system of the alpine foldbelt increasingly separated the paratethys from the mediterranean tethys paratethys connections remained extant and sufficiently effective for limited communication between both basins they governed many features of the cyclic depositional history and biogeographic evolution of the eastern paratethys

tectonic and climatic controls on asymmetric half graben sedimentation inferences from 3 d numerical modeling the tectono sedimentary evolution of asymmetric extensional systems driven by the activity of major normal faults or detachments associated with footwall exhumation is often characterized by a sequence of slower faster and ultimately again slower subsidence rates in the center of hanging wall half grabens during their synkinematic and postkinematic evolution we have studied this specific evolution by the means of 3 d stratigraphic numerical modeling that accounts for the variability of the sediment and water flux combined with climatic and sea level variations and sediment compaction the model setup is constrained by observations from the pannonian back arc basin of central europe our modeling predicts the formation of low order tectonic and higher order sea level and climate driven transgressive regressive sedimentary cycles furthermore we model and analyze the autocyclic nature of the depositional systems retrograding prograding cycles are visible on the proximal flank of the half grabens by their different spatial and temporal expressions while depocenters record large water depth variations linked to the specific and episodic activity of normal faults and their migration with time the application to a system of multiple half grabens in the pannonian basin which are activated in different locations at different times and with different kinematics demonstrates a complex interplay between direct sediment sourcing and the sediments ability to bypass trapping subbasins and paleo reliefs created by eroded footwalls

observed and modelled ice temperature and velocity along the main flowline of east rongbuk glacier qomolangma mount everest himalaya knowledge of present day ice temperature and velocity is important in order to determine how fast a glacier will respond to present and future climate change we apply a two dimensional higher order thermomechanical flowband model to simulate present day ice temperature and velocity along the main flowline of east rongbuk glacier qomolangma mount everest himalaya we use recent 2005 11 observational data to validate the numerical model modelled and observed ice surface velocities exhibit good agreement modelled ice temperatures agree well with observed values in two shallow boreholes that are similar to 18 m deep the model suggests that the ablation zone of east rongbuk glacier km 4 to km 10 from the glacier head is underlain by temperate ice

hydrological characteristics of the drainage system beneath a surging glacier a rare combination of natural circumstances permits assessment of current theories on water flow beneath glaciers outburst floods from the subglacial lake grimsvotn in iceland took place before during and after surging of skei ararjokull the glacier beneath which the outburst floods drain the observable drainage patterns associated with these floods show the different nature of the basal water conduit system of the glacier during surge and non surge phases during surge conditions basal water is dispersed slowly across the bed in a distributed drainage system but when the glacier is not surging water is transported rapidly through a system of tunnels

the age and paleoenvironment of a late miocene floodplain alongside lake pannon rodent and mollusk biostratigraphy coupled with authigenic 10be 9be dating in the northern danube basin of slovakia abstract we present new age constraints for the late miocene volkovce formation of slovakia alluvial facies that accumulated adjacent to lake pannon facies analysis and authigenic 10be 9be dating was undertaken at the bernolakovo and triblavina localities while the latter outcrop also yielded additional small mammal and mollusk assemblages as well as remains of flora the results of seven radiometric dating ages yielded a weighted mean age of 9 65 0 61 ma for the triblavina outcrop and 8 85 0 32 ma for the bernolakovo outcrop the small mammal assemblage at the triblavina outcrop is indicative of the lowermost mn11 zone which in the western european standard definition suggests an age of

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

teleseismic tomography of the mantle in the carpathian pannonian region of central europe summary subducted slab roll back lithospheric instability and asthenospheric extrusion have all been proposed as mechanisms that explain the evolution of the extensional pannonian basin within the convergent arc of the alpine carpathian mountain system in central europe we determine the p and s wave velocity structure of the mantle to depths of 850 km beneath this region using tomographic inversion of relative arrival time residuals from 225 p waves and 124 s waves teleseismic earthquakes recorded by 56 stations of the carpathian basins project cbp temporary seismic network 16 month duration and 44 permanent seismic stations the observed median p wave relative arrival time residuals vary between 1 13 s early in the alps and 1 12 s late at the western end of the carpathians s wave relative arrival time residuals are about twice as large 2 13 s and 3 39 s we tested the effect of deterministic corrections on our relative arrival time residuals using crustal velocity models from controlled source experiments but show that the use of station terms in the inversion provides a robust method of correcting for near surface crustal variation our tomographic models reduce the p wave rms residual by 71 per cent to 0 130 s and our s wave rms residual by 59 per cent to 0 624 s at shallow sublithospheric depths we image several localized lower velocity regions correlated with higher heat flow and interpreted as upwelling asthenosphere we image a high velocity structure down to depths of about 350 km beneath the eastern alps further east beneath the pannonian basin a deeper continuation of the eastern alps fast anomaly is imaged trending e w from 300 km depth and extending into the mantle transition zone mtz in the mtz we image a fast anomaly extending outwards as far as the carpathians the dinarides and the eastern alps this higher velocity mantle material is interpreted as being produced by a mantle downwelling whose detachment from the lithosphere above may have triggered the extension of the pannonian basin

shallow shelf approximation as a sliding law in a thermomechanically coupled ice sheet model 1 the shallow shelf approximation a balance of membrane stresses for ice flow is an effective sliding law for ice sheet modeling our use of it as a sliding law becomes a standard model for ice stream flow when the sliding velocity is large 100 m a 1 and faster following schoof 2006a we describe the basal resistance as plastic till for which the yield stress is given by a mohr coulomb formula pore water pressure is related to basal melt rate the velocity field used in the mass continuity and conservation of energy equations is an average of velocities from the shallow shelf approximation and the nonsliding shallow ice approximation using this scheme our model has realistic time dependent ice streams which exhibit the range of surface velocities seen in actual ice streams we demonstrate the model at high spatial resolution 5 km grid over multiple millenia using its implementation in the parallel ice sheet model numerical experiments show that the entire scheme is stable with respect to many parameter changes some experiments reveal significant ice stream variability in a hypothetical steady climate with characteristic cycles on the order of 1000 years we believe this is the first practical whole ice sheet model with a unified treatment of vertical shear stresses and membrane stresses it is capable of high resolution thermomechanically coupled multimillenia simulations of ice sheets containing ice streams

miocene pliocene tectonic evolution of the slovenian periadriatic fault implications for alpine carpathian extrusion models the periadriatic line pal is a remarkable several hundred kilometer long fault system of the alpine orogen its dextral character was documented by several authors using diverse criteria but detailed kinematics and timing of movements had not been investigated along its whole length structural and paleomagnetic measurements mapping and stratigraphic and sedimentological studies have helped to unravel the miocene pliocene evolution of the slovenian segment of the pal brittle deformation was characterized by nw se to n s compression and perpendicular tension deformation has resulted in dextral strike slip faulting folding and tilting of beds the first transpressional event corresponds to the first phase of lateral extrusion of the east alpine western carpathian northern pannonian block in the early miocene 24 17 5 ma after a short period of transtension during the karpatian 17 5 16 5 ma dextral transpression reoccurred during the middle miocene to pliocene and lasted up to the quaternary middle miocene dextral slip can be connected to the second phase of extrusion the highly deformed rocks within the dextral shear zones show variable clockwise sometimes counterclockwise rotations the mechanism of rotation seems to be complex ranging from regional rotation to local folding due to pure or simple shear domino type rotation

application of a degree day model for the determination of contributions to glacier meltwater and runoff near keqicar baqi glacier southwestern tien shan a so called warm and wet transition of climate has occurred in the arid part of northwestern china since the late 1980s a result of this climatic transition is an increase in runoff in xinjiang and neighboring regions in a warming and wetting change of climate scenario we attempt to evaluate the impact of glacier meltwater and precipitation on the increase in outlet discharge runoff from keqicar baqi glacier southwestern tien shan china in our research we have applied a degree day model which is one of the most widely used methods of ice and snowmelt computations for a multitude of purposes such as hydrological modeling ice dynamic modeling and climate sensitivity studies it is concluded that under the warming and wetting scenario the primary supply for the runoff in this catchment is glacier meltwater with precipitation being the dominant secondary source 84 and 8 of total runoff respectively

modeling the flow of glaciers in steep terrains the integrated second order shallow ice approximation isosia 1 the rugged topography of mountain ranges represents a special challenge to computational ice sheet models simulating past or present glaciations in mountainous regions the topography steers glaciers through relatively narrow and steep valleys and as a consequence hereof the flow rate of alpine style glaciers varies significantly at length scales comparable to that of the topography localized flow rate undulations generate longitudinal and transverse stress gradients within the ice which in turn are of known importance to the flow itself whether by internal deformation of the ice or by basal sliding and to the interaction with topography through glacial erosion standard models capable of simulating mountain range scale glaciations build on the so called shallow ice approximation which among other parameters neglects the longitudinal and transverse stress gradients and therefore fails to capture the full effects of the rugged topography and related feedbacks between erosion by glacial sliding and the extent and style of glaciation here we present and test a new depth integrated model framework which on the one hand takes into account the higher order effects related to steep and rugged bed topography while it still on the other hand provides the computational efficiency needed for three dimensional simulations of glaciation and landscape evolution in response to for example long term climate variations the model framework integrated second order shallow ice approximation isosia is based on depth integration of the second order shallow ice approximation although depth integration is not guaranteed to maintain so called second order accuracy the results of computational benchmark experiments show that isosia in spite of its efficient depth integrated structure performs well in situations with steep and rapidly undulating bed topography

glacier changes in the central and northern tien shan during the last 140 years based on surface and remote sensing data this research presents a precise evaluation of the recession of akshiirak and ala archa glaciers tien shan central asia based on data of geodetic surveys from 1861 69 aerial photographs from 1943 1963 1977 and 1981 1 25 000 scale topographic maps and srtm and aster data from 2000 03 the akshiirak glacierized massif in the central tien shan contains 178 glaciers covering 371 6 km 2 and the ala archa glacier basin in the northern tien shan contains 48 glaciers covering 36 31 km 2 the tien shan glaciers retreated as much as 3 km from the 1860s to 2003 area shrinkage of akshiirak and ala archa was 4 2 and 5 1 respectively from 1943 to 1977 and 8 7 and 10 6 respectively from 1977 to 2003 the volume of the akshiirak glaciers was reduced by 3 566 km 3 from 1943 to 1977 and 6 145 km 3 from 1977 to 2000 the total reduction of the tien shan glaciers is 14 2 during the last 60 years 1943 2003 the northern and central tien shan have not experienced a significant precipitation increase during the last 100 years but they have experienced an increase in summer air temperatures especially observable since the 1970s which accelerated the recession of the tien shan glaciers

reduction in soil aggregation in response to dust emission processes abstract dust emission by aeolian wind soil erosion depends on the topsoil properties of the source area especially on the nature of the aggregates where most dust particles are held although the key role of soil aggregates in dust emission the response of soil aggregation to aeolian processes and its implications for dust emission remain unknown this study focuses on aggregate size distribution asd analyses before and after in situ aeolian experiments in semiarid loess soils that are associated with dust emission wind tunnel simulations show that particulate matter pm emission and saltation rates depend on the initial asd and shear velocity under all initial asd conditions the content of saltator sized aggregates 63 250 m increased by 10 34 due to erosion of macro aggregates 500 m resulting in a higher size ratio sr between the saltators and macro aggregates following the aeolian erosion the results revealed that the saltator production increases significantly for soils that are subjected to short term anthropogenic disturbance of the topsoil the findings highlight a decrease in soil aggregation for all initial asd s in response to aeolian erosion and consequently its influence on the dust emission potential changes in asd should be considered as a key parameter in dust emission models of complex surfaces

a hydrologically coupled higher order flow band model of ice dynamics with a coulomb friction sliding law 1 the influence of hydrologic transience and heterogeneity on basal motion is an often neglected aspect of numerical ice flow models we present a flow band model of glacier dynamics with a coulomb friction sliding law that is coupled to a model of the basal drainage system by means of subglacial water pressure the ice flow model contains higher order stress gradients from the stokes flow approximation originally conceived by blatter 1995 the resulting system of nonlinear equations is solved using a modified picard iteration that is shown to improve the rate of convergence a parameterization of lateral shearing is included to account for the effects of three dimensional geometry we find that lateral drag has a discernible effect on glacier speed even when glacier width exceeds glacier length variations in flow band width are shown to have a greater influence on flow line speed than either different valley cross sectional shapes or the presence or absence of glacier sliding along valley walls modeled profiles of subglacial water pressure depart significantly from pressures prescribed as a uniform fraction of overburden thus producing profiles of glacier sliding that are distinctly different from those that would be described by a sliding law controlled by overburden pressures simulations of hydraulically driven glacier acceleration highlight the value of including a representation of basal hydrology in models aiming for improved predictive capability of glacier dynamics

competition between grain growth and grain size reduction in polar ice static or normal grain growth i e grain boundary migration driven solely by grain boundary energy is considered to be an important process in polar ice many ice core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain size reduction by dynamic recrystallization the growth factor k in the normal grain growth law is important for any process where grain growth plays a role and it is normally assumed to be a temperature dependent material property here we show using numerical simulations with the program elle that the factor k also incorporates the effect of the microstructure on grain growth for example a change in grain size distribution from normal to log normal in a thin section is found to correspond to an increase in k by a factor of 3 5

the shallow ice approximation for anisotropic ice formulation and limits ice sheet flow modeling is generally based on the shallow ice approximation sia developed for isotropic ice we extend this approximation to anisotropic ice and check its validity for both the isotropic and anisotropic cases by comparing the results of up to second order sia with those obtained from a model solving the full set of mechanical equations the theory is developed for a constitutive relation describing newtonian and non newtonian behavior but numerical results are shown only for a newtonian behavior the results are compared for plane flow of isothermal ice under steady state conditions sia gives an excellent representation of the newtonian flow of an isotropic ice sheet and a good description for the anisotropic case the zero order approximation is sufficient to describe ice flow precisely over flat bedrock for the anisotropic and isotropic cases even close to an ice divide for uneven bedrock the second order sia gives excellent results for isotropic ice and acceptable results for anisotropic ice finally we quantify the error introduced by using an enhancement factor to represent the anisotropy when longitudinal stresses are taken into account

alpine tectonics of the pannonian basin the neogene evolution of the pannonian basin is fairly well understood in terms of back arc extension behind the carpathian thrust fold belt this middle miocene holocene basin however is superimposed on an earlier middle eocene early miocene basin traditionally called the paleogene basin of hungary although the paleogene stratigraphy of the basin is well known its structural evolution is not clear however a transtensional origin is assumed analogous to the overlying pannonian basin the existing data set on the paleogene basin can be integrated easily into a compressional basin model other intra carpathian paleogene basins such as the transylvanian and slovenian basins are now considered to be flexural in origin systematic interpretation of reflection seismic data shows that these tertiary basins are superimposed on a cretaceous alpine thrust fold belt the internal geometry of this belt in the basement of the pannonian basin indicates a close relationship to the surrounding mountain belts alps carpathians and dinarides whereas the neogene pannonian basin is in a mature stage of exploration the underlying paleogene flexural basins are much less explored furthermore the cretaceous thrust fold belts should be regarded as frontier areas for future oil and gas exploration efforts

towards a mechanical model for the formation of the pannonian basin abstract new maps showing crustal and lithospheric thickness variations in the pannonian basin and the surrounding east alpine carpathian and dinaric mountains have been prepared on the basis of recent seismic seismologic and electromagnetic data a map presenting miocene faults of regional significance has been also constructed for the same region by using a wealth of recently available national and or more local studies it is suggested that observed crustal and lithospheric structural contrasts have been controlled primarily by neogene kinematic history of the region kinematic history is characterized by the following main patterns 1 1 indentation by adria and large scale backthrusting in the southern alps 2 2 eastward escape and extension of the eastern alps 3 3 extensional collapse in the pannonian basin area 4 4 formation of broad wrench fault systems along strike in the dinarides and southern carpathians and the western carpathians with dextral and sinistral shear respectively 5 5 compression and accretion of the external thrust and fold belt in the eastern carpathians these kinematic patterns are thought to be interrelated and all are manifestations of the late stage evolution of an overthickened orogenic wedge in order to arrive at a better understanding of the mechanism of extension which formed the pannonian basin deep crustal seismic profiles hydrocarbon exploration reflection lines and borehole data have been analyzed in the little hungarian plain this plain represents the transition zone between the alps and the pannonian lowlands and the results are illustrated by eight interpreted cross sections one result of regional importance is the clear recognition that the transdanubian central range at the southeastern flank of the little hungarian plain is composed of alpine pre senonian thrust sheets this finding marks the end of a century of debate the allochthony of the substrata of the pannonian basin can be now considered proven another result of more general interest is that these cross sections document the mode of lithospheric extension preexisting compressional detachment planes reactivate as low angle normal faults and lead to tectonic unroofing of deeply buried metamorphic terranes characterized by ductile flow along subhorizontal lineation

transient glacier response with a higher order numerical ice flow model in this paper a higher order numerical flowline model is presented which is numerically stable and fast and can cope with very small horizontal grid sizes 10 m the model is compared with the results from blatter and others 1998 on haut glacier d arolla switzerland and with the european ice sheet modelling initiative benchmarks huybrechts and others 1996 results demonstrate that the significant difference between calculated basal drag and driving stress profiles in a fixed geometry disappears when the glacier profile is allowed to react to the surface mass balance conditions and reaches a steady state dynamic experiments show that the mass transfer in higher order models occurs at a different speed in the accumulation and ablation areas and that the front position is more sensitive to migration compared to the shallow ice approximation

large scale ice flow over a viscous basal sediment theory and application to ice stream b antarctica recent seismic studies of ice stream b antarctica and field analysis of mid latitude glacial deposits suggest that deformable basal sediments e g water saturated till are important in determining ice sheet flow if the ratio of till viscosity to effective ice viscosity is small vertical shear associated with horizontal flow is confined to the deforming bed alone ice flow over a deformable bed is thus akin to that of floating ice shelves because ice shelves flow over inviscid seawater for some antarctic ice streams and possibly for portions of the late wisconsin ice sheets in north america and eurasia basal drag associated with deforming basal sediment does not induce significant vertical gradients of horizontal velocity instead basal drag affects the flow as if it were a horizontal body force balanced by longitudinal and transverse deviatoric stress gradients comparison of the observed flow of ice stream b to finite element simulations incorporating a viscous basal till suggest that a simple till theology is sufficient to explain the current velocity profile these simulations also highlight the importance of horizontal deviatoric stress in regions where driving stress and basal stress do not locally balance while bed deformation is critical to ice stream existence sensitivity tests suggest that ice shelf back pressure is still a crucial control affecting ice stream response to atmospheric and oceanic climate

geodynamical models of lithospheric deformation rotation and extension of the pannonian basin of central europe article i nfo the two major crustal blocks of the pannonian basin alcapa alpine carpathian pannonian and tisza underwent a complex process of rotation and extension of variable magnitude during the tertiary the northward push of the adriatic block initiated the eastward displacement and rotation of both the alcapa and tisza blocks we have constructed geodynamical models of the rotation and extension of the two pannonian blocks we analyse this process in terms of the competing influences of a ne push by the adriatic block a ne pull from a retreating subduction zone on the eastern carpathians and the internal buoyancy forces arising from crustal thickness variations deformation of the blocks included substantial strike slip movements together with shortening and possible extension across the mid hungarian line which now separates the two domains we use an idealised thin viscous sheet model of the continental lithosphere in which deformation is described by a nonlinear viscous constitutive relationship our approach is based on the finite element method and we consider several distinct models of initial geometry boundary conditions and constitutive parameters rotation and deformation vary across both blocks with anticlockwise rotation occurring in the alcapa plate and clockwise rotation in the tisza block the opposite rotations of the two plates led to nw se convergence in the space between the two intra carpathian terranes subsequently both domains underwent extension dominantly in the ne sw direction extension and internal rotation can be represented using a thin sheet model in which deformation is driven by an east or northeast directed outward traction of order 1 to 3 mpa internal buoyancy forces produced by thick crust from a prior phase of alpine style convergence appear to be a necessary element in the force balance that drives the extension process

an outline of neotectonic structures and morphotectonics of the western and central pannonian basin abstract neotectonic deformation in the western and central part of the pannonian basin was investigated by means of surface and subsurface structural analyses and geomorphologic observations the applied methodology includes the study of outcrops industrial seismic profiles digital elevation models topographic maps and borehole data observations suggest that most of the neotectonic structures in the pannonian basin are related to the inverse reactivation of earlier faults formed mainly during the miocene syn and post rift phases typical structures are folds blind reverse faults and transpressional strike slip faults although normal or oblique normal faults are also present these structures significantly controlled the evolution of landforms and the drainage pattern by inducing surface upwarping and river deflections our analyses do not support the postulated tectonic origin of some landforms particularly that of the radial valley system in the western pannonian basin the most important neotectonic strike slip faults are trending to east northeast and have dextral to sinistral kinematics in the south western and central eastern part of the studied area respectively the suggested along strike change of kinematics within the same shear zones is in agreement with the fan shaped recent stress trajectories and with the present day motion of crustal blocks derived from gps data

glacier and lake variations in the mapam yumco basin western himalaya of the tibetan plateau from 1974 to 2003 using remote sensing and gis technologies

paleogeographic evolution of the late miocene lake pannon in central europe abstract the paleogeographic evolution of lake pannon within the pannonian basin is reconstructed with eight maps ranging from the middle miocene to the early pliocene the maps are based on the distribution of selected biozones and specific fossils and on complementary sedimentological and seismic information our reconstruction shows that the history of lake pannon can be divided into three distinct intervals an initial stage with low water level which resulted in isolation from the sea at about 12 ma and might have led to temporary fragmentation of the lake an interval of gradual transgression lasting until ca 9 5 ma and a long late interval of shrinkage and infilling of sediments that persisted into the early pliocene the deep subbasins of the lake formed during the transgressive interval in more basinward locations than the deep basins of the preceding sarmatian age the southern shoreline running parallel with the sava and danube rivers along the northern foot of the dinarides changed very little during the lifetime of the lake while the northern shoreline underwent profound changes

estimation of glacier runoff and future trends in the yangtze river source region china glacier runoff from the yangtze river source region yrsr china is estimated for the period 1961 2000 using a degree day approach in the investigation area glacier runoff accounts for 11 0 of the total river runoff during the period 1961 2000 in the 1990s its contribution to river runoff rises to 17 0 due to the current rate of glacier decline the impact of glacier runoff on river runoff has recently increased in the source region based on two different climate change scenarios derived from echam5 mpi om future glacier runoff is assessed for the period 2001 50 in all climate change scenarios annual glacier runoff shows a significant increase due to intensified ice melting there is an increase in glacier runoff during spring and early summer yet a significant decrease in late summer this study highlights the current and future impact of glacier runoff on river runoff in the yrsr

englacial drainage systems formed by hydrologically driven crevasse propagation recent work has shown that surface to bed drainage systems re form annually on parts of the greenland ice sheet and some high arctic glaciers leading to speed up events soon after the onset of summer melt surface observations and geophysical data indicate that such systems form by hydrologically driven fracture propagation herein referred to as hydrofracturing although little is known about their characteristics using speleological techniques we have explored and surveyed englacial drainage systems formed by hydrofracturing in glaciers in svalbard nepal and alaska in hansbreen svalbard vertical shafts were followed through 60 m of cold ice and 10 m of temperate basal ice to a subglacial conduit deep hydrofracturing occurred at this site due to a combination of extensional ice flow and abundant surface meltwater at a glacier confluence the englacial drainage systems in khumbu glacier nepal and matanuska glacier alaska usa formed in areas of longitudinal compression and transverse extension and consist of vertical slots that plunge down glacier at angles of 558 or less the occurrence of englacial drainages initiated by hydrofracturing in diverse glaciological regimes suggests that it is a very widespread process and that surface to bed drainage can occur wherever high meltwater supply coincides with ice subjected to sufficiently large tensile stresses

the link between tectonics and sedimentation in back arc basins new genetic constraints from the analysis of the pannonian basin the architecture of sedimentary basins reflects the relationship between accommodation space and sediment supply their rates and localization being variable during basin evolution the mechanisms driving the interplay between tectonics and sedimentation in extensional back arc basins overlying rheological weak zones inherited from an earlier orogenic evolution are less understood a typical example is the pannonian back arc basin of central europe it is floored by continental lithosphere and was affected by large amounts of extension driven by the subduction rollback that took place in the carpathians and or dinarides a novel kinematic and seismic sequence stratigraphic interpretation calibrated by wells allows the quantification of the link between the formation of half grabens and coeval sedimentation in the great hungarian plain part of the basin while the lower order tectonic induced cycles characterize the main phases of extension in various subbasins the higher order cyclicity and associated unconformities define individual moments of fault re activation our novel interpretation of a temporal and spatial migration of extension during miocene times explains the contrasting present day strike of various subbasins as a result of their gradual clockwise rotation incorporating the observed asymmetry in particular the associated footwall exhumation infers that the amount of extension is much larger than previously thought the quantitative link between tectonics and sedimentation has allowed the definition of a novel model of sedimentation in asymmetric basins that can be ported to other natural scenarios of similarly hyperextended back arc basins observed elsewhere

ice sheet modelling at different spatial resolutions focus on the grounding zone a high resolution time dependent two dimensional flowline model was developed which takes into account all relevant stresses i e both shear and longitudinal stresses and which is solved on a fixed finite difference grid special attention was paid to the computational efficiency a comparison is made with a similar model that solves the velocity field according to the shallow ice approximation both models were applied to an east antarctic flowline for which the data on surface and bedrock elevation were sampled at different spatial resolutions the numerical analysis deals with the importance of longitudinal stresses at the ice sheet ice shelf interface at different grid sizes and the importance of basal drag versus driving stress in basal sliding laws at a grid resolution of 5 to 10 km the force balance indicates that all stress components are of equal importance in an area that is larger than the nominal grid size when sliding becomes dominant this transition zone considerably widens furthermore the longitudinal stress deviator is found to vary considerably with depth due to the thermomechanical coupling fpattyn pmg nipr ac jp

characteristics of collisional orogens with low topographic build up an example from the carpathians sequence stratigraphy in the hinterland kinematic analysis of thin skinned thrusting in the foreland and thermochronological tracking of exhumation in the orogenic core are combined to quantify the mechanics of an orogen with low topographic build up the carpathian system demonstrates that collisional deformation can couple and thicken the lower orogenic plate along reverse faults that dip more steeply than the subduction zone defining a foreland coupling type of collision near the surface this is expressed by wide antiforms in the upper plate and the thin skinned orogenic wedge a sequence stratigraphic analysis of the back arc transylvanian basin demonstrates that the sedimentary architecture records orogenic uplift pulses with both short and long wavelengths these correspond to the activation of individual thrust sheets in the thin skinned wedge and to lower plate coupling events respectively

classification of rifted sedimentary basins of the pannonian basin system according to the structural genesis evolutionary history and hydrocarbon maturation zones abstract we apply the concept that sedimentary basins can be classified according to their structural genesis and evolutionary history to the tertiary rifts of the pannonian basin of eastern europe we have approached the classification by breaking the basins down into the cycles or stages that they comprise this approach helps us to understand the basin evolution better and allows us to compare the basins more easily the drivers that define the cycles of basin history are 1 basin forming tectonics 2 sedimentary processes and 3 basin modifying tectonics we link common elements of petroleum systems and plays to these natural cycles or stages in basin evolution to improve the prediction of which plays could be expected to occur in a particular basin or region this concept is constructed through several steps these steps are 1 to identify standard evolutionary patterns related to geodynamic drivers 2 to group the basins with similar tectono stratigraphic evolution and correlate these with petroleum system development 3 to relate basin trap types to basin history and 4 to calculate characteristic hydrocarbon maturation zones by thermal modeling we present an application to the pannonian basin system of eastern europe an area formed by miocene back arc extension and affected by compressional reactivation during its late stage evolution the sub basins of the pannonian basin system appear to have experienced comparable magnitudes of deformation to have developed similar trap types and to have experienced a characteristic hydrocarbon maturation history in a way that supports play prospectivity

glacier retreat as a result of climate warming and increased precipitation in the tarim river basin northwest china the tarim river basin a river system formed by the convergence of nine tributaries is the most heavily glacierized watershed in arid northwest china in the basin there are 11 665 glaciers with a total area of 19 878 km 2 and a volume of 2313 km 3 glaciers in the basin play a significant role in the water resource system it is estimated that they provide about 133 10 8 m 3 of meltwater annually contributing 39 of the total river runoff under the influence of global warming northwest china has experienced a generally warmer and drier climate since the mid 19th century however a so called warm and wet transition has occurred since the late 1980s evidenced by an increase in both precipitation and stream discharge in the xinjiang autonomous region and neighboring regions this paper describes how glaciers in the tarim river basin have responded to such warming and increased precipitation and the impact of these glacier changes we analyzed the variations of more than 3000 glaciers since the 1960s using topographical maps high resolution satellite images and aerial photographs of the river basin our results indicate that glaciers in the basin have been mostly in retreat in the past 40 years and ice wastage has significantly influenced water resources in the tarim river basin estimation by a degree day meltwater model shows the positive anomaly in stream runoff of the tailan river can be partly attributed to the increase in glacier runoff amounting to one third of the stream discharge and a rough estimation using observed average ablation on the termini of 15 glaciers in china verifies that the mass loss calculated by a glacier area volume relation is reasonable 1 study area

a continuous simulation of global ice volume over the past 1 million years with 3 d ice sheet models sea level records show large glacial interglacial changes over the past million years which on these time scales are related to changes of ice volume on land during the pleistocene sea level changes induced by ice volume are largely caused by the waxing and waning of the large ice sheets in the northern hemisphere however the individual contributions of ice in the northern and southern hemisphere are poorly constrained in this study for the first time a fully coupled system of four 3 d ice sheet models is used simulating glaciations on eurasia north america greenland and antarctica the ice sheet models use a combination of the shallow ice and shelf approximations to determine sheet shelf and sliding velocities the framework consists of an inverse forward modelling approach to derive a self consistent record of temperature and ice volume from deep sea benthic 18o data over the past 1 million years a proxy for ice volume and temperature it is shown that for both eustatic sea level and sea water 18o changes the eurasian and north american ice sheets are responsible for the largest part of the variability the combined contribution of the antarctic and greenland ice sheets is about 10 for sea level and about 20 for sea water 18o during glacial maxima however changes in interglacials are mainly caused by melt of the greenland and antarctic ice sheets with an average time lag of 4 kyr between melt and temperature furthermore we have tested the separate response to changes in temperature and sea level for each ice sheet indicating that ice volume can be significantly influenced by changes in eustatic sea level alone hence showing the importance of a simultaneous simulation of all four ice sheets this paper describes the first complete simulation of global ice volume variations over the late pleistocene with the possibility to model changes above and below present day ice volume constrained by observations of benthic 18o proxy data

tertiary paleomagnetic results and structural analysis from the transdanubian range hungary rotational disintegration of the alcapa unit abstract we carried out an integrated paleomagnetic and structural study in the transdanubian range western and central hungary as a result the tertiary tectonic history of this area can be characterized by three events of counterclockwise ccw rotation and four or five phases of brittle deformation the change of the orientation of stress axes between phases is mainly apparent and reflects the rotation of the faults predating a particular rotation event the first two rotation events r1 and r2 were probably governed by the rollback mechanism of the subducting european plate we suggest that these rotations were taking place from 18 17 and 16 14 5 ma respectively i e simultaneously with the rotations of the north hungarian paleogene basin and the main part of the western carpathians however the angle of both rotations was less in the transdanubian range due to increasing distance from the subduction front the differential rotation was accommodated by extensional faulting by formation of a graben system on the other hand the youngest rotation event r3 seems to be connected to the renewed rotation of the adriatic plate around 5 ma our combined data set strongly supports earlier conclusions namely that the different subunits of the eastern alpine western carpathian northern pannonian unit alcapa did not form a rigid unit although they moved in similar manner

a full stokes flow thermo mechanical model for firn and ice applied to the gorshkov crater glacier kamchatka the gorshkov crater glacier at ushkovsky volcano kamchatka is characterized by a large aspect ratio and special thermodynamic conditions at the bedrock caused by a locally enhanced and spatially varying geothermal heat flux furthermore large parts of this glacier consist of firn rather than pure ice which alters the rheological properties such as viscosity and compressibility of the glacier we present a newly developed thermo mechanically coupled three dimensional flow model based on the finite element fe modeling software elmer and apply it to the gorshkov crater glacier by assuming steady state conditions the present day velocity field temperature field basal melting rate and age distribution are simulated we find that flow velocities are generally small 10 s of centimeters per year horizontal and vertical velocities are of comparable magnitude which shows that the shallow ice approximation is not applicable owing to the spatially variable volcanic heat flux the thermal regime at the ice base is cold in the deeper parts of the glacier and temperate in the shallower parts the measured temperature profile and age horizons at the k2 borehole are reproduced quite well and remaining discrepancies may be attributed to transient non steady state conditions firn compressibility is identified as a crucial element for the modeling approach

paleogene retroarc flexural basin beneath the neogene pannonian basin a geodynamic model abstract the neogene middle miocene recent pannonian basin is superimposed on an earlier paleogene middle eocene early miocene basin complex as a result of back arc extension although the stratigraphy of the latter is very well known due to raw material exploration its formation and structural evolution is much less understood a transtensional origin was generally proposed for the paleogene basin of hungary assuming an origin analogous to that of the overlying neogene pannonian basin we suggest an alternative geodynamic scenario for the development of the paleogene basin complex as we think that the observations are better understood in terms of a retroarc foredeep basin model according to this a flexural basin developed south of the backthrust inner west carpathian units the thrust load resulted in a generally deep underfilled flysch basin during middle eocene early oligocene times in the late oligocene early miocene predominantly shallow marine and continental deposition occurred indicating the gradual cessation of thrusting in the adjacent thrust fold belt and the beginning of molasse sedimentation throughout the whole paleogene a shift can be observed of the bathyal dominantly siliciclastic in the axis of the foredeep and neritic partly carbonate in the foreland flank of the foredeep facies belts this migration of the middle eocene early miocene depocenters of the hpb hungarian paleogene basin to the east northeast in present day coordinates is the result of two processes 1 1 the advancement of backthrusting to the southeast 2 2 along strike shift of thrusting to the northeast while a thin skinned thrust front can be reconstructed for the late eocene buda anticline the diosjeno hurbanovo line is interpreted as the result of a major thick skinned thrusting event at the base of the np24 zone 31 ma the subsidence pattern the distinct depositional environments and the structural observations can be more easily integrated into a flexural basin model than into a wrench basin model based on the flexural basin model of this work the early tertiary western carpathians formed a compressional arc while this arc probably developed above a b subduction zone during the late eocene with a corresponding trench magura a forearc basin central carpathian or podhale and a retroarc flexural basin hungarian paleogene from the early oligocene to the early miocene it was characterized by a subduction with a corresponding peripheral foredeep dukla and silesian and a retroarc flexural basin hungarian paleogene

ongoing tectonic reactivation of the outer carpathians and its impact on the foreland results of borehole breakout measurements in poland abstract the direction of present day maximum horizontal compression shmax tectonic stress was interpreted for 62 wells in poland using the method of borehole breakout analysis of 4 arm and 6 arm dipmeter logs the study area covers complex tectonic junction of the carpathian orogen and its foreland which comprises the east european craton eec divided by the teisseyre tornquist zone ttz from the palaeozoic platform of western poland for this area frequent deviation of the shmax direction from nw se characteristic for the atlantic ridge push has been interpreted in terms of the alcapa tectonic push in the upper silesian segment of the polish outer carpathians poc nne ssw oriented shmax in the accretionary wedge differs significantly from nnw sse shmax in the autochthonous basement the above discrepancy points to uncoupled type of the suture in this segment of the poc in this scenario the alcapa push involves the nappes and is compensated in the top of the basement which is expressed by systematic shmax rotations in the accretionary wedge of the eastern malopolska segment shmax follows the trend perpendicular to the strike of nappes it is in general agreement with nne ssw oriented shmax in the autochthonous basement that also parallels the alcapa push direction similarity in stress orientation between these structural levels implies coupled suture zone in this segment of the poc further to the north alcapa push is transmitted into the foreland plate where it causes n s orientation of shmax as determined for sedimentary cover of the eec within the baltic portion of the eec further shmax rotation towards the intermediate nnw sse position suggests balance between the alcapa push and the ridge push components within the ttz common shmax rotations from n s to nw se indicate structurally controlled accommodation of the alcapa push in the palaeozoic platform of western poland mesozoic complex of the fore sudetic monocline reveals nne ssw directed shmax that differs from nw se oriented shmax in the variscan accretionary wedge here mechanical decoupling along zechstein evaporates is likely presented set of breakout data from poland shows that recent compressive reactivation of the carpathians exerts strong impact on the stress field of the foreland plate at a distance of 700 km from the suture due to this effect the fore carpathian stress domain within the north european stress province can be discriminated

effects of spatially variable accommodation rate on channel belt distribution in an alluvial sequence authigenic 10be 9be based bayesian age depth models applied to the upper miocene volkovce fm northern pannonian basin system slovakia abstract relationships between spatially variable accommodation rate and the distribution of channel belt deposits are important issues in alluvial stratigraphy this segment of sedimentology still records important progress using experimental models and field examples this study focuses on the alluvial stratigraphy of the volkovce fm which was deposited between 9 0 6 0 ma in the northern pannonian basin system and it provides an excellent natural laboratory to study this topic the spatial variability of channel belt distribution was determined in 809 borehole logs drilled to 200 300 m depths while the facies associations were defined on the outcrops a significant variance in channel belt content was observed since it reaches 10 40 of the stratigraphic column in the southwestern part of the study area and only 0 15 in the northeastern portion moreover the transition between the areas of different channel belt distribution is oriented perpendicular to the paleo drainage network axis geochronology was then established by applying the authigenic 10be 9be dating method to three borehole cores the bayesian age depth models used herein proved a decrease in average accommodation rates from 200 m myr to 50 m myr towards the area with

phases of compression during the evolution of the pannonian basin and its bearing on hydrocarbon exploration abstract progress in understanding the structural evolution of the pannonian basin is reported this has been driven by the application of seismic stratigraphy constrained by magnetostratigraphic data and the recent release of a great amount of hydrocarbon exploration data this has led to a redefinition and better understanding of the syn rift period and style of rifting in addition a complex structural evolution history during the post rift phase has been recognized two compressive events are defined one in the early stage and another in the late stage of evolution the importance of these findings for hydrocarbon exploration includes an improved knowledge of the timing of trap formations and a possible explanation for remarkably variable reservoir pressures in pools of the great hungarian plain

glacier changes from a new inventory nianchu river basin tibetan plateau the ice cover of the nianchu river basin southern tibetan plateau was mapped for 2005 using a spot5 scene and for 1990 and 2000 from landsat tm etm digital elevation models dems were generated from 1 50 000 scale topographical maps the results show that in 2005 there were 136 glaciers in this basin with a total area of 224 km 2 of these 37 glaciers had an area 1 km 2 and 10 were larger than 5 km 2 the average snout altitude was 5608 m a s l a comparison of outlines from the last 15 years shows that most glaciers have decreased in size none have advanced from 1990 to 2005 xiaquepu glacier no 56 and shimozongpu glacier no 38 retreated 310 and 560 m respectively the mean reduction in glacier surface area was 5 10 a 1 while the area of glacial lakes expanded by 10 nine new lakes formed in this basin over the 15 year period because air temperatures here have been increasing while precipitation has remained steady glacier retreat is considered to be related to rising temperature

sensitivity of greenland ice sheet projections to model formulations physically based projections of the greenland ice sheet contribution to future sea level change are subject to uncertainties of the atmospheric and oceanic climatic forcing and to the formulations within the ice flow model itself here a higher order three dimensional thermomechanical ice flow model is used initialized to the present day geometry the forcing comes from a high resolution regional climate model and from a flowline model applied to four individual marine terminated glaciers and results are subsequently extended to the entire ice sheet the experiments span the next 200 years and consider climate scenario sres a1b the surface mass balance smb scheme is taken either from a regional climate model or from a positive degree day pdd model using temperature and precipitation anomalies from the underlying climate models our model results show that outlet glacier dynamics only account for 6 18 of the sea level contribution after 200 years confirming earlier findings that stress the dominant effect of smb changes furthermore interaction between smb and ice discharge limits the importance of outlet glacier dynamics with increasing atmospheric forcing forcing from the regional climate model produces a 14 31 higher sea level contribution compared to a pdd model run with the same parameters as for ipcc ar4

birth life and death of the pannonian lake abstract the miocene pliocene pannonian lake formed in an extensional basin system behind the compressional arc of the carpathians its size and depth were comparable to those of the caspian sea subsidence began in middle miocene times forming deep pelagic basins separated by reef bearing ridges clastic influx filled the marginal basins during middle miocene time prograding deltas dissected the lake and completed the infilling of the basin system by the end of the pliocene basin plain prodelta delta front delta plain beach fluviatile and marsh environments can be recognized terminal miocene uplift of the carpathians isolated the pannonian region from the rest of paratethys the subsequent decrease of salinity resulted in the evolution of an endemic freshwater mollusc fauna rich nutrient influx from rivers supported high organic productivity dinoflagellates diatoms nannoplankton foraminifers ostracods etc yielding organic rich sediments preservation of organic matter was helped by a stratified water column and oxygen deficient bottom conditions deep burial continuing subsidence and high geothermal flux due to an extremely thin crust led to the formation of commercially exploitable oil and gas accumulations shallow lacustrine zones of basin margins provided suitable environments for a rich congeria melanopsis mollusc fauna wave action on beaches produced commercially exploitable pure quartz sand deposits taxodium and alnus forests flourished around the lake producing enormous lignite deposits besides a rich land snail and mammal fauna prehominids lived in the forests there was a warm temperate climate with probably frostfree winters basaltic volcanoes overlooked the landscape and maars hosted minor lakes with rich algal flora forming oil shale the catchment area included most of the carpathians and parts of the apls and dinarides the positive water balance resulted in a supposed overflow in the southern margin supplying exotic fauna to the south carpathian and dacian basins of the eastern paratethys the pannonian lake was completely filled by the end of pliocene recent lakes in the carpathian basin are not descendants of it

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

in the wake of a counterclockwise rotating adriatic microplate neogene paleomagnetic results from northern croatia in northern croatia the neogene sediments cover complicated basement rocks which consist of alpine and dinaridic elements in the zagorje area and variscan alpine formations of the tisia tisza megatectonic unit in the slavonian mountains mts the neogene sediments were deposited in two separate basins before the karpatian but sedimentation became uniform from the karpatian onwards 17 5 ma of the 24 localities that we have studied so far paleomagnetically from northern croatia 16 localities are of karpatian or younger age while the rest are pre karpatian

velocity and stress fields in grounded glaciers a simple algorithm for including deviatoric stress gradients a new and efficient algorithm for computing the three dimensional stress and velocity fields in grounded glaciers includes the role of deviatoric stress gradients a consistent approximation of first order in the aspect of ratio of the ice mass gives a set of eight field equations for the five stress and three velocity components and the corresponding boundary conditions a coordinate transformation mapping the local ice thickness on to unity and approximating the derivatives in the horizontal direction by centred finite differences yields five ordinary differential and three algebraic equations this allows use of the method of lines starting the integration with prescribed stress and velocity components at the base and a simple iteration procedure converges rapidly the algorithm can lie used for a wide range of stress strain rate relations as long as strain only depends on deviatoric and shear stresses and on temperature sensitivity tests using synthetic and realistic ice geometries show the relevance of normal deviatoric stresses in the solutions for the velocity components even for ice sheets stress and velocity fields may deviate substantially from the widely used shallow ice approximation

neogene exhumation in the outer western carpathians terra nova 23 283 291 2011 abstract apatite fission track analysis was used to investigate the cenozoic tectonic evolution of the polish sector of the outer western carpathians where thrusting was overlapped by extension in the last 10 ma the results show a general decrease of burial degree towards the european foreland and a range of cooling ages between 26 and 7 ma younger ages 10 7 ma are confined to the eastern region whereas exhumation in the central western region is about 10 ma older and is characterized by no major age differences among structural units therefore exhumation of the chain is inferred to have occurred since the early miocene when it appears to have been essentially coeval with thrusting whereas extensional tectonics is likely to have played an important role during late miocene exhumation

seasonal variability in the dynamics of marine terminating outlet glaciers in greenland recent studies indicate that the dynamics of fast flowing marine terminating outlet glaciers of the greenland ice sheet may be sensitive to climate and ocean forcing on sub annual timescales observations of seasonal behavior of these glaciers at such high temporal resolution however are currently few here we present observations of front position flow speed near surface air temperature and ocean conditions for six large marine terminating glaciers in the uummannaq region of west greenland to investigate controls on short term glacier dynamics as proposed by other studies we find that seasonal front advance and retreat correlates with the formation and disappearance of an ice melange our data suggest that high sea surface temperature anomalously low sea ice concentration and reduced melange formation in early 2003 have triggered multi year retreat of several glaciers in the study area which is consistent with other regions in greenland of the stable glaciers only rink isbrae exhibits a seasonal speed variation that correlates with variations in front position with the others undergoing mid summer deceleration that indicates the effects of subglacial meltwater discharge and drainage system evolution drainage of supraglacial lakes and water filled crevasses results in substantial decreases in speed 40 60 on fast flowing glaciers our results demonstrate that attempts to model ice sheet evolution must take into account short timescale flow dynamics resulting from drainage events and oceanographic conditions

evolution of the stress fields in the carpatho pannonian area during the neogene abstract observations of microtectonic faults in and around the pannonian basin suggest that the tertiary evolution of the area was controlled by large scale strike slip fault activity statistical analysis of the fault pattern for different localities makes it possible to separate several conjugate sets of strike slip faults and related dilatational and compressive structures these stress fields have a distinct rotation pattern with time inversion of fault data suggests a characteristic rotation of the principal stress axes with time some rigid body rotations are indicated by paleomagnetic data there are basically three contrasting mechanisms to explain this observation 1 1 appropriate rotation of the regional e g european stress field 2 2 rotation of larger tectonic units e g microcontinents under a stable regional stress field and 3 3 coherent rotation of smaller detached continental blocks under a stable regional stress field our model for the neogene tectonic evolution of the pannonian area combines these mechanisms moderate microcontinent rotation may have occurred during the paleogene early miocene in the early middle miocene the microcontinents were dissected by a system of strike slip and normal faults created by a n s compressive e w extensive stress field gravity spreading of the pannonian units and block rotation within bounding strike slip faults are suggested to explain rotated magnetic directions and fault patterns in the late neogene clockwise rotation of the general stress field by at least 40 is thought to be responsible for the reactivations of older strike slip faults and for the creation of new sets this change in the orientation of the stress field is related to the eastward and then southward shift of the carpathian subduction activity

a three dimensional climate ice sheet model applied to the last glacial maximum a quasi three dimensional climate model sellers 1983 was used to simulate the climate of the last glacial maximum in order to provide climatic input forthe modelling of the northern hemisphere ice sheets the climate model is basically a coarse gridded gcm with simplified dynamics and was subject toappropriate boundary conditions for ice sheet elevation atmospheric co2 concentration and orbital parameters when compared with the present daysimulation the simulated climate at the last glacial maximum is characterized by a global annual cooling of 3 5deg c and a reduction in global annualprecipitation of 7 5 which agrees well with results from other more complex gcm s also the patterns of temperature change compare fairly with mostother gcm results except for a smaller cooling over the north atlantic and the larger cooling predicted for the summer rather than for the winter overeurasia the climate model is able to simulate changes in northern hemisphere tropospheric circulation yielding enhanced westerlies in the vicinity of thelaurentide and eurasian ice sheets however the simulated precipitation patterns are less convincing and show a distinct mean precipitation increase over thelaurentide ice sheet nevertheless when using the mean monthly fields of lgm minus present day anomalies of temperature and precipitation rate to drive athree dimensional thermomechanical ice sheet model it was demonstrated that within realistic bounds of the ice flow and mass balance parameters veryreasonable reconstructions of the last glacial maximum ice sheets could be obtained

on the formation and evolution of the pannonian basin constraints derived from the structure of the junction area between the carpathians and dinarides 1 the large number and distribution of rollback systems in mediterranean orogens infer the possibility of interacting extensional back arc deformation driven by different slabs the formation of the pannonian back arc basin is generally related to the rapid miocene rollback of a slab attached to the european continent a key area of the entire system that is neglected by kinematic studies is the connection between the south carpathians and dinarides in order to derive an evolutionary model we interpreted regional seismic lines traversing the entire serbian part of the pannonian basin the observed deformation is dominantly expressed by the formation of miocene extensional detachments and half grabens the extensional geometries and associated synkinematic sedimentation that migrated in time and space allow the definition of a continuous and essentially asymmetric early to late miocene extensional evolution this evolution was followed by the formation of few uplifted areas during the subsequent latest miocene quaternary inversion the present day extensional geometry changing the strike across the basin is an effect of the clockwise rotation of the south carpathians and apuseni mountains in respect to the dinarides our study infers that the carpathian rollback is not the only mechanism responsible for the formation of the pannonian basin an additional middle miocene rollback of a dinaridic slab is required to explain the observed structures furthermore the study provides constraints for the pre neogene orogenic evolution of this junction zone including the affinity of major crustal blocks obducted ophiolitic sequences and the sava suture zone

latest pannonian and quaternary evolution at the transition between eastern alps and pannonian basin new insights from geophysical sedimentological and geochronological data the transition zone between eastern alps and pannonian basin is a key area for the investigation of the interplay between regional uplift local tectonic subsidence and depositional environment our study area the western margin of the little hungarian plain is characterized by gentle hills plateaus and depressions of which several are filled by lakes including one of austria s largest and shallowest lakes lake neusiedl geological investigation is hampered by the scarcity of outcrops and thus direct observation of sedimentological or structural features is difficult despite a long research history in the area a consistent landscape evolution model considering all relevant constraints is lacking so far in this study we apply multidisciplinary methods to decipher the complex tectonic and fluvial depositional evolution of the region local data from shallow lake drilling and seismic investigation are combined with regional data from industrial seismics and core data to gain new insights into the latest pannonian late miocene and quaternary evolution shallow lake seismic data show the erosionally truncated pannonian sediments dipping and thickening toward southeast toward the modern depocenter of the little hungarian plain overlying quaternary fluvial sediments show a very similar thickening trend except for the area on the plateau north of the lake indicating ongoing subsidence in major parts of the basin drill cores from locations along the lake seismic lines were analyzed concerning their age mineralogy and heavy minerals and compared with outcrop samples from the surrounding plains and the plateau to derive indications on sediment provenance a key observation is the apparent lack of a significant gravel layer on top of the tilted pannonian sediments beneath lake neusiedl small scale faults can be observed in the lake seismic sections along with key sedimentary features significant differences of the current elevation of the top pannonian between the surrounding plains and the plateau indicate post pannonian normal faulting which is a key process in shaping the present day morphology of the region luminescence ages of samples from the quaternary fluvial gravels on top of the pannonian sediments are a significantly higher 300 ka compared to the gravels in the plain 102 11 and 76 8 ka suggesting ongoing tectonic subsidence

modelling west antarctic ice sheet growth and collapse through the past five million years changes in earth s orbit are known to influence climate shifts from cold glacials to warm interglacials how the vast west antarctic ice sheet responds to these fluctuations is uncertain but because its collapse could raise sea levels by about 5 metres of great interest naish et al have analysed the and 1b ocean sediment core extracted from beneath the ross ice shelf as part of the andrill drilling project and find evidence that the ice sheet collapsed periodically during the early pliocene 3 5 million years ago when atmospheric co2 levels were similar to or slightly higher than today s the pattern of collapse suggests an influence of approximately 40 000 year cycles in the tilt of earth s rotational axis obliquity also in this issue of nature in a numerical modelling study focused on the past 5 million years in antarctica david pollard and robert deconto combine ice sheet land supported and ice shelf water supported modelling approaches to simulate the movement of the grounding line the border between land and sea ice their results show that over the past 5 million years the west antarctic ice sheet transitioned between full intermediate and collapsed states in just a few thousand years this means that the ice sheet is likely to disintegrate if ocean temperatures in the area rise by 5 c if the west antarctic ice sheet wais melted sea levels would rise by about 5 m such changes are thought to have occurred in the past but could not be simulated by models pollard and deconto combine ice sheet with ice shelf modelling and show that over the past 5 million years the wais transitioned among full intermediate and collapsed states in only a few thousand years suggesting possible disintegration of the wais if ocean temperatures in the area rise by 5 c the west antarctic ice sheet wais with ice volume equivalent to 5 m of sea level1 has long been considered capable of past and future catastrophic collapse2 3 4 today the ice sheet is fringed by vulnerable floating ice shelves that buttress the fast flow of inland ice streams grounding lines are several hundred metres below sea level and the bed deepens upstream raising the prospect of runaway retreat3 5 projections of future wais behaviour have been hampered by limited understanding of past variations and their underlying forcing mechanisms6 7 its variation since the last glacial maximum is best known with grounding lines advancing to the continental shelf edges around 15 kyr ago before retreating to near modern locations by 3 kyr ago8 prior collapses during the warmth of the early pliocene epoch9 and some pleistocene interglacials have been suggested indirectly from records of sea level and deep sea core isotopes and by the discovery of open ocean diatoms in subglacial sediments10 until now11 however little direct evidence of such behaviour has been available here we use a combined ice sheet ice shelf model12 capable of high resolution nesting with a new treatment of grounding line dynamics and ice shelf buttressing5 to simulate antarctic ice sheet variations over the past five million years modelled wais variations range from full glacial extents with grounding lines near the continental shelf break intermediate states similar to modern and brief but dramatic retreats leaving only small isolated ice caps on west antarctic islands transitions between glacial intermediate and collapsed states are relatively rapid taking one to several thousand years our simulation is in good agreement with a new sediment record andrill and 1b recovered from the western ross sea11 indicating a long term trend from more frequently collapsed to more glaciated states dominant 40 kyr cyclicity in the pliocene and major retreats at marine isotope stage 31 1 07 myr ago and other super interglacials

styles of extension in the pannonian basin abstract structural interpretation of reflection seismic profiles reveals distinct modes of upper crustal extension in the pannonian basin while some subbasins in the pannonian basin complex show little extension planar rotational normal faults others are characterized by large magnitude of extension detachment faults metamorphic core complexes gravitational collapse of the intra carpathian domain combined with subduction zone roll back is thought to be the driving mechanism of the neogene back arc extension the very heterogeneously distributed extension is accommodated by transfer faults which bound regions characterized by different polarity direction or amount of extension in cross section these transfer faults are characterized by flower structures typical for strike slip faults seismic stratigraphic interpretations indicate that the non marine post rift sedimentary fill of the pannonian basin can be described in terms of sequence stratigraphy the exceptionally good seismic sequence resolution allows recognition of third order and also fourth order depositional sequences which may reflect the interplay of tectonics and eustasy and milankovitch scale climatic variations respectively

subglacial modulation of the hydrograph from glacierized basins the extent of basin glacierization has important implications for the hydrograph in part because snow firn and ice impart different delays in water transport through the system here the significance of subglacial drainage morphology in modulating the hydrograph is examined with a one dimensional physically based model the conceptual model of subglacial drainage comprises both fast and slow elements respectively associated with summer and winter drainage regimes the additional possibility of a permeable glacier substrate is taken into account by allowing water transport in a subglacial aquifer forced by prescribed rates of melt water delivery to the glacier bed the model predicts glacier discharge by drainage system provenance the effects of 1 hard versus soft glacier beds 2 subsurface permeability and groundwater flow and 3 glacier geometry are then investigated hydrograph character in the form of peak timing and amplitude symmetry with respect to the forcing and the amplitude of diurnal fluctuations is affected by the partitioning of water through the various flow elements hard beds and impermeable substrates maximize the discharge routed through the fast drainage system in the simulations generally resulting in higher seasonal discharge maxima and stronger diurnal variations in discharge high hydraulic transmissivities either at the glacier bed or in underlying strata hinder the development of the fast drainage system in the simulations producing hydrographs of lower amplitude glacier geometry has a modest effect with adverse bed slopes very thick or very thin ice and short glacier lengths favouring prolonged drainage through the slow system these results suggest that the morphology and evolution of the subglacial drainage system may play a significant role in determining the character of the hydrograph from glacierized basins

neogene sequences in the pannonian basin hungary abstract the rifting in the extensional pannonian basin occurred in the middle miocene the subbasins within the pannonian system formed under the control of expansional tectonics during this time sequence stratigraphic analysis on well logs revealed a single third order synrift sedimentary sequence developed due to tectonically enhanced eustatic sea level change in shallow marine environments the pannonian basin became an isolated lake by its postrift phase during the middle late miocene boundary the first postrift sequence formed under peculiar conditions when the basin lost its marine connections and simultaneously a considerable differential subsidence began the large volume of freshwater input supplied by rivers and the rapid subsidence of the basement caused the basin to be a deep freshwater lake the lacustrine postrift infill was studied by sequence stratigraphy using seismic reflection well log and magnetostratigraphic data numerous unconformities can be revealed which represent relative lake level fluctuations of different magnitudes the water level and volume of the large inland lake was very sensitive to different effects the most important ones are lake water budget sediment influx and differential subsidence of the basement the style of extension and sedimentation show differences with respect to passive continental margins that are reflected in the sedimentary architecture a significant third order water level change has been discovered in the eastern part of the pannonian basin while the western side did not experience such a great change in lake level this fact gives credit to the view of different interplay of lake level influencing effects in different areas of the basin this major third order lake level change has been age dated using magnetostratigraphy and a very close match was found with the age of the mediterranean salinity crisis the pannonian basin offers the possibility to study the infilling style and stratigraphic evolution of an inland rifted basin detailed sequence analysis allows the recording of the apparent sea lake level motion which can be compared to those observed in the surrounding seas further tectono stratigraphic evaluations of the pannonian basin may reveal hidden facts on the nature of lake level fluctuations and contribute new data to the discipline of sequence stratigraphy

third order middle miocene early pliocene depositional sequences in the prograding delta complex of the pannonian basin abstract few studies exist in the geologic literature that show the distribution of seismic facies and depositional sequences within a lacustrine basin the pannonian basin of central europe offers a unique opportunity to evaluate the influence of the eustatic signal on lacustrine deposition seismic stratigraphie and sedimentological studies indicate that the middle miocene early pliocene infill of the transtensional pannonian basin was formed by large delta systems systematic sequence stratigraphie analysis of 6000 km of reflection seismic data and more than 100 hydrocarbon exploration wells in hungary allowed the identification of twelve third order sequence boundaries in the late neogene sedimentary fill this number of depositional sequences corresponds to that of the published global eustatic curve for this time period furthermore based on magnetostratigraphic and radiometric data the ages of these depositional sequences can be tentatively correlated with the global eustatic curve the pannonian basin became isolated from the world sea at the sarmatian pannonian 11 5 ma boundary and formed a large lake the stratal patterns and sedimentary facies of individual systems tracts within the lacustrine sequences display the same characteristics as marine depositional sequences the relatively low rate of thermal subsidence and the high rate of sediment supply resulted in a good sequence resolution within the third order sequences higher order sequences can be recognized with an average duration of about 0 1 0 5 ma

post rift compressional reactivation potential of passive margins and extensional basins poly phase deformation of a compressional nature is a common feature in the post rift evolution of passive margins and rifts the compressional mode of deformation in these sedimentary basins originally formed by extension in an intraplate setting is characterized by a spectrum of spatial wavelengths spanning several tens of kilometres up to several hundreds of kilometres the actual mode of compressional deformation appears to be strongly affected by the rheological structure of the underlying lithosphere the level of the regional intraplate stress field and the geometry of the rifted basin configuration prior to late stage compressional reactivation the interplay of plumes and intraplate compressional deformation can lead to temporal transitions from basin inversion to lithospheric folding these modes of deformation lead to substantial differential vertical motions late stage anomalies in subsidence and uplift patterns the development of innovative combinations of numerical and analogue modelling techniques is the key to differentiating different modes of compressional deformation of passive margins and extensional basins the geological society of london 2008

numerical simulation of the flow velocity and temperature of the dongkemadi glacier the flow velocity and ice temperature of a glacier reflect the response of the glacier to climate change however because of the restrictions of observation conditions it is often difficult to acquire the ice velocity and temperature field for the entire glacier profile in this study we use a two dimensional ice flow model and energy balance model to simulate the ice velocity and temperature using field measurements made with ground penetrating radar for the profile of the small dongkemadi glacier and verify the simulated surface velocity with interferometric synthetic aperture radar data the simulation for the flow velocity shows that the velocity depends on the surface and bedrock slopes glacier profile shape and mass supply way and the surface velocity increases with an increase in the surface slope sensitivity analysis shows that the terrain and slope affect the profile velocity simulation results for temperature show that the ice body temperature is highest in the lower ice body at a subglacial position altitude of 5520 m a s l this location not only gathers melt water most easily but also undergoes the strongest effect of geothermal heat flow the distributions of the ice velocity and ice body temperature provide a good reference for research on glacier vulnerability assessment and the response of glaciers to climate change

connected fluid evolution in fractured crystalline basement and overlying sediments pannonian basin se hungary abstract uplifted crystalline basement highs have played an important role in the hydrologic history of the pannonian basin providing conduits for fluid migration during basin evolution petrographic stable isotope electron microprobe and fluid inclusion studies support a five step basin evolution 1 formation of crystalline core complexes 2 percolation of meteoric water through shear zones 3 basinwide thermal subsidence 4 hydrologic inversion and 5 tectonic inversion brittle fractures in the basement are the results of uplift during core complex formation and contain pyrite kaolin illite chlorite calcite and quartz hydrocarbon stains between calcite and quartz and yellow fluorescent primary hydrocarbon inclusions in quartz are indicative of migrations of hydrocarbon bearing fluids during uplift from mid crustal depth further uplift was associated with meteoric water infiltration along shear zones as recorded by light 13 c and 18 o values low trace element concentrations all liquid primary fluid inclusions and encased pollens and cuticules of terrestrial plants in a second fracture calcite crystallised after quartz a simultaneous meteoric influence in the overlying pannonian 12 7 3 ma sediments is indicated by extensive plagioclase dissolution calcite cement geochemistry and low salinity all liquid fluid inclusions the thermal subsidence of the basin led to isolation of the hydrologic system from the surface diminishing meteoric influence is recorded by increasing fluid inclusion salinities of secondary inclusions in calcite and quartz in the basement fractures and of primary inclusions hosted in late calcite and quartz in the sediments a sudden decrease of the fluid inclusion salinities from 4 5 to 1 wt nacl eq at 130 c both in burial cements and fracture filling minerals represents a newly established hydrological system which redistributed the interstitial fluids including hydrocarbons this hydraulic inversion is indicated by abundant fluorescent secondary fluid inclusions in fracture filling minerals finally the pliocene to recent tectonic inversion reopened fractures in the crystalline basement and induced a rapid crystallisation of laumontite these results support a long standing late miocene to recent hydraulic connection between fractured crystalline basement and overlying sediments in the central part of the pannonian basin

sedimentology stratigraphy and glacier dynamics western scottish highlands glacial sediments of the western scottish highlands are comprehensively described and characterized here for the first time enabling the first glacial stratigraphy for the area to be proposed this classification is based on the results of extensive geological mapping and field investigation of sedimentary sequences and their structures x ray diffraction and particle size distribution analyses and comparison with deposits formed in contemporary glaciated environments these new data are subsequently appraised in terms of their implications for late pleistocene glacier evolution and dynamics together the data suggest that much of the landscape is palimpsest and can be attributed to the weichselian late devensian glaciation subsequent glacier advance during the younger dryas did little to modify the area suggesting that ice flow was dominated by sliding on a meltwater lubricated rigid bed with deformation of basal sediments playing a more limited role final deglaciation was marked by a significant increase in basal meltwater flux reflecting the warming climate and increasing precipitation these new palaeoglaciological and palaeoenvironmental insights advance our understanding of former glacier dynamics in the western scottish highlands improve our knowledge of pleistocene landscape evolution of this area and enable comparisons to be made with sedimentary sequences elsewhere