decoupled flexure in the south pyrenean foreland complex subsidence patterns during the mid late eocene of the easternmost south pyrenean foreland are well explained by a decoupled flexure model in which upper crustal buckling is accommodated by ductile flow in the mid lower crust while simultaneously and independently the lower lithosphere flexes above a ductile asthenosphere the resulting predicted subsidence values agree with observation to well within the estimated uncertainties the resulting lithospheric effective elastic thickness eet estimate 10 3 km is low but similar to values obtained in the south pyrenean foreland by other authors the separate eet obtained for the upper crust 1 5 0 8 km also agrees with tentative values given by other workers

pliocene uplift of the eastern iberian margin inferences from quantitative modelling of the valencia trough we present the results of quantitative modelling of subsidence in the valencia trough and associated uplift in the catalan coastal ranges and the balearic islands basement subsidence moho depth and gravity anomalies are calculated for different effective elastic thicknesses eet and durations of rifting along two profiles constrained by recently collected multichannel seismic and gravity data the tectonic evolution of the catalan coastal ranges cannot be explained with traditional two layer lithospheric stretching models for the valencia trough but is consistent with a thermomechanical model invoking lithospheric necking combined with a late stage uplift event the modelling of the topography of the balearic islands suggests an interaction of extension in the valencia trough with extension in the south balearic basin our study supports a rifting model with low values for the flexural rigidity an intermediate level of necking and one finite duration stretching event propagating from the northeast towards the southwestern part of the valencia trough the modelling provides constraints on the magnitude of a large scale pliocene uplift of the eastern margin of the iberian peninsula

the late spring maximum of rainfall over the u s central plains and the role of the low level jet abstract the seasonal rainfall over the u s central plains features a late spring maximum a spring fall annual mode revealed from the empirical orthogonal function analysis on rainfall delineates a maximum center over the central plains that coincides with the large late spring rainfall this paper examines the large scale dynamical and hydrological processes in forming the rainfall center the ncep department of energy doe reanalysis 2 data reveal that the baroclinic structure of the continental scale circulation during late spring may and june induces a vertically out of phase divergent circulation forming strong convergence of water vapor flux over the central plains such circulation features generate concentrated convective activity in this region the upper level anticyclone development with the north american monsoon in july replaces the late spring baroclinic structure and in turn reduces the convective activity the great plains low level jet llj plays a role in the downscaling process

lacustrine basin dynamics and organosulphur compound origin in a carbonate rich lacustrine system late oligocene mequinenza formation se ebro basin ne spain abstract the late oligocene mequinenza formation se ebro basin ne spain records the development of extensive shallow low gradient lacustrine zones which evolved under a subtropical warm climatic regime affected by humidity aridity cycles carbonate dominated inner lacustrine sequences which include thin coal seams are laterally related to muddy carbonate and siliciclastic marginal lacustrine assemblages where evaporites occur water solute concentration of the lacustrine zones changed during the alternative high and low stand episodes with lacustrine waters ranging mainly from fresh to oligosaline nonsulphurised nsc and sulphurised osc organic compounds occur in the inner lacustrine facies and record significant contributions from aquatic and terrestrial higher plants bacteria cyanobacteria photosynthetic anaerobic bacteria and algae these biomarkers show that the lacustrine system was eutrophic and the water column was poorly oxygenated and sometimes stratified as evidenced by occasional finely laminated facies and gammacerane organic matter s c ratio lower in carbonate than in coal and coal related facies suggests significant variations in the lacustrine autotrophic production and or the allochthonous organic matter contribution higher plant biomarkers were recorded mainly as normal nonsulphurised lipids by contrast bacterial and algal lipids hopanoids steroids and isoprenoids under intense sulphate reduction conditions incorporated sulphur in their hydrocarbon skeleton and gave rise to osc with distributions of thienyl and thiolanylhopanoids epithiosteranes and polyprenoids linear thiols are new biomarkers which probably were generated by the early incorporation of sulphur into funtionalised precursors e g alkanols intense methanogenesis was enhanced in some lacustrine zones owing to high organic matter input and as a consequence biomarkers of methanotrophic and methylotrophic bacteria related to methane emission are also found

causes of recent himalayan uplift deduced from deposited patterns in the ganges basin the hypothesis1 that late cenozoic uplift of many of the world s mountain ranges was a response to climate change rather than to tectonic processes is based on the premise that enhanced erosion in an altered climate led to a reduction in both the total mass of a mountain range and its mean elevation this reduction was coeval with increased regional relief and with passive isostatic uplift of the remaining summits the hypothesis is difficult to evaluate because both climate and tectonic forces affect uplift in many active ranges in the absence of sufficient denudational and uplift data from the mountains themselves depositional patterns in adjacent basins may sometimes be used to distinguish between uplift arising from erosional or from tectonic processes in foreland basins uplift of the proximal basin and a reduction or absence of asymmetric subsidence are predicted responses to erosionally driven uplift2 here i show that patterns of sediment accumulation and the position of major rivers in the neogene gangetic foreland basin seem to have changed markedly in plio pleistocene times these changes lend support to the hypothesis that the importance of erosional unloading has increased in the himalayas during the past 4 myr

atmospheric response to zonal variations in midlatitude sst transient and stationary eddies and their feedback midwinter storm track response to zonal variations in midlatitude sea surface temperatures ssts has been investigated using an atmospheric general circulation model under aquaplanet and perpetual january conditions zonal wavenumber 1 sst variations with a meridionally confined structure are placed at various latitudes having these sst variations centered at 308n leads to a zonally localized storm track while the storm track becomes nearly zonally uniform when the same sst forcing is moved farther north at 408 and 508n large small baroclinic energy conversion north of the warm cold sst anomaly near the axis of the storm track near 408n is responsible for the large small storm growth the equatorward transfer of eddy kinetic energy by the ageostrophic motion and the mechanical damping are important to diminish the storm track activity in the zonal direction significant stationary eddies form in the upper troposphere with a ridge trough northeast of the warm cold sst anomaly at 308n heat and vorticity budget analyses indicate that zonally localized condensational heating in the storm track is the major cause for these stationary eddies which in turn exert a positive feedback to maintain the localized storm track by strengthening the vertical shear near the surface these results indicate an active role of synoptic eddies in inducing deep tropospheric scale response to midlatitude sst variations finally the application of the model results to the real atmosphere is discussed

variable winds on venus mapped in three dimensions 1 we present zonal and meridional wind measurements at three altitude levels within the cloud layers of venus from cloud tracking using images taken with the virtis instrument on board venus express at low latitudes zonal winds in the southern hemisphere are nearly constant with latitude with westward velocities of 105 ms 1 at cloud tops altitude 66 km and 60 70 ms 1 at the cloud base altitude 47 km at high latitudes zonal wind speeds decrease linearly with latitude with no detectable vertical wind shear values lower than 15 ms 1 indicating the possibility of a vertically coherent vortex structure meridional winds at the cloud tops are poleward with peak speed of 10 ms 1 at 55 s but below the cloud tops and averaged over the south hemisphere are found to be smaller than 5 ms 1 we also report the detection at subpolar latitudes of wind variability due to the solar tide

south polar features on venus similar to those near the north pole venus has no seasons slow rotation and a very massive atmosphere which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets infrared observations by previous missions to venus revealed a bright dipole feature surrounded by a cold collar at its north pole the polar dipole is a double eye feature at the centre of a vast vortex that rotates around the pole and is possibly associated with rapid downwelling the polar cold collar is a wide shallow river of cold air that circulates around the polar vortex one outstanding question has been whether the global circulation was symmetric such that a dipole feature existed at the south pole here we report observations of venus south polar region where we have seen clouds with morphology much like those around the north pole but rotating somewhat faster than the northern dipole the vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper the spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition

factors controlling late cenozoic continental margin growth from the ebro delta to the western mediterranean deep sea abstract the ebro continental margin sedimentation system originated with a messinian fluvial system this system eroded both a major subaerial canyon cutting the margin southeastward from the present ebro delta and an axial valley that drained northeastward down valencia trough post messinian submergence of this topography and the pliocene regime of high sea levels resulted in a marine hemipelagic drape over the margin late pliocene to pleistocene glacial climatic cycles drainagebasin deforestation and sea level lowstands combined to increase sediment supply cause the margin to prograde and create a regime of lowstand sediment gravity flows in the deeper margin the depositional patterns of regressive transgressive and highstand sea level regimes suggest that location of the sediment source near the present ebro delta throughout the late cenozoic southward current advection of sediment and greater subsidence in the southern margin combined to cause generally asymmetric progradation of the margin to the southeast thicker less stable deposits filling the messinian subaerial canyon underwent multiple retrograde failures eroded wide gullied canyons and formed unchanneled base of slope sediment aprons in the central margin area other margin areas to the north and south developed a series of channel levee complexes on the basin floor the formation of valencia valley over the messinian subaerial valley and earlier faults led to draining of about 20 of the ebro pleistocene sediment from channel levee complexes through the valley to prograde valencia fan as much as 500 km northeast of the margin thus the ebro margin has two growth directions mainly southeastward during higher sea levels and eastward to northeastward during lower sea levels the northeastward draining of turbidity currents has produced unusually thin and widely dispersed turbidite systems compared to those on ponded basin floors during the past few centuries man s impact has exceeded natural controls on ebro margin growth deforestation of the drainage basin more than doubled the normal holocene sediment supply and construction of dams then reduced the supply by 95 this reduction of the past 50 years has caused erosion of the delta and contamination of bottom sediment because normal holocene sediment discharge is not available to prograde the delta or help dilute pollutants

maintenance of northern summer stationary waves in a gcm abstract the maintenance of northern summer stationary waves is studied with data from a 15 year integration of the general circulation model gcm experiment performed at the geophysical fluid dynamics laboratory the model has relatively high resolution rhomboidal 30 wavenumbers 9 vertical levels and simulates the summertime stationary waves reasonably well a steady linear baroclinic model is used to understand the various forcing mechanisms for the northern summer stationary waves the linear model response to global diabatic heating is found to play a dominant role in maintaining the summertime stationary waves in the gcm especially in the subtropics this response to diabatic heating shows a baroclinic structure in the vertical with a node at about 0 5 on the other hand stationary nonlinear interaction terms are found to be largely responsible for the extratropical equivalent barotropic stationary wave features it is hypothesized that this nonlinear interaction is a result of the therm

ten million year history of a thrust sheet the final deformed state of a fold and thrust belt may be reached by an infinite number of kinematic paths two end member kinematic paths are due to continuous or discontinuous rates of deformation we have used a new magnetostratigraphic section from the spanish pyrenees to calibrate the emplacement history over 10 m y of a major thrust sheet the sierras marginales thrust sheet and the deformation of both its hanging wall and footwall six time windows from before 36 5 ma until after 24 7 ma were recognized on the basis of structural and stratigraphic relationships between syntectonic strata and major structures footwall deformation of the sierras marginales thrust sheet occurred continuously on a detachment within the foreland basin sequence 4 5 km net shortening shortening rates steadily increased from 0 14 to 1 5 mm yr with time although the detachments at the base of the foreland and the detachment at the base of the sierras marginales thrust sheet were active coevally the rate of displacement on the sierras marginales detachment decayed with time and shows considerable variability emplacement of the thrust sheet may be divided into three distinct periods a rapid 13 8 km translation from 37 0 to 36 5 ma 27 6 mm yr a gradual climb of the toe of the thrust sheet up a 4 3 km long ramp across the foreland basin succession from 36 5 to 32 0 ma 0 95 mm yr and a final 8 9 km translation from 32 0 to 29 5 ma 3 56 mm yr internal deformation of the thrust sheet occurred only after it reached its present position at some time before 29 5 ma shortening rates steadily decreased from 0 6 mm yr between 29 5 and 27 8 ma to 0 26 mm yr from 27 8 until after 24 7 ma only 1 km of shortening accumulated during each of the two periods the last shortening localized on the most northerly thrust in the study area folding and subsequent faulting above the detachment beneath the foreland suggest that slip was transmitted to its tip point continuously throughout the deformation in contrast translation followed by internal deformation on the hinterland side of the toe of the sierras marginales thrust sheet indicates a successive deactivation of the southern parts of the detachment with time rate of deformation on both detachments was discontinuous and shows substantial variability about the mean in general the spatial and temporal pattern of deformation was distributed and continuous in detail however shortening was spatially and temporally discontinuous above each detachment and structures related to each one display distinctly different deformational patterns rates and styles

formation of internally drained contractional basins by aridity limited bedrock incision 1 low internal relief aridity and internal drainage characterize the puna altiplano plateau and the tibetan plateau and the tarim basin structurally these areas are reverse fault bounded terrains with intervening wedge top basins that store thick accumulations of sediment for millions of years orographic barriers along the margins of these basins are oriented normal to moisture bearing winds resulting in regional aridity the combination of this aridity rapid shortening and uplift rates and resistant exposed lithologies coincides with the location of these internally drained basins we hypothesize that these large internally drained areas persist indefinitely when uplift overwhelms the fluvial systems and defeats the channel network to test this hypothesis we developed models of channel defeat to examine the threshold conditions required to fragment the channel network the results of these models suggest that low erodibility rocks moderate to high uplift rates and low precipitation favor defeat of orogen traversing channels most coupled tectonic landscape development models prevent the development of internal drainage and so may overestimate the voracity of erosion in regimes that favor internal drainage profoundly influencing predicted orogenic growth patterns

numerical modeling of simultaneous extension and compression the valencia trough western mediterranean a two dimesional kinematic model which incorporates lateral accommodation of extension and differential stretching is used to investigate the geodynamic evolution of the valencia trough this neogene basin located between the iberian peninsula and the balearic promontory underwent two rifting episodes the first one being coeval with compression model predictions are compared with observations of tectonic subsidence bouguer gravity anomaly surface heat flow and the present day crustal structure the best fitting model assumes three stages in the evolution of the basin during the first stage late oligocene early miocene extension is mainly restricted to the central and northwestern parts of the basin whereas its southeastern margin is locked by the alpine deformation front the material expelled from the axial area is partly accommodated under the balearic promontory producing compression and crustal thickening during the second rifting stage middle miocene extension affects a much broader area including the balearic promontory and the algero provencal basin the third stage late miocene to recent corresponds to a postrift thermal relaxation phase our results put further constraints on the geodynamic evolution of the area

influence of venus topography on the zonal wind and uv albedo at cloud top level the role of stationary gravity waves based on the analysis of uv images at 365 nm of venus cloud top altitude 67 2 km collected with vmc venus monitoring camera on board venus express vex it is found that the zonal wind speed south of the equator from 5 s to 15 s shows a conspicuous variation from 101 to 83 m s with geographic longitude of venus correlated with the underlying relief of aphrodite terra we interpret this pattern as the result of stationary gravity waves produced at ground level by the up lift of air when the horizontal wind encounters a mountain slope these waves can propagate up to the cloud top level break there and transfer their momentum to the zonal flow such upward propagation of gravity waves and influence on the wind speed vertical profile was shown to play an important role in the middle atmosphere of the earth by lindzen 1981 but is not reproduced in the current gcm of venus atmosphere from lmd in the equatorial regions the uv albedo at 365 nm varies also with longitude we argue that this variation may be simply explained by the divergence of the horizontal wind field in the longitude region from 60 to 10 where the horizontal wind speed is increasing in magnitude stretch it triggers air upwelling which brings the uv absorber at cloud top level and decreases the albedo and vice versa when the wind is decreasing in magnitude compression this picture is fully consistent with the classical view of venus meridional circulation with upwelling at equator revealed by horizontal air motions away from equator the longitude effect is only an additional but important modulation of this effect this interpretation is comforted by a recent map of cloud top h2o fedorova et al 2015 showing that near the equator the lower uv albedo longitude region is correlated with increased h2o we argue that h2o enhancement is the sign of upwelling suggesting that the uv absorber is also brought to cloud top by upwelling

superrotation of venus atmosphere analyzed with a full general circulation model 1 a general circulation model gcm has been developed for the venus atmosphere from the surface up to 100 km altitude based on the gcm developed for earth at our laboratory key features of this new gcm include topography diurnal cycle dependence of the specific heat on temperature and a consistent radiative transfer module based on net exchange rate matrices this allows a consistent computation of the temperature field in contrast to previous gcms of venus atmosphere that used simplified temperature forcing the circulation is analyzed after 350 venus days 111 earth years superrotation is obtained above roughly 40 km altitude below the zonal wind remains very small compared to observed values which is a major pending question the meridional circulation consists of equator to pole cells the dominant one being located within the cloud layers the modeled temperature structure is globally consistent with observations though discrepancies persist in the stability of the lowest layers and equator pole temperature contrast within the clouds 10 k in the model compared to the observed 40 k in agreement with observational data a convective layer is found between the base of the clouds around 47 km and the middle of the clouds 55 60 km altitude the transport of angular momentum is analyzed and comparison between the reference simulation and a simulation without diurnal cycle illustrates the role played by thermal tides in the equatorial region without diurnal cycle the gierasch rossow williams mechanism controls angular momentum transport the diurnal tides add a significant downward transport of momentum in the equatorial region causing low latitude momentum accumulation

the basic ingredients of the north atlantic storm track part ii sea surface temperatures abstractthe impact of north atlantic sst patterns on the storm track is investigated using a hierarchy of gcm simulations using idealized aquaplanet and semirealistic boundary conditions in the atmospheric component hadam3 of the third climate configuration of the met office unified model hadcm3 this framework enables the mechanisms determining the tropospheric response to north atlantic sst patterns to be examined both in isolation and in combination with continental scale landmasses and orography in isolation a gulf stream sst pattern acts to strengthen the downstream storm track while a north atlantic drift sst pattern weakens it these changes are consistent with changes in the extratropical sst gradient and near surface baroclinicity and each storm track response is associated with a consistent change in the tropospheric jet structure locally enhanced near surface horizontal wind convergence is found over the warm side of strengthened sst gradients associated with ascending air and i

analysis of the geological evolution and vertical movements in the valencia trough area western mediterranean abstract the valencia trough located between the iberian peninsula and the balearic islands corresponds to the south west prolongation of the provencal basin the analysis of recently released seismic lines shows that the present day tectonics of the valencia trough are the result of the coeval development of 1 a system of horsts and grabens in the north west part of the basin during the late oligocene early miocene catalan valencian domain and 2 a thrust and fold system which lasted up to the middle miocene and which was followed by extensional tectonics during the late miocene betic balearic domain in an attempt to characterize the evolution of the valencia trough subsidence curves have been calculated for 18 wells and three regional cross sections distributed across the basin backstripping of these data shows two major stages of tectonic subsidence history 1 a first stage coeval with basin formation 30 15 my characterized by a rapid and strong tectonic subsidence which attains its maximum values in the central basin areas and close to the balearic islands and 2 a second stage 15 0 my in which the tectonic subsidence decreases gradually the amount of crustal thinning estimated from a comparison of the observed and modelled tectonic subsidence ranges between 1 5 iberian margin areas and 4 5 central and south western basin areas these values agree with the crustal thicknesses inferred from seismic refraction data and gravimetric modelling nevertheless such a degree of thinning cannot be explained by the neogene extensional structure the presence of thick mesozoic deposits suggests that the present crustal thinning is partly due to previous mesozoic extension

the neogene structure of the eastern iberian margin structural constraints on the crustal evolution of the valencia trough western mediterranean abstract the presence of a thinned crust beneath the valencia trough has been recognized for a long time however to date no attempt to link this thinning inferred from geophysical data with the superficial structures has been made a quantification of the neogene extensional processes in the crustal evolution of the valencia trough is presented as a consequence of the complexity of the betic balearic domain the analysis has been done for the catalan valencian domain northwestern areas of the trough crustal and superficial data in this area show that neogene extension was accommodated by a listric normal fault system detached in a deep upper crustal level 13 15 km in the marginal zone of the domain quantitative analysis of the neogene structure shows the incoherence between the upper crustal thinning inferred from the geometric analysis of the superficial structures factor 1 4 1 5 and from geophysical data 1 8 although the latter value agrees with that deduced from the analysis of neogene subsidence this incoherence suggests that the present thinned crust would be partially inherited from the mesozoic extension in this way mesozoic subsidence analysts and the recognized mesozoic structure show that the mesozoic extension was almost as important as the neogene one

venus s southern polar vortex reveals precessing circulation initial images of venus s south pole by the venus express mission have shown the presence of a bright highly variable vortex similar to that at the planet s north pole using high resolution infrared measurements of polar winds from the venus express visible and infrared thermal imaging spectrometer virtis instrument we show the vortex to have a constantly varying internal structure with a center of rotation displaced from the geographic south pole by 3 degrees of latitude and that drifts around the pole with a period of 5 to 10 earth days this is indicative of a nonsymmetric and varying precession of the polar atmospheric circulation with respect to the planetary axis

orogeny and orography the effects of erosion on the structure of mountain belts a numerical model of the coupled processes of tectonic deformation and surface erosion in convergent orogens is developed to investigate the nature of the interaction between these processes crustal deformation is calculated by a two dimensional finite element model of deformation in response to subduction and accretion of continental crust erosion operates on the uplifted surface of this model through fluvial incision which is taken to be proportional to stream power the relative importance of the tectonic and erosion processes is given by a dimensionless erosion number relating convergence velocity rock erodibility and precipitation rate this number determines the time required for a system to reach steady state and the final topographic shape and size of a mountain belt fundamental characteristics of the model orogens include asymmetric topography with shallower slopes facing the subducting plate and an asymmetric pattern of exhumation with the deepest levels of exhumation opposite to subduction these characteristics are modified when the regional climate exhibits a dominant wind direction and orographically enhanced precipitation on one side of the mountain belt the two possible cases are dominant wind in the direction of motion of the subducting plate and dominant wind direction in the opposite direction of the subducting plate velocity models of the former case predict a broad zone of exhumation with maximum exhumation in the orogen interior models of the latter case predict a focused zone of exhumation at the margin of the orogen and at high erosion number a reversal in the topographic asymmetry natural examples of these two cases are presented the southern alps of new zealand exhibits the climate and exhumation asymmetry characteristic of wind in the direction opposite to motion of the subducting plate the asymmetry of topography suggests that erosion is not efficient enough to have reversed the topographic asymmetry the contrasting example of dominant wind in the direction of subduction motion is provided by the olympic mountains of washington state in this case exhumation of deep levels of the cascadia accretionary wedge shows a broad domal pattern consistent with the observed orographic precipitation

a chaotic long lived vortex at the southern pole of venus a whirling vortex has been observed in the atmosphere at the south pole of venus cloud motions tracked by the venus express spacecraft suggest that the south polar vortex is long lived erratic and baroclinic in character

atmospheric structure and dynamics as the cause of ultraviolet markings in the clouds of venus details about the atmosphere on venus are gradually emerging from the once apparently impenetrable global cloud cover simultaneous imaging in the ultraviolet and infrared by venus express provides a new view of the ultraviolet patterns seen in the cloud tops the picture that emerges is one of dark low latitudes dominated by convective mixing in the sulphuric acid clouds bringing unknown ultraviolet absorbers up from the lower atmosphere the cloud top morphology revealed in the southern hemisphere by venus express resembles that found earlier by pioneer venus and venera 15 in the north suggesting global symmetry between the two hemispheres when seen in ultraviolet light venus has contrast features that arise from the non uniform distribution of unknown absorbers within the sulphuric acid clouds this paper reports multi wavelength imaging that reveals that the dark low latitudes are dominated by convective mixing that brings the ultraviolet absorbers up from depth the bright and uniform mid latitude clouds reside in the cold collar which suppresses vertical mixing in low and middle latitudes the visible cloud top is located at a constant altitude of 72 1 km in both the ultraviolet dark and bright regions indicating that the brightness variations result from compositional differences caused by the colder environment when seen in ultraviolet light venus has contrast features that arise from the non uniform distribution of unknown absorbers within the sulphuric acid clouds1 2 3 and seem to trace dynamical activity in the middle atmosphere4 it has long been unclear whether the global pattern arises from differences in cloud top altitude which was earlier3 estimated to be 66 72 km compositional variations or temperature contrasts here we report multi wavelength imaging that reveals that the dark low latitudes are dominated by convective mixing which brings the ultraviolet absorbers up from depth the bright and uniform mid latitude clouds reside in the cold collar an annulus of cold air characterized by 30 k lower temperatures with a positive lapse rate which suppresses vertical mixing and cuts off the supply of ultraviolet absorbers from below in low and middle latitudes the visible cloud top is located at a remarkably constant altitude of 72 1 km in both the ultraviolet dark and bright regions indicating that the brightness variations result from compositional differences caused by the colder environment rather than by elevation changes the cloud top descends to 64 km in the eye of the hemispheric vortex which appears as a depression in the upper cloud deck the ultraviolet dark circular streaks enclose the vortex eye and are dynamically connected to it

sedimentary processes related to the groundwater flows from the mesozoic carbonate aquifer of the iberian chain in the tertiary ebro basin northeast spain abstract in this work the importance of groundwater in the formation and evolution of evaporitic lacustrine facies in the iberian chain and ebro basin contact spain is studied there are outcrops of geological materials from palaeozoic to quaternary times these materials have been classified into eight hydrostratigraphic units the jurassic carniolas and limestones in the iberian chain hu 4 and 5 are the materials which have the best hydraulic properties for underground water catchment and for forming the regional aquifer the triassic gypsum and marl of hu 3 form the impermeable substratum of the overlying jurassic and cretaceous carbonated aquifers and they are therefore the impermeable base of the aquifers being studied the equipotential line map of the regional aquifer shows the pattern of the groundwater flowing to specific points which mark the springs producing the underground drainage of the iberian chain the volume of water throughout the aquifer is currently evaluated at approximately 250 hm3 year which discharge through springs with high flowrates or through diffuse discharges in the riverbeds and in wetlands saline lakes the water discharged in these springs has a high mineralisation with a dry residue of over 1000 mg l calcium sulphate compositions dominate originating in the presence of soluble anhydrous materials within the lias and keuper formations the current sedimentation in relation to the groundwater flows from the iberian chain can only be found in the areas of diffuse discharge where the evaporitic sedimentation can be observed because of the frequently endorheic character on the right bank of the ebro river more than 60 depressions are known where very mineralised lakes form these are locally referred to as saladas during the miocene the hydrogeological functioning would be similar to the present one leaving the groundwater and the dissolved salts in a non marine basin they would therefore accumulate in large areas of diffuse discharge creating lakes where the evaporites would precipitate the deep regional groundwater flows would ascend to the surface from the overthrust lamina fronts going through thick tertiary alluvial deposits in the ebro basin and therefore the discharges were mainly diffuse

assessing the long term variability of venus winds at cloud level from virtis venus express abstract the venus express vex mission has been in orbit to venus for more than 4 years now the visible and infrared thermal imaging spectrometer virtis instrument onboard vex observes venus in two channels visible and infrared obtaining spectra and multi wavelength images of the planet that can be used to sample the atmosphere at different altitudes day side images in the ultraviolet range 380 nm are used to study the dynamics of the upper cloud at 66 72 km while night side images in the near infrared 1 74 m map the opacity of the lower cloud deck at 44 48 km here we present a long term analysis of the global atmospheric dynamics at these levels using a large selection of orbits from the virtis m dataset covering 860 earth days that extends our previous work sanchez lavega a et al 2008 geophys res lett 35 l13204 and allows studying the variability of the global circulation at the two altitude levels the atmospheric superrotation is evident with equatorial to mid latitudes westward velocities of 100 and 60 m s 1 in the upper and lower cloud layers these zonal velocities are almost constant in latitude from the equator to 50 s from 50 s to 90 s the zonal winds at both cloud layers decrease steadily to zero at the pole individual cloud tracked winds have errors of 3 10 m s 1 with a mean of 5 m s 1 and the standard deviations for a given latitude of our zonal and meridional winds are 9 m s 1 the zonal winds in the upper cloud change with the local time in a way that can be interpreted in terms of a solar tide the zonal winds in the lower cloud are stable at mid latitudes to the tropics and present variability at subpolar latitudes apparently linked to the activity of the south polar vortex while the upper cloud presents a net meridional motion consistent with the upper branch of a hadley cell with peak velocity v 10 m s 1 at 50 s the lower cloud meridional motions are less organized with some cloud features moving with intense northwards and southwards motions up to v 15 m s 1 but on average with almost null global meridional motions at all latitudes we also examine the long term behavior of the winds at these two vertical layers by comparing our extended wind tracked data with results from previous missions

subsidence history crustal structure and thermal evolution of the valencia trough a young extensional basin in the western mediterranean the valencia trough is an extensional basin that began rifting during the late oligoceneearly miocene yet it is located within a region of compression between the european and african plates seismic reflection seismic refraction well gravity and geoid data have been used to determine the relative importance of extensional and compressional processes in controlling the structure and evolution of the trough although the trough appears symmetric on bathymetric maps seismic and gravity and geoid data indicate a fundamental asymmetry in its deep crustal and upper mantle structure two dimensional flexural backstripping techniques have been used to estimate the total amount of crustal stretching along a transect of the trough between the catalan coastal ranges and mallorca there is good agreement between the predicted depth to the mono based on a stretching model and the seismically constrained depth beneath the catalan margin but poor agreement beneath mallorca the seismic moho beneath mallorca can be explained by a model in which the crust was modified by the flexural effects of thrust fold loading geoid data suggest that the differences in the crustal structure between the two margins extend into the upper mantle the catalan margin is characterized by a thermal and mechanical boundary which marks the transition between cold unstretched lithosphere and hot thin lithosphere while mallorca is located above a broad region of lithospheric thinning the subsidence history and amount of crustal thinning in the catalan margin resemble that of typical atlantic type nonvolcanic margin however a narrow transition zone 60 km the lack of any evidence for a conjugate margin and the absence of oceanic crust suggest fundamental differences in the way that extensional processes may occur in convergent plate settings

the basic ingredients of the north atlantic storm track part i land sea contrast and orography understanding and predicting changes in storm tracks over longer time scales is a challenging problem particularly in the north atlantic this is due in part to the complex range of forcings land sea contrast orography sea surface temperatures etc that combine to produce the structure of the storm track the impact of land sea contrast and midlatitude orography on the north atlantic storm track is investigated through a hierarchy of gcm simulations using idealized and semirealistic boundary conditions in a highresolution version of the hadley centre atmosphere model hadam3 this framework captures the largescale essence of features such as the north and south american continents eurasia and the rocky mountains enabling the results to be applied more directly to realistic modeling situations than was possible with previous idealized studies the physical processes by which the forcing mechanisms impact the large scale flow and the midlatitude storm tracks are discussed the characteristics of the north american continent are found to be very important in generating the structure of the north atlantic storm track in particular the southwest northeast tilt in the upper tropospheric jet produced by southward deflection of the westerly flow incident on the rocky mountains leads to enhanced storm development along an axis close to that of the continent s eastern coastline the approximately triangular shape of north america also enables a cold pool of air to develop in the northeast intensifying the surface temperature contrast across the eastern coastline consistent with further enhancements of baroclinicity and storm growth along the same axis

latest oligocene late miocene lacustrine systems of the north central part of the ebro basin spain sedimentary facies model and palaeogeographic synthesis abstract in the central part of the ebro basin spain north of the ebro river three allostratigraphic or tectosedimentary units differentiated within the latest oligocene late miocene upper agenian vallesian interval are sedimentologically characterized these deposits represent carbonate and sulphate lacustrine environments fed by pyrenean alluvial systems luna system and huesca system in each unit several facies associations or lithofacies were mapped these interfinger through time gypsum lithofacies occupy the southernmost part of the study area and are surrounded by carbonate and or detrital lithofacies to the north each lithofacies consists of different carbonate sulphate and or detrital facies arranged in simple sequences decimetres to metres thick the four types of sequences characterized reflect a complex shallowing evolution involving carbonate or sulphate contexts thus each lithofacies represents the sedimentation in a particular lacustrine or alluvial subenvironment a single lacustrine system is proposed for the central part of the basin its evolution followed cycles of water level variations which caused kilometre scale migrations of the lake shoreline in this model two distinct situations or lakes alternated through time a one represents high levels associated with a single body of dilute carbonate water where massive carbonate facies formed influenced by organism proliferation these lakes had wide palustrine vegetated margins in which bioturbated facies developed b the other represents low levels that correspond to a playa lake model laminated sulphate deposits formed in the lake waters while nodular gypsum originated in the surrounding saline mud flats and within the exposed previously deposited carbonate sediments transitions from one situation to the other including minor water level fluctuations within carbonate sedimentation conditions were marked by the development of laminated and stromatolitic facies lake level variations were caused by climatic cycles and gave rise to the simple sequences and to the lithofacies lateral relationships recognized in this study correlation among tectosedimentary units in the studied pyrenean domain and in the iberian domain of the ebro basin shows that for units n1 and n2 the facies that resulted from dilute carbonate waters are rare in the lacustrine areas of the iberian margin this indicates that a strong hydrological contrast existed between both regions on this basis a theoretical asymmetrical facies model is proposed for the single lacustrine basin that extended over these regions

controls on post mid cretaceous landscape evolution in the southeastern highlands of australia insights from numerical surface process models the tectonic and geomorphic evolution of the southeastern australian highlands has been a subject of controversy among geophysicists geologists and geomorphologists for several decades we employ a numerical surface process model that includes long range fluvial transport hillslope diffusion and landsliding in order to quantitatively assess the tectonic lithological and structural controls on the landscape evolution and denudation history of se australia we constrain fluvial erosion parameters for our model by fitting river profiles rockfall and landsliding are the most important processes controlling the concentration of erosion in river valleys we therefore model hillslope evolution using a very low diffusion coefficient and a threshold slope for landsliding the initial prebreakup topography of the highlands provides a fundamental control on their subsequent evolution together with the style and rate of fluvial incision secondary controls are exerted by lateral variations in lithology and local tectonic uplift along faults our modeling results indicate that 1 the observed highlands morphology requires that the drainage divide was established at its present location prior to opening of the tasman sea whether the divide is inherited from paleozoic orogeny or resulted from mesozoic syn rift uplift cannot be established however 2 in contrast to traditional interpretations escarpment retreat does not appear to be the fundamental process eroding the highlands and 3 the observed barbed river drainage may be imprinted as a result of lithological variation it does not necessarily evolve through capture the driving mechanism that is most consistent with the inferred uplift pattern of the southeastern highlands appears to be magmatic underplating

the nature of the near infrared features on the venus night side near infrared images of the venus night side show bright contrast features that move from east to west in the direction of the cloud top atmospheric superrotation recently acquired images of the venus night side along with earlier spectroscopic observations allow identification of the mechanisms that produce these features their level of formation and the wind velocities at those levels the features are detectable only at wavelengths near 1 74 and 2 3 micrometers in narrow atmospheric windows between the co 2 and h 2o bands the brightest features have brightness temperatures near 480 kelvin whereas the darkest features are more than 50 kelvin cooler several factors suggest that this radiation is emitted by hot gases at altitudes below 35 kilometers in the venus atmosphere the feature contrasts are produced as this thermal radiation passes through a higher cooler atmospheric layer that has horizontal variations in transparency the 6 5 day east west rotation period of the features indicates that equatorial wind speeds are near 70 meters per second in this upper layer similar wind speeds have been measured by entry probes and balloons at altitudes between 50 and 55 kilometers in the middle cloud layer the bright features indicate that there are partial clearings in this cloud deck the presence of these clearings could decrease the efficiency of the atmospheric greenhouse that maintains the high surface temperatures on venus

crustal structure and the mechanical properties of extended continental lithosphere in the valencia trough western mediterranean seismic refraction and reflection gravity and well data have been used to constrain the structure and evolution of the valencia trough a young extensional basin in the western mediterranean seismic refraction data reveal the present day crustal structure while backstripping of seismic reflection and well data reveal the structure at the time of rifting by comparing the seismically constrained crustal structure to that inferred from backstripping we have been able to evaluate whether the moho is in the expected position given the tectonic subsidence uplift and sediment loading history of the trough the best overall fit between the predicted and seismically constrained crustal structure in the trough is for a model in which the extended continental crust and lithosphere has acquired little or no strength following rifting a low strength is in accord with the observed free air gravity anomaly as well as results from other types of rift basins such as the north sea and the continental margin off the east coast of the usa there are discrepancies between the observed and predicted moho depths beneath the flanks of the valencia trough but they are attributed to either the removal of crustal material during or following rifting iberian peninsula or to orogenic loading of previously extended continental crust mallorca the largest discrepancy up to 10 km correlates with the ebro delta which has prograded into the trough by more than 60 km since the pliocene the discrepancy cannot be explained by the same large scale processes that modified the moho beneath the trough flanks and requires that the lithosphere beneath the ebro delta region is associated with a high 60 t c

global maps of venus nightside mean infrared thermal emissions obtained by virtis on venus express one of the striking features about venus atmosphere is its temporal variability and dynamics with a chaotic polar vortex large scale atmospheric waves sheared features and variable winds that depend on local time and possibly orographic features the aim of this research is to combine data accumulated over several years and obtain a global mean state of the atmosphere focusing in the global structure of the clouds using the cloud opacity and upper cloud temperatures we have first produced global maps using the integrated radiance through the infrared atmospheric windows centred around 1 74 m and 2 25 m that show the spatial variations of the cloud opacity in the lower clouds around 44 48 km altitude and also provide an indirect estimation of the possible particle size we have also produced similar global maps using the brightness temperatures seen in the thermal region at 3 8 m and 5 0 m which provide direct indication of the temperatures at the top of the clouds around 60 70 km altitude these maps have been generated using the complete dataset of the visible and infrared thermal imaging spectrometer mapping channel virtis m on board venus express with a wide spatial and long temporal coverage in the period from may 2006 until october 2008 our results provide a global view of the cloud opacity particle size and upper cloud temperatures at both hemispheres showing the main different dynamical regions of the planet the profiles obtained also provide the detailed dependencies with latitude local time and longitude diagnostic of the global circulation flow and dynamics at various altitude layers from about 44 up to 70 km over the surface

understanding the seasonality of orographically forced stationary waves interaction between mechanical and thermal forcing abstract idealized simulations of the atmosphere s stationary response to the rockies tibetan plateau and the greenland ice sheet are made using a nonlinear quasigeostrophic model and are compared to observations observational data indicate low level heating cooling occurs above the rockies and tibet in the summer winter low level cooling is found above greenland in both seasons the atmosphere responds to both diabatic heating termed thermal forcing and low level flow being obstructed by the mountain s presence termed mechanical forcing the response to thermal and mechanical forcing together can be very different from the response to either forcing individually the presence of modest low level heating or cooling 1 5 k day 1 causes significant changes to the mechanical forcing and thereby to the stationary wave response for example while the nonlinear response to mechanical forcing and low level heating is characterized by a cyclone over the orography the response to mechanical forc

stable isotope characterization of the miocene lacustrine systems of los monegros ebro basin spain palaeogeographic and palaeoclimatic implications the lacustrine carbonate facies from three allostratigraphic units n1 n2 and n3 of miocene age in the los monegros region ebro basin are characterized isotopically the dominant facies are marls laminated limestones stromatolitic limestones massive limestones and bioturbated limestones these are associated with lacustrine sulphate deposits and distal alluvial facies palaeohydrological reconstructions of the study area are supported by the isotopic and the mineralogical composition of the carbonates massive and bioturbated limestones occupy a very similar compositional domain and have the lowest isotopic compositions of all the facies 9 18opdb 4 5 and 6 4 13cpdb 0 4 reflecting a short residence time of the water and variable commonly high influence of biogenic co2 laminated limestones and stromatolites define a comparatively enriched domain with 18o values ranging from 6 to 0 and 13c values ranging from 3 5 to 0 these values indicate stronger evaporation and enhanced 12c assimilation due to intense biological activity during periods of longer water residence time marls have isotopic values intermediate between these two domains and correspond to periods of lacustrine dilution dolomite bearing samples mainly laminated and stromatolitic facies show a 18odol cal 7 5 with respect to calcite from the same facies while 13c values show very little enrichment up to 1 the positive correlation r 0 85 between 18o and dolomite contents suggests that dolomite resulted from the progressive evaporative concentration of a single water mass and not from the mixing of waters of different compositions the dolomite is thought to be primary or at most the product of very early diagenetic processes the isotopic composition of the facies and their spatial and temporal variations depend on the depositional environment and were constrained by changing regional paleogeography isotopic trends from units n1 to n3 upper agenian vallesian period display a regular depletion in heavy isotopes that indicates a climatic change towards wetter conditions

lithic materials in high fluvial terraces of the central pyrenean piedmont ebro basin spain abstract lithic materials from lower palaeolithic are scarce in the ebro basin archaeological surveys carried out in some alluvial terraces on central pyrenean piedmont have unearthed three new sites with remains of lithic industries related to cobble and core technology and large cutting tools in the upper terrace levels t1 and t2 from the alcanadre and cinca rivers some pieces have been recovered on the surfaces cobble tools at las fitas and bifacial tools at san quilez the approximate age of these levels ranges between 780 ka and 1000 ka established by paleomagnetism and evolutionary stages of calcrete a cleaver was interbedded into a terrace t5 level of a minor tributary of the cinca river olriols whose age has been established at a regional scale between 178 151 ka this t5 level is related to one of the cold phases of greater advance of pyrenean glaciers during mis 6 these new findings help us to widen our knowledge of a poorly known period of the human occupation of the middle iberian basin the chronological imprecision of most of the lithic materials has been partially overcome by means of geomorphological data which offers a generic chrono cultural framework for the people who used them

structure and formation mechanisms of the northern hemisphere summertime subtropical highs abstract three dimensional structure and dynamics of the climatological mean summertime subtropical highs over the north pacific and atlantic i e the azores high are investigated each of the observed surface highs is accompanied by a meridional vorticity dipole aloft exhibiting barotropic and baroclinic structures in its northern and southern portions respectively in a manner dynamically consistent with the observed midtropospheric subsidence each of the highs develops over the relatively cool eastern ocean where a pronounced near surface thermal contrast exists with a heated landmass to the east the authors demonstrate through numerical experiments that those highs can be reproduced in response to a local shallow cooling heating couplet associated with this thermal contrast although the upper level response is somewhat underestimated the model experiments suggest that the near surface thermal contrasts associated with those surface subtropical highs over the pacific and atlantic can act as s

origin and evolution of sarinena lake central ebro basin a piping based model abstract the origin and nature of the numerous lakes in the central ebro basin have been interpreted according to the prevailing arid or semiarid conditions the easily eroded materials and the solubility of the gypsum and or carbonate rich tertiary cenozoic substratum involving important dissolution karstic and or aeolian deflation however the origin of sarinena lake the largest in the central ebro basin remains unknown since the typical lake generating processes in the region are not applicable this work provides significant clues to the genesis and evolution of sarinena lake in a regional context the combination of geomorphological mapping and high resolution lidar data together with sedimentological observations the characterisation of soils and sediments around the lake and the application of high resolution geophysical techniques suggest that piping is the major genetic process driving the evolution of the sarinena depression and lake field evidence demonstrates that piping is at present the most important erosive process in the region generating significant collapse and surface lowering sarinena lake is located within a deep endorheic depression excavated from na rich tertiary materials this work hypothesises that once an early fluvially originated palustrine area had developed the progressive lowering of the regional water table linked to regional fluvial incision favoured the establishment of a hydrological gradient high enough to trigger piping processes within the claystones and siltstones underlying the original palustrine area the quaternary evolution of the sarinena lacustrine basin was then controlled by successive water table fluctuations linked to different phases of incision and alluvial deposition in the surrounding fluvial systems all the evidence supporting a piping related origin for this lake together with examples of lakes generated by similar processes in different contexts is used to propose a new genetic type of lacustrine depression generated by piping processes under favourable conditions

hominin multiple occupations in the early and middle pleistocene sequence of vallparadis barcelona spain abstract the archaeological site at vallparadis barcelona spain contains a continuous archaeostratigraphic sequence that extends from the upper limit of the jaramillo subchron 0 98 ma to the first half of the middle pleistocene c 0 6 ma evidence of human occupation lithic tools and cut marks has been identified in this sequence in the levels with reverse polarity from the early pleistocene evt7 4 and in the levels with normal polarity from the middle pleistocene evt3 2 in contrast to unit evt7 which was excavated using an extensive archaeological methodology the other levels were a rescue excavation the latter yielded a reduced lithic assemblage providing evidence of a multiple occupation sequence by hominins at vallparadis this evidence call into question the proposal that there was a gap in the hominin settlement before the appearance of mode 2 technology in europe a hypothesis that is based on stratigraphic sequences such as gran dolina atapuerca spain and the mid loire region massif central france regarding the early pleistocene lithic tools from unit evt7 at vallparadis the upper phase of the sequence evt4 2 shows longer chaines operatoires an increase in size of the lithic artefacts and the selection of better quality raw materials which in turn indicate changes in the source areas from which they were selected

modeling the evolution of the guadalquivir foreland basin southern spain 1 previous quantitative studies dealing with the origin of foreland basins have focused primarily either on the rheological basis of the lithosphere mechanical response or on the relationship between orogenic loading and sediment geometry to link the evolution of the guadalquivir foreland basin south iberia with the thermomechanical stratification of the iberian lithosphere we combine quantitative approaches to deep and shallow processes thrust loading lithospheric flexure thickness changes of the crust and the lithospheric mantle and surface mass transport a planform flexural analysis of the present day load distribution shows that basement subsidence is related not only to upper crustal thrusting but also to a deep seated additional load on the basis of the observed gravity and geoid fields we propose this additional load to be related to a lithospheric mantle thickening larger than the coeval crustal thickening further modeling of the evolution of a basin cross section reveals that the architecture of the sedimentary basin is additionally related to the lithosphere rheological response the quantitative study of the evolution of basement faulting and the forebulge uplift of sierra morena leads us to conclude that viscous stress relaxation and or plastic yielding within the lithosphere are key processes to explain the flexural evolution of the basin

large scale karst subsidence and accelerated fluvial aggradation during mis6 in ne spain climatic and paleohydrological implications abstract fluvial systems crossing evaporitic bedrock are commonly affected by karstic subsidence which may result in river adjustments recorded by anomalous alluvial thickening a remarkable study case is the gallego river at the central ebro basin ne spain where dissolution of evaporite bedrock gave rise to a subsidence induced depositional basin 30 km long by 8 km wide infilled with alluvial sediments in excess of 110 m in thickness a detailed morpho sedimentary analysis of alluvial deposits supported with optically stimulated luminescence dating has revealed that paleokarst subsidence and accelerated fluvial aggradation occurred during discrete time periods the most recent one being at 140 155 kyr end of mis 6 subsequent alluvial terrace formation occurred at 110 kyr 63 48 kyr and 17 kyr linked to fluvio glacial activity at the pyrenean headwaters large scale bedrock dissolution and associated alluviation appear to be sensitive to 1 long lasting periods of glacial outwash discharges 2 high effective runoff from the extensive valley slopes and 3 increased surface groundwater exchange and groundwater circulation the last large scale subsidence episode 140 155 kyr correlates with hydrological proxies reflecting a prolonged 141 149 kyr salinity drop in the western mediterranean previously interpreted as linked to a heinrich event but which may instead represent an anomalous period of enhanced river discharge fed by extensively glaciated mountains

tectonic and climatic controls on the development of foreland fan deltas montserrat and sant llorenc del munt systems middle eocene ebro basin ne spain abstract along an early cenozoic foreland hinterland boundary in northeastern spain we synthesize the depositional environment climatic conditions structural evolution age catchment geometry and altitudinal characteristics from sedimentologic palynologic stratigraphic structural and paleomagnetic data as the transpressional catalan coastal ranges rose during the paleogene two large fan deltas prograded into the ebro foreland basin adjacent to the northeastern part of the range the apices of the fans likely were localized by lateral ramps or tear faults along which rivers from hinterland catchments debouched into the foreland beginning in the late lutetian proximal debris flow sheetflood and distal fluvial deposits maintained the fan surface at or above sea level despite rapid basin subsidence during the succeeding 4 4 my palynological data suggest that a warm humid climate prevailed throughout this interval the mapped extent of the two fans permits an estimation of their volumes whereas the spatial distribution of distinctive lithologies within the ancestral catalan coastal ranges serves to delimit the approximate catchment areas for each of the fans we estimate mean hinterland denudation rates to range from 100 to 180 m my and mean catchment elevation to range from 700 to 1250 m the steep gradients between these catchments and the low lying fan deltas is attributed to the tectonic style of the ancestral catalan coastal ranges which are characterized by an uplifted basement block along a steep frontal thrust accompanied by folding of cover rocks the considerable topographic relief of these catchments is inferred to have combined with co seismic shaking to produce landslides and rockfalls which were reworked as debris and fluid gravity deposits on the fan surfaces

basin infill architecture and evolution from magnetostratigraphic cross basin correlations in the southeastern pyrenean foreland basin magnetostratigraphy numerical dating and facies mapping have been combined to provide the first cross basin correlation of the eocene southeastern pyrenean foreland basin in northeastern spain this has enabled 1 depositional systems on the northern and southern margins of the basin to be dated and correlated across the basin and 2 changes in the rates of sediment accumulation in time and space to be evaluated by sampling correlative intervals at several locations in a transect across the basin magnetozones were detected that otherwise may have been misinterpreted due to recent magnetic overprinting or missed by wide sampling intervals in previous magnetostratigraphic surveys results of this study indicate that marginal marine strata of the southeastern part of the foreland near the vic area of spain are 5 m y older than previously thought the base of the interval 46 ma being middle lutetian in age by proposing an age of at least 35 68 ma for the overlying cardona evaporite unit the age span of the marine interval in the studied part of the foreland is 10 m y contrary to earlier interpretations no major southward migration of the southeastern pyrenean foreland basin depocenter is recorded by the basin stratigraphy during the initial stages of middle eocene marine sedimentation in the southern margin of the basin however marked basin asymmetry is observed later in its evolution as the top of the marine deposits records northward increase in the thickness of chron c17n 1n 37 47 36 61 ma this asymmetry is also proved by the presence of a larger number of magnetozones within marine strata at the top of the marine interval in the northern sector these results imply that previous age calibrations and the estimated rates of tectonic processes and sedimentation within the foreland need to be reassessed the implications for basin infill architecture evolution through time and space subsidence analysis and depocenter evolution through time are addressed

variations in north american summer precipitation driven by the atlantic multidecadal oscillation understanding the development and variation of the atmospheric circulation regimes driven by the atlantic multidecadaloscillation amo isessentialbecausethesecirculationsinteractwithotherforcingsondecadaland interannual time scales collectively they determine the summer june july and august precipitation variations for north america in this study a general circulation model gcm is used to obtain such understanding with a focus on physical processes connecting the amo and the summertime precipitation regime change in northamerica twoexperimentalrunsareconductedwithseasurfacetemperature sst anomaliesimposedin the north atlantic ocean that represent the warm and cold phases of the amo climatological ssts are used elsewhere in the oceans model results yield summertime precipitation anomalies in north america closely matching the observed anomaly patterns in north america suggesting that the amo provides a fundamental control on summertime precipitation in north america at decadal time scales the impacts of the amo are achieved by a chain of events arising from different circulation anomalies during warm and cold phases of the amo during the warm phase the north atlantic subtropical high pressure system nash weakens and the north american continent is much less influenced by it a massive body of warm air develops over the heated land in north america from june august associated with high temperature and low pressure anomalies in the lowertroposphereandhighpressureanomaliesintheuppertroposphere incontrast duringthecoldphaseofthe amo the north american continent particularly to the west is much more influenced by an enhanced nash cooler temperatures and high pressure anomalies prevail in the lower troposphere and a frontal zone forms in the upper troposphere these different circulation anomalies further induce a three cell circulation anomaly pattern over north america in the warm and cold phases of the amo in particular during the cold phase the three cell circulation anomaly pattern features a broad region of anomalous low level southerly flow from the gulf of mexico into the u s great plains superimposed with an upper troposphere front more frequent summertime storms develop and excess precipitation occurs over most of north america a nearly reversed condition occurs during the warm phase of the amo yielding drier conditions in north america this new understandingprovides a foundation for further studyand better prediction of the variations of north american summer precipitation especially when modulated by other multidecadal variations for example the pacific decadal oscillation and interannual variations associated with the enso and the arctic oscillation

new cloud morphologies discovered on the venus s night during akatsuki abstract during the years 2016 to 2018 the instruments akatsuki ir2 jaxa and irtf spex nasa acquired a large set of images at 1 74 2 26 and 2 32 m to study the nightside mid to lower clouds 48 60 km of venus here we summarize the rich variety of cloud morphologies apparent in these images from frequent wave packets and billows caused by shear instabilities to features reported decades ago like the circum equatorial belts bright blotches and equatorial troughs and previously unseen features like dark spots sharp dark streaks at mid latitudes and fully developed vortices

multi storey calcrete profiles developed during the initial stages of the configuration of the ebro basin s exorrheic fluvial network abstract multi storey calcrete profiles developed in the quaternary on strath terraces of the cinca and alcanadre rivers tributaries of the ebro river in ne spain two calcrete profiles tor 1 and tor 2 near the village of el tormillo show horizons with an arrangement that differs from that of commonly described calcrete profiles significant lateral changes occur in these profiles within a distance of less than 200 m reflecting their pedofacies relationship the tor 1 profile on terrace qt1 the highest and oldest consists of six horizons from bottom to top 1 coarse fluvial gravels 2 mudstones with carbonate nodules 3 a chalky horizon 4 laminar horizons including one peloidal horizon 5 a multi storey horizon formed of at least six minor sequences each of which includes a lower detrital layer a pisolithic horizon and a thin discontinuous laminar horizon these sequences indicate several cycles of brecciation and or reworking and 6 a topmost laminar and brecciated horizon also including reworked pisoliths some 200 m to the north of tor 1 horizon 5 undergoes a lateral change to channel fill deposits the infill of the channels shows a fining upwards sequence ranging from clasts of about 10 cm in diameter to red silts with sparse pebbles all the clasts come from the underlying calcrete horizons laminar horizons are interbedded with the clastic channel deposits the youngest calcrete profiles developed on terrace qt3 of the cinca river and on the qp4 and qp6 mantled pediment levels all show relatively simple profiles composed mostly of lower horizons of coated gravels with thin laminar horizons at the top most of the horizons especially the laminar ones show biogenic features such as alveolar septal structures calcified filaments biofilms spherulites micropores and needle like calcite crystals these features indicate the important role of vegetation in the formation of all the above profiles the interbedding of clastic sediments and pisolithic horizons within the tor 2 profile indicates several stages of stabilisation during profile formation these sequences are an indication of the sedimentation soil formation and reworking processes operating on the soil surface the alternation of these processes is interpreted as the result of climate vegetation changes the channel fills of tor 2 indicate erosion and reworking of the hard laminar calcrete horizon both tor 1 and tor 2 are multi storey profiles reflecting the complex sedimentation erosion pedogenesis relationships at the final stages of the development of its corresponding fluvial terrace the study of these calcretes shows that these supposedly abandoned terraces continue to be active even though the fluvial network is entrenched both the pedofacies relationships and the complexity shown by tor 1 and tor 2 reflect the complex and unstable geomorphic setting in which these profiles developed after the establishment of the exorrheic network less complex calcrete profiles were produced in the lower terraces

the anso transect of the southern pyrenees basement and cover thrust geometries a balanced geological section through the western central pyrenees allows the alpine geometry of hercynian basement to be determined this shows marked differences with other transects of the southern part of the chain basement involved thrust sheets do not form an antiformal stack but are imbricated and define steps separated by frontal culmination limbs basement thrusts propagate upwards and have formed distinct thrust systems in the cover in this transect the north pyrenean zone is bounded to the south by gently dipping thrusts of large displacement and the axial zone massif at its western termination area is a flat topped culmination caused by a single thrust fault the gavarnie thrust this thrust emerges to the south in the interior of the syntectonic jaca basin the geometry of which is also controlled by underlying basement thrusts various generations of structures can be correlated with distinct episodes of syntectonic sedimentation a sequential restoration of the section illustrates how successive foreland sedimentary wedges were generated and progressively involved in deformation tectonic shortening is 48 km almost half of that estimated further to the east for the southern pyrenees the structure deduced at the ecors pyrenees seismic section cannot be translated to this transect

a quaternary soil chronosequence study on the terraces of the alcanadre river semiarid ebro basin ne spain abstract a sequence of dated alluvial terraces can provide an excellent geomorphological framework for studying soil evolution over time the aim of this study is to establish a soil chronosequence over the last million years on the calcareous fluvial deposits of the alcanadre river in the semiarid ebro basin ne spain moreover two methods for determining total caco 3 content are compared by calcimetry in the lab and by a portable xrf analyzer in the field pedogenic caco 3 accumulation is the most characteristic age related pedofeature in the studied semiarid conditions this accumulation directly affects soil classification the soils evolved from an initial calcaric fluvisol into haplic calcisol and later into petric calcisol as well as some management properties e g reducing water holding capacity from 170 to 14 mm profile the young holocene soils that developed on the lower terraces maintain their original fluvic and calcaric properties but calcic horizon can be found as pendants on soils from the early holocene to late pleistocene from 10 1 ka on middle pleistocene from 176 14 ka terraces petrocalcic horizon is found whose thickness is greatest on the soil evolved on oldest early pleistocene surface this net retention of carbonates over time suggests the predominance of dry periods over wet ones during soil evolution the measure of total carbonates by xrf in the field and those on fine earth by calcimetry in the laboratory shows a highly significant linear regression r 2 0 91 which highlights the efficiency of in situ approach for measuring them

evolution of the central catalan margin of the valencia trough western mediterranean abstract the evolution of the central catalan margin was conditioned by major fault activity and thermal processes generated by crustal thinning the continental margin structure is characterised by major ne sw striking southeast dipping basement faults which have given rise to a graben half graben and horst system these faults acted essentially as normal faults no major neogene strike slip activity has affected the continental margin although minor episodic variations from the dominant extensional regime to strike slip tectonics cannot be discounted two major structural evolutionary stages took place at the margin the transition from one stage to the other being gradual 1 rifting stage late oligocene to early burdigalian related to the opening of the valencia trough and from which originated both the barcelona and valles penedes half grabens 2 thermal subsidence stage late burdigalian to present generated by the subsequent crustal cooling and thinning fault activity during this stage was essentially concentrated in the major half graben bounding faults the sedimentary evolution of the central sector of the catalan margin was controlled by the tectonic and crustal evolution as well as by the successive sea level and paleoclimatic changes which affected the region drastic changes in the depositional systems took place during the transition from the rifting stage into the thermal subsidence stage during aquitanian langhian time characterized by an overall trend of pulsating encroachment of marine conditions over the continental margin a noticeable diversity of depositional systems alluvial lacustrine coastal evaporitic fan delta bay shelf carbonate platform systems developed from the latest serravallian up to the present the depositional framework was less varied due to a general lowering of sea level and to the final onlapping of most of older structural highs which are now buried below the miocene sediments two progradational terrigenous shelf talus systems separated by the messinian erosive surface developed during the latest serravallian tortonian and pliocene quaternary

atmospheric responses to north atlantic sst anomalies in idealized experiments part i northern hemispheric circulation abstractidealized model experiments using the ncar cesm1 0 5 under equinox conditions are designed and performed to address two fundamental questions about the effects of the sea surface temperature sst variation associated with the atlantic multidecadal oscillation amo on circulation and precipitation in north america and europe 1 is the observed relationship between the amo sst and the warm season precipitation in north america a statistical coincidence and 2 why is the response of negative precipitation anomaly to warm sst in the amo fairly uniform across most of north america whereas the positive precipitation anomaly in the cold sst rather spotty model experiments are done with either a warm or cold sst anomaly in an aquaplanet a planet with idealized continents and a planet with both idealized continents and orography major results show that the atmospheric response to warm sst anomaly in the north atlantic is fairly similar among the three sets of experiments in the lower troposphere

three dimensional flexural modelling of the ebro basin ne iberia summary the ebro basin the southern foreland basin of the pyrenees has undergone a complex evolution in which apart from the pyrenees the iberian range and the catalan coastal ranges have played an important role both as sediment sources and as basin confining structures the deflected basement underlying the ebro basin dips north suggesting a lithospheric scale control on the structure of this basin this is compatible with the results of subsidence analyses which show that the study area is not in a local mode of isostatic compensation in order better to understand the mechanisms that led to the present configuration of the ebro basin and particularly the relevance of the various kinds of un loading e g surrounding fold and thrust belts basin topography subsurface loads we carried out a 3 d kinematic modelling study that accounts for the flexural state of the lithosphere subjected to various loads applied at its lateral boundaries and the sedimentary fill of the basin we also included the effect of neogene extensional tectonics along the eastern basin margin which is related to the opening of the valencia trough we show the suitability of the 3 d lithospheric scale flexural modelling approach to the study of ne iberia modelling results point to a relatively strong lithosphere in this area with values of effective elastic thickness ranging from 10 to 35 km in the ebro basin increasing towards the pyrenees we also find that the topographic tectonic load itself is insufficient to explain the observed basement deflection thus an extra subsurface load beneath the pyrenees corresponding to the underthrusted iberian lithosphere is required the effect of lithospheric stretching in the valencia trough on the ebro basin is appreciable only in its eastern part where the lithosphere was uplifted this had considerable repercussions on the sedimentary and erosional regime of the ebro basin we have analysed the link between the stretching related tectonically uplifted areas and the erosional patterns observed onshore northeast iberia

syntectonic burial and post tectonic exhumation of the southern pyrenees foreland fold thrust belt in the oligocene to earliest miocene the entire southern pyrenean foreland fold and thrust belt was backfilled and buried in up to 3 km of syntectonic continental conglomerates from the range9s own erosional debris then starting in the mid to late miocene the pyrenees were exhumed by erosional excavation to their present relief a model is proposed for this unusual development whereby late eocene oligocene tectonic uplift of the margins of the ebro basin raised local base level and blocked normal dispersal of erosional debris to adjacent oceans thus causing the basin to fill then backfill northwards across the entire southern flank of the pyrenees subsequent miocene rifting of the catalan mediterranean margin and the messinian salinity crisis lowered base level allowing the ebro river to cut headward capture the ebro basin and re excavate the pyrenees

lithospheric folding in iberia integration of stress indicator data gravity data crustal kinematics data and analysis of topography and recent vertical motions demonstrates the occurrence of consistently oriented spatial patterns of large scale alpine to recent intraplate deformation in iberia the inferred upper crustal and lithospheric deformation patterns and the timing of the associated expressions at or near the surface support the existence of a close coupling with plate boundary processes operating at the margins of iberia patterns of lithosphere and upper crustal folds are oriented perpendicular to the main axis of present day intraplate compression in iberia inferred from structural analysis of stress indicator data and focal mechanism solutions these findings suggest the presence of lithospheric folds with wavelengths compatible with theoretical predictions of folding wavelengths of variscan lithosphere stress induced intraplate deformation set up by plate interactions is compatible with indications for the absence of present day deep mantle lithosphere interactions inferred from seismic tomography

vertical structure of the venus cloud top from the vera and virtis observations onboard venus express abstract we investigate the venus cloud top structure by joint analysis of the data from visual and thermal infrared imaging spectrometer virtis and the atmospheric temperature sounding by the radio science experiment vera onboard venus express the cloud top altitude and aerosol scale height are derived by fitting virtis spectra at 4 5 m with temperature profiles taken from the vera radio occultation our study shows gradual descent of the cloud top from 67 2 1 9 km in low latitudes to 62 8 4 1 km at the pole and decrease of the aerosol scale height from 3 8 1 6 km to 1 7 2 4 km these changes correlate with the mesospheric temperature field in the cold collar and high latitudes the cloud top position remarkably coincides with the sharp minima in temperature inversions suggesting importance of radiative cooling in their maintenance this behaviour is consistent with the earlier observations spectral trend of the cloud top altitude derived from a comparison with the earlier observations in 1 6 27 m wavelength range is qualitatively consistent with sulphuric acid composition of the upper cloud and suggests that particle size increases from equator to pole

topographical and local time dependence of large stationary gravity waves observed at the cloud top of venus the existence of large stationary gravity waves was discovered during akatsuki s first observation sequence in 2015 in this study the further detection of large stationary gravity waves in brightness temperature images over a 1 5 year period is reported the waves periodically appeared mostly above four specific highland regions in the low latitudes when these regions were in the local afternoon the wave amplitudes attenuated after the wave locations passed beyond the evening terminator and the locations of the waves tended to slowly drift eastward over their lifetimes the appearances of stationary waves depend not only on surface topography but also on latitude and local time suggesting that solar heating during the daytime and atmospheric structure affected by solar heating may control the excitation and propagation of stationary waves

sea level events in the south pacific linked with the messinian salinity crisis cores drilled through the carbonate cap of niue a mid oceanic carbonate platform in the south pacific contain an unusually well resolved stratigraphic section of the latest miocene at 35 to 140 m depth below sea level intensely leached and chalky intervals associated with pronounced 18 o and 13 c depletions mark the position of dissolution unconformities representing eight episodes of eustatic falls that outstripped the local rate of subsidence we demonstrate on the basis of sr isotope chronostratigraphy that these eustatic changes are correlative with the messinian salinity crisis events in the mediterranean sea level changes of about 10 m amplitude commenced at 6 14 ma and culminated in a large sea level fall that reached at least 30 m at 5 26 ma corresponding to the miocene pliocene boundary evaluation of the sea level history reported here and the contemporaneous mediterranean events supports the model of coupling between tectonic and eustatic factors that caused the onset and demise of the salinity crisis the available evidence suggests that during messinian time glacio eustatic falls and rises are likely to have modulated the connection between the atlantic and the mediterranean and influenced the evaporite deposition and may have contributed significantly to the final phase of isolation and desiccation of the mediterranean and its subsequent refilling during the zan clean deluge

planetary boundary layer and slope winds on venus few constraints are available to characterize the deep atmosphere of venus though this region is crucial to understand the interactions between surface and atmosphere on venus based on simulations performed with the ipsl venus global climate model the possible structure and characteristics of venus planetary boundary layer pbl are investigated the vertical profile of the potential temperature in the deepest 10 km above the surface and its diurnal variations are controlled by radiative and dynamical processes the model predicts a diurnal cycle for the pbl activity with a stable nocturnal pbl while convective activity develops during daytime the diurnal convective pbl is strongly correlated with surface solar flux and is maximum around noon and in low latitude regions it typically reaches less than 2 km above the surface but its vertical extension is much higher over high elevations and more precisely over the western flanks of elevated terrains this correlation is explained by the impact of surface winds which undergo a diurnal cycle with downward katabatic winds at night and upward anabatic winds during the day along the slopes of high elevation terrains the convergence of these daytime anabatic winds induces upward vertical winds that are responsible for the correlation between height of the convective boundary layer and topography

investigation of air temperature on the nightside of venus derived from virtis h on board venus express abstract we present the spatial distribution of air temperature on venus night side as observed by the high spectral resolution channel of virtis visible and infrared thermal imaging spectrometer or virtis h on board the esa mission venus express the present work extends the investigation of the average thermal fields in the northern hemisphere of venus by including the virtis h data we show results in the pressure range of 100 4 mbar which corresponds to the altitude range of 65 80 km with these new retrievals we are able to compare the thermal structure of the venus mesosphere in both hemispheres the major thermal features reported in previous investigations i e the cold collar at about 65 70 s latitude 100 mbar pressure level and the asymmetry between the evening and morning sides are confirmed here by comparing the temperatures retrieved by the virtis spectrometer in the north and south we find that similarities exist between the two hemispheres solar thermal tides are clearly visible in the average temperature fields to interpret the thermal tide signals otherwise impossible without day site observations we apply model simulations using the venus global circulation model venus gcm lebonnois s hourdin f forget f eymet v fournier r 2010b international venus conference aussois 20 26 june 2010 of the laboratoire de meteorologie dynamique lmd we suggest that the signal detected at about 60 70 latitude and pressure of 100 mbar is a diurnal component while those located at equatorial latitudes are semi diurnal other tide related features are clearly identified in the upper levels of the atmosphere

altimetry of the venus cloud tops from the venus express observations 1 simultaneous observations of venus by visible and infrared thermal imaging spectrometer and venus monitoring camera onboard the venus express spacecraft are used to map the cloud top altitude and to relate it to the ultraviolet uv markings the cloud top altitude is retrieved from the depth of co2 absorption band at 1 6 m in low and middle latitudes the cloud top is located at 74 1 km it decreases poleward of 50 and reaches 63 69 km in the polar regions this depression coincides with the eye of the planetary vortex at the same latitude and hour angle cloud top can experience fast variations of about 1 km in tens of hours while larger long term variations of several kilometers have been observed only at high latitudes uv markings correlate with the cloud altimetry however the difference between adjacent uv dark and bright regions does not exceed several hundred meters surprisingly co2 absorption bands are often weaker in the dark uv features indicating that these clouds may be a few hundred meters higher or have a larger scale height than neighboring clouds ultraviolet dark spiral arms which are often seen at about 70 correspond to higher altitudes or to the regions with strong latitudinal gradient of the cloud top altitude cloud altimetry in the polar region reveals the structure that correlates with the thermal emission maps but is invisible in uv images this implies that the uv optically thick polar hood is transparent in the near ir

escarpment evolution on high elevation rifted margins insights derived from a surface processes model that combines diffusion advection and reaction experiments with a surface processes model of large scale 1 1000 km long term 1 100 m y erosional denudation are used to establish the controls on the evolution of a model escarpment that is related to the rifting of a continent the model describes changes in topographic form as a result of simultaneous short and long range mass transport representing hillslope diffusive processes and fluvial transport advection respectively fluvial entrainment is modeled as a first order kinetic reaction which reflects the credibility of the substrate and therefore the fluvial system is not necessarily carrying at capacity one dimensional and planform models demonstrate that the principal controls on the evolution of an initially steep model escarpment are 1 antecedent topography drainage 2 the timescale or equivalently a length scale in the fluvial entrainment reaction 3 the flexural response of the lithosphere to denudation and 4 the relative efficiencies of the short and long range transport processes when rainfall and substrate lithology are uniform a significant amount of discharge draining over the escarpment top causes it to degrade only when the top of the model escarpment coincides with a drainage divide can escarpment retreat occur for these conditions an additional requirement for retreat of a model escarpment without decline is a long reaction time scale for fluvial entrainment this corresponds to a substrate that is hard to detach by fluvial erosion and therefore to fluvial erosion that is not transport limited continuous backtilting of an escarpment due to flexural isostatic uplift in response to denudational unloading helps maintain the scarp top as a divide it is essential if the escarpment gradient is to be preserved during retreat in a uniform lithology low flexural rigidities promote steep and slowly retreating escarpments for given rainfall and substrate conditions the morphology of a retreating model escarpment is determined by the ratio of the short range diffusive and long range advective transport efficiencies a low ratio which is interpreted to correspond to a relatively arid climate and weathering limited conditions promotes steep sharp topped escarpments with straight main slopes and escarpment retreat occurs over a wide range of height scales a high ratio interpreted to correspond to a more humid temperate climate produces a convex upper slope and concave lower slope morphology and only major escarpments are predicted to preserve a high scarp gradient lithological contrasts in the model produce more complex morphologies and predict the formation of scarps crowned by an erosionally resistant caprock however resistant caprocks are not an essential requirement for model scarps to retreat we conclude that the inferred controls and model behavior are both consistent with the present day morphology of rifted continental margins and with modern conceptual models of landscape evolution

palustrine sedimentation in an episodically subsiding basin the miocene of the northern teruel graben spain lacustrine deposits form most of the sedimentary record accumulated throughout the miocene in the northern part of the teruel graben a landlocked basin situated in ne spain three main stratigraphic units units i iii spanning late vallesian to late turolian in age are distinguished in the area the two former units comprise mainly carbonate lacustrine deposits that were deposited in a palustrine or a more permanent but shallow lacustrine setting the latter being related mainly to periods of lake expansion under more humid and cooler climatic conditions in contrast deposition of unit iii characterised by gypsiferous lacustrine sediments in central parts of the basin reflects the influence of source rocks of evaporitic nature upper triassic formations that were emplaced by diapiric uplift in the eastern margin during the middle turolian carbonate lake sediments belonging to units i and ii consist of four main lithofacies associations a distal alluvial lake margin deposits b lacustrine carbonates and pedogenically modified lacustrine carbonates c carbonate fill channels and d organic rich marlstone and carbonate marshes lithofacies association a shows typically a sequential arrangement formed from bottom to top of red mudstone carbonate palaeosols and biomicrite beds sequence type 1a these sequences are interpreted as a result of slow but continuous aggradation of the floodplain areas and subsequent rise of the water table probably reflecting equilibrium between subsidence and sedimentation lithofacies association b consisting of biomicrite beds passing upward into palaeosols sequence type 1b is thought to be caused by marked pulses of tectonic subsidence that created the accommodation space required for fast development of a carbonate lake carbonate fill channels showing erosive lower surfaces dig out on previous channels marsh deposits and or lacustrine carbonates exhibit well developed prismatic structure at their bed tops the sequential arrangement suggests similar tectonic constrains than the envisaged for lithofacies 1b the comparison of depositional styles of the lake systems with the palaeoclimatic evolutionary pattern of the basin throughout the miocene indicates that the combined effect of tectonism climate and source rock played a major role in the stratigraphic framework of the basin during this period

interplay between tectonics climate and fluvial transport during the cenozoic evolution of the ebro basin ne iberia 1 three dimensional modeling that integrates fluvial sediment transport crustal scale tectonic deformation and lithospheric flexural subsidence is carried out to simulate the landscape and drainage evolution of the ebro sedimentary basin ne iberia the ebro basin underwent a long period of closed intramountain drainage as a result of tectonic topography generation at the pyrenees the iberian range and the catalan coastal range in the late oligocene the catalan coastal range underwent extension leading to the formation of the valencia trough nw mediterranean but the ebro basin remained closed for nearly 15 myr more before the ebro river cut through the remnants of the topographic barrier this drainage opening caused widespread basin incision that shaped spectacular outcrops of the syntectonic and posttectonic infill here we investigate the processes controlling these major drainage changes the modeling results constrained by a large data set on the tectonic and transport evolution of the area predict a closed phase characterized by a large lake in the central eastern ebro basin dry climatic conditions probably lowered the lake level and contributed together with rift flank uplift to prolong this endorheic basin stage the age and amount of reworked sediment after the opening are consistent with an onset of basin incision between 13 and 8 5 ma as a result of lake capture by escarpment erosion and lake level rise associated with sediment accumulation and wetter climatic conditions sea level changes in the mediterranean had no major impact in the large scale drainage evolution of the ebro basin index terms 1625 global change geomorphology and weathering 1824 1886 1815 hydrology erosion and sedimentation 3210 mathematical geophysics modeling 3344 meteorology and atmospheric dynamics paleoclimatology 8102 tectonophysics continental contractional orogenic belts keywords pyrenees drainage evolution lake sediment budget erosion flexure

galileo infrared imaging spectroscopy measurements at venus during the 1990 galileo venus flyby the near infaied mapping spectrometer investigated the night side atmosphere of venus in the spectral range 0 7 to 5 2 micrometers multispectral images at high spatial resolution indicate substanmial cloud opacity variations in the lower cloud levels centered at 50 kilometers altitude zonal and meridional winds were derived for this level and are consistent with motion of the upper branch of a hadley cell northern and southern hemisphere clouds appear to be markedly different spectral profiles were used to derive lower atmosphere abundances of water vapor and other species

atmospheric responses to north atlantic sst anomalies in idealized experiments part ii north american precipitation abstractthis is the second part of a two part paper that addresses deterministic roles of the sea surface temperature sst anomalies associated with the atlantic multidecadal oscillation amo in variations of atmospheric circulation and precipitation in the northern hemisphere using a sequence of idealized model runs at the spring equinox conditions this part focuses on the effect of the sst anomalies on north american precipitation major results show that in the model setting closest to the real world situation a warm sst anomaly in the north atlantic ocean causes suppressed precipitation in central western and northern north america but more precipitation in the southeast a nearly reversed pattern of precipitation anomalies develops in response to the cold sst anomaly further examinations of these solutions reveal that the response to the cold sst anomaly is less stable than that to the warm sst anomaly the former is dynamically charged in the sense that positive eddy kinetic energy eke

potential vorticity of the south polar vortex of venus venus atmosphere shows highly variable warm vortices over both of the planet s poles the nature of the mechanism behind their formation and properties is still unknown potential vorticity is a conserved quantity when advective processes dominate over friction and diabatic heating and is a quantity frequently used to model balanced flows as a step toward understanding the vortices dynamics we present maps of ertel s potential vorticity epv at venus south polar region we analyze three configurations of the south polar vortex at the upper cloud level p 240 mbar z 58 km based on our previous analyses of cloud motions and thermal structure from data acquired by the visual and infrared thermal imaging spectrometer instrument on board venus express additionally we tentatively estimate epv at the lower cloud level p 2200 mbar z 43 km based on our previous wind measurements and on static stability data from pioneer venus and the venus international reference atmosphere vira model values of epv are on the order of 10 6 and 10 8 k m2 kg 1 s 1 at the upper and lower cloud levels respectively being 3 times larger than the estimated errors the morphology observed in epv maps is mainly determined by the structures of the vertical component of the relative vorticity this is in contrast to the vortex s morphology observed in 3 8 or 5 m images which are related to the thermal structure of the atmosphere at the cloud top some of the epv maps point to a weak ringed structure in the upper cloud while a more homogenous epv field is found in the lower cloud

crustal structure and orogenic material budget in the west central pyrenees surface and subsurface data are combined to construct a crustal scale cross section of the western central pyrenees france and spain at the boundary between the european and iberian plates the position of moho reflections in the ecors arzacq reflection profile suggests a tectonic wedge of european crust and upper mantle had indented the iberian plate at lower crustal levels the european wedge is overlain by an upper iberian wedge thus constituting a double stacked wedge geometry the upper wedge was delaminated and deformed giving rise to the pyrenean orogenic prism manifested as a bivergent fan in upper crustal levels the underthrust lower iberian plate has been imaged to depths of 55 60 km but crustal budget considerations based on a palinspastic reconstruction require that this continental root subducted to depths up to 90 km total orogenic contraction calculated from surface structures is about 75 80 km which was accomplished between the latest cretaceous and the early miocene at an averaged rate of 1 2 mm yr consistent with these moderate values exhumation of the orogen is much less than in the more shortened eastern parts of the range paleozoic basement and preorogenic mesozoic rocks are little eroded and much of the exhumation involved cannibalization of early foreland basins which once covered the entire poorly emergent orogen at this transect this resulted in a continuous process of sediment recycling and coupled with a considerable lateral arrival of material a bulk negative erosion sedimentation budget