effect of salt exclusion from lake ice on seasonal circulation we describe the circulation of tailings lake located 220 km north of yellowknife northwest territories canada from jul 2004 to sep 2007 temperature and conductivity profiles were collected together with data from three moored temperature chains and a meteorological station the salt content of the lake was elevated salinity 1gl 21 relative to surrounding natural waters 0 1 g l21 winter ice cover included 60 80 cm of transparent black ice which excluded up to 99 of the salt from the water as the ice formed during winter the salt excluded from the ice was mixed throughout the water column under the ice in spring ice melt and snow runoff resulted in a freshwater cap the density contrast between this fresh epilimnion and the more saline hypolimnion was sufficient to inhibit spring turnover in summer the epilimnion was deepened by storms mixing anoxic water from the hypolimnion into the surface layer because spring turnover was suppressed oxygen replenishment of the hypolimnion occurred only in fall although tailings lake has been subject to numerous anthropogenic changes similar effects can be expected in other natural and manmade water bodies with elevated salinity and significant ice cover

morphodynamic modeling of the basal boundary of ice cover on brackish lakes 1 the analysis considers a cold region brackish lake that develops an ice cover on its surface in winter as the ice cover thickens due to freezing black ice grows on the bottom side the freezing process excludes the salt from the ice resulting in an increase in dissolved salt concentration in the lake water just below the bottom of the ice the density profile in this type of lake is then governed by two opposing factors the water temperature distribution generally produces a stable stratification whereas the excess salinity produced by exclusion tends to increase the density of the upper layers of the lake resulting in an unstable contribution to stratification competition between these two factors can lead to unstable density gradients so an initially motionless lake with a slowly thickening plane ice cover develops a convective flow field this flow field can then feed back into the evolution of the morphology of the ice cover itself resulting in a morphodynamic interaction between water and ice this paper aims at investigating this morphodynamic instability a mathematical model for the stability of a lake covered with an initially plane ice cover growing in time is proposed here the results reveal threshold values of the main dimensionless parameters expressed in the form of rayleigh numbers and in particular define a ratio between buoyancy effects and diffusivity that governs neutral stability conditions when the system is unstable i e for rayleigh numbers above 103 depending on the values of the input parameters the analysis predicts the growth of convective flow circulation cells responsible for the morphodynamic evolution of the ice water interface

the antarctic viewpoint of the central paratethys cause timing and duration of a deep valley incision in the middle miocene alpine carpathian foredeep of lower austria global glacio eustatic sea level changes massively influenced the depositional history of the central paratethyan region here we correlate middle miocene global 18o shifts with ice volume changes on antarctica and sea level changes with corresponding phases of erosion valley incision and deposition in the lower austrian part of the alpine carpathian foredeep this allows the exact dating of the valley formation two periods of positive 18o shifts resulted in sea level drops of about 60 and 40 m respectively the first drop in the late langhian middle badenian at c 13 9 ma mi3b was fast and caused severe erosion on the emerged foredeep in a second less pronounced step around 13 0 ma mi4 in the middle serravallian late badenian the base level was further deepened after a period of alternating erosion and deposition the combined sea level change 80 120 m fits well with the maximum thickness of sarmatian sediments drilled within incised valley 110 m the global sea level falls affected not only the geological history of the foredeep the intensive erosion valley incision is combined with delta progradation in the adjacent vienna basin due to this massive sea level drop the interruption of marine connections resulted in vast salt deposits and faunal crises within the central paratethys during this time

paleoenvironmental evolution of central paratethys sea and lake pannon during the cenozoic abstract deep wells penetrated cenozoic sedimentary record of two different basins 1 oligocene retro arc basin which is buried under the 2 miocene back arc danube basin this study is focused on biotic and abiotic proxies discussed in terms of existing biostratigraphical paleoenvironmental and sedimentological data biotic proxies are represented by palynofacies and biomarkers palynomorphs aom phytoclasts toc pr ph ratio steranes abiotic proxies are represented by inorganic geochemistry e g cia sr ba ga rb th u sio2 al2o3 corg p and enrichment factors the biotic and abiotic proxies helped to refine the knowledge about the changes in redox conditions salinity depositional system and paleoclimate in the study area five temporally different environments are observed 1 sedimentation in the oligocene fragment of the retro arc hungarian paleogene basin that took place on a highly proximal part of the shelf a major dysoxic event connected with humid marsh environment is documented within last rupelian transgression ru4 ch1 ch2 2 after a hiatus the danube basin initiated with early badenian langhian stable oxic to slightly dysoxic shelf with minor salinity changes lan2 ser1 ser2 transgression 3 late badenian early serravallian dysoxic deposition similar in all basins of the central paratethys was influenced by upwelling connected with the ser2 ser3 transgression 4 sarmatian late serravallian dysoxic event associated with subsequent flooding ser3 ser4 tor1 which created shallow marginal marine environment 5 pannonian tortonian messinian sedimentation took place on an oxic shelf of the lake pannon near a fluvio deltaic source most likely represented by the paleo danube delta system

cyclic paleo salinity changes inferred from benthic foraminiferal assemblages in the upper burdigalian lower miocene korneuburg basin austria abstract the late burdigalian karpatian korneuburg basin gives an excellent insight into the continuous modification of its paleo environments and paleo ecology and therefore into its dynamics over geological time scales the investigated outcrops provided a unique opportunity to study the change of foraminiferal assemblages in an early miocene estuarine marine system as a response to climate precipitation oscillations to this end we studied foraminiferal assemblages ostracods provided additional information paleo salinities were estimated by applying a transfer equation using modern frequency distributions of indicative foraminiferal taxa this technique is used here for the first time to reconstruct salinity in the past and may facilitate further studies in shallow water paleo environments elsewhere on the basis of the recorded benthic foraminiferal assemblages their modern distribution and several diversity indices fisher shannon dominance evenness we were able to discriminate between five paleo environments paleo salinity was the most important environmental factor that governed the distribution of taxa in the korneuburg basin low diverse brackish environments yielded ammonia and aubignyna slightly reduced salinity conditions are dominated by ammonia with additional taxa and are more diverse normal marine salinities are indicated by the dominance of heterolepa gyroidinoides or bulimina and go along with a more balanced assemblage composition hypersaline conditions are characterized by cycloforina and ammonia and an intermediate diversity distribution freshwater samples are free of benthic foraminifera environmental changes and consequent ecological stress resulted in an overall low diverse paleo ecosystem salinity variations are interpreted as being caused by freshwater influx into the system seventeen combined increases and decreases of paleo salinity indicate a coupling with obliquity cycles and a linkage to regional climate changes the estuarine system of the korneuburg basin that lasted over 700 000 years shows distinct effects of the regional climate regimes on the local micro fauna

gratkorn a benchmark locality for the continental sarmatian s str of the central paratethys this paper presents one of the richest and most complete vertebrate faunas of the late middle miocene 12 ma of central europe up to now sixty two vertebrate taxa comprising all major groups fishes amphibians reptiles birds mammals have been recorded based on sedimentological and palaeobiological evidences this fossillagerstatte is assumed to originate from a floodplain paleosol formed on top of a braided river sequence the fauna points to a highly structured somewhat vegetated landscape with a wide array of habitats e g fluvial channels sporadically moist floodplains short lived ponds savannah like open areas and screes it was preserved due to a rapid drowning and the switch to a freshwater lake environment palaeoclimatological data derived from pedogenic features as well as from biota indicate an overall semi arid subtropical climate with distinct seasonality mean annual precipitation 486 252 mm mean annual temperature 15 c this underlines the late middle early late miocene dry spell in central europe from taphonomical point of view the irregularly distributed but roughly associated larger vertebrate remains refer to an in situ accumulation of the bone bed splintered bones gnawing marks as well as rhizoconcretions and root corrosion structures record some pre and post burial modification of the taphocoenose however the findings of pellet remains argue for a very fast burial and thus to a low degree of time averaging for this reason the fossil fauna reflects the original vertebrate community rather well and is a cornerstone for the understanding of late middle miocene terrestrial ecosystems in this region certainly gratkorn will be one of the key faunas for a high resolution continental biostratigraphy and the comprehension of europe s faunal interchanges near the middle late miocene transition

paleobiogeography of scleractinian reef corals changing patterns during the oligocene miocene climatic transition in the mediterranean abstract during the oligocene miocene greenhouse to icehouse climatic transition the biogeography of reef corals or zooxanthellate like scleractinian corals was gradually changing from a pan tropical tethyan province in the eocene to three reef coral provinces of the western atlantic caribbean indo pacific and mediterranean our reefcoral database encompasses updated and homogenized data on paleoenvironmental and systematics of scleractinian corals occurring in the oligocene and miocene outcrops from circum mediterranean regions provided by most of relatively recently published data in the literature and by the study of published and unpublished collections of coral specimens from the same area including the important collections housed at the mnhn paris and our own collections as there is no validated direct criterion for the identification of the coral zooxanthellate symbiosis in the fossil record and considering the difficulty to use the biogeochemical approaches in the context of this study the subjectivity of the morphological criteria and the relative recent age of the fossil corals we are dealing with a uniformitarian approach has been used for inferring the symbiotic status of scleractinian genera in reefcoral among the 158 genera included in our database 93 can be considered as zooxanthellate and 10 have a doubtful zooxanthellate status this relatively exhaustive database was used to reconstruct the temporal and spatial distribution of scleractinian corals in the mediterranean during the oligocene miocene time in order to discuss the interplaying effects of the global cooling at that time the re organization of the tethyan realm resulting from the african arabian and eurasian plate collision and the emergence of the alpine chains driving the gradual northward movement of the whole region outside the tropical subtropical belt it is shown that the structure of the mediterranean z coral oligocene miocene paleobiodiversity was characterized by many geographically restricted genera with a moderate to short stratigraphical range and a few long ranging widespread genera a major consequence of this structure is that the extinction pattern has proceeded through the preferential extinction of rare occurrence genera through time the potential rapid long distance dispersal of most coral larvae compared to the size of the oligocene miocene mediterranean explains why no biogeographical subprovinces can be distinguished for the z coral fauna on a local scale ecological processes tend to sort coral taxa by limiting z coral development to geographically restricted and discontinuous areas this accounts for the large amount of geographically restricted taxa forming the mediterranean coral fauna the interaction of plate tectonics alpine orogenesis and climate at local to subregional scales exerts strong controls over the spatio temporal distribution of z coral assemblages within the circum mediterranean realm in particular we suggest that the richness and composition of the eastern atlantic coral fauna are indirectly related to the opening and closure of the eastern seaway connection with the indian ocean which controlled the e w circulation of surface waters and hence the westwards dispersal of pelagic larvae at the scale of the whole region the gradual regional climatic change produced by the northwards migration of the entire area superimposed on the global cooling appears in large part responsible for the extinction pattern of z corals through time in the mediterranean biogeographical province

coeval lower miocene subsidence of the eisenstadt basin and relative updoming of its austroalpine frame implications from high resolution geophysics at the oslip section northern burgenland austria a fault system southeast of eisenstadt was investigated with high resolution geophysics using electric resistivity tomography seismics and gravimetry the st margarethen fault separates the neogene succession of the eisenstadt basin from the north south trending rust range which belongs to the austroalpine frame the interpretation of profiles down to a depth of 350 m derived from reflection and refraction seismics combined with the density model along the oslip road section clearly reveals a listric fault which dips westward towards the eisenstadt basin bed thickness of growth strata regularly increases from west to east and normal fault drags visible in the seismic profile west of the st margarethen fault allow for interpreting this structure as a hanging wall syncline thickness distribution of neogene deposits reveals that the eisenstadt basin can be interpreted as a half graben bounded by the listric st margarethen normal fault which developed at the western flank of rust range the subsidence of the eisenstadt basin during lower to middle sarmatian times was accompanied by concurrent updoming of the rust range of at least 70 m for the mechanism of the updoming of the rust range footwall uplift during hanging wall subsidence is inferred

the age of the sarmatian pannonian transition in the transylvanian basin central paratethys abstract a marked paleoenvironmental change took place at the beginning of the late miocene in the central paratethys with dominantly marine sarmatian successions grading rapidly into mainly brackish pannonian deposits a long and excellently exposed section comprising the sarmatian pannonian transition has been investigated at oarba de mures in the transylvanian basin romania in this paper we focus on both radiometric and magnetostratigraphic dating to provide a chronology for the sarmatian pannonian transition in transylvania two volcaniclastic layers located approximately 40 m below the sarmatian pannonian transition yield excellent 40ar 39ar ages the weighted mean plateau age for biotite and sanidine separates provided isotopic ages of 11 62 0 12 ma and 11 65 0 13 ma this implies deposition during the magnetic chron c5r 2r which is in agreement with the magnetostratigraphic results of the oarba de mures composite section rock magnetic analyses indicate greigite as the main magnetic carrier with characteristics very similar to the magnetosomal greigite found in the carpathian foredeep the newly obtained chronology at oarba de mures constrains the age of the sarmatian pannonian transition in the transylvanian basin to 11 3 0 1 ma slightly younger than the 11 61 ma postulated in the styrian and vienna basins

palaeoenvironmental reconstruction of the sarmatian middle miocene central paratethys based on palaeontological and geochemical analyses of foraminifera ostracods gastropods and rodents paleoenvironmental changes in the upper middle miocene central parathetys were reconstructed by using qualitative and quantitative palaeontological analyses of foraminifera and ostracods coupled with trace elemental mg ca and stable isotope delta 18 o and delta 13 c analyses of their carbonate skeletons and of gastropod sheets mean annual air temperatures were estimated using the oxygen isotope composition of contemporaneous rodent teeth the studied aquatic fossils come from two boreholes in the zsambek basin northern central hungary while the terrestrial ones are from localities in ne hungary and e romania in the studied sarmatian successions three zones could be distinguished based on palaeontological and geochemical results at the badenian sarmatian boundary faunal diversity decreased markedly in the lower zone a transgressive event culminated in a seawater incursion into the semi open basin system of the central paratheys stable bottom water temperature similar to 15 degrees c and variable salinites 20 22 are estimated for the early sarmatian sea the faunal changes notably a strong reduction in biodiversity occuring at the boundary between the lower and the middle zone can be explained by a sea leval highstand with dysoxic conditions a relative sea level fall is documented at the end of this middle zone after a short regressive event a marine connection between the paratethys and mediterranean was established at the beginning of the upper zone this is indicated by an increased microfaunal diversity and the re appearance of marine bademan ostracods and foraminifera which are completely absent from the older samatian series during the upper zone the temperatures and salmities are estimated to have fluctuated from 15 degrees c to 21 degrees c and from 15 parts per thousand to 43 parts per thousand respectively

a limnic ostracod fauna from the surroundings of the central paratethys late middle miocene early late miocene styrian basin austria abstract aquatic biota of the marine middle miocene paratethys and the late miocene pannonian lake a long lived lake in central and eastern europe are well known however knowledge of the marginal freshwater environments is still rather poor recently a thin shelled ostracod fauna was discovered in late sarmatian to early pannonian sediments of a clay pit at the northern margin of the styrian basin st stefan n graz 11 taxa are described taxonomically of which some are left in open nomenclature due to insufficient preservation vestalenula cylindrica straub 1952 paracandona cf euplectella robertson 1889 candona camptocypria gratkornensis n sp candona sp cf candonopsis arida sieber 1905 cypria sp cyclocypris nitida sieber 1905 cf bradleystrandesia reticulata zaddach 1844 stenocypris sp cypridopsis sp striate ostracod sp the ostracod associations point to a shallow sometimes richly vegetated limnic environment indications of a warm maybe subtropical climate are suggested by the occurrences of vestalenula cf candonopsis cypridopsis and stenocypris the ostracod fauna indicates a freshwater environment detached from the marine sarmatian sea and respectively from the brackish pannonian lake and provides hereby an insight into the palaeohabitats of the surrounding wetlands

correlations of cave levels stream terraces and planation surfaces along the river mur timing of landscape evolution along the eastern margin of the alps the transition zone of the eastern alps to the pannonian basin provides one of the best sources of information on landscape evolution of the eastern alpine mountain range the region was non glaciated during the entire pleistocene thus direct influence of glacial carving as a landscape forming process can be excluded and relics of landforms are preserved that date back to at least the late neogene in this study we provide a correlation between various planation surfaces across the orogen basin transition in particular we use stream terraces planation surfaces and cave levels that cover a vertical spread of some 700 m our correlation is used to show that both sides of the transition zone uplifted together starting at least about 5 ma ago for our correlation we use recently published terrestrial cosmogenic nuclide tcn burial ages from cave sediments new optically stimulated luminescence osl ages of a stream terrace and u th ages from speleothems minimum age constraints of cave levels from burial ages of cave sediments covering the last 4 ma are used to place age constraints on surface features by parallelizing cave levels with planation surfaces the osl results for the top section of the type locality of the helfbrunn terrace suggest an early wurm development 80 5 3 7 to 68 7 4 0 ka the terrace origin as a penultimate gravel deposit in classical alpine terminology riss is therefore questioned u series speleothem ages from caves nearby indicate formation during marine isotope stages mis 5c and 5a which are both interstadial warm periods as osl ages from the terrace also show a time of deposition during mis 5a ending at the mis 5 4 transition this supports the idea of temperate climatic conditions at the time of deposition in general tectonic activity is interpreted to be the main driving force for the formation and evolution of these landforms whilst climate change is suggested to be of minor importance obvious hiatuses in miocene to pleistocene sediments are related to ongoing erosion and re excavation of an uplifting and rejuvenating landscape

badenian sarmatian chronostratigraphy in the polish carpathian foredeep abstract the miocene of the northern part of the polish carpathian foredeep contains a record of events particularly important in the evolution of the central paratethys basin there the paratethyan badenian salinity crisis resulted in the deposition of evaporite gypsum deposits of the krzyzanowice formation the ensuing post evaporite marine badenian deposition is recorded by the marly pecten beds the transition to the overlying clays of the syndesmya beds represents the initial deterioration of normal marine conditions within the basin and is associated with the disappearance of typical stenohaline faunal components during the badenian sarmatian extinction event and the subsequent appearance of endemic sarmatian taxa the history of these paratethyan events has hitherto been only poorly dated new 40ar 39ar dating of biotite and volcanic glass from a rhyolite tuff within the pecten beds babczyn 2 core constrains its depositional age to 13 06 0 11 ma this age suggests that the faunal extinction presumably took place after 13 06 0 11 ma and that the salinity crisis ended before then this result is consistent with other reliable radiometric age constraints that collectively suggest that the crisis began shortly after 13 81 0 08 ma de leeuw et al 2010 and that evaporite deposition took place ca 13 60 0 07 ma de leeuw et al 2010 both the badenian evaporites and the pecten beds in carpathian foredeep are thus serravallian in age and represent the lower part of neogene nannoplankton zone 6 nn 6

climate changes in the early to middle miocene of the central paratethys and the origin of its echinoderm fauna abstract this study uses echinoderm diversity to assess climatic changes in the early to middle miocene of the central paratethys it is based mainly on a taxonomically standardised dataset of central paratethys echinoids supplemented by data on asteroid ophiuroid crinoid and holothuroid distributions potential constraints of the raw diversity data are explored and possible biases are identified these include a heterogeneous rock record in terms of outcrop area and facies of the preserved sedimentary rocks stage duration and sampling bias the latter was overcome by utilising rarefaction analysis to investigate species richness these analyses show that the patterns observed in the raw data are robust and not severely biased by sampling intensity the potential influence of a heterogeneous rock record was assessed by comparing surface outcrop areas of the various stages to standing diversity a second bias involving a heterogeneous rock record the non preservation of distinct habitats was overcome by carrying out within habitat comparison of standing diversity and faunal composition the observed patterns were therefore established as true signals rather than artefacts produced by various biases consequently echinoderm diversity is used to evaluate climate changes during the neogene of the central paratethys as well as to interpret minimum winter and summer sea surface temperatures in the badenian middle miocene climatic conditions during the deposition of the badenian leitha limestone were addressed along with the presence of n s gradients within the central paratethys the presently available data suggest warm temperate conditions for the late eggenburgian early burdigalian followed by a brief temperature drop in the ottnangian early late burdigalian temperatures increased again in the karpatian and a climatic optimum was reached in the early badenian a slight cooling during the middle badenian was reflected by the southwards shift of predominantly temperate genera from the northern fringes of the central paratethys in the early badenian to the central parts in the late badenian the faunal gradients observed in the early badenian of the central paratethys suggest that the boundary between the warm temperate and tropical zone lay somewhere within the paratethys at that time considering the more southerly position of the study area about 34 palaeolatitude in the early middle miocene this implies that the tropical climate zone was much wider during the early middle miocene than today biogeographic investigations of the central paratethyan echinoid faunas show that the overwhelming part of the central paratethys echinoid species are immigrants from the mediterranean area immigration occurred in three distinct waves during the late eggenburgian the karpatian and early badenian while no common echinoid species were identified between the boreal region and the central paratethys two species of asteroids from the northern most fringes of the central paratethys also occur in the north sea basin endemism is low in most of the stages except for the ottnangian when geodynamic processes and global cooling resulted in a large scale re organisation of central paratethyan faunas

the myth of the brackish sarmatian sea the biota of the 1 5 ma period of the middle miocene sarmatian of the central paratethys lack stenohaline components this was the reason to interpret the sarmatian stage as transitional between the marine badenian and the lacustrine pannonian stages however our new data indicate that brackish water conditions could not have prevailed sarmatian foraminifera molluscs serpulids bryozoans dasycladacean and corallinacean algae as well as diatoms clearly indicate normal marine conditions for the entire sarmatian during the lower sarmatian however a sea level lowstand forced the development of many marginal marine environments during the late sarmatian a highly productive carbonate factory of oolite shoals mass occurrences of thick shelled molluscs and larger foraminifera as well as marine cements clearly point to normal marine to hypersaline conditions this trend is not restricted to the western margin of the pannonian basin system but can be observed in the entire central and even eastern paratethys

paleobiogeography and historical biogeography of the non marine caenogastropod family melanopsidae abstract we investigate the distributions of representatives of the family melanopsidae gastropoda caenogastropoda cerithioidea from the late cretaceous to present day the present contribution discusses and partly revises former schemes of melanopsid dispersal during the cenozoic all of which were based on outdated stratigraphic and tectonic concepts as well as an incompletely considered fossil record conflating a comprehensive and stratigraphically well constrained fossil record modern paleogeographical reconstructions and contemporary climate data our goal is to present a thorough model of melanopsid distribution and its changes over the cenozoic as well as its paleogeographical and climatic constraints the family melanopsidae evolved about 90 ma ago in the late turonian from brackish cerithioidean ancestors cretaceous and paleogene species occur in marginal marine to brackish environments along the shores of the tethys and paratethys seas the extant clades of melanopsis likely derive from the evolution of freshwater melanopsis on the balkan peninsula back in the late early miocene up to the pliocene freshwater species spread toward southwestern and southeastern europe and successively replaced brackish water representatives paralleling a general decline of latter systems during the late cenozoic the southwards expansion of melanopsis and its simultaneous retreat from northern latitudes resulted in the disjunct distribution pattern observed today the genus holandriana first appeared in northern italy in the late early miocene the genera microcolpia and esperiana both first occurred in the late miocene and likely derive from brackish water melanopsis species native to peri paratethyan lakes the present day biogeographic isolation of the three latter genera and melanopsis roots in the climatic deterioration and the disappearance of major lake systems in southeastern europe while thermophilous melanopsis retreated to the warm dry climates of the mediterranean and middle east holandriana microcolpia and esperiana adapted to the seasonal cold temperate climate of southeastern and eastern europe and some species became restricted to thermal springs

marine carbonate systems in the sarmatian middle miocene of the central paratethys the zsambek basin of hungary the study of eight stratigraphic sections at the margin of the semi enclosed zsa mbe k basin hungary allows the sedimentary anatomy of oolitic bioclastic systems in the sarmatian of the central paratethys to be reconstructed the mollusc foraminiferal and ostracod associations indicate that the carbonate systems are latest badenian to late sarmatian in age the lower upper sarmatian deposits are organized in superimposed subaqueous dunes prograding towards the basin on a low angle ramp during the late sarmatian the ramp underwent subaerial erosion linked to a moderate relative fall in sea level lagoonal deposits were later formed and microbial nubeculariid bryozoan serpulid buildups were emplaced the abnormal marine conditions of the sarmatian conducive to the development of a poorly diversified flora and fauna and dominant non skeletal grains are linked to fluctuating salinities mesotrophic to eutrophic conditions and perhaps high alkalinity

evolutionary mechanisms of the paratethys sea and its separation into the black sea and caspian sea abstract a possible mechanism leading to the transformation of the paratethys seas i e the sarmatian sea lake meotian sea pontian sea lake etc is here proposed the time period from the formation of the closed sarmatian sea lake to the present is also considered it will be shown that the main reason for the collapse of the sarmatian sea lake into the black and caspian seas was development of a canyon that cut through the mountains separating the black and mediterranean seas later this canyon was transformed into the bosporus and the dardanelles straits the canyon was formed mainly by erosive activity of a river that had periodically emerged from the paratethys abrasion of the canyon bottom and the related erosional lowering of its level led to gradual drainage of the paratethys basins the consequences of the messinian salinity crisis in the mediterranean sea contributed to the penetration of salt water into the paratethys and then to its temporary isolation and transformation into a closed sea lake later its level rose and the river was formed again that river flowed into the mediterranean sea in the process eroding its own bed during low levels of the world ocean the riverbed experienced increased erosion eventually dropping below high ocean level at which time the river was flooded by mediterranean water this process led to the formation of a corridor linking the seas together this corridor developed over the course of many glacioeustatic fluctuations in the world ocean

aeolian stratigraphy describes ice age paleoenvironments in unglaciated arctic alaska abstract terrestrial paleoenvironmental records with high dating resolution extending into the last ice age are rare from the western arctic such records can test the synchronicity and extent of ice age climatic events and define how arctic landscapes respond to rapid climate changes here we describe the stratigraphy and sedimentology of a yedoma deposit in arctic alaska the carter section dating to between 37 000 and 9000 calibrated radiocarbon years bp 37 9 ka and containing detailed records of loess and sand sheet sedimentation soil development carbon storage and permafrost dynamics alternation between sand sheet and loess deposition provides a proxy for the extent and activity of the ikpikpuk sand sea iss a large dune field located immediately upwind warm moist interstadial times ca 37 36 3 32 5 and 15 13 ka triggered floodplain aggradation permafrost thaw reduced loess deposition increased vegetation cover and rapid soil development accompanied by enhanced carbon storage during the last glacial maximum lgm ca 28 18 ka rapid loess deposition took place on a landscape where vegetation was sparse and non woody the most intense aeolian activity occurred after the lgm between ca 18 and 15 ka when sand sheets fringing the iss expanded over the site possibly in response to increasingly droughty conditions as summers warmed and active layers deepened with the exception of this lagged lgm response the record of aeolian activity at the carter section correlates with other paleoenvironmental records from unglaciated siberia and alaska overall rapid shifts in geomorphology soils vegetation and permafrost portray an ice age landscape where in contrast to the holocene environmental change was chronic and dominated by aeolian processes

the stable isotope archive of lake pannon as a mirror of late miocene climate change abstract lake pannon was a long lived miocene and pliocene lake system in central europe with a famous endemic mollusc fauna the radiation of melanopsid gastropods and dreissenid bivalves has been explained simply by the opportunity to settle empty ecological niches after the extinction of marine life at the end of the middle miocene this model however fails to explain the offset in the timings of evolutionary pulses in different mollusc families stable isotope data oxygen carbon indicate a strong climatic forcing on these radiations moreover the investigated time span covers the well known vallesian optimum and subsequent crises in european terrestrial ecosystems during the late miocene the new palaeoclimatic data on the strongly changing isotope patterns of mollusc aragonite of lake pannon might shed light on the mechanisms acting during this crucial period according to the new interpretation the early lake 11 6 ma was still influenced by the latest middle miocene dry spell this phase coincided with a pronounced radiation of melanopsid gastropods during the warm early late miocene 10 ma humidity increased and culminated in a phase with high summer precipitation this caused a reorganisation of the coastal deltaic faunas suppressing the radiation of melanopsids on the other hand high nutrient loads favoured the dispersion of filter feeding dreissenids despite steadily declining salinity lake pannon remained an alkaline lake with pronounced stratification that was apparently periodically disrupted only during the humid early late miocene a separation of the isotope data into genera and ecological guilds is the prerequisite for discussing overall trends of long lived lake systems

geodynamic impact on the stable isotope signatures in a shallow epicontinental sea analyses were made of a mollusc based meta dataset of 859 d 13 c and d 18 o data of miocene nearshore settings in the european paratethys sea and its descendant lake pannon the observed trends document a strong tie to geodynamics which are largely decoupled from miocene open ocean isotope curves semi to fully enclosed initially marine water bodies such as the paratethys sea are prone to switching seawater isotope signatures because they respond rapidly to changes in the evaporation precipitation ratio two phases of positive deviations of oxygen isotope values of water relative to the modern ocean value smow occurred during the middle miocene both were initiated by tectonic constrictions of the seaways and became amplified by global warming and regionally decreasing precipitation with the final disintegration of the paratethys the marine isotope signatures vanish instead the observed isotope trends suggest a comparably simple system of an alkaline lake with steadily declining salinity the oceanderived paratethys sea may thus act as a key for understanding isotope trends in epicontinental seas

from tethys to eastern paratethys oligocene depositional environments paleoecology and paleobiogeography of the thrace basin nw turkey the oligocene depositional history of the thrace basin documents a unique paleogeographic position at a junction between the western tethys and the eastern paratethys as part of the tethys shallow marine carbonate platforms prevailed during the eocene subsequently a three staged process of isolation started with the oligocene during the early rupelian the thrace basin was still part of the western tethys indicated by typical western tethyan marine assemblages the isolation from the tethys during the early oligocene is reflected by oolite formation and endemic eastern paratethyan faunas of the solenovian stage the third phase reflects an increasing continentalisation of the thrace basin with widespread coastal swamps during the late solenovian the mollusc assemblages are predominated by mangrove dwelling taxa and the mangrove plant avicennia is recorded in the pollen spectra the final continentalisation is indicated by the replacement of the coastal swamps by pure freshwater swamps and fluvial plains during the late oligocene mammal zone mp 26 this paleogeographic affiliation of the thrace basin with the eastern paratethys after 32 ma contrasts all currently used reconstructions which treat the basin as embayment of the eastern mediterranean basin

astronomically forced teleconnection between paratethyan and mediterranean sediments during the middle and late miocene abstract a high resolution correlation between an orbital tuned middle and early late miocene record of the central paratethys and an astronomically calibrated mediterranean deep marine composite record is proposed the astronomical tuning of the sarmatian and pannonian sedimentary record in the vienna basin confirms that the beginning of the pannonian regional stage lower tortonian dated in this work at 11 42 my is very close to the miller event mi5 it coincides with a period of minimum amplitude in the 1 2 myr obliquity cycle which in the mediterranean marine record corresponds with a drastic change in the planktonic foraminiferal fauna in addition the warmer period between mi5 and mi6 corresponding to a maximum in the long term 2 3 myr eccentricity cycle coincides with a long interval of lignite deposition in the paratethyan realm the sedimentation pattern shown by high frequency cyclicity between lignite and normal sediments reflects a primary influence of 100 kyr eccentricity cycles on the sedimentation system of the central paratethys which corresponds with small and large scale sapropel clusters hierarchical organization in the mediterranean record the badenian sarmatian boundary astronomically dated at 13 32 myr does not coincide with a low amplitude variation in the 1 2 myr obliquity cycle and any mi events this orbital configuration is supported by the paleoclimatic and paleoecologic data of the late badenian and early sarmatian which both represent a warm temperate system with stagnant bottom water conditions finally the transitional phase from a temperate early sarmatian to a warmer late sarmatian associated with predominant carbonate sedimentation coincides with the glacio eustatic isotope event mi4 while the entire late sarmatian spans a complete 1 2 myr obliquity cycle

miocene connectivity between the central and eastern paratethys constraints from the western dacian basin abstract the dacian basin formed an important link between the central and eastern parts of the paratethys a chain of late tertiary inland seas and lakes this study presents constraints on miocene sea and lake level fluctuations in the dacian basin and on the connectivity between it and other paratethys basins based on the interpretation of seismic lines a micropalaeontological study and lithofacies analysis of a large number of outcrops it is shown that relative sea level fluctuations in the western part of the dacian basin during the middle miocene were primarily driven by tectonic activity in the nearby carpathian mountains from the maeotian late miocene onwards however tectonic activity was minor and relative sea level fluctuations were primarily driven by changes in basin connectivity and climate the connection between the central and eastern paratethys was broken at the end of the middle miocene leading to the development of an endemic fauna in the former but new data presented here suggest that isolation was not sustained completely as central paratethys species appeared in the dacian basin during the maeotian late miocene besides the isolation two falls in water level occurred in the basin during the latest miocene of these the intra pontian sea level drop is the best known we show however that this drop was preceded by a larger sea or lake level drop in the late sarmatian maeotian this latter event may have affected much larger parts of the paratethys and we recommend more study of the bordering basins the hypothesis that the connection between the dacian and central paratethys basins was located in the region where the danube river presently crosses the carpathians was tested but no supporting evidence was found

circum mediterranean oligo miocene biogeographic evolution the gastropods point of view based on studies in iran qom basin esfahan sirjan basin zagros mountains in turkey mut and sivas basins in the mesohellenic basin and in northeastern egypt a new palaeobiogeographic concept for the oligocene and miocene in the circum mediterranean area with special emphasis on the distribution patterns of gastropod faunas is presented a very strict biogeographic terminology is proposed to avoid the common fusion of geographic faunistic and geodynamic terms in the palaeontologists jargon our main interest focuses on the affinities and the faunistic interactions between the early mediterranean and the early indo pacific regions during the oligo miocene especially the role of the early indo pacific faunas as the mythic centre of origination of early neogene european mollusc faunas as often vaguely indicated in the literature is critically evaluated this leads to the establishment of a mediterranean iranian province and a western indian eastern african province as palaeobiogeographic subunits of the western tethys region during the oligocene due to major geodynamic and related biogeographic changes in the early miocene the western tethys region no longer existed and was replaced by the proto mediterranean atlantic region for the area of the paratethys the palaeobiogeographic unit danubian province which includes the protocaspian subprovince is proposed furthermore the underrated transatlantic communication of the oligo miocene nearshore mollusc faunas is demonstrated altogether this paper is a contribution to the discussion on the biogeographic concepts classification and nomenclature in palaeontology as initiated by westermann palaeogeogr palaeoclimatol palaeobiogeogr 158 2000 1 13 163 2000 49 68 2002 elsevier science b v all rights reserved

cyclostratigraphic dating in the lower badenian middle miocene of the vienna basin austria the baden sooss core the scientific borehole baden sooss penetrates a succession of badenian langhian middle miocene sediments at the type locality of the badenian the old brickyard baden sooss in the vienna basin the sedimentary succession of the 102 m cored interval consists of more than 95 bioturbated medium to dark gray marly shales with carbonate contents between 11 and 25 and organic carbon contents between 0 35 and 0 65 biostratigraphic investigations on foraminifera mainly lower part of upper lagenid zone and calcareous nannoplankton standard zone nn5 indicate an early badenian langhian age cycles in carbonate content organic carbon content and magnetic susceptibility have been identified by power spectra analysis correlations between the three variables are extremely significant using cross correlation periods around 40 m correlate significantly with the 100 kyr 1 eccentricity cycle the 20 m periods with the obliquity cycle and the 15 to 11 m periods with both precession cycles wavelet transformation and decomposition of composite periodic functions were used to obtain the position of the cycle peaks in the profile cross correlation with orbital cycles la2004 dates the baden sooss core between 14 379 1 and 14 142 my 9 kyr

palaeoenvironmental reconstructions by stable isotopes of middle miocene gastropods of the central paratethys abstract the stable isotopes of carbon and oxygen were used to provide information of mixing of marine and freshwater and subsequently used to determine palaeosalinities in the middle to late miocene st margarethen zollhaus section upper sarmatian mactra zone pannonian a succession of three gastropod assemblages indicates changing environmental conditions from a limnic fluviatile to littoral mudflat and a sublittoral marine environment several shells of the main representatives of the three assemblages potamides hartbergensis hilber granulolabium bicinctum brocchi potamides disjunctus sowerby and additionally shells of lymnaea sp a typical freshwater gastropod and pomatias conicus a terrestrial gastropod were taken for stable isotope analyses oxygen and carbon isotope data of the freshwater endmember are distinctively lower 18 o 4 5 13 c 9 than of the marine endmembers 18 o 2 2 13 c 2 3 in contrast to the expected intermediate isotopic composition between the freshwater and marine environment the shells of supposed brackish environments have higher 18 o values than the shells of the marine environment these higher 18 o values are explained by evaporation which affected the protected areas of riverine to lacustrine environments and small pools on mudflats formerly considered to be the habitats of the brackish assemblages thus the oxygen and carbon isotope data extend the already existing palaeoenvironmental information

the oxygen and carbon isotope distribution in the mediterranean water masses abstract the oxygen and carbon stable isotope compositions of the present day mediterranean waters have been measured in order to evaluate their variability which is related to the specific climatic and hydrological conditions within the basin the experimental equation between the 18 o value and the salinity of water based on 300 measurements on surface intermediate and deep waters sampled during the vicomed 2 and 3 cruises in the western central and eastern mediterranean has a slope of 0 27 a value which is significantly lower than the slope of 0 45 as defined in the northeast atlantic ocean this difference in the 18 o salinity relationship which occurs immediately in the alboran basin is basically a characteristic of the climatic regime of the mediterranean i e of an excess evaporation over fresh water input the largest variations of these two parameters 18 o of water and 13 c of co 2 are observed in the surface waters mostly in the western mediterranean this evolution mirrors the progressive eastward restriction which separates the less evaporated and more productive western basins from the more evaporated and less productive eastern basins the intermediate waters constitute a homogeneous layer however their 18 o values decrease eastward by 0 35 at maximum due to progressive dilution by mixing with overlying and underlying water masses their 13 c values decrease also eastward by 0 35 at maximum due to an increasing input of nutrients issued from the regeneration of sinking organic particles the deep waters have similar 18 o values but slightly higher 13 c values often by less than 0 1 than the overlying intermediate waters indicating generally well ventilated conditions due to active winter convection