precipitation driven decadal scale decline and recovery of wetlands of lake pannon during the tortonian high resolution pollen and dinoflagellate analyses were performed on a continuous 98 cm long core from tortonian deposits of lake pannon in the styrian basin in austria the sample distance of 1 cm corresponds to a resolution of roughly one decade allowing insights into environmental and climatic changes over a millennium of late miocene time shifts in lake level surface water productivity on a decadal to centennial scale can be explained by variations of rainfall during the tortonian climatic optimum related to negative fine scale shifts of mean annual precipitation shoreline vegetation belts reacted in an immediate replacement of poaceae by cyperaceae as dominant grasses in the marshes fringing the lake in contrast to such near synchronous ecosystem responses to precipitation a delayed lake level rise of 4 6 decades is evident in the hydrological budget of lake pannon this transgression caused by a precipitation increase up to 1200 mm yr resulted in a complete dieback of marshes simultaneously open water dinoflagellates such as impagidinium took over in the brackish lagoon and fresh water dinoflagellates disappeared as soon as the rainfall switched back to moderate levels of 1100 1200 mm yr the rise of the lake level slowed down the marsh plants could keep up again and the former vegetation belts became re established thus mean annual precipitation more than temperature was the main driving force for high frequency fluctuations in the tortonian wetlands and surface water conditions of lake pannon such high resolution studies focusing on tortonian decadal to centennial climate change will be crucial to test climate models which try to compare the tortonian models with predictions for future climate change

the caspian lake history biota structure and function the elongate endorheic caspian lake has a north south orientation and its main freshwater inflow the volga river enters at the shallow north end two deep basins occupy its central and southern regions these facts lead to horizontal differences in temperature salinity and ecology nutrient levels and primary production are low historically lake level has fluctuated by 6 m but on the geological timescale fluctuations of 200 m have occurred the lake formed in the late miocene first went through a long shrinking phase expanded to three times its present size in the late pliocene and repeatedly rose and fell throughout the pleistocene with corresponding freshenings and salinizations the lake surface has remained below sea level since the last pleniglacial this dynamic history led to the assemblage of a set of euryhaline biota of tethyan and freshwater origin besides baltic elements that invaded with glacial meltwater endemism is as high as in lake baikal but typical marine groups are absent because the lake is oxygenated to the bottom its biota show a vertical zonation but without a true abyssal community suggesting cat o pollution of the volga ural and kura rivers and destruction of the spawning grounds of sturgeon signalling a forthcoming collapse of the world caviar market dumont 1995 the caspian is the endorheic terminus of the volga river which contributes 80 of its total inflow 237 km3 yr on average butorin 1979 with a range of 200 450 km3 the kura river is second in line and discharges only 16 8 km yr i the ural river is third with a discharge of 8 1 km yr i lake surface area situated below sea level is close to 400 000 km2 and lake volume is 78 000 km3 or 40 of the world s continental surface water here i attempt to provide insight into the nature of the caspian ecosystem including its eventful past i outline gaps in our knowledge and suggest research for the future

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

integrated stratigraphy of the early miocene lacustrine deposits of pag island sw croatia palaeovegetation and environmental changes in the dinaride lake system article i nfo an integrated stratigraphic study of a neogene lacustrine succession on the pag island croatia combining quantitative pollen analysis magnetostratigraphy cyclostratigraphy biostratigraphy and gamma ray measurements provides new insights into orbitally controlled variations in palaeo vegetation and depositional patterns in the dinaride lake system the quantitative palynological record shows a cyclical pattern of vegetation changes that closely corresponds to sedimentological patterns the intervals with a high abundance of thermophilous and xeric indicators suggesting a warm and dry climate generally coincide with intervals of frequent lignite deposition and shallow lake facies this suggests that both records are dominantly controlled by variations in past climatic conditions and lake level our data show two large scale warming and shallowing upward cycles which are interpreted to be forced by the 100 kyr eccentricity cycle of the earth s orbit magnetostratigraphic data of the examined section reveal a long 113 m reversed polarity interval followed by a 7 m thick interval of normal polarity at the top the inferred depositional rate of 0 3 mm yr combined with biostratigraphic constraints by mollusks suggests that the most logical correlation of the reversed interval is to chron c5cr this indicates that the pag succession was deposited between 17 1 and 16 7 ma and that it corresponds to the burdigalian stage of the early miocene and the regional karpatian stage of the central paratethys the high relative percentage of thermophilous pollen taxa engelhardia and taxodium type being the most prominent generally indicates a subtropical humid climate for the sw croatian part of the dinaride lake system the observed warming trend is possibly related to the onset of the miocene climatic optimum

tectonics climate and the rise and demise of continental aquatic species richness hotspots continental aquatic species richness hotspots are unevenly distributed across the planet in present day europe only two centers of biodiversity exist lake ohrid on the balkans and the caspian sea during the neogene a wide variety of hotspots developed in a series of long lived lakes the mechanisms underlying the presence of richness hotspots in different geological periods have not been properly examined thus far based on miocene to recent gastropod distributions we show that the existence and evolution of such hotspots in inland water systems are tightly linked to the geodynamic history of the european continent both past and present hotspots are related to the formation and persistence of long lived lake systems in geological basins or to isolation of existing inland basins and embayments from the marine realm the faunal evolution within hotspots highly depends on warm climates and surface area during the quaternary icehouse climate and extensive glaciations limnic biodiversity sustained a severe decline across the continent and most former hotspots disappeared the recent gastropod distribution is mainly a geologically young pattern formed after the last glacial maximum 19 ky and subsequent formation of postglacial lakes the major hotspots today are related to long lived lakes in preglacially formed permanently subsiding geological basins

podzolisation preserves ichnofossils constructed by ghost shrimp ichnofossils of ghost shrimps e g ophiomorpha nodosa and callichirus major are interpreted worldwide as records of sea level fluctuations and provide reliable evidence of sedimentation rate salinity and substrate type the preservation of these ichnofossils was previously ascribed to the polysaccharide mucus produced by ghost shrimps when burrows were built we found evidence that these ichnofossils were preserved due to the impregnation of the burrow walls by dissolved organic matter dom during podzolisation that took place after the galleries had been abandoned our study was conducted on a tropical barrier island in southeastern brazil with a spatial gradient of podzolisation intensity we made a detailed macromorphological description of the ichnofossils at the soil profile scale then we used thin sections of undisturbed soils to identify sand grain arrangements and organic matter om accumulation we detected three macromorphological structures i tubular gallery wall ii sandy infilling of the gallery and iii soil matrix outside the gallery in the micromorphology analysis we identified that the tubular wall is impregnated with monomorphic om also found outside the burrow but in lower concentration sand grains in the wall of the gallery are tightly packed causing a lower porosity than inside and outside the trace fossil the precipitation of monomorphic om is due to stagnation of dom that percolated through the soil water with dom is trapped in the wall of the tubule because of its smaller pores the ghost shrimps constructed their burrows in marine sediments without podzolisation then with the progradation of the shoreline the sediments were colonized by restinga forest adding dom to the soil and podzolisation started the extent to which dom is produced depends on vegetation development therefore the accumulation of dom in the b horizon that enables the preservation of the ichnofossils is constrained by vegetation development and progradation of the shoreline

petrographical and organic geochemical study of the kovin lignite deposit serbia abstract the origin of the organic matter om and the characteristics of the depositional environment of lignites from the upper miocene kovin deposit hosting three coal seams of serbia were evaluated based on petrographic data bulk organic geochemical parameters biomarker analysis and stable isotope geochemistry 13c of individual biomarkers samples were collected from four boreholes gd 601 and gd 603 the a field and kb 79 and kb 91 the b field representing different parts of coal seams i ii and iii investigated lignites are typical humic coals the om of lignites is derived from woody vegetation and herbaceous peat forming plants with prevalence of the former in most samples peat forming vegetation is characterized by abundant decay resistant gymnosperm coniferous plants followed by a low amount of angiosperms lignite forming plants mostly belonged to the gymnosperm families cupressaceae taxodiaceae phyllocladaceae and pinaceae slight input of ferns fungi and aquatic macrophyta to lignite om is also evident distributions of hopanoids and isotopic compositions of these biomarkers reflect the activity of various microbial populations represented by methanotrophic chemoautotrophic and heterotrophic bacteria during diagenesis prominent c28 28 30 bisnorneohop 13 18 ene was observed for the first time in the lignite extracts according to the 13c value it was probably derived from chemoautotrophic bacteria c28 28 30 bisnorneohop 13 18 ene could be one of the possible precursors of a series of orphan aromatic hopanoids bearing an ethyl group at c 21 via progressive aromatization peatification proceeded in a fresh water environment under variable redox conditions from anoxic to slightly oxic all three coal seams are heterogeneous the lower parts of the coal seams represent a topogenous fresh water peat mire with open water areas which was subjected to inundations the upper parts of coal seams represent a wet forest swamp with relatively stable conditions despite the observed variations in all three coal seams the mean values of petrographic and organic geochemical parameters suggest general increasing of wetness and establishment of more stable conditions from seam iii to seam i maceral and biomarker data indicate that rapid flooding of the bogs stopped peat growth in all three coal seams relatively frequent variations in all three coal seams followed by repetition of lignite characteristics depict well the pronounced seasonality e g short term cycles of the climate during late miocene in investigated area

storm driven mixing and potential impact on the arctic ocean 1 observations of the ocean atmosphere and ice made by ice ocean environmental buoys indicate that mixing events reaching the depth of the halocline have occurred in various regions in the arctic ocean our analysis suggests that these mixing events were mechanically forced by intense storms moving across the buoy sites in this study we analyzed these mixing events in the context of storm developments that occurred in the beaufort sea and in the general area just north of fram strait two areas with quite different hydrographic structures the beaufort sea is strongly influenced by inflow of pacific water through bering strait while the area north of fram strait is directly affected by the inflow of warm and salty north atlantic water our analyses of the basin wide evolution of the surface pressure and geostrophic wind fields indicate that the characteristics of the storms could be very different the buoy observed mixing occurred only in the spring and winter seasons when the stratification was relatively weak this indicates the importance of stratification although the mixing itself was mechanically driven we also analyze the distribution of storms both the long term climatology and the patterns for each year in the past 2 decades the frequency of storms is also shown to be correlated but not strongly to arctic oscillation indices this study indicates that the formation of new ice that leads to brine rejection is unlikely the mechanism that results in the type of mixing that could overturn the halocline on the other hand synoptic scale storms can force mixing deep enough to the halocline and thermocline layer despite a very stable stratification associated with the arctic halocline the warm subsurface thermocline water is not always insulated from the mixed layer

multiproxy reconstruction of the middle miocene požega palaeolake in the southern pannonian basin ne croatia prior to the badenian transgression of the central paratethys sea abstract the pannonian basin of croatia is the largest back arc extensional basin on the european continent located between the alps carpathians and dinarides syn rift subsidence started at 18 ma and predated the onset of the miocene climate optimum mco 17 14 7 ma in this paper we investigate the evolution of the fluvial lacustrine palaeoenvironment just prior to the transgression of the central paratethys sea studies are based on a 17 m thick section of the po ega palaeolake in the southern pannonian basin using palaeobiological mollusks ostracods palynomorphs fish otoliths mineralogical and sedimentological data our results reveal fluctuating freshwater and brackish conditions and a pulsating water budget which we relate to phases in which the basin was alternatively hydrologically open and closed we infer that the alternating environmental conditions can be best explained by dry and wet periods respectively droughts produced stagnant conditions algae overproduction and increased salinity levels supporting the survival of sporadically invading brackish water species the wet periods on the other hand led to lake highstand episodes expansion of lake area and to the widespread development of profundal facies the lake basin eventually became overfilled and connected through outflowing rivers with the central paratethys sea however the absence of brackish marine assemblages in the po ega palaeolake nevertheless indicates that there was no marine water inflow from the central paratethys at that time

neogene lake systems of central and south eastern europe faunal diversity gradients and interrelations abstract the gastropod diversity of 12 neogene lake systems is evaluated in total 1184 gastropod taxa from 119 localities are recorded deriving from the early miocene rzehakia lake system the early to middle miocene dinarid lake system lake skopje the paratethyan sarmatian lakes and the south german lakes the late miocene lake pannon the pliocene lakes dacia transylvania slavonia kosovo and sostanj as well as the holocene lake petea each lake system is characterised according to its faunistic inventory and endemism according to their gastropod faunas the lakes may be divided into pyrgulid hydrobiid viviparid and planorbid dominated ones the generally high endemism rate is between 60 and 98 species diversity and generic diversity are strongly correlated in contrast neither endemism nor lake size are tightly linked with diversity outstandingly high diversities such as observed for lake pannon are rather a result of the combined effect of autochthonous evolution in a long lived system and accumulation of inherited elements examples of parallel evolution in lymnaeids and planorbids are presented

distribution of convective lower halocline water in the eastern arctic ocean 1 we investigate the distribution of convectively formed lower halocline water clhw in the eastern arctic ocean using observational and climatological data the clhw can be defined as the water mass in the cold halocline layer formed by winter convection the presence of clhw is indicated by temperatures close to the freezing point and a sharp bend in the s curve near the salinity of clhw results from ice drifting buoy observations in 2002 show differences in water mass characteristics in the upper ocean among the amundsen basin over the arctic mid ocean ridge and in the nansen basin in 2000 2002 clhw was present over the arctic mid ocean ridge and the nansen basin but was largely absent from the amundsen basin using climatological data we find that clhw was confined to the nansen basin prior to 1990 in the early 1990s clhw still covered only the nansen basin but extended to the northern side of the arctic mid ocean ridge in the mid 1990s and covered the whole of the amundsen basin by the late 1990s in the early 2000s the area of clhw moved back to its present boundary on the northern side of the arctic mid ocean ridge these results correspond roughly to other changes in the arctic ocean circulation and water mass structure but with a time delay we hypothesize that general circulation changes and the cutoff of source water for advective convective modification of the lhw are causes of the change in clhw distribution the lag in changes to clhw distribution behind other changes in the atmosphere and upper ocean are likely related to differences in circulation change with depth and the transit time from clhw formation

complex decapod burrows and ecological relationships in modern and pleistocene intertidal carbonate environments san salvador island bahamas abstract burrowing by thalassinidean shrimp in modern tropical shallow subtidal to intertidal carbonate environments is widespread and a powerful agent of bioturbation particularly within sandy substrates deep and intense burrowing by callianassids commonly occurs along the intertidal margins of hypersaline lagoons throughout the bahamas such as pigeon creek on san salvador island where the sediments of extensive sand flats are thoroughly bioturbated by glypturus acanthochirus in addition to dominating the deep tier infauna g acanthochirus is a true ecosystem engineer and its prodigious burrowing activity results in a highly mounded topography on sand flats individual sediment cones commonly coalesce with time to form large composite mounds with surfaces stabilized by the development of microbial mats this unique biogenetically produced topography sets the stage for colonization by shallow tier burrowers particularly the upogebiid shrimp upogebia vasquezi and several species of fiddler crabs burrow systems of u vasquezi are distinctive and complex they typically consist of a pair of u shaped burrows in close proximity or criss crossing with knobs or short tunnels at their bases the entire u burrow pair is lined by a thick externally pelleted wall inside burrow diameters range from 0 2 to 1 cm and burrow depths are 10 15 cm in contrast to the much deeper callianassid burrows these complex upogebiid burrows also occur as trace fossils in late pleistocene lagoon margin facies of the grotto beach formation on san salvador initially reported as fragmentary burrow fills whole burrow systems virtually identical to the modern upogebiid burrows recently have been found at several localities these fossil burrows are most abundant in beds lying immediately below a terra rossa paleosol that marks the late pleistocene holocene stratigraphic boundary and the beds likely were deposited with sea level stillstand and regression associated with the onset of wisconsinan glaciation with their high potential for preservation these complex upogebiid trace fossils may prove useful as both paleoenvironmental and sea level position indicators in the study of quaternary carbonate sequences throughout the bahamas and other geologically similar regions

delineation of intrabasin structure in a dilational jog of the san jacinto fault zone southern california three high resolution seismic reflection lines were acquired in the northern part of the san jacinto graben the graben a pull apart basin formed by a dilational right step of the san jacinto fault zone has been previously interpreted as a simple rhombochasm the reflection survey located at least one significant and previously unidentified intrabasin fault referred to here as the farm road strand this fault lies approximately halfway between the claremont and casa loma strands of the san jacinto fault zone at the north end of the basin the southwestern boundary of the graben is interpreted to be the newly identified farm road strand and not the casa loma strand as was previously thought the identification of this intrabasin fault allows us to infer that the san jacinto basin comprises coalescing subbasins and is not a simple pull apart basin with an unusually large length width ratio the distances between the en echelon casa loma farm road and claremont strands are between 1 and 2 km this close spacing would likely permit an earthquake rupture to jump between strands and thus propagate through the san jacinto basin

occurrence of bioglyphs on ocypode crab burrows in a modern sandy beach and its palaeoenvironmental implications abstract the ichnological term bioglyph covers biogenic sculpture on burrow walls bioglyphs in the burrows of ocypodid crabs were studied in a modern unconsolidated sandy substrate looseground on irino coast southwestern japan they are seen exclusively on sides and roof of the burrow and are characteristically seen near the distal end of the burrow moist sandy substrate where sand particles are bound together by surface tension of interstitially suspended water might allow the production of such bioglyphs although bioglyphs are only partially developed in such burrows those interpreted to have formed in semi consolidated substrates firmground are known to be sculptured over the entire burrow surface such difference in the modes of bioglyph occurrence can be used as a criterion to reconstruct the substrate consistency in the rock record

first evidence of the cretaceous decapod crustacean protocallianassa from sweden an assemblage of the burrowing ghost shrimp protocallianassa faujasi is described providing the first evidence of this decapod species from sweden the fossils occur in successions of the informal earliest late campanian belemnellocamax balsvikensis zone at asen and the latest early campanian b mammillatus zone at ivo klack both in the kristianstad basin of ne skane numerous heavily calcified chelipeds were found within a restricted bed at a sen that was rich in carbonate cemented nodules based on the burrowing lifestyle of modern mud shrimps we interpret these nodules as infilled burrow chambers the low abundance of molluscs within the protocallianassa beds is also consistent with analogous extant communities indicating that a similar ecologically exclusive relationship ruled within the late cretaceous shallowmarine ecosystems less

a gastropod based biogeographic scheme for the european neogene freshwater systems abstract for the first time a palaeobiogeographic framework is proposed for european neogene freshwater systems the distribution of 2226 species group taxa of freshwater gastropods from over 2700 miocene and pliocene localities was evaluated the localities were grouped into palaeo freshwater systems based on latest palaeogeographic reconstructions cluster analyses were computed for four time slices i e early miocene middle miocene late miocene and pliocene the analyses demonstrate a generally high degree of provincialism for the neogene freshwater systems and allow the definition of biogeographic units the delimitations are based on the cluster analyses the degree of endemicity and geographical coherence the early miocene is characterised by a relatively low degree of provincialism suggesting the distinction of three regions coinciding with the development of many endemic systems on the dinarian anatolian island and in central europe the middle miocene demonstrates a higher degree of provincialism allowing the definition of six biogeographic regions with the onset of the late miocene the retreat of the central paratethys and development of the huge lake pannon massively shaped faunal evolution and palaeobiogeography in general the formation of the lago mare environment fringing the mediterranean basin as well as the development of several restricted freshwater systems in western europe additionally promoted biogeographic division the increasing provincialism allowed the delimitation of six biogeographic regions three of which could be subdivided into seven dominions with the disappearance of lake pannon and the decline of western european and mediterranean faunas at the miocene pliocene boundary biodiversity hotspots shifted towards eastern and southeastern europe for the pliocene four biogeographic regions five dominions and four provinces were defined most of the here proposed biogeographic units and faunal differences are governed by the varied existence of large long lived systems because of their prolonged duration they immensely influenced the community composition on the family level differences of the relative species richnesses per biogeographic region and the rising rate of endemicity the underlying mechanism for this pattern is the ongoing continentalization of europe triggered by the alpidic orogenesis and the simultaneous retreat of the paratethys sea the continuing restriction of this huge intracontinental sea from the mediterranean promoted the evolution of endemic freshwater faunas the arising long lived systems like lake pannon lake dacia or lake slavonia persisted over several millions of years and stimulated the evolution of highly diverse and endemic faunas

changing seas in the early middle miocene of central europe a mediterranean approach to paratethyan stratigraphy the miocene palaeogeographic evolution of the paratethys sea is still poorly constrained here we use modern mediterranean biochronology to provide an up to date overview of changing seas in central europe instead of a paratethys sea that waxed and waned with fluctuating global sea level we show that the evolution of different seas was mainly controlled by tectonic phases the early miocene ottnangian sea 18 ma was connected to the mediterranean via the rhone valley while the karpatian sea 16 5 ma was initiated by a tectonically induced marine transgression through the trans tethyan gateway in most central european basins the establishment of the badenian sea 15 2 ma triggered by subduction related processes in the pannonian and carpathian domain is significantly younger by 1 myr than usually estimated the updated palaeogeographic reconstructions provide a better understanding of the concepts of basin dynamics land sea distribution and palaeoenvironmental change in the miocene of central europe this article is protected by copyright all rights reserved

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

effect of summertime wind conditions on lateral and bottom melting in the central arctic to understand the role of wind conditions on the summertime surface ocean system the ocean ice and atmosphere in the central arctic ocean were observed using two drifting buoys one in 2002 under stormy conditions one in 2003 under calm conditions although the ice concentration near the north pole was the same in 2002 and 2003 during early summer the heat used in bottom melting in 2003 was only about half of that in 2002 to obtain the total heat input into the upper ocean heat used in lateral melting was additionally derived from a time series of ice concentration in 2002 assuming the same heat input into the upper ocean the heat used in lateral and bottom melting was estimated and compared between the years it is thought that the warm fresh water embedded within the ice cover was mixed downward during the frequently stormy mid summer of 2002 enhancing bottom melting by contrast the warm water in 2003 tended to be used for lateral melting due to the relatively calm conditions suggesting that a continuously weak wind favours ice cover decrease during summer a simple calculation of the ice cover evolution reveals that the difference in ice concentration during august between 2002 and 2003 reached 10 which is consistent with the satellite derived ice concentration

commensal worm traces and possible juvenile thalassinidean burrows associated with ophiomorpha nodosa pleistocene southern brazil abstract the pleistocene chui formation at osorio rio grande do sul brazil consists of coastal marine and eolian sands the former containing abundant and well preserved ophiomorpha nodosa burrow systems detailed ichnological study has revealed interesting features associated with them small sized ophiomorpha here assigned to a new ichnospecies o puerilis are interpreted as possible burrows of juvenile thalassinidean crustaceans probably belonging to the same species as the producers of larger o nodosa additionally helicoidal burrows with thick concentrically laminated linings are associated with the walls of o nodosa they are assigned to the new ichnospecies cylindrichnus helix and they are interpreted as dwellings of commensal annelid worms the association of these three ichnospecies constitutes a fossil example of the role of thalassinideans as ecosystem engineers able to modify their environment and to create new space and resources usable by other organisms

magneto biostratigraphy and paleoenvironments of the miocene freshwater sediments of the sarajevo zenica basin abstract the sarajevo zenica basin of bosnia herzegovina was part of the dinaride lake system a large network of miocene long lived freshwater basins in southeastern europe the basin contains a thick sedimentary succession of carbonates coals and mixed siliciclastic deposits that reflects the paleoclimatic and tectonic evolution of the region in this study we present novel integrated magneto bio stratigraphic and sedimentological data and reconstruct the paleoenvironmental evolution of the sarajevo zenica basin during its two main evolutionary phases thrusting and extension the basal oligo miocene freshwater paleoenvironments are characterized by alternating palustrine shallow lacustrine and distal fluvial phases the base level fluctuations are largely controlled by syn sedimentary pulses of tectonic loading during the final phase of thrusting in the internal dinarides the majority of this succession is considered early miocene in age which contrasts with previous oligocene age estimates the subsequent extensional phase initiated not later than 18 4 ma this coarsening upward sequence of lacustrine carbonates silts sands and conglomerates is correlated between 17 2 and 15 ma c5cr c5br by means of integrated bio magnetostratigraphy during this upper extensional phase subsidence and sediment influx was generally controlled by activity along the basin bounding normal fault overruling smaller scale climatic influences we conclude that the existence of the long lived sarajevo lake is coeval with other dinaric and southern pannonian lakes and overlaps in time with the miocene climatic optimum sedimentation in the sarajevo zenica basin terminated at 15 14 ma which concurs with both the end of the climatic optimum as well as the cessation of extension in the dinarides these results will help to better quantify the paleoclimatic changes in the dinaride lake system as well as the regional tectono sedimentary events such as potential migrations of deformation across the dinarides

meteor observations with the european incoherent scatter uhf radar the european incoherent scatter eiscat uhf radar which operates at a nominal frequency of 930 mhz is introduced as a powerful meteor radar its high sensitivity is utilized to detect transient enhanced ionization trails caused by meteors of all orientations in contrast to conventional hf and vhf backscatter radars which observe only the meteor trails oriented approximately normal to the radar beam a comparison shows that eiscat observes almost as high hourly rates of meteors as meteor radars do in spite of its beamwidth being only 0 5 compared to their 100 two different kinds of echoes are seen in the data about three fourths of them are strongly doppler shifted transient echoes which we interpret as head echoes since they move with meteor velocities the remaining echoes are long lived they come from the ionized trails left behind the meteors which drift slowly or not at all there are fundamental differences between the scattering process producing both types of echoes and the scattering from trails observed with the meteor radars for example we have never seen the trail echoes appear after a head echo all our shower echoes are also strongly nonspecular we postulate that some time is required for the trails to expand and for the ionization within them to approach the thermal equilibrium state in order to give detectable incoherent echoes due to the very small beamwidth our radar cannot follow the motion of an individual meteor as the conventional radars can but we can obtain a statistical profile of what happens at different heights as the meteoroids penetrate the atmosphere the altitude distribution of ionized trails shows that they are observable over the whole measurement range from about 65 to 165 km while the head echoes can be detected only within a narrow altitude range the latter effect is probably related to the radio meteor ceiling effect

lidar observations of sporadic sodium layers at mauna kea observatory hawaii the characteristics of very dense narrow upper atmospheric na layers observed above mauna kea hawaii 19 50 n 155 28 w are described these layers were observed on a total of 16 occasions during 30 hours of lidar measurements from january 17 to 22 1987 the most prominent sporadic layer which formed on the night of january 21 exhibited a peak density of 2 8 104 cm 3 near 96 km with a full width of about 2 km the rapid growth and decay of the layer lasted for about 40 min the apparent na production and decay rates of this layer were approximately 60 cm 3 s 1 even after the decay the narrow layer was observed continuously for almost 8 hours during this period the layer moved downward steadily with a mean apparent velocity of 31 cm s 1 the most significant characteristic of the 16 sporadic layers appears to be occurrence times the layers formed either in the late evening between 2100 and 2330 lst or in the early morning between 0300 and 0600 lst the layers of the early morning began forming within a short time span of 15 min from 0253 to 0308 lst on 3 different days the mean time of the maximum peak density of the early morning layers occurred about 6 hours after that of the late evening layers the mechanisms responsible for creating these layers appear to be related to diurnal tides and sporadic e layers

sedimentology and stratigraphy of the neogene rift type north croatian basin pannonian basin system croatia a review abstract development of the rift type north croatian basin located in the south western neogene pannonian basin system and belonging to the central paratethys realm was controlled by tectonics climate volcanic activity and eustatic fluctuations the extrabasinal controls produced a succession of depositional environments from terrestrial to marine and back to terrestrial and the deposits form a large scale transgressive regressive cycle basin evolution is subdivided into the syn rift phase which lasted from the early miocene ottnangian until the middle miocene middle badenian and in the post rift phase from the middle miocene late badenian to the quaternary these complex controls on deposition generated the opening and closing of connections to the open sea that occasionally resulted in the formation of unfossiliferous continental deposits or generated the radiation of endemic species such that it has been necessary to use regional neogene stages for stratigraphic analysis of the central paratethys history earlier stratigraphic studies of the north croatian basin that had been primarily based on biostratigraphy and superposition were improved by recent results yielded from radiometric dating and integrated biostratigraphy they have been focused mainly on the early middle miocene and the miocene pliocene boundaries that separate intervals of the specific depositional evolution of the basin most important depositional and palaeogeographic differences concern a relatively long period of development of the early continental phase that lasted from the ottnangian to the early badenian in contrast to parts of the pannonian basin system characterized by marine deposition in the early badenian the ncb was characterized by long lived fresh water lacustrine deposition the fresh water lake slavonia that developed from the middle pliocene to the early pleistocene indicates an independent phase of evolution of the south pannonian basin system so the cernikian regional stage was introduced for the lacustrine succession those stratigraphic and palaeogeographic differences additionally support the complexity of the pannonian basin system within the central paratethys realm supporting heterogeneous depositional development of continental rift type basins

geomorphological significance of the palaeodrainage network on a karst plateau the una korana plateau dinaric karst croatia abstract karst plateaus often have a complex geological and geomorphological history it is widely accepted that their development requires a long period of karst denudation this study reconstructs the palaeodrainage network of a karst plateau analyses its properties and establishes its geomorphological significance the main purpose of this research was to deepen our understanding of a key stage in the evolution of karst plateaus the transition from a fluvial land surface to one dominated by karst surface processes the study was conducted on a large part of the una korana plateau the largest plateau in the dinaric karst the majority of the plateau is made of carbonate rocks of triassic jurassic and cretaceous age that set the conditions for the development of the karst we have reconstructed the palaeodrainage network based on 1 25 000 topographic maps with 10 m contours the transition of the surface drainage network to the underground karst drainage network is still in progress so depending on the degree of karstification the drainage network was divided into three categories active dry and relict it was found that 90 5 of the pre existing drainage network has undergone some degree of karstification the active surface drainage network gradually shifted to a dry network then to a relict network the surface drainage network is gradually replaced by a dense network of dolines today the flat and karstified inter fluvial area is drained underground towards the main watercourses and these drain the entire region over the surface towards the pannonian basin this is the largest known karst palaeodrainage network in the dinaric karst that has been reconstructed in this way

paleobiogeography of early middle miocene terrestrial gastropods in central europe an approach using similarity indices abstract terrestrial gastropods are a common faunal element in continental miocene fossil lagerstatten of europe although having lived during a time span that includes the miocene climatic optimum and the devastating ries steinheim meteorite impacts the state of knowledge about their faunal composition and geographic distribution is surprisingly incomplete the land snail faunas of 30 different early and middle miocene deposits of central europe european mammal neogene zones mn 4 to mn 8 were compared using statistical methods cluster and nmds analyses using the ochiai simpson and kulczynski indices this includes 300 different taxa identified so far most of the analyzed deposits were part of the miocene paratethys and are today located in france sw germany baden wurttemberg state se germany bavaria state austria poland and hungary cluster analyses resulted in different clusters the majority of which can be explained by their geographic situation and or by their distribution in time e g the consistently recovered baden wurttemberg and bavaria clusters and the bakony mountains cluster the remaining clusters cannot be fully explained so far but some possibilities are explored here our results reveal the power of a solid taxonomic framework as a basis for palaeobiogeographic studies as such more basic palaeontological studies are required to strengthen future analyses

biotic and abiotic response to palaeoenvironmental changes at lake pannons western margin central europe late miocene a multidisciplinary study was performed on a c 30 m thick limnic deltaic sequence in the styrian basin austria geophysical gamma ray activity rock magnetism geochemical organic carbon sulphur and sedimentological observations were combined with palaeontological information mainly ostracods on this base several ecological factors were deduced terrigenous influx salinity water depth and oxygenation based on integrated stratigraphy as well as on palaeomagnetic results the whole section is set to chron c5r 2r 1n 11 308 11 263 ma and covers a period of less than 45 kyr in addition to the long term record we analysed short term changes by high resolution sampling 5 mm sample interval ostracods magnetic susceptibility this 2 3 m thick interval spans in total 3500 yr with an individual sample resolution of a few years only the combination of these data permit the description of the palaeoenvironmental evolution of the section in detail at the base of the section the development of a conifer swamp on the lakeside of lake pannon is documented this almost freshwater swamp existed for some centuries before it became extinct within a few decades due to a rise of the water table the drowning is related to a transgression of lake pannon which triggered the establishment of a brackish water fauna as well as greigite formation in the lake sediments in general the ongoing transgression favoured benthic life due to increased salinity up to mesohaline conditions the high resolution ostracod and magnetic susceptibility record reflect short term fluctuations in bottom water ventilation these oscillations probably range in the order of centuries and decades and are possibly related to climatic shifts later the successive deepening of the lake resulted in a significant faunal turnover a meromictic system with a well established oxygen depleted hypolimnion developed finally the limnic phase was replaced by a prograding deltaic system where the amplified input of coarse grained material and freshwater also affected benthic life periodic changes in clay illite content were detected by the gamma ray log throughout the entire section the observed cycles 5 12 kyr of the gamma ray log may reflect a super ordinate modulation of the sedimentary record by climatically forced changes in precipitation or run off

lidar observations of mesospheric fe and sporadic fe layers at urbana illinois lidar measurements of mesospheric fe were conducted at urbana il 40 degree n 88 degree w during 4 nights in late october 1989 the average fe abundances layer centroid heights and rms widths varied between 1 0 2 0 times 10 sup 10 cm sup minus 2 89 0 90 5 km and 3 2 4 1 km respectively the peak densities of the layer near 90 km varied between 15 25 times 10 sup 3 cm sup minus 3 considerable gravity wave and tidal activity was observed in the fe profiles on 3 nights the formation and dissipation of 3 large sporadic fe fe sub s layers was observed these are the first observations of this phenomenon the 2 largest fe sub s layers formed at 102 4 km and 91 4 km over a period of about 20 min and their widths were approximately 2 3 km fwhm the peak densities of the fe sub s layers were as high as 31 times 10 sup 3 cm sup minus 3 and the abundances were as high as 5 8 times 10 sup 9 cm sup minus 2 the observations are compared with previous measurements of mesospheric fe and with recent observations of sporadic na na sub s layers

benchmark data of a changing sea palaeogeography palaeobiogeography and events in the central paratethys during the miocene abstract the reconstruction and interpretation of terrestrial ecosystems and vegetational patterns in the central european miocene have to take into account the influence of a vast landlocked water body namely the paratethys sea as a northern appendage of the early mediterranean sea it spanned a north south gradient of at least 4 latitude and has been suggested to represent some kind of palaeothermometer which reflected slight expansions or restrictions of climatic belts due to its vulnerable marine connections it was also highly susceptible to major global sea level fluctuations which are reflected in phases of endemism hence a fairly continuous record of marine nearshore assemblages throughout the miocene reflects an extraordinary interplay of sea level fluctuations changes in climate immigrations and blooms in autochthonous elements whilst biostratigraphic implications of these patterns were recognised early in palaeontology a biogeographic model is still lacking the intermingling of palaeogeographic terms with those restricted to biogeography is still commonly used a situation which can be overcome by integrating data from different biota into a new palaeobiogeographic scheme herein a data set of 1809 species level taxa gastropoda and foraminifera serves as the base for interpretations gastropods in particular turned out to be of greatest value for the differentiation of palaeobiogeographic units due to sensitive reactions to all environmental parameters and occupying a wide range of ecological niches based on the excellent gastropod record the proto danubian province early danubian p danubian p balatonian p and a proto caspian subprovince are defined the biogeographic reorganisations are associated with five major biotic events within the gastropod faunas these big five comprise four extinctions the late ottnangian extinction event loee the mid badenian extinction event mbee the badenian sarmatian extinction event bsee the sarmatian pannonian extinction event spee and one exceptional immigration origination event termed the early badenian build up event ebbe foraminifera are less valuable for palaeobiogeographic purposes in the area and time slice studied endemisms are generally lower and turn over rates less dramatic they are however very useful for stratigraphic correlations with the mediterranean and atlantic areas this fairly well calibrated marine biostratigraphy of the central paratethys serves as stratigraphic backbone and control for continental stratigraphy

palaeoenvironmental evolution of lake gacko southern bosnia and herzegovina impact of the middle miocene climatic optimum on the dinaride lake system in the early to middle miocene a series of lakes collectively termed the dinaride lake system dls spread out across the north western part of the dinaride anatolian continental block its deposits preserved in numerous intra montane basins allow a glimpse into the palaeoenvironmental palaeobiogeographic and geodynamic evolution of the region lake gacko situated in southern bosnia and herzegovina is one of the constituent lakes of the dls and its deposits are excellently exposed in the gracanica open cast coal mine a detailed study of the sedimentary succession that addresses facies sediment petrography geophysical properties and fossil mollusc palaeoecology reveals repetitive changes in lake level these are interpreted to reflect changes in the regional water budget first order chronologic constraints arise from the integration of radio isotopic and palaeomagnetic data 40ar 39ar measurements on feldspar crystals from a tephra bed in the upper part of the sedimentary succession indicate a 15 31 0 16 ma age for this level the reversed magnetic polarity signal that characterises the larger part of the investigated section correlates to chron c5br of the astronomically tuned neogene timescale guided by these chronologic data and a detailed cyclostratigraphic analysis the observed variations in lake level evident as two 40 m and seven 10 m scale transgression regression cycles are tuned to 400 kyr and 100 kyr eccentricity cycles from the tuning it can be inferred that the sediments in the gacko basin accumulated between 15 8 and 15 2 ma the economically valuable lignite accumulations in the lower part of the succession are interpreted to indicate the development of swamp forests in conjunction with lake level falls corresponding to 100 kyr eccentricity minima pedogenesis rhizoliths and palustrine carbonate breccias in the upper part of the section reveal long term aridity coinciding with a 400 kyr eccentricity minimum eccentricity maxima are interpreted to trigger lake level high stands these are accompanied by eutrophication events caused by enhanced denudation of the surrounding basement and increased detrital input into the basin the presented age model proves that lake gacko arose during the middle miocene climatic optimum and that the optimum climatic conditions triggered the formation of this long lived lake

thin and thinner sea ice mass balance measurements during sheba 1 as part of a large interdisciplinary study of the surface heat budget of the arctic ocean sheba we installed more than 135 ice thickness gauges to determine the sea ice mass balance while installing these gauges during the fall of 1997 we found that much of the multiyear ice cover was only 1 m thick considerably thinner than expected over the course of the yearlong field experiment we monitored the mass balance for a wide variety of ice types including first year ice ponded ice unponded ice multiyear ice hummocks new ridges and old ridges initial ice thicknesses for these sites ranged from 0 3 to 8 m and snow depths varied from a few centimeters to more than a meter however for all of their differences and variety these thickness gauges sites shared a common trait at every site there was a net thinning of the ice during the sheba year the thin ice found in october 1997 was even thinner in october 1998 the annual cycle of ice thickness was also similar at all sites there was a steady increase in thickness through the winter that gradually tapered off in the spring this was followed by a steep drop off in thickness during summer melt and another tapering in late summer and early fall as freeze up began maximum surface melting was in july while bottom ablation peaked in august combining results from the sites we found an average winter growth of 0 51 m and a summer melt of 1 26 m which consisted of 0 64 m of surface melt and 0 62 m of bottom melt there was a weak trend for thicker ice to have less winter growth and greater net loss for the year however ice growth was also impacted by the snow depth considerable variability was observed between sites in both accretion and ablation the total accretion during the 9 month growth season ranged from zero for thick ridged ice to more than a meter for young ice ponds tended to have a large amount of surface melting while ridges had considerable bottom ablation

strong evidence for the influence of solar cycles on a late miocene lake system revealed by biotic and abiotic proxies the late miocene paleogeography of central europe and its climatic history are well studied with a resolution of c 106 years small scale climatic variations are yet unresolved observing past climatic change of short periods however would encourage the understanding of the modern climatic system therefore past climate archives require a resolution on a decadal to millennial scale to detect such a short term evolution a continuous 6 m core of the paleo lake pannon was analyzed in 1 cm sample distance to provide information as precise and regular as possible measurements of the natural gamma radiation and magnetic susceptibility combined with the total abundance of ostracod shells were used as proxies to estimate millennial to centennial scale environmental changes during the mid tortonian warm period patterns emerged but no indisputable age model can be provided for the core due to the lack of paleomagnetic reversals and the lack of minerals suitable for absolute dating therefore herein we propose another method to determine a hypothetic time frame for these deposits based on statistical processes including lomb scargle and redfit periodograms along with wavelet spectra several distinct cyclicities could be detected calculations considering established off shore sedimentation rates of the tortonian vienna basin revealed patterns resembling holocene solar cycle records well the comparison of filtered data of miocene and holocene records displays highly similar patterns and comparable modulations a best fit adjustment of sedimentation rate results in signals which fit to the lower and upper gleissberg cycle the de vries cycle the unnamed 500 year and 1000 year cycles as well as the hallstatt cycle each of these cycles has a distinct and unique expression in the investigated environmental proxies reflecting a complex forcing system hence a single proxy analysis as often performed on holocene records should be considered cautiously as it might fail to capture the full range of solar cycles

paleogeographic evolution of the southern pannonian basin 40ar 39ar age constraints on the miocene continental series of northern croatia the pannonian basin originating during the early miocene is a large extensional basin incorporated between alpine carpathian and dinaride fold thrust belts back arc extensional tectonics triggered deposition of up to 500 m thick continental fluvio lacustrine deposits distributed in numerous sub basins of the southern pannonian basin extensive andesitic and dacitic volcanism accompanied the syn rift deposition and caused a number of pyroclastic intercalations here we analyze two volcanic ash layers located at the base and top of the continental series the lowermost ash from mt kalnik yielded an 40ar 39ar age of 18 07 0 07 ma this indicates that the marine continental transition in the slovenia zagorje basin coinciding with the onset of rifting tectonics in the southern pannonian basin occurs roughly at the eggenburgian ottnangian boundary of the regional paratethys time scale this age proves the synchronicity of initial rifting in the southern pannonian basin with the beginning of sedimentation in the dinaride lake system beside geodynamic evolution the two regions also share a biotic evolutionary history both belong to the same ecoregion which we designate here as the illyrian bioprovince the youngest volcanic ash level is sampled at the glina and karlovac sub depressions and both sites yield the same 40ar 39ar age of 15 91 0 06 and 16 03 0 06 ma respectively this indicates that lacustrine sedimentation in the southern pannonian basin continued at least until the earliest badenian the present results provide not only important bench marks on duration of initial synrift in the pannonian basin system but also deliver substantial backbone data for paleogeographic reconstructions in central and southeastern europe around the early middle miocene transition

evolution turnovers and spatial variation of the gastropod fauna of the late miocene biodiversity hotspot lake pannon abstract lake pannon constituted the biggest hotspot of biodiversity in the late cenozoic of europe comprising a total diversity of almost 600 gastropod species the gastropod fauna of this huge brackish system which existed over about seven million years from the late miocene to earliest pliocene within the pannonian basin system has been well documented by a great many of taxonomic works in contrast the faunal development within the lake has not been properly addressed from a statistical point of view the present investigation demonstrates that species were not homogeneously distributed across space and time generating uneven and temporally shifting patterns of species richness and degree of point endemism across the lake the faunal compositions of the time intervals analyzed were highly different contrasting simple species accumulation as suggested by the overall numbers shifting patterns of local diversity within the lake reflect changing paleo shorelines resulting from prograding river systems entering and successively diminishing the lake surface area as mainly herbivorous grazers and predominantly shallow water inhabitants the gastropods traced the moving shelf margins and vegetation belts accordingly producing the observed diversity shifts in addition each time interval is characterized by a high degree of provincialism which is considered to reflect high habitat diversity this claim is supported by the complex subaqueous topography and the presence of extensive delta plains produced by the incoming river systems a potential driver for provincialism might be the adaptation of species to distinct water depths and related parameters finally the notable differences among the faunal compositions of the upper pannonian strata and the succeeding lower viviparus beds especially regarding family level indicate an environmental turnover at the transition brackish water species are mostly replaced by typical freshwater elements indicating strong fluvial influence based on our results and latest stratigraphic data we conclude that the viviparus beds were deposited in a different environment replacing lake pannon in the southern pannonian basin in the early pliocene

kinematics of foreland vergent crustal accretion inferences from the dinarides evolution one of the most common observation in mediterranean areas is the migration of contractional deformation and associated slabs through time towards external orogenic areas associated with lower plate crustal accretion the dinarides orogen of central europe is an optimal place to study such a sequence of contractional deformation compared with other areas contraction in the dinarides was less overprinted by subsequent extension while a remnant of the subducted slab is observed in a far external orogenic position understanding the deformational evolution of the dinarides is hampered by the reduced availability of kinematic studies therefore we have performed a surface kinematic study in the external parts of the dinarides by correlating with available geophysical and evolutionary constraints we constructed two large scale kinematically controlled regional transects the results demonstrate a long lived evolution of shortening that affected the dinarides lower orogenic plate while the late jurassic earliest cretaceous deformation was associated with an earlier obduction moment the latest cretaceous onset of continental collision has gradually focused deformation at inherited rheological weakness zones we show that shortening was interrupted by a period of miocene extension that affected all orogenic areas and created the dinarides lake system the extension was followed by renewed shortening that started during the latest miocene and remains presently active whose kinematics in the central and se part of the dinarides is revealed for the first time by our study these results indicate a lower plate crustal accretion mechanism that was spatially and temporally connected with gradual slab retreat in the dinarides

palaeoenvironment and palaeoclimate of the middle miocene lake in the steinheim basin sw germany a reconstruction from c o and sr isotopes of fossil remains a differentiated reconstruction of palaeolimnologic environmental and climatic conditions is presented for the middle miocene long term freshwater lake 14 3 to 13 5 ma of the steinheim basin on the basis of a combined c o and sr isotope study of sympatric skeletal fossils of aquatic and terrestrial organisms from the lake sediments the oxygen isotope composition for lake water of the steinheim basin 18oh2o 2 0 0 4 vsmow n 6 was reconstructed from measurements of 18opo4 of aquatic turtle bones the drinking water calculated from the enamel of large mammals proboscideans rhinocerotids equids cervids suids has 18oh2o values 18oh2o 5 9 1 7 vsmow n 31 typical for middle miocene meteoric water of the area this 18oh2o value corresponds to a mean annual air temperature mat of 18 8 3 8 c calculated using a modern day 18oh2o mat relation hence large mammals did not use the lake water as principal drinking water in contrast small mammals especially the then abundant pika prolagus oeningensis drank from 18o enriched water sources 18oh2o 2 7 2 3 vsmow n 7 such as the lake water differences in sr and o isotopic compositions between large and small mammal teeth indicate different home ranges and drinking behaviour and support migration of some large mammals between the swabian alb plateau and the nearby molasse basin while small mammals ingested their food and water locally changes in the lake level water chemistry and temperature were inferred using isotopic compositions of ostracod and gastropod shells from a composite lake sediment profile calcitic ostracod valves ilyocypris binocularis 18o 1 7 1 2 vpdb 13c 0 5 0 9 vpdb n 68 and aragonitic gastropod shells gyraulus spp 18o 2 0 1 3 vpdb 13c 1 1 1 3 vpdb n 89 have 18o and 13c values similar to or even higher than those of marine carbonates 13c values of the biogenic carbonates parallel lake level fluctuations while 18o values scatter around 2 2 and reflect the short term variability of meteoric water inflow vs longer term evaporation 87sr 86sr ratios of aragonitic gyraulus spp gastropod shells parallel the lake level fluctuations reflecting variable inputs of groundwater and surface waters using a water 18oh2o value of 2 0 vsmow water temperatures calculated from skeletal tissue 18o values of ostracods are 16 7 5 0 c gastropods 20 6 5 6 c otoliths 21 8 1 4 c and fish teeth 17 0 2 7 c the calculated mat 19 c lake water temperatures 17 to 22 c and the 18o enriched water compositions are indicative of warm temperate climatic conditions possibly with a high humidity during this period vegetation in the area surrounding the basin was largely of the c3 type as indicated by carbon isotopic compositions of tooth enamel from large mammals 13c 11 1 1 1 vpdb n 40

the slanicul de buzau section a unit stratotype for the romanian stage of the dacian basin plio pleistocene eastern paratethys abstract climatic changes cause large paleoenvironmental responses in semi isolated basins we analyze here the sedimentary successions of the dacian basin romania to evaluate late pliocene and early pleistocene paleoenvironmental changes through macro and micropaleontology these changes are dated by creating a magnetostratigraphic time frame for two long and continuous sections with a combined total thickness of 2850 m the studied succession spans the time interval between 4 7 ma and 1 6 ma and records both the mid pliocene warm period 3 3 2 9 ma and the onset of large scale glaciations on the northern hemisphere 2 7 ma due to progressive basin infill the paleoenvironment changes from brackish to fluvio lacustrine with a major extinction event of lymnocardiine bivalves around 4 15 ma rich and dominantly freshwater mollusk and ostracod faunas develop from this moment onwards between 3 2 ma and 2 95 ma the reappearance of lymnocardiines identifies a short moment of higher salinities the previously identified plescoi event in time this correlates closely to the warmest interval of the pliocene and is therefore most likely related to connectivity to the black sea during maximum sea level after the climatic optimum deposition continues in a fluvio deltaic setting with only scarce finds of fauna increasing amounts of coarse grained fluvial sediments show a close relationship with the progressive cooling during the pleistocene

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

crayfish burrows from late jurassic late cretaceous continental deposits of patagonia argentina their palaeoecological palaeoclimatic and palaeobiogeographical significance abstract the trace fossil loloichnus baqueroensis igen and isp nov from late jurassic late cretaceous continental deposits of patagonia argentina includes thickly lined mostly passively filled and y branched burrows other important features of this ichnofossil are the inner surface texture of lining showing transversal elongated and adjacent grooves and less commonly the pelletal filling of burrows l baqueroensis is recorded from the bajo grande bajo tigre punta del barco and laguna palacios formations which were deposited in different volcaniclastic environments of the deseado massif and san jorge basin geological provinces respectively the described burrows are found in many levels of palaeosols developed in reworked piroclastic deposits where they are the main component of the ichnofabrics in association with meniscate and thinly lined burrows and a diffuse and complex boxwork of small diameter burrows root traces are also present and in many cases occur inside l baqueroensis considering general morphology surface texture filling types palaeoenvironments in which they occur and comparisons with extant and fossil decapod burrows the likely trace makers of l baqueroensis were crayfishes decapoda astacidea probably parastacidae the producers of l baqueroensis inhabited soils where their burrows probably reached the water table and contained roots that were used for feeding considering climatic preferences of extant parastacids it is proposed a temperate climate for central patagonia during the deposition of the studied units the widespread presence of crayfishes during late jurassic late cretaceous times in central patagonia supports the monophyletic origin of this group during the triassic and suggests that the present restricted geographic distribution in southern south america is a relict of a broader one

horizontal and vertical structure of the major sporadic sodium layer events observed during aloha 90 sporadic na nas layers have been observed frequently at low and high altitude sites primarily in the northern hemisphere nas layers are very dense and very thin 1 km fwhm and can form over periods ranging from a few minutes to several hours radar and lidar observations by our group at arecibo have shown conclusively that nas layers are linked to the formation of sporadic e es layers large nas events were observed on several flights during aloha 90 to extend over horizontal distances of approximately 1800 km atmospheric tides and gravity waves were observed to have an effect on the vertical motion of these layers we describe the 22 march event which was observed from maui 21 n to near the equator 5 n and the 27 march event which was observed from maui 156 w to almost the international date line 172 w

miocene vegetation and climate dynamics in eastern and central paratethys southeastern europe abstract from the cretaceous to modern time the earth s climate system has changed repeatedly from a greenhouse to an icehouse the miocene appeared as the last warm episode in earth history prior to the establishment of large northern hemisphere ice sheets furthermore the miocene was characterized by both large scale marine transgressions and pronounced episodes of regressions e g opening and closure of marine corridors as well as appearance and disappearance of lakes and swamps the sea level changes and instability of the climate system strongly influenced not only marine ecosystems but also the terrestrial biota to throw new light on the miocene evolution of european ecosystems and climate dynamics we compared plant assemblages from southeastern europe palaeogeographically this area is a transitional belt between tethyan and paratethyan realms and it thus constitutes a crucial geographical position when one tries to comprehend the exchange pathways of various floristic elements appearance and evolution of steppe vegetation interaction between forest and steppe vegetation and of course the corresponding climates influencing the vegetation dynamics both macro and microfloristic plant associations were considered in our analysis large palaeofloristic and palaeocoenotic transformations occurred during the miocene the early to middle miocene flora is rich and diverse in thermophilous elements which formed polydominant mesophytic to hygromesophytic forests early miocene climate was warm and humid with mean annual temperatures mainly above 16 c and annual rainfalls over 1000 mm the middle miocene was the warmest period of the whole miocene with annual temperatures ranging from 17 c to 19 c and winter temperatures from 7 c to 12 5 c climatic changes after the miocene climatic optimum caused changes in floristic composition and vegetation structure the vegetation shows a decreasing trend in abundance of palaeotropic and thermophilous elements reduction of macrothermic elements and disappearance of evergreen laurel forests together with these changes is a corresponding increase in the role of arctotertiary species in plant communities and they became dominants in mesophytic forests the available data indicate that major vegetation changes occur in the late miocene this period is characterized by more diverse climatic conditions which were directed by global climatic changes and probably complicated by regional palaeogeographic reorganizations and tectonic processes slight cooling and some drying is recorded for the beginning of the late miocene followed by fluctuations of palaeoclimate parameters observed which display cycling change of humid dryer and warmer cooler conditions our study provides a new insights on the miocene vegetation and climate dynamics and evolution in southeastern europe

life in the sublittoral zone of long lived lake pannon paleontological analysis of the upper miocene szak formation hungary life and depositional environments in the sublittoral zone of lake pannon a large brackish paratethyan lake from the late miocene were reconstructed from fossils and facies of the szak formation this formation is exposed in several roughly coeval 9 4 8 9 ma outcrops located along strike of the paleo shelf break in northwestern hungary the silty argillaceous marl of the formation was deposited below storm wave base at 20 30 to 80 90 m water depth the abundance of benthic organisms indicates that the bottom water was usually well oxygenated interstitial dysoxia however may have occurred immediately below the sediment water interface as evidenced by occasional preservation of trace fossils such as diplocraterion the fauna comprised endemic mollusks including brackish cockles of the subfamily lymnocardiinae dreissenid mussels congeria and highly adapted uniquely large sized deep water pulmonate snails planorbids and lymnaeids ostracods were dominated by endemic species and in some cases endemic genera of candonids leptocytherids cypridids and loxoconchids fish remnants include a sciaenid otolith and the oldest skeletal occurrence of perca in europe the phytoplankton comprised exclusively endemic coccolithophorids mostly endemic dinoflagellates prevailingly spiniferites and cosmopolitan green algae the late miocene fauna and flora of lake pannon were in many ways similar to the modern caspian biota and in particular cases can be regarded as its precursor

psilonichnus upsilon frey curran and pemberton 1984 burrows and their environmental significance in transgressive albian lower cretaceous sands of glanow stroniczki cracow upland southern poland abstract a considerable upper albian sand lithosome developed on the external margin of the albian epicontinental sea in the polish jura chain miechow synclinorium southern poland is recognized as a shallowing up sequence within the generally transgressive albian sands in particular burrows described as the ichnospecies psilonichnus upsilon frey curran and pemberton 1984 have a particular ecologic and sedimentological significance and constitute the primary focus of this paper in the glanow stroniczki section cracow upland southern poland such burrows seem to be a crucial tool in the interpretation of basin bathymetry indicating a foreshore to backshore beach facies and probably recording a temporary break in sedimentation they were infilled by sand with pebbles or pebble material potentially during hurricane or strong storm action lithification of the burrow infillings and their enveloping concretionary halos should have progressed in a beachrock mode the glanow horst composed of jurassic biohermal limestones was likely an emerged element that neigboured or was surrounded by a beach with active fauna the psilonichnus upsilon burrows in glanow stroniczki closely resemble burrows of the modern ghost crab ocypode in modern settings representatives of ocypode are encountered in extremely shallow marine foreshore intratidal and backshore supratidal to dune environments the ichnological data from glanow stroniczki suggests that fauna behaviorally similar to ocypode may have occupied the beach backshore and to a lesser extent the foreshore zone near the emerged glanow horst

population bottleneck triggering millennial scale morphospace shifts in endemic thermal spring melanopsids for more than hundred years the thermal spring fed lake pe ea near oradea romania was studied for its highly endemic subfossil and recent fauna and flora one point of focus was the species lineage of the melanopsid gastropod microcolpia parreyssii which exhibited a tremendous diversity of shapes during the earlier holocene as a consequence many new species subspecies and variety names have been introduced over time trying to categorize this overwhelming variability in contrast to the varied subfossil assemblage only a single phenotype is present today we critically review the apparent speciation event implied by the taxonomy based on the presently available information and new data from morphometric analyses of shell outlines and oxygen and carbon isotope data this synthesis shows that one turning point in morphological evolution coincides with high accumulation of peaty deposits during a short time interval of maximally a few thousand years the formation of a small highly eutrophic swamp with increased input of organic matter marginalized the melanopsids and reduced population size the presented data make natural selection as the dominating force unlikely but rather indicates genetic drift following a bottleneck effect induced by the environmental changes this claim contrasts the obvious trend and shows that great morphological variability has to be carefully and objectively evaluated in order to allow sound interpretations of the underlying mechanisms

horizontal structures in sporadic sodium layers at 23 s during 1979 and 1980 the inpe lidar located at sao jose dos campos brazil was operated in a steerable mode measuring the sodium profiles sequentially at three points in the sky twelve sporadic sodium layer events ssls which occurred in this period are studied in the present work the evolution of the sporadic peaks at the three positions shows short time structures generally separated by consistent time lags in almost all events on some occasions the time evolution at one position is very different than at the other two these data indicate that short duration ssls have cloud like structures which are advected over the measuring station by the horizontal winds and the long duration layers show a patchy and wave like structure in no case did we observe rapid growth in the sodium density to occur simultaneously at all 3 measuring points on this basis we believe that there is no evidence for fast production of sodium and consequently that there is no need for theories for the formation of ssls to be consistent with such fast production

the muddy bottom of lake pannon a challenge for dreissenid settlement late miocene bivalvia abstract the late miocene dreissenids of lake pannon a long existing eastern central european lake bear witness to two very different modes of life which allowed these bivalves to successfully settle in what appears to be an inhospitable environment one guild is restricted to the genera mytilopsis conrad 1858 and sinucongeria lorenthey 1894 these representatives are extreme r strategists which tend to produce temporal boom and bust populations during time windows of improved ecological conditions these opportunities are interpreted here to correlate with cyclic shifts in the epilimnion hypolimnion relation and the corresponding oxygenation of bottom waters events which are probably triggered by low frequency orbital forcing the second guild is composed solely of congeria partsch 1836 the paradox of the proliferation of a single species characterised by extreme size and weight in a muddy oxygen deficient lake environment avoided by nearly all other molluscs points to a hidden mechanism not accessible to other species we tentatively link this mechanism with chemosymbiosis functional morphology in interplay with a highly sulphidic over saturated interstitial water support an interpretation of the large congeria subglobosa as a successful h2s pump model

ocean to ice heat flux at the north pole environmental observatory 1 data from drifting buoys deployed in april 2002 as part of the north pole environmental observatory project have been analysed to estimate ocean heat flux in the time period from 1 may 2002 to 11 mar 2003 prior to late january the observatory remained in deep water but subsequently drifted directly over the yermak plateau a relatively shallow feature north of svalbard while over deep water heat flux was dominated by storage and release of solar energy in the ocean boundary layer during summer the most likely annual average value for 2002 was 2 6 w m 2 less than previous determinations in the western arctic over yermak plateau heat flux at the interface came from mixing of warmer water into the boundary layer from below when the observatory was in water with depths less than 1200 m the average heat flux was around 22 w m 2

late miocene to early pliocene chronostratigraphic framework for the dacic basin romania abstract new magnetostratigraphic results and calcareous nannofossil data of seven sections in the dacic basin of southern romania covering the latest maeotian to early romanian time span 6 4 4 0 ma allow a correlation with the current astronomical polarity time scale this establishes a chronological framework for the pontian and dacian stages of the paratethys and facilitates to correlate the paratethys stages with those of the mediterranean the maeotian pontian boundary is estimated at 6 15 0 11 ma within subchron c3an 1n while the age of the pontian dacian boundary is 5 30 0 1 ma within subchron c3r the odessian portaferrian and portaferrian bosphorian substage boundaries can be placed at about 6 0 and 5 6 ma at the base and near the end of chron c3r respectively consequently the pontian stage has a duration of approximately 0 85 myr and is coeval with the upper half of the messinian stage the base of the dacian stage corresponds to the onset of the pliocene and is coeval with the pontian kimmerian boundary of the euxinic black sea basin the dacian romanian boundary is recorded either at 4 58 0 05 ma in subchron c3n 2n nunivak or at 4 25 0 05 ma in subchron c3n 1n cochiti the length of the dacian stage is therefore about 0 7 myr or approximately 1 ma the transition of the getian into the parscovian substage can be dated at 4 83 ma within subchron c3n 3n sidufjall or at 4 55 ma within subchron c3n 2n nunivak the occurrence of calcareous nannofossil assemblages in the lower portaferrian and near the portaferrian bosphorian transition belonging to the upper part of the discoaster quinqueramus nn11 zone and in the middle bosphorian belonging to the amaurolithus tricorniculatus nn12 zone indicates the presence of ephemeral marine connections between the paratethys basin and the mediterranean during the late messinian another marine influx inferred from nannofossil species characteristic of the nn12 zone and found in lower dacian sediments near the top of subchron c3n 4n thvera post dates the basal pliocene transgression of the mediterranean basin

temperature difference across the lomonosov ridge implications for the atlantic water circulation in the arctic ocean 1 drifting buoy observations in the arctic ocean indicate that unlike climatological conditions the temperature of the upper atlantic water was higher in the makarov basin side of the lomonosov ridge than in the amundsen basin side in 2004 hydrographic data from 1991 to 2004 has been compared with climatology to examine the relative phase of atlantic water temperature change in these regions on the amundsen basin side of the lomonosov ridge a positive temperature anomaly in the atlantic water began in the early 1990s continued from the mid 1990s to the early 2000s and started decreasing in 2004 in contrast positive temperature anomalies were first apparent on the makarov basin side of the lomonosov ridge in 2000 and continue in 2004 recent historical data indicates that the arrival of temperature anomalies on the makarov basin side of the lomonosov ridge is delayed about 7 years after arrival on the amundsen basin side our results support the idea that atlantic water circulates cyclonically around the periphery of the makarov basin at a propagation speed of 1 2 cm s 1

stable isotopic evidence of salinity change influence on the evolution of melanopsid gastropods in the late miocene pannonian basin the radiation of the gastropod melanopsis in the pannonian basin of eastern and central europe provides an excellent case study of the tempo and mechanisms of evolutionary diversification we analyzed the carbon and oxygen isotopic ratios of melanopsid shells from before during and after the radiation in order to provide a more detailed paleoenvironmental frame work in which to interpret the morphological changes observed the authors samples fall into two groups those from before and during the radiation late sarmatian and pannonian stages form a tight cluster a second more scattered group of points represents samples from after the radiation pontian stage the late sarmatian pannonian samples have higher ratios of both isotopes means of minus 2 11 for delta sup 18 o and 1 27 for delta sup 13 c than do the succeeding pontian stage samples minus 4 16 for minus 2 22 respectively we interpret this shift as indicative of a basinwide drop in salinity an interpretation supported by paleofaunal evidence our isotopic data refine the environmental scenario in two important ways the tight cluster of late sarmatian pannonian data indicates that the shallow waters of the basin were relatively uniform and relatively stable with respect to salinity rather than locally variable or steadily changing across this time interval the shiftmore to fresher water in the pontian stage coincides with the extinction of two widespread and abundant melanopsid species but several species go extinct earlier than the salinity drop and two species pass through it seemingly unaffected less

late miocene quaternary volcanism tectonics and drainage system evolution in the east carpathians romania abstract middle miocene sarmatian convergence created the fold and thrust belt of the eastern carpathians of romania which subsequently experienced post collisional crustal deformation combined with calc alkaline and alkalic basaltic volcanism in late miocene quaternary time this deformation led to the rise of the c limani gurghiu harghita volcanic mountains and to the subsidence of the n s oriented intramontane borsec bilbor gheorgheni ciuc and brasov pull apart basins and the e oriented monocline related f g ras basin the regional drainage network is the composite of 1 older e se and s flowing rivers which cross the carpathians radiate towards the foreland and were probably established during the middle miocene sarmatian collision event 2 a more recent drainage system related to the contemporaneous development of the volcanoes and intramontaneous basins which generally drains westward into the transylvanian basin since late miocene time and has been capturing the older river system the older river drainage system has also been modified by late pliocene quaternary folding thrusting and monoclinal tilting along the pericarpathian orogenic front and by reactivated transverse high angle basement faults which cross the eastern carpathian foreland

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

the role of shortwave radiation in the summer decay of a sea ice cover heat balance models of ice leads and the underlying water column were used to investigate the role of shortwave radiation in the summer decay of a sea ice cover because of the potential importance of positive feedback between decreasing ice concentration and increasing solar input to the ocean particular emphasis was given to the treatment of heat transfer and lateral melting in leads the rate of heat loss to floe edges was calculated from lead temperatures using an empirical boundary layer parameterization coefficients for this parameterization were obtained from field measurements in the dynamically active ice cover of the greenland sea during the 1984 marginal ice zone experiment and in the static ice of mould bay northwest territories field coefficients were found to be considerably larger than those previously obtained in the laboratory suggesting that heat transfer rates near floe edges were controlled more by winds and currents than by local density differences model studies of individual leads indicate that heat losses to the atmosphere cause lateral melt rates to asymptotically approach a constant value as lead size increases thus although very wide leads transmit considerable energy to the underlying ocean they have relatively little effect on lateral melting other results provide information on the relative importance of horizontal heat transfer rates ice thickness floe perimeter atmospheric forcing and oceanic heat flux in general the calculations indicate that much of the shortwave radiation entering the ocean is absorbed below the ice where it contributes to bottom ablation rather than lateral melting this suggests that previous work has seriously overestimated the magnitude of the feedback between ice concentration and incident shortwave radiation

centennial to decadal scale environmental shifts in and around lake pannon vienna basin related to a major late miocene lake level rise a detailed ultra high resolution analysis of a 37 cm long core of upper miocene lake sediments of the long lived lake pannon has been performed despite a general stable climate at c 11 9 ma several high frequency oscillations of the paleoenvironments and depositional environments are revealed by the analysis over a short time span of less than 1000 years shifts of the lake level associated with one major 3rd order flooding are reflected by all organisms by a cascade of environmental changes on a decadal scale within a few decades the pollen record documents shifting vegetation zones due to the landward migration of the coast the dinoflagellate assemblages switch towards offshore type due to the increasing distance to the shore the benthos is affected by low oxygen conditions due to the deepening this general trend is interrupted by smaller scale cycles which lack this tight interconnection especially the pollen data document a clear cyclicity that is expressed by iterative low pollen concentration events these negative cycles are partly reflected by dinoflagellate blooms suggesting a common trigger mechanism and a connection between terrestrial environments and surface waters of lake pannon the benthic fauna of the core however does not reflect these surface water cycles this forcing mechanism is not understood yet but periodic climatic fluctuations are favoured as hypothesis instead of further lake level changes short phases of low precipitation reducing pollen production and suppressing effective transport by local streams might be a plausible mechanism this study is the first hint towards solar activity related high frequency climate changes during the vallesian late miocene around lake pannon and should encourage further ultra high resolution analyses in the area

ghost shrimps decapoda axiidea callianassidae as producers of an upper miocene trace fossil association from sublittoral deposits of lake pannon vienna basin slovakia numerous trace fossils are described from the late miocene sediments of the bzenec formation exposed at the gbely section the vienna basin slovakia during deposition of the sediments the area was part of the large long lived brackish to freshwater lake pannon most of the trace fossils are attributed herein to egbellichnus jordidegiberti igen et ispec nov and are interpreted as burrows produced by decapod crustaceans specifically by a ghost shrimp of the family callianassidae this interpretation is based on two independent lines of evidence environmental requirements of large bioturbators and the burrow morphology itself the new ichnotaxon is distinguished from other related ichnotaxa by a combination of typically inclined roughly at an angle of 45 cylindrical burrows absence of lining and tunnels making loops or bends at approximately right angles the burrow systems at gbely document the survival of ghost shrimp long after the closure of all seaways and the origin of lake pannon as today no ghost shrimp are known from long lived brackish lakes egbellichnus from gbely is the only although indirect record of ghost shrimp from a brackish lake environment reported so far

the link between tectonics and sedimentation in asymmetric extensional basins inferences from the study of the sarajevo zenica basin abstract the coupled tectonic and depositional history of extensional basins is usually described in terms of stratigraphic sequences linked with the activity of normal faults this depositional kinematic interplay is less understood in basins bounded by major extensional detachments or normal fault systems associated with significant exhumation of footwalls of particular interest is the link between tectonics and sedimentation during the migration of normal faulting in time and space across the basin one area where such coupled depositional kinematic history can be optimally studied is the late oligocene miocene sarajevo zenica basin located in the dinarides mountains of bosnia and herzegovina this intra montane basin recorded oligocene pliocene sedimentation in an endemic and isolated lake environment we use field kinematic and sedimentological mapping in outcrops correlated with existing local and regional studies to derive a high resolution evolutionary model of the basin the novel results demonstrate a close correlation between moments of normal faulting and high order sedimentological cycles while the overall extensional basin was filled by a largely uni directional sediment supply from the neighbouring mountain chain the migration in time and space of listric ne dipping normal faults was associated with a gradual shift of the sedimentological environment transgressive regressive cycles reflect sequential displacements on normal faults and their footwall exhumation defining a new sedimentological model for such basins this early middle miocene extension affected the central part of the dinarides and was associated with the larger opening of the neighbouring pannonian basin the extension was preceded and followed by two phases of contraction the oligocene early miocene thrusting took place during the final stages of the dinarides collision while the post middle miocene contraction is correlated with the regional indentation of the adriatic continental unit this latter phase inverted the extensional basin by reactivating the inherited basal listric detachment

palaeoenvironment assessment of pliocene lom lignite bulgaria from bitumen analysis and preparative off line thermochemolysis abstract the dacian coal bearing province is located in nw bulgaria coal formation is thought to be connected with desiccation of the dacian basin during a prolonged regression in the late pontian and pliocene dacian romanian age a lom lignite sample was characterized via micropetrography bulk chemical analysis spectral methods and thermochemolysis the pollen record was poor suggesting coal formation under oxygen rich conditions during peatification straight chain alkanes alkan 2 ones alkanols des a triterpenoids aromatized triterpenoids aromatized hopane hopene hopanes and triterpenoids with a strong dominance of oleanane derived structures were present in the extracted bitumen the residue after extraction was subjected to preparative off line tetramethylammonium hydroxide tmah thermochemolysis the aliphatic products released were c22 c27 fatty acid fa methyl esters i e methoxymethyl esters c22 c28 even numbered diacids dimethyl esters with a smooth distribution and traces of i and ai c15 acid methyl esters trapped and bound fas were distinguished using tetraethylammonium acetate teaac treatment the main thermochemolysis products were phenols structurally related to lignin vanillyl and syringyl units were produced in similar amounts indicating nonwoody angiosperm vegetation as the main plant input to the palaeo swamp probably originating from marsh or grassland sources the bitumen provided unequivocal information for an angiosperm contribution to the mire while the results of the tmah pyrolysis revealed a concomitant angiosperm and gymnosperm input the biomarker assemblage makes the lom lignite unique in bulgaria all the other bulgarian neogene lignites being dominated by coniferous vegetation with only traces of angiosperm contributions

high resolution analysis of upper miocene lake deposits evidence for the influence of gleissberg band solar forcing article i nfo a high resolution multi proxy analysis was conducted on a 1 5 m long core of tortonian age 10 5 ma late miocene from austria europe the lake sediments were studied with a 1 cm resolution to detect all small scale variations based on palynomorphs pollen and dinoflagellate cysts ostracod abundance geochemistry carbon and sulfur and geophysics magnetic susceptibility and natural gamma radiation based on an already established age model for a longer interval of the same core this sequence can be limited to approx two millennia of late miocene time with a resolution of 13 7 years per sample the previous study documented the presence of solar forcing which was verified within various proxies on this 1 5 m core by a combination of redfit spectra and gaussian filters significant repetitive signals ranged in two discrete intervals corresponding roughly to 55 82 and 110 123 years fitting well within the lower and upper gleissberg cycle ranges based on these results the environmental changes along the 2000 year late miocene sequence are discussed no major ecological turnovers are expected in this very short interval nonetheless even within this brief time span dinoflagellates document rapid changes between oligotrophic and eutrophic conditions which are frequently coupled with lake stratification and dysoxic bottom waters these phases prevented ostracods and molluscs from settling and promoted the activity of sulfur bacteria the pollen record indicates rather stable wetland vegetation with a forested hinterland shifts in the pollen spectra can be mainly attributed to variations in transport mechanisms these are represented by a few phases of fluvial input but mainly by changes in wind intensity and probably also wind direction such influence is most likely caused by solar cycles leading to a change in source area for the input into the lake furthermore these solar induced variations seem to be modulated by longer solar cycles the filtered data display comparable patterns and modulations which seem to be forced by the 1000 year and 1500 year cycles the 1000 year cycle modulated especially the lake surface proxies whereas the 1500 year cycle is mainly reflected in hinterland proxies indicating strong influence on transport mechanisms

taphonomy of ghost shrimps decapoda axiidea callianassidae associated with their burrows within a middle miocene mud volcano complex of persian arabian gulf kuwait abstract shallow marine strata of the ghar formation exposed along the kuwait arch in the north of kuwait contains fields of mud volcanoes associated with an assemblage dominated by pectinid bivalves and callianassid ghost shrimps the depositional palaeoenvironment is interpreted to be intertidal to subtidal with the water depth not exceeding 50 m and with normal to hypersaline conditions based on the microfossil assemblage a middle miocene age early langhian is inferred suggesting a longer stratigraphic span of the formation despite the previous studies treating the ghar formation as strictly early miocene callianassid body fossils and numerous trace fossils assignable to ophiomorpha have been identified ghost shrimp remains consisting of isolated cheliped elements are assigned to neocallichirus s l which is the likely producer of ophiomorpha burrows as documented by cheliped elements present within burrows and in the substrate around them stable isotopes discrimination modelling confirmed that fluids in the substrate were derived from at least two sources implying the presence of active mud volcanoes in the environment inhabited by ghost shrimps effusive activity of mud volcanoes further enhanced disarticulation and fragmentation of callianassid remains the micritic matrix of ghost shrimp exoskeletons is indicated to have resulted from a mixture of local seawater with fluid of continental origin this ghost shrimp occurrence is the first formal report of fossil decapod crustaceans from kuwait

observations of strong wind shears and temperature enhancements during several sporadic na layer events above haleakala we describe two sporadic na nas layer events observed on 26 september and 6 october 1993 by the na wind temperature w t lidar above haleakala maui 20 8 n 156 2 w during aloha 93 both events occurred between 90 and 95 km altitude and appeared to be associated with large amplitude gravity waves both were accompanied by temperature enhancements of more than 40 k the temperature and na density variations at the peak of the nas as well as the vertical motions of the nas layers and regions of elevated temperature were highly correlated the vertical wind structure exhibited no unusual characteristics in the vicinities of the nas the zonal wind profile for the 6 october event exhibited a very strong vertical shear approximately 1 km below the nas layer that approached the dynamic instability limit of 42 m s km however the polarity of the shear was opposite that predicted by the classical wind shear theory of sporadic e layers es formation

the winneshiek biota exceptionally well preserved fossils in a middle ordovician impact crater the winneshiek shale middle ordovician darriwilian was deposited in a meteorite crater the decorah impact structure in ne iowa this crater is 5 6 km in diameter and penetrates cambrian and ordovician cratonic strata it was probably situated close to land in an embayment connected to the epicontinental sea typical shelly marine taxa are absent the konservat lagerstatte within the winneshiek shale is important because it represents an interval when exceptional preservation is rare the biota includes the earliest eurypterid a giant form as well as a new basal chelicerate and the earliest ceratiocarid phyllocarid conodonts some of giant size occur as bedding plane assemblages bromalites and rarer elements including a linguloid brachiopod and a probable jawless fish are also present similar fossils occur in the coeval ames impact structure in oklahoma demonstrating that meteorite craters represent a novel and under recognized setting for konservat lagerstatten

possible ghost shrimp burrows from the mid holocene of northeastern buenos aires argentina implications for breeding and postlarval settlement behavior abstract large and tiny ophiomorpha nodosa lundgren 1891 and thalassinoides suevicus rieth 1932 and the postlarval chamber maiakarichnus currani are described from the mid holocene destacamento rio salado member northeastern buenos aires province argentina large specimens of o nodosa consist of variably bifurcated horizontal galleries connected in some cases by vertical shafts and lined with pellets of different shape large t suevicus are fewer and possess smooth outer walls the smaller burrows of o nodosa and t suevicus are only a few centimeters from or even embedded in the outer wall of the larger burrows and are interpreted as the first settlement traces a revised diagnosis of the spheroidal chamber m currani connected with o nodosa and probably with t suevicus is submitted the probable producer of these burrows and chambers is the ghost shrimp audacallichirus mirim morphological descriptions and burrowing behavior of a mirim in modern and fossil populations from argentina and brazil suggest that this producer is represented at a higher level of ichnological abundance than previously recorded

chronology and integrated stratigraphy of the miocene sinj basin dinaride lake system croatia article i nfo ar 39 ar dating mollusk evolution conohyus in the miocene the intra montane basins of the dinaric mountain chain harbored a series of long lived lakes constituting the so called dinaride lake system the thick lacustrine sedimentary records of these lakes provide an excellent opportunity to study evolution and radiation of mollusks in an isolated environment the 500 m thick infill that accumulated in the sinj basin is one of the key records because of its excellent mollusk preservation recent studies on the depositional history pollen assemblages and large mammals have enhanced the understanding not only of lake sinj but also of the regional climatic developments and faunal migratory patterns a reliable chronology of the development of lake sinj which is crucial for global correlation of its endemic realm was still lacking in this paper we present a detailed time frame for the miocene sinj basin based on palaeomagnetic and 40 ar 39 ar data we conclude that deposition took place between 18 0 to 15 0 ma a time span that correlates with the upper burdigalian and lower langhian mediterranean stages and ottnangian karpatian and lowermost badenian paratethys stages furthermore we determined the timing of several events in mollusk evolution important for correlation across the dinarides an age of 15 0 ma is attributed to the large mammals conohyus and gomphotherium preserved in the upper part of the basin stratigraphy 2010 elsevier b v all rights reserved

daytime lidar measurements of tidal winds in the mesospheric sodium layer at urbana illinois the first daytime lidar observations of the mesospheric na layer at urbana illinois 40 degrees n 88 degrees w were made in january and march 1986 the data show strong 12 hour oscillations of the na density and layer centroid height which appear to be caused by the semidiurnal tide the peak to peak variations in column abundance and centroid height were of the order of 100 and 3 km respectively the vertical wind velocities were inferred from the temporal variations of the density gradients on the layer topside the inferred wind amplitudes and vertical wavelengths for the semidiurnal tide were approximately 30 cm s sup minus 1 and approximately 50 km respectively the maximum upward vertical velocity occurs at about 1 100 lst and 2 300 lst

cedar lidar observations of sporadic na layers at urbana illinois in march and april of 1988 five short lived sporadic na layers were observed in the late evening above urbana il 40 n 88 w with the new cedar lidar instrument the layers were very narrow 140 m fwhm and very dense with maximum densities exceeding 24 000 cm 3 the layers formed in the late evening between 2100 lst and midnight at altitudes between 82 and 89 km the average duration of the layers was 100 s some of the layers moved rapidly both upward and downward with velocities as high as 9 ms 1 compared to similar phenomena observed at andoya norway von zahn et al 1987 and mauna kea hawaii kwon et al 1988 the sporadic layers above urbana appear to occur much less frequently at generally lower altitudes contain less na and are of much shorter duration the five sporadic na layers described in this letter may have resulted from the advection of meteor trails across the lidar field of view