cyclic climate and vegetation change in the late miocene of western bulgaria abstract a late miocene paludal to lacustrine sequence from a carbonate basin in nw bulgaria staniantsi basin is analysed displaying up to 27 rhythmically bedded sedimentary cycles in the lower part of the sequence the cycles consist of alternating autochthonous brown coal and marls containing diverse mollusc assemblages the upper part of the sequence is characterized by alternating dark to light grey clays and calcareous silts a palynomorph record comprising 163 samples is analysed by statistical means to reconstruct vegetation changes the coexistence approach is used to calculate quantitative palaeoclimate records for 6 parameters the studied section displays hierarchical cyclicity patterns longer term cycles possibly related to eccentricity period 100 kyr are present in the palynomorph record and show climate changes of warmer wetter and cooler drier periods in combination with frequency oscillations of thermophilous elements short term cycles most probably related to precession period 21 7 kyr are expressed by alternations of brown coal and marl shell beds and show cyclic change in peat forming vegetation related to oscillations of the groundwater level as a triggering mechanism wetter warmer and drier cooler climate phases related to orbital precession are probable in addition sections sampled at high resolution display small scale climate and vegetational variability as is shown by the analysis ferns were an important component of the peat forming vegetation while outside the mire a wetland vegetation consisting of pioneers and a mixed mesophytic forest with evergreen shrubs existed an oligo to mesotrophic slightly alkaline lake became repeatedly established with a diverse mollusc fauna and a dense hydrophytic vegetation with characean meadows in the upper part of the section a spreading of herbaceous vegetation is observed also known from other contemporaneaous palynomorph records in bulgaria and surrounding areas the increase of asteraceae in the upper part of the section combined with a marked decrease in woody taxa points to an opening of habitats and a decrease in mean annual precipitation this trend is paralleled by the mollusc fauna which yields several terrestrial partly xerophilous taxa

quantitative reconstruction of middle and late eocene paleoclimate based on palynological records from the huadian basin northeastern china evidence for monsoonal influence on oil shale formation abstract the eocene was an interval of climate evolution when the extreme high temperatures of the earliest cenozoic gave way to a global cooling trend fine grained lacustrine sediments of eocene age from northeastern china represent an excellent archive to study long term environmental and climatic changes at high resolution the huadian basin is a cenozoic fault bounded basin in jilin province northeastern china though small in area it contains numerous oil shale and coal bearing layers which provide an abundant middle to late eocene palynoflora eighty five palynomorph genera and one hundred palynomorph species were identified in the huadian formation allowing to distinguish 4 palynozones the nearest living relatives of the recovered palynomorph taxa suggest the presence of subtropical evergreen and deciduous broad leaved forests during deposition of the huadian formation using the coexistence approach ca we calculated seven paleoclimatic parameters which indicate a subtropical warm and humid climate with a mean annual temperature above 13 6 c and a mean annual precipitation of at least 887 mm however the climate became cooler and drier during the transition from the lower oil shale member to the upper carbonaceous shale member palaeoclimatic data from the various middle and late eocene basins of northeastern china i e the huadian fushun yilan hunchun and jishu basins were compared with data from north american and european basins middle eocene climate in the northern hemisphere was generally warm and humid and the mean annual temperature and precipitation in northeastern china were similar to those in north america though slightly lower than those of europe similar trends in temperature and precipitation on different continents support the existence of a global mid eocene cooling event this paper is the first systematic study of middle to late eocene seasonality in the huadian basin our results show an apparent differentiation in both temperature and precipitation between summer and winter supporting the view that the east asian monsoon was established in northeastern china already during the middle to late eocene this middle and late eocene monsoon was likely driven by the development of pacific trade winds and an alternating seasonal high and low pressure system over siberia the climatic changes observed in our dataset especially the precipitation changes appear to have played an important role in controlling oil shale formation in the huadian basin a warmer and more humid climate with abundant precipitation and high subsidence rates formed a deeper huadian depositional lake high productivity and stable stratification provided the abundant organic matter and favorable preservation conditions necessary for oil shale accumulation

middle miocene badenian vegetation and climate dynamics in bulgaria and poland based on pollen data abstract the miocene represents a time in eurasia when evergreen and thermophilous dominated paleogene vegetation was replaced by deciduous and temperate plants climatically it is the transition from a greenhouse to an icehouse world with the middle miocene climatic optimum as the last warm episode of earth history processes of plant evolution transformation of vegetation and coenotic structure were significantly forced by both changes in the global climate system and also by significant palaeogeographic reorganizations to give new insight in the middle miocene evolution of european ecosystems and climate dynamics we compared plant assemblages from northern bulgaria and southern poland southern paratethyan and polish lowlands realms based on palaeoecological analysis the main palaeocommunities are distinguished in hygro hydrophytic herbaceous palaeocoenoses reed marshes hygrophytic forest palaeocoenoses swamp forest and bush swamp riparian forests and mixed mesophytic forests despite some differences in taxonomic composition of these fossil floras and the proportion of individual taxa the vegetation shows similar composition and trends through time the main trend in the vegetation dynamics is a general decrease in the abundance of palaeotropic and thermophilous elements of semi evergreen forests together with these changes is a corresponding increase in the role of arctotertiary species in plant communities and these plants became dominant in the mesophytic forests changes in swamp vegetation are climatically related too but these reflect mainly local environmental dynamics and changes in inundation of the basin climate data from bulgaria and poland lack significant latitudinal climate gradient thus confirming more or less homogenous climatic conditions within europe in the middle miocene

what controlled mid late miocene long term aridification in central asia global cooling or tibetan plateau uplift a review abstract debate continues over whether global cooling or uplift of the tibetan plateau provided the first order driver for the aridification moisture levels of central asia throughout the mid late miocene between about 17 and 5 ma this review attempts to throw new light on the relations between the aridification and these two key factors this paper examines the evolution of miocene climate both moisture and temperature within five separate regions of eurasia to help understand the large scale controls of long term moisture in central asia the five regions include 1 europe 2 high latitude asia 3 the east asian monsoon region 4 the south asian monsoon region and 5 central asia itself because moisture reaching central asia has to firstly cross at least one of the other four regions temperature proxy data compiled from these five regions correlate with ocean temperatures from the global deep sea oxygen isotope records furthermore compiled moisture proxy data from the four regions surrounding central asia co vary and correlate with each other this can be explained by positive feedbacks between drying and cooling and supports the assumption that global cooling provides a dominant driving factor for the drying of eurasia global cooling reduces the amount of water vapor held in the atmosphere and thereby can cause terrestrial drying however in central asia the moisture evolution shows less similarity with its surroundings the uplift of the tibetan plateau including the tianshan mountains could provide a possible explanation for this difference the changing topography resulting from uplift events over time and space strongly influenced the moisture patterns in central asia during miocene times future research on the spatial timing and amplitude of tibetan plateau uplift should be useful to understand the moisture processes in central asia during the miocene

palynological evidence for the latest oligocene early miocene paleoelevation estimate in the lunpola basin central tibet uplift of the tibetan plateau is ultimately driven by the cenozoic collision between the indian and eurasian plates and their continued convergence one approach for studying the tibetan plateau uplift is to verify the paleoelevation changes from collision to present day this is important for understanding both the tectonics and the climatic effects the new high resolution palynological record of the uppermost oligocene to the lowest miocene strata from the lunpola basin indicates that the vegetation types during the latest oligocene earliest miocene were dominated by mixed coniferous broadleaved forests being different from the modern steppe vegetation by using the coexistence approach to the fossil pollen records after calibration the effects of temperature difference and the lapse rate a maximum paleoelevation of 3190 100 m asl was estimated in the lunpola basin in the latest oligocene earliest miocene being 1500 to 2000 m lower compared with the previous oxygen isotope paleoelevation in the same region

spatial and temporal variation in european neogene large mammals diversity abstract large mammals diversity i e ungulates or hoofed mammals is investigated over the whole european geographic area and through a period extending from the late oligocene around 27 ma ago to the early pliocene around 3 ma ago qualitative and quantitative spatial and temporal patterns are discussed thanks to the analysis of a large dataset of localities 695 that yielded large mammals and distributed over this period and area we show that the miocene is a key period in the installation of modern faunas in europe modern ruminants mainly cervids and bovids largely develop during the period considered and replace the oligocene inherited dominant faunas these replacements are triggered by different factors often extrinsic and constitute the roots of the present situation indeed a complex interplay between geographic palaeogeographic reorganisations and climatic factors warming and cooling events can be invoked to understand how faunas change geography seems to play a crucial role in the early miocene when it allows migration routes to open between europe asia and africa and in turn leads to a drastic increase of ungulate diversity that seems to be maintained in the middle miocene under the warm equable climates of the miocene climatic optimum the late miocene sees a global climatic deterioration leading to a decline in large mammals diversity and represents the root of the extant depleted situation regional comparisons indicate that endemism was already strong in the miocene especially in south eastern europe and that strong climatic belts already seem to have an impact on mammal communities since the late miocene the roots of the extant situation endemism and low diversity are therefore more complex and probably older than previously thought they are to be looked for before the quaternary climatic cycles and are the by product of deep time geographic and climatic events

paleoenvironmental reconstruction of the early to middle miocene central paratethys using stable isotopes from bryozoan skeletons stable carbon and oxygen isotope values from single bryozoan colonies were used to reconstruct the paleoenvironments of the early to middle miocene ottnangian to badenian sediments of the central paratethys this approach utilizes a locally abundant allochem while avoiding matrix and multiple allochem contamination from bulk rock samples bryozoan colonies and a few foraminifera and rock matrix samples from 14 localities yielded 399 carbon and oxygen isotope values data from six of the localities 15 of the total number of samples were interpreted as having been diagenetically altered and were rejected the remaining data indicate a primarily localized upwelling signal with lesser variation caused by global climatic and regional tectonic forcing of sea level salinity and temperature paleotemperatures were calculated to range from 12 to 21 c despite potential taxonomic and diagenetic problems bryozoan colonies are a powerful underutilized source of paleoenvironmental carbon and oxygen isotope data

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

palaeontological evidence of communication between the central paratethys and the mediterranean in the late badenian early serravalian abstract in the middle miocene the area of present day eastern slovenia was situated at the eastern mouth of the slovenian corridor a hypothetical seaway connecting the central paratethys and the mediterranean the exact location and time of closure of a seaway between the two neighbouring marine realms are still a matter of debate we studied badenian late langhian and early serravallian calcareous nannoplankton assemblages from eastern slovenia for their palaeogeographical significance by comparing them to contemporaneous central paratethyan and mediterranean assemblages and the assemblages described in selected odp and iodp reports assemblage composition and the sequence of biostratigraphic events observed in slovenia were very similar to that in several mediterranean sites comparison with the world ocean suggests that this similarity reflects communication between the mediterranean and paratethyan populations rather than a universal trend of nannoplankton evolution late badenian assemblages from different localities within the central paratethys exhibit considerable variation with respect to the presence of discoasters considered as typical of the mediterranean and the presence of rhabdosphaera poculi and hayella challengeri considered as typical of the eastern paratethys our results suggest the mixing of mediterranean and eastern paratethyan influences throughout the entire central paratethys during the late badenian the observed variability explains how opposing views on the status of the marine connection between the central paratethys and the mediterranean in the late badenian can arise from palaeontological studies of fossil assemblages considering only a single site or a small area the gastropod species pereiraea gervaisi migrated from the mediterranean to the central paratethys where it is only known from the immediate proximity of the hypothesised slovenian corridor this supports the thesis that the communication between the two seas took place via the slovenian corridor and not some other marine connection like the hypothetical axios vardar trench

palaeoclimatic evolution and vegetational changes during the late oligocene miocene period in western and central anatolia turkey abstract neogene basins are widespread in turkey and contain important lignite deposits in this study we reconstruct quantitatively the late oligocene miocene climate evolution in western and central anatolia by applying the coexistence approach to the palynofloras obtained from the published literatures and ongoing studies the coexistence approach results show that sedimentation occurred mainly under warm subtropical climatic conditions during the chattian and aquitanian period in western anatolia 16 5 21 3 c mean annual temperature mat and 5 5 13 3 c mean temperature of coldest month cmt rare occurrences of dinoflagellate cysts in the chattian and aquitanian indicates a marine influence after the regression of the sea during the burdigalian period climate becomes cooler due to a decrease of the palaeotropical arctotertiary ratio during the latest burdigalian langhian vegetation developed under terrestrial conditions which had started in the burdigalian time in western and central anatolia and continued to the early middle serravallian period the climate was subtropical in western and central anatolia during the early late serravalian 17 2 to 20 8 c for mat and 9 6 to 13 1 c for cmt besides increase of the cmt and mat values in western and central anatolia supports the latest chattian earliest aquitanian warming and middle miocene climatic optimum being also globally observed warm temperate climatic conditions are observed in the late miocene during the early middle tortonian the values are 15 6 to 20 8 c for the mat 5 5 to 13 3 c for the cmt and 823 and 1520 mm for the mean annual precipitation map they had experienced dry seasons due to lower boundary of map lying at 823 mm during the middle late tortonian the palaeotopography of central anatolia was higher compared to that of western anatolia during the middle late miocene as indicated by a rich species diversification in mountain forests this study provides the first quantitative model for late oligocene miocene palaeoclimatic evolution in western and central anatolia

paleoenvironmental settings of the sofia lignite basin insights from coal petrography and molecular indicators abstract compositions of balsha lignite sofia coal bearing basin bulgaria and carbonaceous shales are studied by petrological and geochemical proxies the macropetrographic characteristic of profiles is relatively constant the lignite is generally composed of dull matrix coal containing significant amounts of xylite fragments the typical microscopic constituents of the lignite are the ulminite and less frequently textinite lenses scattered within attrinitic groundmass the maceral composition of the organic matter in carbonaceous shales does not differ significantly from that of the lignite samples biomarker assemblages of the extractable portions are determined by gas chromatography mass spectrometry additional information for the compositions of residues after extractions is obtained by tmah thermally assisted hydrolysis methylation petrographic contents lipid assemblage and tmah thermally assisted hydrolysis methylation data imply that the original peat bog is formed in fresh water forest swamp preferably composed by gymnosperms polar diterpenoids argue for cupressaceae s l taxodiaceae as the most probable vegetation for one of the profiles appreciable angiosperm rich herbaceous type flora contribution is assumed polar oleanane triterepenoids and their aromatized derivatives argue for angiosperm input the relevance of a norfriedel 8 en 10 one friedelin ratio for groundwater level appraisal is discussed it admits long period of high water level in the paleomire high content of vanillyl structures and subordinated presence of syringyl units in products of tmah thermally assisted hydrolysis methylation are hint for gymnospermae input in the paleoswamp and angiospermae contribution to one of the profiles cinnamyl phenolic units indicating non woody angiosperm vegetation presence are registered as well flavonoids in products are considered as taxonomic markers of cupressaceae plants in the paleoswamp

proportions of convective and stratiform precipitation revealed in water isotope ratios distinguishing convective and stratiform rainfall is key to understanding how the water cycle responds to climate change an analysis of satellite and surface data shows that rain isotope ratios reflect the proportions of these types of rain

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

tree diversity in the miocene forests of western eurasia abstract in the present study published miocene mega and microfloral records compiled from a total of 92 localities in western eurasia are analysed with respect to diversity of different plant functional types pfts to study spatial diversity patterns and their evolution three time intervals are selected corresponding to the langhian 16 3 13 6 ma the serravallian 13 6 11 6 and the earlier part of the tortonian 11 6 8 5 ma first all arboreal species occurring in the floras are classified using a total of 13 different pfts functional types of trees and climatically defined subtypes in a next step diversity spectra with respect to these pfts are generated for each site cluster analysis is then performed in order to obtain groups of floras with similar spectra that are interpreted in terms of vegetation type their spatial distribution in each time interval is shown in maps according to these results zonally arranged patterns are obtained broadleaved deciduous forests are most important in the higher latitudes while mixed mesophytic forests dominate the mid latitudes in western eurasia broadleaved evergreen forests are of minor importance in the area of interest the observed diversity patterns and their changes in time are correlated with spatial climate patterns and the continental palaeoclimate evolution during the late miocene cooling broadleaved evergreen forests completely disappear from the mid latitudes of western eurasia and mixed mesophytic forests of the mid latitudes are mostly replaced by broadleaved deciduous vegetation types in the context of this cooling a drier season became established in western europe during the tortonian as is evident from reconstructed arboreal diversity data and precipitation data in central europe vegetation types indicating permanently humid conditions persisted throughout all the three time intervals analysed

mantle dynamics uplift of the tibetan plateau and the indian monsoon convective removal of lower lithosphere beneath the tibetan plateau can account for a rapid increase in the mean elevation of the tibetan plateau of 1000 m or more in a few million years such uplift seems to be required by abrupt tectonic and environmental changes in asia and the indian ocean in late cenozoic time the composition of basaltic volcanism in northern tibet which apparently began at about 13 ma implies melting of lithosphere not asthenosphere the most plausible mechanism for rapid heat transfer to the midlithosphere is by convective removal of deeper lithosphere and its replacement by hotter asthenosphere the initiation of normal faulting in tibet at about 8 3 ma suggests that the plateau underwent an appreciable increase in elevation at that time an increase due solely to the isostatic response to crustal thickening caused by india s penetration into eurasia should have been slow and could not have triggered normal faulting another process such as removal of relatively cold dense lower lithosphere must have caused a supplemental uplift of the surface folding and faulting of the indo australian plate south of india the most prominent oceanic intraplate deformation on earth began between about 7 5 and 8 ma and indicates an increased north south compressional stress within the indo australian plate a tibetan uplift of only 1000 m if the result of removal of lower lithosphere should have increased the compressional stress that the plateau applies to india and that resists india s northward movement from an amount too small to fold oceanic lithosphere to one sufficient to do so the climate of the equatorial indian ocean and southern asia changed at about 6 9 ma monsoonal winds apparently strengthened northern pakistan became more arid but weathering of rock in the eastern himalaya apparently increased because of its high altitude and lateral extent the tibetan plateau provides a heat source at midlatitudes that should oppose classical symmetric hadley circulation between the equator and temperate latitudes and that should help to drive an essentially opposite circulation characteristic of summer monsoons for the simple case of axisymmetric heating no dependence on longitude of an atmosphere without dissipation theoretical analyses by hou lindzen and plumb show that an axisymmetric heat source displaced from the equator can drive a much stronger meridianal monsoonlike circulation than such a source centered on the equator but only if heating exceeds a threshold whose level increases with the latitude of the heat source because heating of the atmosphere over tibet should increase monotonically with elevation of the plateau a modest uplift 1000 2500 m of tibet already of substantial extent and height might have been sufficient to exceed a threshold necessary for a strong monsoon the virtual simultaneity of these phenomena suggests that uplift was rapid approximately 1000 m to 2500 m in a few million years moreover nearly simultaneously with the late miocene strengthening of the monsoon the calcite compensation depth in the oceans dropped plants using the relatively efficient c4 pathway for photosynthesis evolved rapidly and atmospheric co2 seems to have decreased suggesting causal relationships and positive feedbacks among these phenomena both a supplemental uplift of the himalaya the southern edge of tibet and a strengthened monsoon may have accelerated erosion and weathering of silicate rock in the himalaya that in turn enhanced extraction of co2 from the atmosphere thus these correlations offer some support for links between plateau uplift a downdrawing of co2 from the atmosphere and global climate change as proposed by raymo ruddiman and froehlich mantle dynamics beneath mountain belts not only may profoundly affect tectonic processes near and far from the belts but might also play an important role in altering regional and global climates

late miocene and pliocene large land mammals and climatic changes in eurasia the fossil teeth of land mammals offer a powerful tool to map the regional details of past climate change in the terrestrial realm we use meanplant eaterhypsodonty molarcrownheight oflateneogenemammallocalitiestomaplatemioceneandpliocenepalaeoprecipitation on the eurasian continent and with higher temporal resolution in europe the results show that the mid latitude drying in eurasia affected thecentral parts ofthecontinentfirst and thatthedrying of western europeafter about7 8maseemstohavecoincidedroughlyintimewith a return to more humid conditions in eastern asia with a return to a drier east and more humid west in the pliocene within europe the hypsodonty based palaeoprecipitation maps suggest that the sequence from mn 9 to mn 12 ca 11 1 6 8 ma was dominated by an east west continental marine humidity gradient which gradually intensified and with a shift of dryer conditions eastwards in mn 12 ca 7 5ma thiswaspartlyoverlainfrommn13onwardsbyanorth southorientedgradient whichpersistedatleasttotheendofthepliocene the maps for both the earliest late miocene mn 9 ca 11 1 9 7 ma and the earliest pliocene mn 14 ca 4 9 4 2 ma show very low regional differentiation possibly suggesting perturbed phases in the evolution of the mammal communities analysis of hypsodonty and dietary structure of the mammalian plant eater community in europe during the entire interval shows that the miocene pliocene boundary was marked by a strong decrease in mesodont species and mixed feeders and an increase in brachydont species and omnivores in this view the shift in the latest miocene from east west to partly north south polarised hypsodonty patterns corresponds mainly to an increase in hypsodont species and grazers it seems probable that the east west gradient was primarily driven by precipitation while the north south gradient would also have been strongly influenced by temperature related effects of humidity

the coexistence approach a method for quantitative reconstructions of tertiary terrestrial palaeoclimate data using plant fossils abstract the coexistence approach is introduced as a method for quantitative terrestrial palaeoclimate reconstructions in the tertiary it is based on the assumption that tertiary plant taxa have similar climatic requirements to their nearest living relatives the aim of the coexistence approach is to find for a given fossil flora and a given climate parameter the climatic interval in which all nearest living relatives of the fossil flora can coexist for this purpose we have developed a data base climbot containing for over 800 tertiary plant taxa the nearest living relatives and their climatic requirements and an algorithm for analysis climst for all types of fossil floras the coexistence approach thus allows the rapid quantitative reconstruction of 10 different climate parameters including the mean annual temperature temperature of the warmest month temperature of the coldest month mean annual precipitation maximum monthly precipitation minimum monthly precipitation precipitation of the warmest month relative humidity potential evaporation as well as the ratio of mean annual precipitation over potential evaporation the reliability and resolution of the coexistence approach are tested with various techniques and proved to be reasonably good for instance the resolution with respect to the mean annual temperature can be up to 1 c applications to various modern and fossil floras are illustrated and the advantages and disadvantages of the coexistence approach are discussed

late miocene to early pliocene vegetation of southern europe 7 4ma as reflected in the megafossil plant record abstract assemblages of plant megafossils from the late miocene to early pliocene sites in southern europe have been re evaluated in order to get data for reconstructing the development of vegetation and climate during this time interval 7 4 ma main areas of the survey are centred in greece and adjacent countries italy southern france and spain as a product of this study maps of the studied area for the late miocene have been produced showing main physiognomic features of the forests expressed in the proportions of broad leaved deciduous broad leaved evergreen legume type and sclerophyllous components respectively

geochemical appraisal of palaeovegetation and climate oscillation in the late miocene of western bulgaria abstract palaeobotanical methods and geochemical techniques were used to assess plant contribution and palaeoenvironment for the staniantsi basin bulgaria the aim was to connect palaeovegetation change and climate oscillation based on pollen and statistical analysis with organic geochemical proxies for a late miocene lacustrine to paludial sedimentary succession three samples from lignite marl cycles were studied the biomarker assemblage and bulk chemical data indicated that gymnosperms were not important in the palaeomire the presence of des a triterpenoids 17 21 seco triterpenoids hopanes a high content of a d ring monoaromatic hopane and aromatized triterpenoids suggested that photochemical and microbial processes significantly contributed to the alteration of the organic matter om a prolonged period of high water table and severe mechanical destruction promoted microbial activity prior to burial and enhanced decay a geochemical appraisal of short term climate oscillation ca 21 7 kyr was attempted within the limitations of the small number of samples studied the cycles are expressed as lignite marl clay layers combined with cyclic changes in swamp vegetation related to cyclic changes in groundwater level and inundation of the basin in periods of low water level swamp phase lignite accumulation took place preliminary results for selected samples suggest that the oscillation may be reflected in the content of friedelin vs possible degradation products the ratio of a chromatographic peak tentatively assigned as a norfriedel 8 en 10 one to friedelin is proposed as a means of detecting short term environmental cycles where values 1 reflect periods of inundation however time series analysis using densely sampled lignite clay layer oscillations are needed to confirm the value of this biomarker ratio for environmental reconstruction

cenozoic volcanism and tectonic evolution of the tibetan plateau abstract cenozoic volcanism on the tibetan plateau which shows systematic variations in space and time is the volcanic response to the india asia continental collision the volcanism gradually changed from na rich k rich to potassic ultrapotassic adakitic compositions along with the india asia collision shifting from contact collision i e soft collision or syn collision to all sided collision i e hard collision the sodium rich and potasium rich lavas with ages of 65 40 ma distribute mainly in the lhasa terrane of southern tibet and subordinately in the qiangtang terrane of central tibet the widespread potassic ultrapotassic lavas and subordinate adakites were generated from 45 to 26 ma in the qiangtang terrane of central tibet subsequent post collisional volcanism migrated southwards producing ultrapotassic and adakitic lavas coevally between 26 and 8 ma in the lhasa terrane then potassic and minor adakitic volcanism was renewed to the north and has become extensive and semicontinuous since 20 ma in the western qiangtang and songpan ganze terranes such spatial temporal variations provide important constraints on the geodynamic processes that evolved at depth to form the tibetan plateau these processes involve roll back and break off of the subducted neo tethyan slab followed by removal of the thickened lhasa lithospheric root and consequently northward underthrusting of the indian lithosphere the tibetan plateau is suggested to have risen diachronously from south to north whereas the southern part of the plateau may have been created and maintained since the late oligocene the northern plateau would have not attained its present day elevation and size until the mid miocene when the lower part of the western qiangtang and songpan ganze lithospheres began to founder and detach owing to the persistently northward push of the underthrust indian lithosphere

a reconstruction of late miocene mediterranean circulation patterns using benthic foraminifera abstract extensive research on the late miocene mediterranean has solved a number of questions concerning the development of the area but questions remain on for instance the mediterranean water circulation patterns knowledge of preferably quantitative oxygen contents of water masses could be of help to reconstruct paleo circulation and understand how this contributed to the development of the mediterranean messinian salinity crisis msc bottom water oxygenation is usually estimated qualitatively or semi quantitatively at best from abundances of infaunal benthic foraminifera from stable carbon isotope data or redox sensitive elements we present data from six mediterranean land sections and one section located at the atlantic side of the rifian corridor as an atlantic reference location we introduce a semi quantitative reconstruction of oxygen levels at the sediment water interface employing a simple index that operates on a scale from 1 low oxygen to 5 normal to high oxygen using this method we present a tentative reconstruction of the mediterranean water circulation in the period preceding the continuous development towards the msc which started at 7 17 ma we found that during the late miocene an anti estuarine circulation was likely quite comparable to the modern pattern deep water formation appears to have existed in the central northeastern part of the basin around 7 2 ma constriction of the rif corridor morocco led to restricted exchange of mediterranean and atlantic water masses a reduction of the deep circulation and decreasing bottom water ventilation deep water formation weakened and the mediterranean hydrography changed thoroughly eventually contributing to the development of the msc

the andean type gangdese mountains paleoelevation record from the paleocene eocene linzhou basin abstract paleoelevation reconstruction using oxygen isotopes is making a significant contribution to understanding the cenozoic uplift of the himalayas and the tibetan plateau this paper presents new oxygen and carbon isotopic compositions from well dated tertiary paleosols lacustrine calcareous carbonates and marls from the nianbo 60 54 ma and upper pana formations 51 48 ma of the linzizong group in the linzhou penbo basin the sediments of the nianbo formation which are 180 m thick were deposited in alluvial fans braided rivers fan deltas and on nearshore to offshore lacustrine settings whereas those of the upper pana formation are 100 m thick and are comprised predominantly of proximal alluvial fan and braided river deposits correlations between the lithofacies and stable isotopic compositions suggest that the basin was mainly a hydrologically open environment it is confirmed that the 18 o c and 13 c c values from nianbo and pana formations have not yet been reset by late stage diagenesis based on petrographic examination oxygen isotope of the fossil ostracodes and tectonic deformation of strata the paleoelevations are reconstructed using the corrected most negative paleosurface water 18 o psw values these imply that the linzhou area had attained an elevation of 4500 400 m during the period of the indo asian collision i e achieved a near present elevation and may form an andean type mountain range stretching the gangdese arc before collision the gangdese mountains probably maintained high elevations since at least the paleocene and could play a crucial role in the climate change in the interior of the tibetan plateau during the early cenozoic the paleogeomorphic scenario of the eocene tibet is proposed to exist at two high mountains in excess of 4500 m that sandwiched a low elevation basin

palaeoclimatic evolution during eocene and its influence on oil shale mineralisation fushun basin china the fushun basin is a small explored coal and oil shale bearing cenozoic fault basin in the liaoning province northeast china the basin mainly consists of eocene swamp to lacustrine deposits of the guchengzi to xilutian formation and contains the biggest opencast oil shale mine in asia this mine has provided an ideal opportunity to undertake palaeoclimate reconstruction in this basin based on a single geological profile and the analyses of 93 samples using various approaches namely field geological observation clay mineralogical and geochemical sr ba sr cu stable c and o isotope analyses all of which were compared with palaeobotanical data the eocene climate of fushun basin evolved from warm temperate to north subtropical and generally changed from warm humid to subhumid semiarid paleoclimatic and geochemical parameters shows that the very warm and humid climate during jijuntun formation increased the initial productivity of lake water and caused a steady stratification of the lake water then caused oxygen lack in the bottom of water productivity of the lake provides the mean origin of organic matters for oil shale formation and steady anoxic environment is beneficial for the conservation of organic matters

high resolution palynological analysis in late early middle miocene core from the pannonian basin hungary climatic changes astronomical forcing and eustatic fluctuations in the central paratethys high resolution palynological analysis in the karpatian sarmatian late early middle miocene interval of the borehole tengelic 2 hungary reveals the existence of a forest organized in altitudinal belts developed in a subtropical warm temperate humid climate reflecting the so called miocene climatic optimum pollen changes from the late early miocene to the middle miocene are related to climatic variations values of mean annual temperature ta between 18 and 20 8c and mean annual precipitation pa between 1200 and 1400 mm have been estimated bclimatic amplitude methodq for the badenian decreasing during late badenian and sarmatian ta and pa about 16 8c and 1100 mm have been interpreted as a climatic cooling correlated with the bmonterey cooling eventq and related to the development of the east antarctic ice sheet eais alternation in pollen taxa thermophilous vs altitudinal elements reflects the astronomical forcing on temperature and precipitation and then on vegetation where obliquity and eccentricity cycles dominated eustatic changes determine pinus and pinaceae and dinocyst variations

palynological evidence for miocene climate change in the forecarpathian basin central paratethys nw bulgaria abstract we reconstruct quantitatively the middle to upper miocene climate evolution in the southern forecarpathian basin central paratethys area northwest bulgaria by applying the coexistence approach to 101 well dated palynofloras isolated from three cores the climatic evolution is compared with changes in vegetation and palaeogeography the middle miocene was a period of a subtropical warm temperate humid climate with mean annual temperature mat between 16 and 18 c and mean annual precipitation map between 1100 and 1300 mm thereby during the entire middle miocene a trend of slightly decreasing temperatures is observed and only small climate fluctuations occur which are presumably related to palaeogeographic reorganisations the vegetation shows a corresponding trend with a decrease in abundance of palaeotropic and thermophilous elements the upper miocene is characterised by more diverse climatic conditions probably depending on palaeogeographic and global climatic transformations the beginning of this period is marked by a slight cooling and a significant drying of the climate with mat 13 3 17 c and map 652 759 mm after that fluctuations of all palaeoclimate parameters occur displaying cycles of humid dryer and warmer cooler conditions which are again well reflected in the vegetation our study provides a first quantitative model of the middle upper miocene palaeoclimate evolution in southeastern europe and is characterised by a relatively high precision and resolution with respect to the climate data and stratigraphy

cooling mediterranean sea surface temperatures during the late miocene provide a climate context for evolutionary transitions in africa and eurasia abstract in the late miocene grasslands proliferated succulent plants diversified in the mid latitudes and the desert like conditions appeared in the sahara despite this major environmental change on land the coeval deep sea oxygen isotope record does not provide evidence for significant high latitude cooling or continental ice growth making it difficult to relate widespread terrestrial environmental change to global climatic changes a u 37 k derived sea surface temperature sst reconstruction spanning 13 to 6 ma from uplifted hemipelagic sediments in northern italy provides the first continuous mid latitude temperature record with which to compare the evolution of aridity and biotic events at similar latitudes in northern africa and pakistan between 13 and 8 8 ma mediterranean sst lay near the upper limit of the alkenone temperature proxy 28 c exceeding modern sst at the site by as much as 10 c throughout the record sapropel layers correspond to local sst maxima suggesting that late miocene hydrological conditions in the mediterranean responded to insolation forcing via mechanisms similar to those documented for the plio pleistocene mediterranean sst cooled rapidly beginning at 8 ma with an episode of intense cooling to 19 c between 7 2 ma and 6 6 ma followed by a rebound to 25 c preceding the messinian salinity crisis at 5 9 ma these observations establish for the first time a direct relationship between increasing aridity in the northern hemisphere mid latitudes and significant cooling evidently this cooling was not accompanied by significant growth in continental ice volume the extreme warmth and subsequent cooling of the mediterranean sea are not well represented in current late miocene climate models which our results suggest underestimate regional warmth prior to the late miocene cooling evidence of secular cooling during the late miocene gives new support to the much debated link between a possible decline in atmospheric co2 levels and late miocene changes in vegetation on land

a methodology for targeting palaeo proxy data acquisition a case study for the terrestrial late miocene when planning the acquisition of new palaeo proxy data for reconstructing past climates many factors influence the decision of where the proxies are to be collected one such influence is the likelihood of recording a significant climate change relative to the modern another consideration which is less often considered is the desire to target regions in which there is significant uncertainty in numerical model predictions of past climate change new proxy data in these regions enables a more rigorous test of model simulations and results in better constraints on the various boundary conditions used to force the models in this paper we present a methodology for targeting new palaeo proxy data based on model simulations we use the terrestrial late miocene 11 6 to 5 3 ma as a case study the late miocene climate provides insights into future climate behavior as it is believed to have been considerably warmer than the modern we carry out a suite of late miocene atmosphere only general circulation model simulations which we initially evaluate relative to an example dataset of terrestrial temperature and precipitation in terms of targeting future data acquisition we locate those regions in the model which exhibit the largest change in temperature and or precipitation relative to the pre industrial we also locate those regions which display the largest variability between the model simulations because new data in these regions are most likely to provide a strict test of the reliability of the model results among other regions the amazon basin the chad basin central canada and northern india are identified as potentially useful areas to collect data

palaeoclimate estimates for the middle miocene schrotzburg flora s germany a multi method approach we present a detailed palaeoclimate analysis of the middle miocene uppermost badenian lowermost sarmatian schrotzburg locality in s germany based on the fossil macro and micro flora using four different methods for the estimation of palaeoclimate parameters the coexistence approach ca leaf margin analysis lma the climate leaf analysis multivariate program clamp as well as a recently developed multivariate leaf physiognomic approach based on an european calibration dataset elpa considering results of all methods used the following palaeoclimate estimates seem to be most likely mean annual temperature 15 16 c mat coldest month mean temperature 7 c cmmt warmest month mean temperature between 25 and 26 c and mean annual precipiation 1 300 mm although cmmt values may have been colder as indicated by the disappearance of the crocodile diplocynodon and the temperature thresholds derived from modern alligators for most palaeoclimatic parameters estimates derived by clamp significantly differ from those derived by most other methods with respect to the consistency of the results obtained by ca lma and elpa it is suggested that for the schrotzburg locality clamp is probably less reliable than most other methods a possible explanation may be attributed to the correlation between leaf physiognomy and climate as represented by the clamp calibration data set which is largely based on extant floras from n america and e asia and which may be not suitable for application to the european neogene all physiognomic methods used here were affected by taphonomic biasses especially the number of taxa had a great influence on the reliability of the palaeoclimate estimates both multivariate leaf physiognomic approaches are less influenced by such biasses than the univariate lma in combination with previously published results from the european and asian neogene our data suggest that during the neogene in eurasia clamp may produce temperature estimates which are systematically too cold as compared to other evidence this pattern however has to be further investigated using additional palaeofloras

mosaic of environments recorded by bryozoan faunas from the middle miocene of hungary the marine sediments of the badenian middle miocene of hungary pannonian basin central paratethys are composed of abundant bryozoan skeletal grains seventy one bulk samples collected at 18 localities outcrops and boreholes yielded a total number of 238 bryozoan species in order to reconstruct the badenian palaeoenvironments the present study investigates the composition of this very diverse fauna using a combination of statistical and palaeoecological methods the statistical analyses make use of cluster analysis and non metric multi dimensional scaling the palaeoecological approaches are based on the known ecological requirements of the bryozoan colonial growth forms and of the numerous extant species five facies have first been differentiated on the basis of sedimentological and palaeontological features coral buildups coralline algal limestones biocalcarenites sands and marls each of them is characterized by the abundance the diversity and the types of growth forms of the bryozoans the palaeoecological statistical and facies analyses further permitted to identify four depositional settings carbonate platform distal and proximal terrigenous platform slope and basin these environments developed at depths between 0 to about 300 m in a mixed carbonate siliciclastic depositional system skeletal production and spatial distribution of carbonate factories were predominantly controlled by terrigenous input this resulted in a complex mosaic of facies habitats where rich bryozoan faunas could thrive many warm water organisms among them foraminifers zooxanthellate corals molluscs bryozoans and echinoids were recorded from the study sites the coexistence of coralgal and bryomol carbonate skeletal assemblages in this subtropical setting is explained mostly by variations in the productivity of surface waters periods of nutrient enrichment and increased benthic eutrophication affected coral diversity and abundance in favour of bryozoans

india eurasia collision chronology has implications for crustal shortening and driving mechanism of plates the motion of the indian plate is determined in an absolute frame of reference and compared with the position of the southern margin of eurasia deduced from palaeomagnetic data in tibet the 2 600 900 km of continental crust shortening observed is shown to have occurred in three different episodes subduction of continental crust intracontinental thrusting and internal deformation and lateral extrusion the detailed chronology of the collision and plate reorganizations in the indian and pacific oceans supports the hypothesis that slab pull is a dominant driving mechanism of plate tectonics

magnetostratigraphy of cenozoic sediments from the xining basin tectonic implications for the northeastern tibetan plateau 1 the xining subbasin of the longzhong basin holds the longest continuous cenozoic stratigraphic record at the margin of the northeastern tibetan plateau despite a rich biostratigraphic content including the xiejia mammal fauna the tectonic evolution of the basin is largely unconstrained in this study we present stratigraphic biostratigraphic and magnetostratigraphic results that provide a basis for reconstructing the cenozoic tectonic evolution of the xining basin with respect to adjacent regions of the northeastern tibetan plateau magnetostratigraphic analysis from three red bed sections in the xining basin indicates continuous deposition at low and nearly constant accumulation rates average 2 2 cm kyr from 52 0 to 17 0 ma we interpret this result to indicate that no major regional tectonic event implying large sediment accumulation variations has affected the xining basin deposition during this considerable time window in detail accumulation rate variations outline a three stage evolution with 1 8 cm kyr from 52 0 ma to 34 5 ma 4 1 cm kyr from 34 5 to 31 0 ma and 2 3 cm kyr from 31 0 to 17 0 ma the second order increase between 34 5 and 31 0 ma can be interpreted to result from either a distal tectonic event or to be of climatic origin although the region was tectonically quiescent for much of the cenozoic tectonic activity occurred during basin initiation or reactivation at circa 55 0 52 5 ma and during intense basin deformation after 17 0 ma

global miocene tectonics and the modern world abstract an amazing congruence of seemingly unrelated diverse global events began in the middle and upper miocene and established our modern world two global orogenic belts were active mostly in the middle and upper miocene while backarc basins formed along the eastern margin of asia coincident with these events global temperatures cooled in both the ocean and atmosphere desertification occurred from central asia into and across most of northern africa and also in australia and in southern south america coincident with the expansion of the antarctic ice cap at 14 ma there was initial widespread deep sea erosion and changes in patterns of deep sea sedimentation muddy pelagic sedimentation increased six fold in the north and central atlantic and pacific oceans and global changes in circulation lead to more diatomites in the pacific and fewer in the atlantic by the end of the miocene most of the mediterranean sea had evaporated broadly coincident with these events many old large river systems were destroyed and new ones formed as much of the world s landscape changed collectively these global on shore tectonic and ocean atmospheric events provide the foundation for our modern world a mixture of new and rejuvenated orogenic belts and their far field effects distant epiorogenic uplift rain shadow deserts large alluvial aprons and distant deltas as inherited gondwanan landscapes persisted remote from plate boundaries thus at the end of the miocene much of the world s landscape except for that changed by pleistocene continental glaciation would be recognizable to us today we argue that all of these events had the same ultimate common cause an internal earth engine that drove plate motions in two broad ways first the opening and closing of seven key gateways to deep water oceanic currents radically altered global heat transfer and changed a lingering greenhouse to an icehouse world secondly these events were in part coincident with renewed heat flow in the african and pacific superplumes that energized global plate motions in the middle and upper miocene we hope this global synthesis will stimulate more research on the many global events of the miocene to understand better both our modern world and earlier global orogenies

regional scale palaeoclimate modelling on soft proxy data basis an example from the upper miocene of the lower rhine embayment abstract a new method in palaeoclimatology initially proposed by mosbrugger and schilling 1992 which makes it possible to extract a maximum of information from the available proxy data is tested it possesses a capacity to produce a detailed palaeoclimate reconstruction which is consistent with both proxy data and the physics of atmospheric models since proxy data information is particularly poor on a global scale our method focuses on smaller scale regions of better proxy data coverage it consists of an iterative coupling of inverse mesoscale atmospheric modelling with proxy based palaeoclimate reconstruction using this method the palaeoclimate of the tortonian upper miocene of the lower rhine embayment northwest germany is reconstructed with a high spatial resolution the results include a physically consistent inter and extrapolation of proxy derived palaeoclimate data in space and onto variables not accessible from geological palaeontological proxies alone moreover the method delivers statistics of the large scale atmospheric flows as information on the coupling of the regional climate to global fields

middle miocene latitudinal climatic gradient in western europe evidence from pollen records abstract pollen analysis of sections spanning the middle miocene langhian and serravallian from southern spain to switzerland has been carried out with the aim of reconstructing the existing latitudinal environmental gradient floral assemblages indicate a tropical subtropical to warm temperate climate for the entire area during the middle miocene the presence in all pollen spectra of taxa with high temperature requirements demonstrates that the latitudinal gradient in temperature was relatively low the development of a diverse subarid flora in southern spain including neurada lygeum prosopis calligonum nitraria caesalpiniaceae etc points to a very dry climate with a marked seasonality these features clearly indicate that a very warm and dry climate i e a steppe environment was already present during the langhian in the northwestern mediterranean area on the other hand milder conditions are progressively inferred towards the north as subdesertic elements gradually disappeared and taxa with higher water requirements increased the latter dominates the pollen assemblages in the eastern central part of france and switzerland thus precipitations would have been evenly distributed throughout the year we interpret this gradient from subdesertic vegetation in the south to humidity adapted plant environments in the north as the result of a latitudinal gradient in precipitation

significant mid latitude aridity in the middle miocene of east asia abstract the east asian climate history during the neogene is a complicated and contentious issue in particular because of its bearing on the development of the east asian monsoon and tibetan uplift chronology here we present a paleoprecipitation analysis based on mean molar tooth height hypsodonty of large herbivorous mammals to investigate the spatial pattern of climate zonation in east asia during the middle miocene we show a generally humid and uniform situation before the late middle miocene replaced by a mid latitude arid belt from the late middle miocene into the earlier part of the late miocene these findings are concordant with the global phenomena of the middle miocene climate optimum and the subsequent cooling and suggest that the predominant climate in east asia for most of the miocene was planetary rather than monsoonal our results support a late initiation of the east asian summer monsoon coincidentally with the beginning of eolian red clay deposition in the later late miocene at 7 8 ma

a late eocene palynological record of climate change and tibetan plateau uplift xining basin china climate models suggest that asian paleoenvironments monsoons and continental aridification were primarily governed by tectonic uplift and sea retreat since the eocene with potential contribution of global climate changes however the cause and timing of these paleoenvironmental changes remain poorly constrained the recently well dated continental mudflat to ephemeral saline lake sedimentary succession situated in the xining basin at the northeastern margin of the tibetan plateau nw china provides a unique opportunity to develop additional proxy successions in this area that are placed accurately in time here a palynological record from this succession is reported high abundances of desert and steppe desert taxa such as ephedripites and nitrariadites nitraripollis are found which can be differentiated by the presence of broad leaved deciduous forest taxa in the lower part of the section particularly up to 36 4 ma magnetochron c16r and a sudden increase of pinaceae pinuspollenites piceaepollenites and abiespollenites which is dated at 36 1 ma c16n 2n coexistence approach coa indicates that from 39 9 to 36 4 ma c17n 1n regional climate was warm and wet while from 36 4 to 33 5 ma c16n 2n c13r climate tends to be cooler and drier the data indicate that paleoenvironmental and palynological changes on the ne part of the tibetan plateau resulted from a combination of long term tectonic uplift forcing and long and short term climate changes the increase of taxa such as piceaepollenites and abiespollenites indicates not only a cooling and drying trend prior to the eocene oligocene e o boundary but also the existence of high altitude mountain habitats in the periphery of the xining basin the sudden pinaceae event correlates closely in time with a marked aridification step as viewed from the lithology of the xining basin that was linked to the sea retreat out of the tarim basin

precipitation gradients during the miocene in western and central turkey as quantified from pollen data abstract in the present paper we have analyzed thirty five palynofloras covering the time span from the early miocene aquitanian to the late miocene middle tortonian in turkey the results obtained are presented in tables and maps showing temporal palaeoprecipitation values the mean annual precipitation map exceeds 1200 mm during the aquitanian and early middle serravallian it is suggested to have been between 1000 and 1300 mm in the latest serravallian earliest tortonian in western and central turkey in the early middle tortonian the lower boundary of map decreases to below 1000 mm in central and eastern turkey today maps are represented by lower values around 600 1000 mm in western and 400 600 mm in central turkey for the driest month lmp the rainfall was not distributed homogeneously in the aquitanian the calculations are between 36 and 48 mm with humid conditions in western and eastern turkey during the burdigalian and middle miocene the driest month precipitation varied with respect to locations however it is clear that there was a reduction in precipitation during the early middle tortonian with values around 26 27 mm in central and eastern turkey the same pattern is observed for the wettest month precipitation hmp with estimates higher than 200 mm during the aquitanian and earliest tortonian although some areas received low rainfall hmp was reduced between 130 and 140 mm in the early middle tortonian the warmest month precipitation wmp varied from 96 to 140 mm except for konya ilgin kirsehir hacibektas and manisa soma that received 88 mm during the early middle miocene in the early middle tortonian the amount of summer rainfall lay between 58 and 88 mm the reason of the decrease in all rainfall parameters during the early middle tortonian could be related to several factors such as climatic cooling altitude aridification palaeotopograhy or continentality however it is necessary to indicate that the tortonian cooling had previously been proposed by akgun et al 2007 as the explanation using a large number of palynological assemblages in turkey we also observe a decrease in precipitation parameters during the middle miocene this could be related to fact that either low species diversity can result in wide coexistence intervals or the monterey cooling event was related to a cooling during the langhian and serravallian

quantitative reconstruction of miocene climate patterns and evolution in southern china based on plant fossils abstract southern china especially yunnan has undergone high tectonic activity caused by the uplift of himalayan mountains during the neogene which led to a fast changing palaeogeography previous study shows that southern china has been influenced by the asian monsoon since at least the early miocene however it is yet not well understood how intense the miocene monsoon system was in the present study 63 fossil floras of 16 localities from southern china are compiled and evaluated for obtaining available information concerning floristic composition stratigraphic age sedimentology etc based on such reliable information selected mega and micro floras have been analysed with the coexistence approach to obtain quantitative palaeoclimate data visualization of climate results in maps shows a distinct spatial differentiation in southern china during the miocene higher seasonalities of temperature and precipitation occur in the north and south parts of southern china respectively during the miocene most regions of southern china and europe were both warm and humid central eurasia was likely to be an arid center which gradually spread westward and eastward our data provide information about miocene climate patterns in southern china and about the evolution of these patterns throughout the miocene and is also crucial to unravel and understand the climatic signals of global cooling and tectonic uplift

paleoenvironmental evolution of the eastern mediterranean during the messinian constraints from integrated microfossil data of the pissouri basin cyprus abstract integrated data of calcareous nannofossils as well as planktonic and benthic foraminifera from the pissouri motorway section on cyprus allow the reconstruction of surface and bottom water paleoenvironments of the eastern mediterranean during the interval preceding the messinian salinity crisis msc contrary to deeper water locations where benthic foraminifera faunas are suppressed or absent just after the tortonian messinian boundary sediments deposited at intermediate water depths do contain benthic assemblages from the earliest messinian onwards a development towards increasingly unfavourable paleoenvironments is reflected in the planktonic and benthic microfossil records of the pissouri section and proceeds with rather discrete time steps that can be correlated to sequences throughout the mediterranean shortly after the tortonian messinian boundary a transition is recorded in the sedimentology and the open marine deeper water taxa disappear from the benthic foraminifera assemblages subsequently the diversity of all fauna groups diminishes the changes recorded at species level in both surface water and sea floor dwelling taxa suggest decreasing circulation of the bottom waters associated with changes in the surface waters most likely due to increasing stratification from 6 73 ma onwards our data indicate a prominent change to more restricted conditions and increasing salinity at the sea floor together with intermittently rising surface water salinity the dominance of oligotypic and monospecific assemblages and the frequent shifts in assemblage compositions of all microfossil groups indicate severely stressed environments after 6 4 ma probably related to increased salinity the major changes in paleoenvironmental conditions including oxygen deprivation due to stagnation and hypersalinity can be explained by hydrographical changes in the mediterranean basin which are probably caused by tectonic movements in the rif corridor acting in concert with astronomical cyclicity evaluation of the paleodepth proxies indicates that the depth of the pissouri basin remained rather constant at 300 500 m with a minimum of 200 m until deposition of the barre jaune the transitional interval towards the evaporites and that early shallowing to neritic depths as was proposed before is highly unlikely

central paratethys paleoenvironment during the badenian middle miocene evidence from foraminifera and stable isotope δ13c and δ18o study in the vienna basin slovakia stable isotope data of the foraminiferal carbonate shells and bulk sediment samples from the central paratethys were investigated to contribute to better knowledge of the paleoenvironmental changes in badenian middle miocene five benthic uvigerina semiornata u aculeata ammonia beccarii elphidium sp and heterolepa dutemplei and three planktonic taxa globigerina bulloides g diplostoma and globigerinoides trilobus characterising the bottom intermediate and superficial layers of the water column were selected from the vienna basin w slovakia the foraminiferal fauna and its isotope signal point out to temperature stratified nutrient rich and consequently less oxygenated marine water during the middle late badenian negative carbon isotope ratios indicate increased input of 12c enriched organic matter to the bottom of the vienna basin positive benthic 18o implies that the global cooling tendency recorded in the middle miocene has also affected the intramountain vienna basin in this time the central paratethys has been in the process of isolation our stable isotope trend suggests that the communication with mediterranean sea has been still more or less active on the south of vienna basin slovak part in the late badenian whereas the seawater exchange towards north was apparently reduced already during the middle badenian

high resolution cyclostratigraphic analysis of multiple climate proxies from a short langhian pelagic succession in the conero riviera ancona italy abstract a high resolution analysis of multiple climate proxies from a rhythmic mid langhian pelagic limestone marl succession northeastern apennines of italy yields information on the pacing and nature of palaeoenvironmental changes in this part of the mid miocene mediterranean the variations in stable isotopes magnetic susceptibility and a variety of geochemical parameters through the section although modified by diagenetic changes are broadly consistent with a model of climate cycles in which the limestones represent cold dry periods and the marls represent warm wet periods fourier analysis of the multiple proxies constrained by radioisotopic dates and aided by partial tuning to either eccentricity or obliquity show that these proxies respond in synchrony to orbitally forced climate changes with obliquity being the dominant influence in this succession

stable isotope ecology of hippotherium from the late miocene pannonian basin system abstract the retreat of the paratethys sea in the middle to late miocene left behind a series of intermontane lakes across central europe ancient lake pannon which existed in present day hungary and surrounding countries was gradually filled in by fluvial sedimentation from 10 to 4 ma this infilling allowed for the migration of mammals such as the horse hippotherium into the pannonian basin system pbs stable carbon and oxygen isotope records from hippotherium are used here to reconstruct changing environmental conditions of the late miocene in this region our emphasis is on understanding the vegetation and surface water of the basin because these in turn affected the isotopic composition of lake pannon we analyzed the enamel of 68 hippotherium teeth from 23 localities in the pbs for carbon and oxygen isotope composition carbon isotope records indicate that hippotherium in the central regions of the basin were feeding in more open habitats than those in the northwest we find no evidence of the expansion of c4 grasses into the pbs oxygen and carbon isotope values from the vienna basin nw part of the pbs generally covary whereas those from more central regions do not the oxygen values of the central pbs are generally lower than those of the vienna basin these data suggest that the interior of the pbs was generally dry which forced hippotherium to use water sources that were not strongly evaporated such as rivers originating from outside the basin the dry interior was likely caused by a rain shadow east of the alps and north of the dinarides consequently much of the surface inflow into lake pannon would have been influenced by runoff from high elevations around or outside the basin by understanding the terrestrial environment better constraints can be placed on lake conditions in future work

palaeoclimate and vegetation change in serbia during the last 30 ma abstract in the present study 14 published megafloras from the serbian cenozoic are analyzed with respect to vegetation type palaeoclimate and palaeogeographic settings the floras cover a time span from the oligocene to the late miocene the results obtained are compared with continental climate records from other parts of europe and discussed in the context of global climate change to obtain a quantitative palaeoclimate record a total of seven different climate variables is calculated for each of the floras using the coexistence approach it is shown that basic patterns of vegetation change such as the immigration of arcto tertiary deciduous floristic elements during the early miocene and the decreasing diversity of laurophyllous taxa during the late miocene are ruled by climate change and a changing palaeogeography the serbian cenozoic climate record shows a steep cooling gradient during the oligocene that is most probably is connected to a northward movement of tectonic plates the globally observed middle miocene climate optimum and the late miocene cooling are well reflected according to the palaeotemperatures calculated a warm temperate climate existed in serbia throughout the time span examined the late miocene cooling is most pronounced in winter temperatures and is connected to increasing seasonality precipitation rates obtained for the serbian cenozoic especially those of the warmest and wettest months tend to be lower when compared to the central european cenozoic according to climate analysis and the interpretation of vegetational data there is evidence for regionally drier conditions and increased seasonality of precipitation in the time span from the late badenian to the early sarmatian

miocene climate in europe patterns and evolution to improve our understanding of long term climate changes during the neogene in eurasia the international research network neclime neogene climate evolution in eurasia was established in the year 2000 in this first synthesis results of neclime activities focussing on the miocene of europe as one key area are combined to present a summary of the climate evolution in time and space more than 300 miocene fossil floras have been compiled and quantitatively analysed in terms of several climatic parameters during the last few years in this volume alone about 75 new data sets are available to synthesize the results of this volume quantitative climate maps for europe are generated on palaeogeographic maps for langhian and early tortonian for the first time characteristic climate patterns appear for each time interval and can be related to both global climate change and alpine tectonics generally the climate maps combine and support the individual results discussed in this volume for the individual regions

facies analysis of the balta formation evidence for a large late miocene fluvio deltaic system in the east carpathian foreland abstract deposits of the balta fm are preserved in a large arcuate sediment body that covers about 60 000 km 2 and is up to 350 m thick the balta fm spans ca 5 ma as constrained by underlying tortonian bessarabian and overlying messinian early pontian paratethys strata it contains frequent terrestrial mammal fossils and fresh as well as brackish water paratethys molluscs and ostracods over the past 140 years our understanding of the sedimentary architecture of the formation and its origins has remained in its infancy which has limited insight into the evolution of the east carpathian foreland here we provide the first modern sedimentary facies analysis of the balta fm which is integrated with an extensive review of previously published local literature it is supported with micropalaeontological results and a wealth of historical borehole information we show that the balta fm has a tripartite vertical division its lowermost part is clay dominated and consists of subordinate delta front sand bodies interspersed between muds the middle unit contains separate delta plain channels or channel belts encased in thick muds these are overlain by a unit with amalgamated delta plain channel deposits with only minor amounts of associated mud the abundance of upper flow regime sedimentary structures in channel sands the absence of peats or coals and the presence of calcareous nodules suggest a strongly seasonal and relatively dry climate with a flashy discharge regime deposition of the balta fm in an area previously characterized by distal shelf and prodelta environments indicates large scale progradation triggered by high sediment volume from the uplifting carpathian orogen and enhanced by a general lowering of paratethys sea level the tripartite internal architecture of the balta fm indicates that progradation continued during deposition its wedge shaped geometry suggests that tectonic activity in the carpathians generated a 300 km wide foreland basin that allowed for significant delta plain aggradation despite of the generally regressive trend in paratethys sea level

the coexistence approach theoretical background and practical considerations of using plant fossils for climate quantification the coexistence approach was established by mosbrugger and utescher 1997 as a plant based method to reconstruct palaeoclimate by considering recent climatic distribution ranges of the nearest living relatives of each fossil taxon during its existence for over more than 15 years its basics have been tested and reviewed in comparison with other terrestrial and marine climate reconstruction techniques and climate modelling data however some controversies remain about its underlying data or its applicability in general in view of these controversies this paper discusses the power and limitations of the coexistence approach by summarising past results and new developments we give insights into the details and problems of each step of the application from the assignment of the fossil plant to the most suitable nearest living relative the crucial consideration of the usefulness of specific taxa towards their climatic values and the correct interpretation of the software based suggested palaeoclimatic intervals furthermore we reflect on the fundamental data integrated in the coexistence approach by explaining different concepts and usages of plant distribution information and the advantages and disadvantages of modern climatic maps additionally we elaborate on the importance of continually updating the information incorporated in the database due to new findings in e g palaeo botany meteorology and computer technology finally for a transparent and appropriate use we give certain guidelines for future applications and emphasize to users how to carefully consider and discuss their results we show the coexistence approach to be an adaptive method capable of yielding palaeoclimatic and palaeoenvironmental information through rime and space c 2014 elsevier b v all rights reserved

a tortonian late miocene 11 61 7 25 ma global vegetation reconstruction for the tortonian age of the miocene epoch 11 6 7 25 ma we present a global palaeobotanical and palaeoecologically based vegetation dataset combined with a best fit late miocene climate vegetation model experiment to create an advanced global data model hybrid biome reconstruction this new palaeoecological database and global vegetation reconstruction can be used both for the purposes of validating future palaeoclimate model simulations as well as a land cover dataset to initialise palaeoclimate modelling experiments our tortonian reconstruction shows significant changes in the distribution of vegetation compared to modern natural vegetation for example in contrast to the modern scenario in the northern hemisphere boreal forests reached 80 n and temperate forests were present above 60 n warm temperate forests covered much of europe coastal north america and south east asia our reconstruction shows a spread of temperate savanna in central usa the middle east and on the tibetan plateau evidence for arid deserts is sparse with the exception of the atacama region south america areas that exhibit arid desert today in the tortonian were instead covered by shrublands grasslands savannas and woodlands the extent of tropical forests in south america was likely reduced but expanded in the indian sub continent and east africa this pattern of global vegetation in the late miocene suggests a warmer and wetter world which is supported by the pattern of climate anomalies predicted by our best fit palaeoclimate vegetation model experiment global mean annual temperature may have been as much as 4 5 c higher than present day with many regions experiencing higher than modern amounts of precipitation over the annual cycle the pattern of temperature and precipitation change reconstructed palaeobotanically and predicted within our climate model experiment infers a global forcing agent on tortonian climate e g such as elevated concentrations of greenhouse gases to explain the observed and modelled climate anomalies this is in contrast to current proxy records of tortonian atmospheric co2 which range from last glacial maximum to mid 20th century levels

late cenozoic eolian deposition in the north pacific asian drying tibetan uplift and cooling of the northern hemisphere a newly constructed record of eolian dust accumulation from the central north pacific shows that dust deposition increased by an order of magnitude quite rapidly at 3 6 ma we associate this sudden drying with the uplift of at least the northern portion of the tibetan plateau shutting off the indian ocean moisture source to central and western china this ten fold increase in atmospheric dust loading appears to be associated with the 1 m y long shift toward heavy 18o values that occurred at 3 6 2 6 ma the dust grain size record of wind intensity begins its late cenozoic coarsening a million years before the drying event at 4 5 ma the northern hemisphere cooling that results in intensification of the subpolar westerly winds may have as its ultimate cause the drawdown of atmospheric co2 in the latest miocene and the early pliocene closing of the panamanian seaway

modelling late miocene vegetation in europe results of the caraib model and comparison with palaeovegetation data abstract the caraib carbon assimilation in the biosphere model is used to study the vegetation distribution during the late miocene tortonian in this version the plant classification is specifically adapted to best represent miocene european vegetation compared to other plant classifications used in global models this adapted classification is more refined since it is specifically developed for european vegetation and it includes various thermophylous tree types which were present in europe during the miocene the corresponding climatic tolerance parameters are based on the study of laurent et al journal of vegetation science 15 739 746 2004 for the tree types currently present in europe and on the distribution of analogue species in southeastern asia and north central america for the thermophylous sub tropical trees the same classification is used to characterize the palaeoflora at the available late miocene localities allowing a model data comparison at the plant functional type level rather than at the biome level the climatic inputs to caraib are obtained from the cosmos atmosphere ocean general circulation model the climatic anomalies tortonian minus present derived from cosmos are interpolated to a higher spatial resolution before being used in the vegetation model these anomalies are combined with a modern climatology to produce climatic fields with high spatial resolution 10 10 this procedure has the advantage of making apparent relief features smaller than the grid cells of the climate model and hence makes easier the comparison with local vegetation data although it does not really improve the quality of the tortonian climate reconstruction the new version of caraib was run over europe at this higher spatial resolution it calculates the potential distribution of 13 different classes of trees including cold cool warm temperate sub tropical and tropical types together with their cover fractions net primary productivities and biomasses the resulting model vegetation distribution reconstructed for the tortonian is compared to available palaeovegetation and pollen data before performing this comparison the tree taxa present at the various data sites are assigned to one or several model classes depending on the identification level of the taxa if several classes are possible for a taxon only those that can co exist with the other tree classes identified at the site are retained this methodology is similar to the co existence approach used in palaeoclimatic reconstructions based on vegetation data it narrows the range of tree types present at the various sites by suppressing in the data the extreme types such as the cold boreal temperate and tropical trees the method allows a comparison with the model simulation on a presence absence basis this comparison provides an overall agreement of 53 between the model and the data when all sites and tree types are considered the agreement is high 85 for needle leaved summergreen boreal temperate cold trees larix sp and for tropical trees intermediate 40 for other boreal temperate cold trees and for needle leaved evergreen temperate cool trees broadleaved summergreen temperate cool trees and broadleaved evergreen warm temperate trees and poor

late miocene vegetation reconstruction with the caraib model abstract climatic outputs from the atmospheric general circulation model echam4 coupled to a mixed layer ocean model are used as inputs to the caraib global vegetation model to reconstruct the distribution of vegetation and the biosphere carbon stocks over the continents during the late miocene tortonian the results show significant changes in the geographical distribution of vegetation during the late miocene compared to the present with a reduction of desert areas and an expansion of tropical seasonal forests which reached temperate latitudes these changes in vegetation distribution are accompanied by a moderate increase of the total biosphere carbon stock by 159 gt sensitivity tests to atmospheric co 2 have also been performed with the vegetation model only i e while keeping constant all climatic variables to their reference tortonian state these tests point out the potential importance of co 2 fertilization both regarding vegetation distribution and biosphere carbon storage the impact of an atmospheric co 2 decrease from 280 to 200 ppmv or increase from 280 to 560 ppmv on the vegetation distribution appears to be at least as large as that of the climate change between the tortonian and the present while in terms of carbon storage the impact of atmospheric co 2 is far much larger than the climatic one although the actual response of vegetation to co 2 fertilization may be much smaller than its theoretical response in the model these results emphasize the need to consider atmospheric co 2 as an important parameter for palaeovegetation reconstructions

geographic and temporal patterns in the late neogene 12 3 ma aridification of europe the use of small mammals as paleoprecipitation proxies abstract present day relations between small mammal community structure and rainfall are used to predict late neogene 12 3 ma precipitation patterns in europe and anatolia new proxy methods are developed which include regressions of mean annual and minimum monthly precipitation on diet invertivory index and locomotion habitat arboreality index a series of precipitation maps and a set of regional precipitation curves through time at 1 myr resolution are presented precipitation curves at a higher temporal resolution are constructed for the region of central spain the miocene results show the existence between 12 and 9 ma of a large wet 800 1200 mm yr zone extending from northern spain to the ukraine and characterized by the whole year penetration of large amounts of moisture far into the continent between 10 9 and 5 ma this european temperate wet zone etwz shrinks and or moves northward resulting in diachronous aridification a coeval northward migration of the subtropical high pressure zone shpz is hypothesized which is also consistent with the predicted onset of seasonal summer dryness between 10 and 8 ma the maximum extension of the etwz at 12 9 ma temporally correlates with northern hemisphere cooling suggesting that climate zonation rather than the global amount of atmospheric moisture controlled european climate at this time the main aridification at 9 8 ma could best be explained by a northward extension shifting of the subtropical high pressure zone and a transition towards less zonal circulation processes which ultimately could have been triggered by uplift of the tibetan plateau a temporary increase of precipitation at 7 6 ma is associated with renewed global cooling the lowest precipitation values less than 400 mm yr occur during the pliocene in southern and eastern europe uplift in eastern europe carpathians shrinking of the paratethys could well explain the aridification in this area and the associated sharpening of east west precipitation gradients across the continent

miocene climate evolution of northern europe a palynological investigation from denmark a palynological investigation has been conducted on lower upper miocene sediments from jylland denmark corresponding to the time interval of about 19 to 8 ma the sediments derived from the sdr vium drill core were deposited in marine to marginal marine environments as shown by the relatively high abundance of dinoflagellate cysts in all samples nevertheless rich and diverse pollen assemblages occur throughout the succession and the palynological analysis reveals that coastal areas of the study area were during the miocene dominated by taxodium swamp forests that also hosted terrestrial angiosperms such as nyssa betula alms and elements of the myricaceae further inland a mixed deciduous evergreen forest prevailed in areas with better drained soils or on elevated areas gymnospermous conifer forests prevailed including taxa such as pinus sequoia and sciadopitys overall the climate in the study area was warm temperate during major parts of the miocene with mean annual temperatures between 15 5 and 20 degrees c by employing the coexistence approach combined with the method of allocating taxa into standardized climatic groups four different climatic miocene events are detected within the studied succession correlated to the coeval climate record of northwestern europe the oldest event is a cooling during the earlier burdigalian at approximately 19 ma coinciding with the mbi 1 oxygen isotope excursion at ca 18 5 ma in mid burdigalian a warming phase is reconstructed characterized by the highest precipitation rates observed in the sedimentary succession a warming trend starting in the latest burdigalian corresponds to the globally recognized middle miocene climatic optimum mmco while a longer term late neogene cooling was initiated in the mid serravallian about 13 ma c 2011 elsevier b v all rights reserved less

late oligocene and miocene climate and vegetation in the eastern paratethys area northeast bulgaria based on pollen data abstract the results of palynological studies of the oligo miocene in the western part of the euxinian basin eastern paratethys are based on the analysis of 57 samples from core c 136a drilled near the town of balchik varna district some samples were barren or contained very little pollen and were not included in the analysis quantitative data are thus confined to 26 polleniferous samples we present results for the upper oligocene as well as the tarkhanian karaganian bessarabian and chersonian stages of the middle to upper miocene mixed deciduous forests were widespread during the time period studied swamp forests are also recorded with distribution maxima observed in the oligocene and in the bessarabian the widest extent of herbaceous vegetation is recorded in the late bessarabian and chersonian when it occupied open landscapes after a marine regressional phase the climatic data reconstructed by the coexistence approach indicate mean annual temperatures mats of ca 15 17 c and mean annual precipitation maps of 800 1300 mm for the upper oligocene the narrowest coexistence intervals of the tarkhanian and karaganian display mats of 14 17 c and maps of 800 1300 mm the most substantial data are for the bessarabian in which the lower part is characterized by mats of 15 6 16 6 c and maps from 800 1200 1300 mm the results for the upper part of the bessarabian are more variable especially with respect to precipitation that is generally lower 700 800 mm the same is true for the chersonian where besides lower precipitation lower annual temperature and temperature of coldest month are observed these results correlate with previous vegetation and palaeoclimate data from the forecarpathian basin nw bulgaria

cenozoic continental climatic evolution of central europe continental climate evolution of central europe has been reconstructed quantitatively for the last 45 million years providing inferred data on mean annual temperature and precipitation and winter and summer temperatures although some regional effects occur the european cenozoic continental climate record correlates well with the global oxygen isotope record from marine environments during the last 45 million years continental cooling is especially pronounced for inferred winter temperatures but hardly observable from summer temperatures correspondingly cenozoic cooling in central europe is directly associated with an increase of seasonality in contrast inferred cenozoic mean annual precipitation remained relatively stable indicating the importance of latent heat transport throughout the cenozoic moreover our data support the concept that changes in atmospheric co2 concentrations although linked to climate changes were not the major driving force of cenozoic cooling

a cretaceous eocene depositional age for the fenghuoshan group hoh xil basin implications for the tectonic evolution of the northern tibet plateau the fenghuoshan group marks the initiation of terrestrial deposition in the hoh xil basin and preserves the first evidence of uplift above sea level of northern tibet the depositional age of the fenghuoshan group is debated as are the stratigraphic relationships between the fenghuoshan group and other terrestrial sedimentary units in the hoh xil basin we present new radiometric dates and a compilation of published biostratigraphic data which are used to reinterpret existing magnetostratigraphic data from the fenghuoshan group from these data we infer an 85 51 ma depositional age range for the fenghuoshan group u pb detrital zircon age spectra from this unit are compared to age spectra from tibetan terranes and mesozoic sedimentary sequences to determine a possible source terrane for fenghuoshan group strata we propose that these strata were sourced from the qiangtang terrane and may share a common sediment source with cretaceous sedimentary rocks in nima basin field relationships and compiled biostratigraphic data indicate that the fenghuoshan and tuotuohe groups are temporally distinct units we report late oligocene ages for undeformed basalt flows that cap tilted fenghuoshan group strata together our age constraints and field relationships imply exhumation of the central qiangtang terrane from the late cretaceous to earliest eocene followed by eocene oligocene deformation and shortening of the northern qiangtang and southern songpan ganzi terranes crustal shortening within the hoh xil basin ceased by late oligocene time as is evident from flat lying basaltic rocks which cap older deformed strata

cenozoic climate gradients in eurasia a palaeo perspective on future climate change abstract recent studies in the frame of the neclime neogene climate evolution in eurasia network provide a comprehensive inventory of continental palaeoclimate data for various time slices reconstructed from the palaeobotanical record the integrative analysis of spatial gradients and patterns observed from the proxy data together with data obtained from numeric modelling studies considerably improved our knowledge about the functioning of the climate system in the cenozoic when compared to the present an overall warmer more humid climate existed cenozoic climates are characterized by warm high latitudes shallow latitudinal and longitudinal gradients and wet continental interiors while concentration of greenhouse gases was about at the present day level or considerably higher thus these past climates potentially are valuable to better understand future climate change because they allow empirical access to climate situations that do not or not yet exist today in the present study continental climate data calculated from micro and macrofloras using the coexistence approach are analysed in order to compare past gradients and patterns and their anomalies relative to present day conditions with future climate change scenarios for the case study three time intervals are selected the mid eocene represents a very warm period of the cenozoic exemplifying greenhouse conditions with high atmospheric co 2 of over 1 100 ppmv the mid miocene is known as outstanding warm time interval as well the concentration of greenhouse gases is still controversially discussed but was certainly below the eocene level a third interval selected the tortonian represents a time span of subsequent cooling with the beginning of arctic glaciation for this period a pre industrial co 2 level is assumed it is shown that the study of past climate patterns provides important clues when evaluating modelling results for future scenarios anomalies predicted under global warming partly coincide with the palaeoclimate data sets as an example for greenhouse conditions the mid eocene data also show a strong warming of the high latitudes and a significant positive anomaly of winter temperatures in the continental interior as in the model study for the future scenario however for the tortonian where a pre industrial co 2 can be assumed data show the best agreement with predicted patterns

environmental factors influencing skeletal grain sediment associations a critical review of miocene examples from the western mediterranean the presence of foramol rhodalgal and bryomol skeletal grain associations in ancient shallow marine limestones is commonly interpreted as evidence for non tropical palaeoclimate despite temperature being only one of several factors influencing skeletal grain associations such interpretations neglect the multitude of factors other than temperature that influence carbonate producing biota these include nutrients water energy water transparency depth of the sea floor salinity oxygen ca2 and co2 concentrations mg ca ratio alkalinity substrate requirements competitive displacement as well as biological and evolutionary trends this uniformitarian approach also disregards the probability that conditions of present day biological systems may not be representative of past conditions of analogous systems here the importance of considering these other factors is illustrated through two examples of carbonate platforms in the western mediterranean these platforms are dominated by foramol rhodalgal and bryomol associations of miocene age in spite of having formed in tropical conditions the platforms discussed are 1 the lower tortonian ramp on menorca balearic islands and 2 the lower middle miocene ramps of the central apennines italy evidence for tropical conditions in the mediterranean during the period of growth of these platforms is provided by species of red algae and larger foraminifera by data from coeval continental basins and by global oxygen isotope data

diffusion as the main process for mass transport in very low water content argillites 2 fluid flow and mass transport modeling 1 on the basis of chloride concentrations of pore water in the tournemire massif part 1 a conceptual model for mass transport in argillites by diffusion is proposed from this conceptual model and current knowledge of the geological history of the massif one dimensional numerical simulations are formulated for chloride transport in tournemire massif over the past 53 ma good agreement between experimental data and calculated values for both diffusion coefficients and concentrations of chloride confirms that diffusion is the main process for mass transport in the massif this model is also tested using deuterium contents of pore water applying variable concentrations to meteoric water circulating in system boundary layers based on the thermal dependency of its isotopic composition these simulations reveal the likely important role of lithologic heterogeneities such as fractures in the horizontal distribution of tracer concentrations

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

tectonics of the northern himalaya since the india asia collision abstract the india asia collision resulted in the construction of the vast himalayan orogen the northern himalayan domain began to experience extensional tectonics since eocene oligocene transition eot when the himalayan orogeny was still in progress major structures generated by the extension in the northern himalaya include the south tibet detachment system stds the north himalayan gneiss domes nhgd and the north south trending rifts nstr the earliest emplacement of syn deformational leucogranite at 36 32 ma along the stds marks the initial transformation from thickening to thinning in the northern himalayan domain at eot the thickening before eot caused crustal partial melting which formed the weak root of the thickened orogen or the so called channel flow this channel flow triggered the collapse of the orogen extrusion of the greater himalayan crystalline complex ghc and the onset of extensional tectonics of the stds the similarities in tectono thermal history and geochemistry of rocks between the stds and nhgd suggest that the formation of the nhgd has a direct relationship to the activity of the stds the extension of stds and the resultant thinning caused further partial melting of the crust leading to the larger scale emplacement of leucogranite during miocene 27 13 ma diapirism of these plutons shaped the domes in nhgd exposing the ghc and the shear zones of the stds in the northern himalaya in gyirong another tectonic transform from extension to shortening occurred after 18 7 ma in dinggye region the stds was offset by the nstr culminating the deformation at 13 ma when the nstr began to be active this indicates another tectonic transform in the northern himalaya at 13 ma when the n s extension of the stds ceased and gave way to e w extension of the nstr marking the end of the peak granitic magmatism in northern himalaya multiple episodes of deformation in the major structures such as the stds mct and nstr and superposition of different structures indicate a multiphase orogenic process in the himalayas in which mountain building and collapse occurred alternately with the formation of nstr and conjugate shear zones in tibet this tectonic scenario was possibly controlled by the india asia convergent rate we propose that the extension was an integral part of the orogenic process rather than a simple marker of the culmination of the orogeny

paleoceanography and climate of the badenian middle miocene 16 4 13 0 ma in the central paratethys based on foraminifera and stable isotope δ 18 o and δ 13 c evidence benthic foraminifera and stable isotopes analyses revealed changes emerging in the paleoceanographic scenery in the paratethys the percentage of inbenthic oxyphylic taxa and diversity in the benthic foraminiferal assemblage showed increasing food supply organic matter decreasing oxygen level and growing stress on the sea floor oxygen isotopes measured in planktonic and benthic foraminifera pointed to strengthening stratification during the badenian period the carbon isotopes indicated intensified accumulation of light marine organic matter this increasing stratification trend is especially pronounced by late badenian 13 5 13 ma when surface water oxygen isotope values are rather negative a simple two layer circulation model was worked out for the badenian paratethys explaining these characteristic environmental changes an antiestuarine lagoonal circulation is assumed for the central paratethys during the early 16 4 15 ma and mid badenian 15 13 5 ma the mid badenian period of time comprises the short episode of evaporite formation in the carpathian foredeep and the transylvanian basin evidence presented here supported a reversal of circulation to estuarine type after the deposition of salts by late badenian 13 5 13 ma the early badenian antiestuarine circulation is suggested to associate with the high temperatures of the mid miocene climatic optimum and the late badenian estuarine circulation with the cooler period following it

the paleoaltimetry of tibet an isotopic perspective stable isotopes provide a valuable perspective on the timing of elevation change of the tibetan plateau we begin our paper by looking in depth at isotopic patterns in modern tibet we show that the 18 o value of surface waters decreases systematically up the himalayan front in central nepal by about 2 8 km in agreement with the patterns documented and modeled by previous research on the tibetan plateau itself there is no apparent correlation between elevation and the 18 o value of flowing surface waters both surface waters and soil carbonates display a northward increase in 18 o values of about 1 5 north of the himalayan crest even though elevation increases modestly the isotopic increase with latitude reduces the isotope elevation gradient for water in the northernmost plateau to 1 to 2 km carbonates in both soils and lakes form at higher temperatures than assumed by previous studies on the plateau temperature estimates from clumped isotope 47 analyses of modern soil carbonates significantly exceed mean annual air t and modeled maximum summer soil temperatures by 15 8 2 8 and 9 7 2 5 c respectively similarly elevated temperatures best account for the 18 o values observed in modern soil and lake carbonates we recalculated paleoelevations from previous studies on the plateau using both higher formation temperatures and latitude corrected isotopic values with one notable exception our revised model produces paleoelevation estimates very close to previous estimates the exception is the reconstruction from late eocene age deposits at xoh xil for which we calculate elevations that are higher and much closer to the current elevation than previously reconstructed therefore there is no evidence for northward progression through time of tibetan elevation change instead the available but admittedly very scanty evidence suggests that much of tibet attained its modern elevation by the mid eocene a truly robust test of the various geodynamic models of uplift await expansion and replication of isotopic records all across tibet especially in the center and north and for 15 ma

the beginning development and termination of the middle miocene badenian salinity crisis in central paratethys abstract middle miocene badenian evaporites of the carpathian region are underlain and overlain by deep water deposits the onset of evaporite deposition was sudden but not synchronous in all facies zones and the deposition of evaporites was controlled by the evolution of carpathian orogen in the carpathian foredeep and most probably in other basins the badenian evaporites represent the lower part of the nn6 zone halite and associated deposits in the central part of the badenian evaporite basin show the same facies successions and marker beds can be traced across and between individual basins characteristic marker beds made it possible to correlate various facies zones of the marginal ca sulfate platform these marker beds seem to reflect events that may be related to sudden and widespread changes in water chemistry which in turn imply major changes in basin hydrology the onset of the evaporitic deposition in the carpathian foredeep was clearly diachronous and the evaporites deposited in the basin centre preceded the beginning of evaporite sedimentation in the marginal basin however depositional history in the marginal basin and the basin centre was the same a general transgressive sequence of evaporites found in the carpathian foredeep resulted from the migration of facies zones induced by the nappe movement isotopic studies of badenian foraminifers occurring below evaporites suggest that the interrupted communication of the paratethys with the ocean was a consequence of eustatic sea level fall possibly related to climatic cooling and it was coupled with a tectonic closure of connection with the tethys thus both tectonics and eustacy have contributed to the origin of salinity crisis sedimentological and geochemical data indicate recycling of evaporites throughout most of the evaporite deposition the recycling at the end of gypsum deposition in the marginal sulfate platform was accompanied by a change in the hydrology of the central paratethys that was tectonically driven and possibly related to the block tectonic phase manifested in the marginal part of the carpathian foredeep basin the change in hydrology implied the dilution of brines by inflowing marine water and this terminated the middle miocene badenian salinity crisis the onset of the badenian salinity crisis shows great similarities to the onset of the messinian salinity crisis and the terminations of both crises were different

geochemical evaluation of fenghuoshan group lacustrine carbonates north central tibet implications for the paleoaltimetry of the eocene tibetan plateau abstract a sedimentologic petrologic and geochemical evaluation of lacustrine carbonates from the eocene oligocene fenghuoshan group of north central tibet provides insight into the paleoenvironmental and paleolimnological setting of the hoh xil basin during the mid tertiary fenghuoshan lacustrine rocks consist primarily of carbonate mudstones and wackestones these carbonates are generally less than 3 m in thickness and are intercalated with siliciclastic lacustrine and fluvial alluvial plain deposits individual limestone beds coarsen and contain increasing amounts of siliciclastic material upward fenghuoshan carbonates also contain abundant ostracode bivalve and charaphyte fossils sedimentologic evidence suggests that carbonate deposition occurred in shallow relatively short lived lacustrine systems that were subsequently filled by alluvial deposits of coeval fluvial systems stable c and o isotopic analysis of fenghuoshan carbonates show 18o values ranging from 11 7 to 10 3 vienna pee de

sensitivity of climate to late cenozoic uplift in southern asia and the american west numerical experiments experiments with general circulation models with no mountains half mountains and full modern mountains show the sensitivity of atmospheric circulation patterns to progressive amounts of uplift the experiments were motivated by geologic evidence for large kilometer scale uplift in the late cenozoic in southern asia and the american west particularly within the last 10 m y in january the amplitude of the mid latitude upper tropospheric planetary waves increased with uplift and the low level winds were progressively blocked or diverted around the topographic features in july the progressive uplift caused monsoonlike circulations to develop in the vicinity of the colorado and tibetan plateaus atmospheric heating rates midtroposphere vertical motion and upper tropospheric planetary wave amplitudes varied approximately linearly with progressive uplift these results suggest that geologically recent kilometer scale uplift may have had climatic consequences comparable in magnitude and pattern to those of earlier stages of uplift comparison of the simulated climatic effects of uplift with the geologic evidence for late cenozoic climatic change especially for the last 10 m y is given in accompanying papers

a late eocene palynological record from the hoh xil basin northern tibetan plateau and its implications for stratigraphic age paleoclimate and paleoelevation abstract the hoh xil basin lying in the central tibetan plateau is key to understanding the cenozoic tectonics paleoelevation and paleoclimate changes that have occurred in the tibetan plateau since the collision of the indian and asian tectonic plates however the stratigraphic age and paleoelevation indicated by the sediments of the hoh xil basin remain hotly debated here we report on one palynological record from the tth c section extracted from the yaxicuo group the stratigraphic unit between the fenghuoshan and wudaoliang groups and analyze its implications for stratigraphic age paleoclimate and paleoelevation in the hoh xil basin the record shows that palynological taxa are mainly dominated by xerophytic ephedripites nitrariadites nitrariapollis and chenopodipollis with few ferns and conifers rich morphologies correspond well with those in the xia ganchaigou formation fm of the qaidam basin to the north palynological percentages are well correlated with the middle member of the xia ganchaigou fm in the qaidam basin as well as the lower member of the mahalagou fm in the xining basin to the northeast the ages of the middle member of the xia ganchaigou and lower member of the mahalagou fms from these two basins are both identical to the bartonian stage 40 37 ma of the late eocene according to their respective high resolution magnetostratigraphic dating this means that the age of the yaxicuo group at least covers the bartonian stage besides the qaidam and xining basins the palynological assemblages of the tth c section are also similar to those of three other sites the jiuquan tu ha and hetao basins indicating similarly arid climates dominated by a northwestern chinese subtropical high and a relatively low paleoelevation in the hoh xil basin mostly

modeling the miocene climatic optimum part i land and atmosphere abstractthis study presents results from the community climate system model 3 ccsm3 forced with early to middle miocene 20 14 ma vegetation topography bathymetry and modern co2 a decrease in the meridional temperature gradient of 6 5 c and an increase in global mean temperature of 1 5 c are modeled in comparison with a control simulation forced with modern boundary conditions seasonal poleward displacements of the subtropical jet streams and storm tracks compared to the control simulation are associated with changes in hadley circulation and significant cooling of the polar stratosphere consistent with previously predicted effects of global warming energy budget calculations indicate that reduced albedo and topography were responsible for miocene warmth in the high latitude northern hemisphere while a combination of increased ocean heat transport and reduced albedo was responsible for relative warmth in the high latitude southern hemisphere compared to the present model data analysis suggest

late miocene climate in the circum alpine realm a quantitative analysis of terrestrial palaeofloras abstract selected mega and microfloras from central and southern europe have been analysed for the time interval tortonian pannonian mn 9 12 with the coexistence approach to obtain quantitative palaeoclimate data the results give a geographically differentiated picture of the late miocene climate in the circum alpine area spatial patterns are presented in maps for mean annual temperature temperature of the coldest month temperature of the warmest month mean annual precipitation and mean annual range of temperature the obtained data show an overall warm humid and homogenous climate with very low latitudinal and longitudinal gradients there is no indication of a mediterranean type of climate palaeogeographic influences on climate patterns are evident the pannonian lake caused mild winters and a lower seasonality of temperature in the pannonian basin

effect of the formation of the isthmus of panama on atlantic ocean thermohaline circulation the late cenozoic closure of the seaway between the north andsouth american continents is thought to have caused extensive changes in ocean circulation and northern hemisphere climate1 2 but the timing and consequences of the emergence of the isthmus of panama which closed the seaway remain controversial1 2 3 4 5 here we present stable isotope and carbonate sand fraction records from caribbean sediments which when compared to atlantic and pacific palaeoceanographic records indicate that the closure caused a marked reorganization of ocean circulation starting 4 6 million years ago shallowing of the seaway intensified the gulf stream and introduced warm and saline water masses to high northern latitudes these changes strengthened deep water formation in the labrador sea over the next million years as indicated by an increased deep water ventilation and carbonate preservation in the caribbean sea and favoured early pliocene warming of the northern hemisphere the evaporative cooling of surface waters during north atlantic deep water formation would have introduced moisture to the northern hemisphere although the pronounced intensification of northern hemisphere glaciation between 3 1 and 2 5 million years ago substantially lagged the full development of north atlantic deep water formation we propose that the increased atmospheric moisture content was a necessary precondition for ice sheet growth which was then triggered by the incremental changes in the earth s orbital obliquity

constraints on the early uplift history of the tibetan plateau the surface uplift history of the tibetan plateau and himalaya is among the most interesting topics in geosciences because of its effect on regional and global climate during cenozoic time its influence on monsoon intensity and its reflection of the dynamics of continental plateaus models of plateau growth vary in time from pre india asia collision e g 100 ma ago to gradual uplift after the india asia collision e g 55 ma ago and to more recent abrupt uplift 7 ma ago and vary in space from northward stepwise growth of topography to simultaneous surface uplift across the plateau here we improve that understanding by presenting geologic and geophysical data from north central tibet including magnetostratigraphy sedimentology paleocurrent measurements and 40ar 39ar and fission track studies to show that the central plateau was elevated by 40 ma ago regions south and north of the central plateau gained elevation significantly later during eocene time the northern boundary of the protoplateau was in the region of the tanggula shan elevation gain started in pre eocene time in the lhasa and qiangtang terranes and expanded throughout the neogene toward its present southern and northern margins in the himalaya and qilian shan

palaeoclimatic and palaeoenvironmental interpretations of the late oligocene late miocene early pliocene in the cankiri corum basin abstract palaeoclimatic and palaeoenvironmental interpretations are reconstructed from the sedimentary sequences of the late oligocene and miocene pliocene boundary in the cankiri corum basin based on evidence obtained from palynofloras and ostracod and mammal faunas information on the main role of mixed mesophytic and broad leaved evergreen forests was obtained from the late oligocene data from the guvendik formation the pollen records of the formation showed a greater proportion of the hygrophytic forest communities thermophilic taxa and the taxonomic diversity of these forest communities developed mainly under dry subtropical climate conditions palynofloras and ostracods of the latest miocene and earliest pliocene were determined from coal bearing sediments of the akasdagi formation in central turkey the latest miocene palynoflora was represented by low diversity and abundance of spores and pollen and it was characterized by mainly grassland species the earliest pliocene palynoflora differs from that of the latest miocene through the presence of abundant and diverse palynomorphs this palaeovegetation diversification from the latest miocene to earliest pliocene can be related to changes in temperature and precipitation in the southern part of the cankiri corum basin the identified ostracods palynomorphs indicative of brackish environments and a high abundance of gypsum crystals observed from the lower part of the akkasdagi formation suggest brackish conditions during the latest miocene palynological evidence and results using the coexistence approach indicate that climate evolution in central turkey during this period can be referred to ongoing tectonic activity in this area and global climate change during the neogene

magnetostratigraphy of paleogene sediments from northern qaidam basin china implications for tectonic uplift and block rotation in northern tibetan plateau abstract we have carried out a detailed magnetostratigraphic study of tertiary sediments in the northern margin of the qaidam basin northern tibetan plateau a total of 400 paleomagnetic samples with an interval of about 2 m were collected from the shanggancaigou and xiagancaigou formations in the hongsanhan section stepwise thermal demagnetization was used to isolate the magnetic components in these samples a higher temperature component htc was separated between 300 and 680 c from most of samples positive fold and reversal tests suggest a primary origin for the htc a magnetic polarity sequence is established and then compared with the geomagnetic polarity time scale ostracoda assemblages and also a fission track age from an adjacent section suggest a tertiary age of the shanggancaigou and xiagancaigou formations in the hongsanhan area the magnetozones in the xiagancaigou formation may correspond to subchrons c16n c18 ranging from 40 to 35 5 ma mid eocene and the shanggancaikou formation to subchrons c8 2n c15 age from 35 5 to 26 5 ma late eocene to late mid oligocene the accumulation of sandy conglomerate and conglomerate layers on top of the shanggancaikou formation and an abrupt increase in sedimentation rates are probably resulted from the main uplift of the north qaidam at about 30 ma when compared with coeval directions expected from eurasia the mean declinations indicate a slight vertical axis rotation of the northern qaidam basin since the mid eocene sinistral shear strain may be concentrated on the altyn tagh fault atf