lateglacial climate development in nw romania comparative results from three quantitative pollen based methods abstract this paper provides quantitative reconstructions of the lateglacial changes in four climate parameters from two fine resolution pollen profiles in the gutaiului mountains nw romania climate estimates are based on two modern analogue techniques with and without considering vegetation types and weighted averaging partial least squares regression wa pls giving evidence for several climatic fluctuations during the period from 14 700 to 11 500 cal yr bp the comparative results of the two modern analogue techniques show consistent trends of climate changes that are also coherent at both sites but these results appear to largely disagree compared with climate reconstruction provided by wa pls the modern analogue techniques revealed four intervals with low temperatures prior to 14 700 cal yr bp between 13 950 and 13 800 13 400 and 13 200 and 12 700 and 11 700 cal yr bp the temperature declines were more pronounced for winter than for summer suggesting an intensification of seasonality which together with a drop in precipitation indicates an increase in continentality the younger dryas is the most pronounced cooling phase with winter temperatures 14 16 c colder than modern conditions annual and summer temperatures 2 5 c and 2 c respectively below present ones precipitation was 400 500 mm half that of present during the bolling and allerod summer temperatures were close to modern values 13 to 17 c whereas winter 6 to 12 c and annual temperatures 0 5 to 6 c as well as precipitation were 550 to 700 mm lower indicating more continental conditions compared to the present day climate

theory of quantitative reconstruction of vegetation i pollen from large sites reveals regional vegetation composition quantitative reconstruction of past vegetation is one of the primary goals in quaternary palynology and palaeoecology but still remains difficult this paper proposes a model reveals that estimates regional vegetation composition using pollen from large lakes that have small site to site variations of pollen assemblages even if vegetation is highly heterogeneous once these data have been used to quantify regional vegetation composition within 104 105 km2 background pollen one of the parameters crucial for vegetation reconstruction can be estimated for smaller sized sites and incorporated into the landscape reconstruction algorithm lra a multistep framework for quantitative reconstruction of vegetation in smaller areas 104 ha simulations using the pollscape modelling show that reveals can provide accurate estimates of regional vegetation composition in various landscapes and under different atmospheric conditions if pollen assemblages from lakes that are much smaller than large lakes a

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

dust flux estimates for the last glacial period in east central europe based on terrestrial records of loess deposits a review loess paleosol sequences are significant records of the mineral dust cycle of glacial interglacial periods as dust particles give rise to direct and indirect radiative forcing obtaining a reliable picture of the global and regional patterns of mineral dust fluxes during glacial periods can lead to a better understanding of the contribution of mineral dust to past climate changes recent progress in absolute dating of loess deposits in the carpathian basin in east central europe made it possible to provide correct aeolian flux estimates for the last glacial period marine isotope stage mis 2 mass accumulation rates mars from chronological data of 33 loess sites exhibited a wide range of values from 150 to 1422 g m 2 a 1 centered around median and mean values of 338 and 417 g m 2 a 1 marpm10marpm10 and marpm2marpm2 estimates have been also calculated using grain size measurements of many loess samples and loess mars in order to facilitate comparison with models and since particles larger than 10 m have a negligible radiative effect here we show that some previous model simulations of the dust cycle at the last glacial maximum lgm significantly underestimated the real aeolian flux ranges of our estimates marpm10 34 324marpm10 34 324 and marpm2 9 3 88 2gm 2a 1 in east central europe for this reason some simulations of dust induced direct radiative forcing of the lgm climate failed to yield reliable results for this mid latitude region as they have been based on three dimensional dust field models that are not capable of estimating the real aeolian fluxes in central europe a recent global model of top of the atmosphere toa radiative forcing by mineral aerosols at the lgm that has been based on more realistic parameterization of dust sources transport and deposition revealed zonally averaged surface cooling of 2 c for the latitudes of our study area this surface cooling and toa radiative forcing 2 to 3 w m 2 are greater than recognized in other models and draws our attention to the importance of further modeling the impact of mineral dust on lgm climate in order to gain insight into the spatial pattern of radiative forcing and better understand resulting climate response in mid latitude loess regions such as east central europe

reconstruction of lake level changes in lake xinias central greece during the last 40 000 years abstract the investigation of lake xinias greece deals with lake level changes since about 40 000 b p particular effort was made to obtain a reconstruction of lake level during the last glacial maximum at about 18 000 b p the reconstruction was based on a transect of sediment cores the cores were pollen stratigraphically correlated and the interpretation of the sediment stratigraphy was based on sediment chemical and mineral magnetic analyses the chronology was based on accelerator and conventional radiocarbon datings the most striking change was a lake level lowering at about 32 000 b p resulting in an overgrowing of the whole lake the lake level probably remained generally low until somewhat before 15 000 b p the period around the last glacial maximum must have been characterized by a low lake level which is in contrast to the hitherto common opinion additional investigations are required to demonstrate that the lake level changes reconstructed in lake xinias are regionally significant and record climatic changes however it may already be suggested that the conflict between pollen and lake level evidence which hitherto has produced controversy about the glacial climate perhaps does not exist the low lake level in lake xinias around the last glacial maximum is in accordance with the pollen evidence of steppe vegetation both recording a dry climate another distinct lowering occurred around the late wurmian holocene boundary at about 10 000 b p some minor lowerings are recorded also during the holocene e g at about 6000 5000 and 3000 b p

biological responses to rapid climate change at the younger dryas holocene transition at krakenes western norway a fine resolution pollen stratigraphical study supported by macrofossil analysis has been made at krakenes lake western norway through the younger dryas holocene transition and the early holocen

vegetation and environmental dynamics in the southern black sea region since 18 kyr bp derived from the marine core 22 gc3 abstract sediments from the black sea a region historically dominated by forests and steppe landscapes are a valuable source of detailed information on the changes in regional terrestrial and aquatic environments at decadal to millennial scales here we present multi proxy environmental records pollen dinoflagellate cysts ca ti and oxygen isotope data from the uppermost 305 cm of the core 22 gc3 42 13 53 n 36 29 55 e collected from a water depth of 838 m in the southern part of the black sea in 2007 the records span the last 18 kyr all ages are given in cal kyr bp the pollen data reveal the dominance of the artemisia steppe in the region suggesting rather dry cold environments 18 14 5 kyr bp warming humidity increase during melt water pulses 16 1 14 5 kyr bp indicated by 18o records from the 22 gc3 core sediment and from the sofular cave stalagmite is expressed in more negative 13c values from the sofular cave usually interpreted as the spreading of c3 plants the records representing the interstadial complex 14 5 12 9 kyr bp show an increase in temperature and moisture indicated by forest development increased primary productivity and reduced surface run off whereas the switch from primary terrigenous to primary authigenic ca origin occurs 500 yr later the younger dryas cooling is clearly demonstrated by more negative 13c values from the sofular cave and a reduction of pines the early holocene 11 7 8 5 kyr bp interval reveals relatively dry conditions compared to the mostly moist and warm middle holocene 8 5 5 kyr bp which is characterized by the establishment of the species rich warm mixed and temperate deciduous forests in the low elevation belt temperate deciduous beech hornbeam forests in the middle and cool conifer forest in upper mountain belt the border between the early and middle holocene in the vegetation records coincides with the opening of the mediterranean corridor at 8 3 kyr bp as indicated by a marked change in the dinocyst assemblages and in the sediment lithology changes in the pollen assemblages indicate a reduction in forest cover after 5 kyr bp which was likely caused by increased anthropogenic pressure on the regional vegetation

integration of modern and past pollen accumulation rate par records across the arctic tree line a method for more precise vegetation reconstructions abstract in order to assess the potential role of the boreal forest in the early to mid holocene global dynamics it is critical that the tree line reconstructions are based on precise palaeorecords pollen accumulation rate par calculations provide a technique for estimating past plant population densities independently for each species when considering tree lines an important concept is the threshold par value for the absence presence and dominance of the most common tree species such threshold values are often based on modern lake sediment core top par values in northern fennoscandia records obtained through pollen monitoring now add an important element to these studies as they allow more precise definitions of the temporal and spatial limits of par values here we compare modern par values based on pollen monitoring data with sediment core top data to evaluate the robustness of the threshold values for the major tree species of finnish lapland we apply these threshold values to two fossil par records from this tree line region and as an example of the potential of the approach map the vegetation patterns in the area at 7000 cal yr bp the results indicate that the extent of the mid holocene tree line advance in northern fennoscandia was substantially less than climate vegetation model simulations have predicted despite their value and potential in vegetation reconstructions the use of par values requires careful validation of the data we stress the importance of basin size of precise and reliable sediment dating age depth modelling and assessment of the sedimentary processes in each study basin as prerequisites for par based studies

the co evolution of black sea level and composition through the last deglaciation and its paleoclimatic significance abstract the black sea was an inland lake during the last ice age and its sediments are an excellent potential source of information on eurasian climate change showing linkages between regionally and globally recognized millennial scale climate events of the last deglaciation here we detail changes from the last glacial maximum lgm through the transition to an anoxic marginal sea using isotopic strontium and oxygen and trace element sr ca ratios in carbonate shells which record changing input sources and hydrologic conditions in the basin and surrounding region sr isotope records show two prominent peaks between 18 and 16 ka bp cal reflecting anomalous sedimentation associated with meltwater from disintegrating eurasian ice sheets that brought black sea level to its spill point following a sharp drop in sr isotope ratios back toward glacial values two stages of inorganic calcite precipitation accompanied increasing oxygen isotope ratios and steady sr isotope ratios these calcite peaks are separated by an interval in which the geochemical proxies trend back toward glacial values the observed changes reflect negative water balance and lake level decline during relatively warm periods bolling allerod and preboreal and increasing river input less evaporation resulting in higher lake levels during the intervening cold period the younger dryas a final shift to marine values in sr and oxygen isotope ratios at 9 4 ka bp cal corresponds to connection with the global ocean and marks the onset of sedimentation on the black sea continental shelf this date for the marine incursion is earlier than previously suggested based on the appearance of euryhaline fauna and the onset of sapropel formation in the deep basin

northern iberian abrupt climate change dynamics during the last glacial cycle a view from lacustrine sediments abstract we present a palaeoclimatic reconstruction of the last glacial cycle in iberia ca 120 000 11 600 cal yrs bp based on multi proxy reconstructions from lake sediments with robust chronologies and with a particular focus on abrupt climate changes the selected lake sequences provide an integrated approach from northern iberia exploring temperature conditions humidity variations and land sea comparisons during the most relevant climate transitions of the last glacial period thus we present evidence that demonstrates i cold but relatively humid conditions during the transition from mis 5 to mis 4 which prevailed until ca 60 000 cal yrs bp in northern iberia ii a general tendency towards greater aridity during mis 4 and mis 3 ca 60 000 to 23 500 cal yrs bp punctuated by abrupt climate changes related to heinrich events he iii a complex highly variable climate during mis 2 23 500 to 14 600 cal yrs bp with the mystery interval mi 18 500 to 14 600 cal yrs bp and not the global last glacial maximum lgm 23 000 to 19 000 cal yrs bp as the coldest and most arid period the last glacial transition starts in synchrony with greenland ice records at 14 600 cal yrs bp but the temperature increase was not so abrupt in the iberian records and the highest humidity was attained during the allerod gi 1a to gi 1c and not during the bolling gi 1e period the younger dryas event gs 1 is discernible in northern iberian lake records as a cold and dry interval although iberian vegetation records present a geographically variable signal for this interval perhaps related to vegetation resilience

itrax description and evaluation of a new multi function x ray core scanner a new automated multi function core scanning instrument named itrax has been developed that records optical radiographic and elemental variations from sediment half cores up to 1 8 m long at a resolution as fine as 200 m an intense micro x ray beam focused through a flat capillary waveguide is used to irradiate samples to enable both x radiography and x ray fluorescence xrf analysis data are acquired incrementally by advancing a split core via a programmable stepped motor drive through the flat rectangular section x ray beam traditional xrf determination of element composition in sediments provides high quality data but it takes a considerable time and normally consumes gram quantities of material that is often only available in limited quantities the itrax core scanner non destructively collects optical and x radiographic images and provides high resolution elemental profiles that are invaluable for guiding sample selection for further destructive detailed sampling this paper presents a description of the construction characteristics and capabilities of the itrax system high resolution itrax data obtained from sediment cores are also presented and compared with results from traditional wavelength dispersive xrf analysis at lower resolution finally some recent technical developments linked to the second generation itrax are presented

millennial scale variability in the productivity signal from the alboran sea record western mediterranean sea primary productivity of the alboran sea western mediterranean is reconstructed for the time interval 48 000 to 28 000 years bp using the following geochemical proxies calcium carbonate barium excess baexcess total organic carbon toc and alkenone concentration the records show a consistent pattern that indicates enhanced productivity during dansgaard oeschger d o warm periods at the same time deep water conditions were favorable for organic matter preservation in the sediments as indicated by the variation in redox sensitive elements such as mn cr or v and by the 13c record of benthic foraminifers the alboran sea productivity variation during d o cycles is explained by the succession of two climatic scenarios that led to latitudinal shifts of the westerly wind system this mechanism would also account for the variability in the deep water ventilation of the western mediterranean sea

weichselian palynostratigraphy palaeovegetation and palaeoenvironment the record from lago grande di monticchio southern italy abstract the palynostratigraphic record from lago grande di monticchio s italy is presented an independent sedimentation rate based chronology provides an age of 101 530 calendar years bp for the lowermost sediments sampled this chronology enables assessment of the rapidity of vegetation changes during the last glacial contrary to widely held views the vegetation showed numerous large magnitude changes in periods of

hydrological changes in eastern europe during the last 40 000 yr inferred from biomarkers in black sea sediments the black sea is connected to a large drainage area including the european russian plain part of the alps and southeastern europe to study the hydrological changes in this basin over the last 40 000 years we measured specific terrigenous biomarkers for wetland vegetation in well dated sediments from the northwestern black sea spanning the last glacial period lacustrine phase and the holocene marine phase low abundances of these biomarkers are observed during the north atlantic ice melting and cooling events known as heinrich events 4 to 2 the last glacial maximum and the younger dryas event increased biomarker inputs characterize the mild climate phases known as dansgaard oeschger interstadials the bolling allerod and preboreal warmings indicating increased erosion due to permafrost degradation higher primary productivity and or wetland extension in the drainage basin the final retreat of the fennoscandian ice sheet from the russian plain occurs during the early part of heinrich event 1 and is characterized by increased biomarker concentrations in a typical series of four deglacial clay layers for the last glacial period the correspondence in timing between the biomarker records and the atmospheric ch4 record from ice cores suggests an important ch4 contribution due to boreal permafrost thawing and wetland emission

holocene and late pleistocene climate in the sub mediterranean continental environment a speleothem record from poleva cave southern carpathians romania the pp10 stalagmite from poleva cave provides a late pleistocene and holocene isotopic record characteristic for the sw of romania a sub mediterranean climatic region the speleothem was dated by eight tims and one alpha u series dates which showed that it was precipitated between 75 ka and 2 ka with at least two hiatuses the basal sector of the stalagmite showed a slow growing regime of 0 26 cm ka while the upper one grew relatively fast with about 5 cm ka the temporal resolution for the isotopic sampling is thus 2 ka sample for the lower sector and 150 years sample for the upper one the relationship between 18 o and temperature was found positive the isotopic record of the lower sector shows two marked cold intervals during 67 and 58 ka and 40 35 ka respectively which correlate well with the villars and soreq records the upper sector record is so far the most detailed holocene isotopic record in romania and the only one available for the regions located at the exterior of the carpathians range the signal shows a gradual warming after the gs1 event punctuated by several cold events at 8 7 2 and 4 2 ka and also by warm oscillations centered at about 5 2 and 3 3 ka the results seem to indicate that if the north atlantic firstorder signals may extend well to the south eastern europe their amplitude and general trend may be diminished by the interferences with the mediterranean circulation

detrital events and hydroclimate variability in the romanian carpathians during the mid to late holocene the romanian carpathians are located at the confluence of three major atmospheric pressure fields the north atlantic the mediterranean and the siberian despite its importance for understanding past human impact and climate change high resolution palaeoenvironmental reconstructions of holocene hydroclimate variability and in particular records of extreme precipitation events in the area are rare here we present a 7500 year long high resolution record of past climatic change and human impact recorded in a peatbog from the southern carpathians integrating palynological geochemical and sedimentological proxies natural climate fluctuations appear to be dominant until 4500 years before present yr bp followed by increasing importance of human impact sedimentological and geochemical analyses document regular minerogenic deposition within the bog linked to periods of high precipitation such minerogenic depositional events began 4000 yr bp with increased depositional rates during the medieval warm period mwp the little ice age lia and during periods of societal upheaval e g the roman conquest of dacia the timing of minerogenic events appears to indicate a teleconnection between major shifts in north atlantic oscillation nao and hydroclimate variability in southeastern europe with increased minerogenic deposition correlating to low nao index values by linking the minerogenic deposition to precipitation variability we state that this link persists throughout the mid to late holocene

vegetation response to abrupt climate changes in western europe from 45 to 14 7k cal a bp the bergsee lacustrine record black forest germany

rapid environmental changes in southern europe during the last glacial period oxygen isotope records from greenland ice cores1 2 indicate numerous rapid climate fluctuations during the last glacial period north atlantic marine sediment cores show comparable variability in sea surface temperature and the deposition of ice rafted debris3 4 5 in contrast very few continental records of this time period provide the temporal resolution and environmental sensitivity necessary to reveal the extent and effects of these environmental fluctuations on the continents here we present high resolution geochemical physical and pollen data from lake sediments in italy and from a mediterranean sediment core linked by a common tephrochronology our lacustrine sequence extends to the past 102 000 years many of its features correlate well with the greenland ice core records demonstrating that the closely coupled ocean atmosphere system of the northern hemisphere during the last glacial4 extended its influence at least as far as the central mediterranean region numerous vegetation changes were rapid frequently occurring in less than 200 years showing that the terrestrial biosphere participated fully in last glacial climate variability earlier than 65 000 years ago our record shows more climate fluctuations than are apparent in the greenland ice cores together the multi proxy data from the continental and marine records reveal differences in the seasonal character of climate during successive interstadials and provide a step towards determining the underlying mechanisms of the centennial millennial scale variability

groundwater flow system as an archive of palaeotemperature noble gas radiocarbon stable isotope and geochemical study in the pannonian basin hungary abstract to establish the increase in temperature and the time span of the transition between the late glacial maximum lgm and the holocene the noble gas content 18 o 2 h 13 c values 3 h and 14 c activity and chemistry were studied in a groundwater flow system in quaternary sediments in hungary the study area is a sub basin of the pannonian basin where the c isotope ratios are not influenced by carbonate reactions along the flow path because the only water rock interaction is ion exchange the 18 o and 2 h values indicate a cold infiltration period followed by warming and finally warm temperature conditions the noble gas data show that the average infiltration temperature was 3 3 c in the cold 12 9 c in the warm and intermediate in the transitional stage using the noble gas temperatures geochemical batch modelling was performed to simulate the chemical processes based on the geochemical model 13 c and 14 c 0 initial radiocarbon activity in the recharging water were calculated transport modelling was used to simulate the distribution of chemical components 18 o 2 h and 14 c 0 along the flow path it was found that the main processes determining the chemical composition of the groundwater were dissolution precipitation of calcite and dolomite during infiltration near the surface and ion exchange along the flow path in the recharge area the 13 c and 14 c 0 were controlled by dissolution and precipitation of carbonate minerals c speciation and fractionation processes all these processes were influenced by the recharge temperature ngts calculated from the dissolved noble gas concentrations showed an average of 3 3 c for cold and 12 9 c for warm infiltration i e for the lgm and for the holocene the temperature difference was thus 9 1 0 8 c which is one of the largest degree of warming detected by noble gases so far the alkalinity indicates that carbonate reactions were unimportant along the flow path owing to the temperature dependence of the equilibrium constants temperature conditions during infiltration have to be taken into consideration in radiocarbon age calculation dispersive transport along the flow path modified the chemical and isotopic composition of infiltrated water the contribution of the old pore water which was free of the 14 c isotope resulted in uncertainties in radiocarbon age determination it was concluded that determination of the radiocarbon age or mean residence time requires detailed knowledge of the hydraulic conditions of groundwater

morphometrical and geochronological constraints on the youngest eruptive activity in east central europe at the ciomadul csomad lava dome complex east carpathians abstract the timing of late pleistocene volcanic activity of the ciomadul csomad dacitic lava dome complex site of the youngest eruptions in the carpathians has been constrained by morphometric analysis and radiometric chronology pelean domes and asymmetric domes coulees built up the volcano including the central edifice that hosts the youngest twin craters of mohos mohos peat bog and lake st ana szent anna a comparative digital elevation model dem based morphometric analysis of lava domes 29 worldwide examples including 5 domes from ciomadul shows that it is the mean slope of the upper dome flank that correlates best with age although the logarithmic relationship is only moderately strong r 0 80 slope characteristics of the ciomadul domes fit to those of 10 100 ka old domes these young ages contradict the previous k ar dates giving as old as 1 ma ages on a number of domes but are supported by ongoing u pb and u th he zircon dating the latter methods constrain the whole volcanic activity to the past 250 ka and the emplacement of most lava domes within the period of 150 100 ka the volcanism at ciomadul produced alternating effusive and explosive eruptions including lava dome collapses and successive crater formations the latest possibly subplinian explosive event formed the well preserved st ana crater radiocarbon dating of organic remains from a sediment core that reached 11 m into the lacustrine infill of st ana suggests that the crater was formed prior to 26 000 years bp

the latest explosive eruptions of ciomadul csomad volcano east carpathians a tephrostratigraphic approach for the 51 29 ka bp time interval abstract the most recent mainly explosive eruptions of ciomadul the youngest volcano in the carpatho pannonian region have been constrained by detailed field volcanological studies major element pumice glass geochemistry luminescence and radiocarbon dating and a critical evaluation of available geochronological data these investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of ciomadul s twin craters st ana and mohos that received tephra deposition during the last eruptions of the volcano our analysis shows that significant explosive activity collectively called eppa early phreatomagmatic and plinian activity started at ciomadul in or around the present day mohos the older crater at 51 ka bp these eruptions resulted in a thick succession of pyroclastic fall deposits found in both proximal and medial distal localities around the volcano characterized by highly silicic rhyolitic glass chemical compositions ca 75 2 79 8 wt sio 2 the eppa stage was terminated by a subplinian plinian eruption at 43 ka bp producing pumiceous pyroclastic fall and flow deposits of similar glass composition probably from a proto st ana vent located at or around the younger crater hosting the present day lake st ana after a quiescent period with a proposed lava dome growth in the st ana crater a new explosive stage began defined as mpa middle plinian activity in particular a significant two phase eruption occurred at 31 5 ka bp producing pyroclastic flows from vulcanian explosions disrupting the preexisting lava dome of sf ana and followed by pumiceous fallout from a plinian eruption column related pyroclastic deposits show a characteristic less evolved rhyolitic glass composition ca 70 2 74 5 wt sio 2 and occur both in proximal and medial distal localities up to 21 km from source the mpa eruptions that may have pre shaped a crater similar to but possibly smaller than the present day st ana crater was followed by a so far unknown but likewise violent last eruptive stage from the same vent creating the final morphology of the crater this stage referred to as lspa latest st ana phreatomagmatic activity produced pyroclastic fall deposits of more evolved rhyolitic glass composition ca 72 8 78 8 wt sio 2 compared to that of the previous mpa stage according to radiocarbon age constraints on bulk sediment charcoal and organic matter from lacustrine sediments recovered from both craters the last of these phreatomagmatic eruptions that draped the landscape toward the east and southeast of the volcano occurred at 29 6 ka bp some 2000 years later than the previously suggested last eruption of ciomadul

short term soil formation events in last glacial east european loess evidence from multi method luminescence dating here we provide a robust luminescence chronology for stayky ukraine a reference profile in european late pleistocene loess stratigraphy based on optically stimulated luminescence osl dating on quartz 4 11 m 63 90 m and post infrared infrared stimulated luminescence pir irsl on polymineral fine grains for the bug loess unit the equivalent of marine isotope stage mis 2 results are in agreement between methods demonstrating that the suite of embryonic soils previously interpreted as reflecting climate variability similar to greenland interstadials gi actually date to 29 27 15 ka with most emplaced around or after 20 ka this temporal span is further confirmed by age depth modelling of available data apart from gi 2 no interstadial type climate events are recorded in greenland ice core data for that time interval as short term pedogenetic phases are also documented in records from central western europe there is a need for more research into the european mid latitude terrestrial environments response to mis 2 hydroclimate variability the dating of vytachiv paleosol previously debatably linked to various gi events within mis 3 resulted in ages of 40 4 ka and 53 4 ka at the lower transition and 26 2 ka to 30 2 ka in the overlying loess these ages indicate that the truncated vytachiv paleosol is either not continuous or that it encompasses a broader age range within mis 3 than previously considered in both cases data would not allow for an unambiguous linking of this paleosol with specific gi events as previously attempted the pir irsl290 dating of the loams immediately underneath pryluky unit in the range of 120 ka to 168 ka and of the pryluky mollisol from 90 ka to 126 ka confirm the broad correspondence of this unit with mis 5 although poor dose recovery results open the possibility for further testing on the degree these ages provide overestimated results quartz data severely underestimate the pir irsl290 ages for these samples the application of pir irsl290 dating for the underlying dnieper till previously linked to the saalian glaciation resulted in natural signals at the level of laboratory saturation yielding minimum ages of c 700 ka for the same sample the natural sar osl signals for 4 11 m quartz were found significantly below laboratory saturation level resulting in finite ages of 250 270 ka interpreted here as underestimates while coarse quartz 63 90 m signals reached about 85 of the laboratory saturation level these data suggest extreme caution must be taken when dating such old samples using quartz osl results from our high resolution luminescence dating raises important implications for the chronological representativeness of stayky as a key loess site in eastern europe beyond mis 2

new seismic and tomography data in the southern part of the harghita mountains romania southeastern carpathians connection with recent volcanic activity the southern part of the southeastern carpathians represents the site of the most recent volcanic eruptions of the entire carpathian pannonian region the products of these eruptions range from 42 to 10 ka radiocarbon ages in the south harghita mountains high k calc alkaline rocks with adakite like features and at 1 2 0 6 ma k ar ages in the persani mountains alkali basalts they were emplaced in a post collisional regime ciomadul volcano is located at the southernmost part of the nw se oriented c limani gurghiu harghita range crossing the inner part of the southeastern carpathians and in the rough proximity of the vrancea seismic zone at ca 60 km toward nw its magma generation is attributed to geodynamic events closely related to the seismogenic area a number of particular geophysical and geochemical features located in the study region including 1 the abrupt attenuation of the seismic waves originating from the vrancea intermediate depth foci 2 the most intense heat flow anomaly in romania 3 the most prominent 3he 4he anomaly measured in natural postvolcanic gas emanations are all in favor of the hypothesis of a still existing hot local magma chamber data acquired during recent seismic monitoring of the vrancea zone and its neighborhoods suggest an enhancement of the local seismicity beneath the southern edge of the south harghita mts both at crustal and subcrustal levels at the same time recent tomography images obtained using local earthquake data correlate well with the presence of a vertically extended low velocity zone coming from the upper mantle to the assumed magmatic chambers located in the crust the present data supporting the presence of an active crustal magma chamber beneath ciomadul allow us to consider that future volcanic activity at this volcano cannot be discarded

holocene vegetation history in the upper forest belt of the eastern romanian carpathians abstract pollen analysis supported by nine ams 14 c dates from the poiana tiol peat sequence 1540 m in the rodnei mountains eastern romanian carpathians romania is used to reconstruct the holocene vegetation history in this mountain region the results are then compared with other sequences from romania and eastern europe in order to better understand the past dynamics of the main forest constituents the vegetation record at poiana tiol starts at ca 11 000 cal yr bp with the occurrence of rather closed woodlands composed of betula pinus picea abies alnus a viridis and ulmus picea abies was the dominant tree species for almost the entire period however during the last 3000 years p abies forests were largely replaced by pinus in the area temperate tree taxa fraxinus quercus acer tilia and corylus avellana were also common but likely at lower elevation c avellana expanded around 10 300 cal yr bp and reached maximum values after 9000 cal yr bp pollen of carpinus betulus and fagus sylvatica was already recorded around 7000 cal yr bp however the spread of c betulus occurred at ca 6000 cal yr bp with maximum values between 4800 cal yr bp and 3000 cal yr bp while f sylvatica spread from ca 3200 cal yr bp and attained maximum values between 2000 and 200 cal yr bp the first indications of human activities appeared around 3200 cal yr bp and intensified within the last 200 years comparison with other sequences from romania and surrounding countries reveals both similarity and great differences related to the location of glacial refugia climate change and human impact

humid glacials arid interglacials critical thoughts on pedogenesis and paleoclimate based on multi proxy analyses of the loess paleosol sequence crvenka northern serbia abstract loess paleosol sequences lps provide unique terrestrial archives for past environmental and climate changes the loess units are generally interpreted to reflect more arid conditions whereas paleosols are thought to document more humid conditions this paradigm may however deserve to be challenged in some regions because it does not take into account past changes in dust accumulation rates here we present a multi proxy sedimentological and geochemical characterization of the lps crvenka serbia spanning the last 140 ka commonly used analyses such as magnetic susceptibility organic carbon content grain size and weathering indices allow the quantification of the intensity of pedogenesis however loess accumulation rates were much higher during glacials than during interglacials so that it is not trivial to infer past rates of pedogenesis and related paleoclimate conditions novel proxies based for example on lipid biomarkers and their isotopic composition are not so directly affected by changes in loess accumulation rates and might provide interesting new insights long chain plant derived n alkanes in the lps crvenka suggest a minor but non negligible contribution of deciduous trees and shrubs c27 and c29 during mis 1 2 4 and 6 whereas grasses and herbs c31 and c33 dominate the alkane input during mis 3 and 5 this is in agreement with the notion that parts of southeast europe served as refugia for deciduous trees during glacials on the other hand edaphic conditions on the drought prone loess plateaus seem to have been more arid during mis 3 and 5 compound specific d analyses on the alkanes show only little changes on glacial interglacial timescale when compared with the isotopic enrichment of the mediterranean sea during the last glacial this likely indicates a complex combination of reduced temperatures increased rainfall reduced evapotranspiration and more advection of north atlantic moisture although disentangling these factors is difficult interpretation in terms of humid glacials and more arid interglacials seems to be supported also by other novel lipid biomarkers so called gdgts glycerol dialkyl glycerol tetraethers

timing and climatic impact of greenland interstadials recorded in stalagmites from northern turkey a 50 kyr long exceptionally well dated and highly resolved stalagmite oxygen 18o and carbon 13c isotope record from sofular cave in northwestern turkey helps to further improve the dating of greenland interstadials gi 1 and 3 12 timing of most gi in the sofular record is consistent within 10 to 300 years with the iconic hulu cave record larger divergences 500 years between sofular and hulu are only observed for gi 4 and 7 the sofular record differs from the most recent ngrip chronology by up to several centuries whereas age offsets do not increase systematically with depth the sofular record also reveals a rapid and sensitive climate and ecosystem response in the eastern mediterranean to gi whereas a phase lag of 100 years between climate and full ecosystem response is evident finally results of spectral analyses of the sofular isotope records do not support a 1 470 year pacing of gi

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

loess accumulation during the last glacial maximum evidence from urluia southeastern romania abstract the eastern european loess steppe represents one of the most substantial landform types on the continent yet the impact on this region of the last glacial maximum lgm the coldest climatic episode during the last full glacial cycle is relatively poorly understood this is in part due to the comparatively small number of sites which have been reliably dated and in part due to the need to better elucidate depositional models for loess environments at both local and regional scales here we present a high frequency age depth profile for the last 40 ky from a loess deposit at urluia in southeastern romania using fine grained quartz optically stimulated luminescence osl dating and environmental magnetism analyses loess accumulation at the site for this period is well constrained by a clearly identifiable tephra deposit corresponding to the ca 39 ka campanian ignimbrite we show that the tephra is directly overlain by a relatively thin layer of loess corresponding to marine isotope stage mis 3 which is partially overprinted by a weakly developed paleosol the sequence is dominated by a 6 8 m package of primary loess of lgm age the eight osl samples from this package group together around a mean age of 21 6 1 5 ka and suggest rapid and substantial deposition during this phase the uppermost part of the section indicates significantly reduced loess accumulation during the deglacial period into the holocene less than 2 m in total thickness the rapid accumulation of loess during the lgm at urluia is consistent with increased sedimentation at other loess profiles in the lower danube basin although the variable thickness of these deposits across the catchment highlights the need to more explicitly investigate depositional models for loess the urluia record complements emerging data which suggests that the lower danube loess steppe was cold dry and windy during the lgm yet experienced milder climates than comparable latitudes further west and north and did not undergo periglacial activity

the full glacial forests of central and southeastern europe the presence of trees in central and southern europe during the last full glaciation has long been a matter of debate a low but persistent presence of fossil tree pollen in central and southern european full glacial paleoecological sequences has been interpreted either as representing long distance pollen transport from southerly refuges or as representing in situ refugial populations here we present macroscopic charcoal results from 31 sequences located throughout hungary that provide unequivocal evidence for the presence of at least seven different tree types between approximately 32 500 and 16 500 14c yr b p this evidence is presented in conjunction with molluscan and pollen analyses to indicate that during the last full glaciation trees grew as far north as hungary probably in microenvironmentally favorable sites these areas provided an important cold stage refugium for the european flora and fauna

vegetation and environmental responses to climate forcing during the last glacial maximum and deglaciation in the east carpathians attenuated response to maximum cooling and increased biomass burning the carpathian mountains were one of the main mountain reserves of the boreal and cool temperate flora during the last glacial maximum lgm in east central europe previous studies demonstrated lateglacial vegetation dynamics in this area however our knowledge on the lgm vegetation compo sition is very limited due to the scarcity of suitable sedimentary archives here we present a new record of vegetation fire and lacustrine sedimentation from the youngest volcanic crater of the carpathians lake st anne lacul sf ana szent anna tto examine environmental change in this region during the lgm and the subsequent deglaciation our record indicates the persistence of boreal forest steppe vegetation with pinus betula salix populus and picea in the foreland and low mountain zone of the east carpathians and juniperus shrubland at higher elevation we demonstrate attenuated response of the regional vegetation to maximum global cooling between 22 870 and 19 150 cal yr bp we find increased regional biomass burning that is antagonistic with the global trend increased regional fire activity suggests extreme continentality likely with relatively warm and dry summers we also demonstrate xerophytic steppe expansion directly after the lgm from 19 150 cal yr bp and regional increase in boreal woodland cover with pinus and betula from 16 300 cal yr bp plant macrofossils indicate local 950 m a s l establishment of betula nana and betula pubescens at 15 150 cal yr bp pinus sylvestris at 14 700 cal yr bp and larix decidua at 12 870 cal yr bp pollen data furthermore support population genetic inferences regarding the regional presence of some temperate deciduous trees during the lgm fagus sylvatica corylus avellana fraxinus excelsior our sedimentological data also demonstrate intensified aeolian dust accumulation between 26 000 and 20 000 cal yr bp

pleistocene water intrusions from the mediterranean and caspian seas into the black sea the hydrological balance of the black sea is governed by riverine input and by the exchange with the mediterranean sea a speleothem record from a cave in northern turkey that tracks the isotopic signature of black sea surface water suggests an open connection to the mediterranean sea in at least twelve periods in the past 670 000 years

dating synthesis and interpretation of palaeoclimatic records of the last glacial cycle and model data integration advances by the intimate integration of ice core marine and terrestrial records cost action es0907 since 2010 the intimate integration of ice core marine and terrestrial records network has been operating as a cost action designated es0907 this paper outlines the accomplishments of the intimate cost action in the context of how the intimate ideas have evolved during the network s twenty year life span and highlights a number of challenges that can guide further work in the second part of the paper the contributions that comprise this intimate special issue are introduced

a cool temperate climate on the antarctic peninsula through the latest cretaceous to early paleogene constraining past fl uctuations in global temperatures is central to our understanding of the earth s climatic evolution marine proxies dominate records of past temperature reconstructions whereas our understanding of continental climate is relatively poor particularly in high latitude areas such as antarctica the recently developed mbt cbt methylation index of branched tetraethers cyclization ratio of branched tetraethers paleothermometer offers an opportunity to quantify ancient continental climates at temporal resolutions typically not afforded by terrestrial macrofl oral proxies here we have extended the application of the mbt cbt proxy into the cretaceous by presenting paleotemperatures through an expanded sedimentary succession from seymour island antarctica spanning the latest maastrichtian and paleocene our data indicate the existence of a relatively stable persistently cool temperate climate on the antarctic peninsula across the cretaceous paleogene boundary these new data help elucidate the climatic evolution of antarctica across one of the earth s most pronounced biotic reorganizations at the cretaceous paleogene boundary prior to major icesheet development in the late paleogene our work emphasizes the likely existence of temporal and or spatial heterogeneities in climate of the southern high latitudes during the early paleogene

rapid vegetation response to lateglacial and early holocene climatic fluctuation in the south carpathian mountains romania abstract high resolution pollen conifer stomata and plant macrofossil analyses of two glacial lake sediments 1740 and 1990 m a s l are used to reconstruct lateglacial lg and early holocene eh vegetation and tree line changes in the retezat mountains our results show that during the lg tree line was between 1750 and 1800 m a s l formed by larix decidua pinus mugo and picea abies early lg spread to high altitudes suggests refugia of these tree species in the mountain the younger dryas cooling resulted in regional steppe tundra expansion but tree line position and composition showed little change the abundance of trees and shrubs decreased at 1740 m a s l but species richness increased with the arrival of pinus cembra our data support climate model hindcasts for only modest decrease in accumulated growing season heat at mid high altitudes regionally the pollen records suggest enhanced aridity and seasonality in the eh tree line reached 2000 m a s l higher than today by 11 100 cal yr bp p mugo p cembra p abies established around the upper lake suggesting rapid increase in summer temperatures the eh maximum of l decidua between 11 200 10 600 cal yr bp was connected to high summer insolation high altitude expansion of abies alba between 10 600 10 300 cal yr bp suggested summer mean temperatures 2 8 c higher then today in comparison with other mountain sites in europe lg interstadial tree line was at similar altitude in the s alps and 350 m higher in the pirin mountains lg tree line fluctuation had similar low amplitude in the se alps retezat and pirin mts suggesting relatively weak influence of the north atlantic thermohaline circulation changes on growing season temperatures

the last interglacial glacial cycle mis 5 2 re examined based on long proxy records from central and northern europe abstract current multi proxy studies on a long sediment sequence preserved at sokli n finland i e in the central area of fennoscandian glaciations are drastically changing classic ideas of glaciations vegetation and climate in northern europe during the late pleistocene the sediments in the sokli basin have escaped major glacial erosion due to non typical bedrock conditions in this review the sokli record is compared in great detail with other long proxy records from central temperate and northern boreal europe these comprise the classic records of la grande pile e france and oerel n germany and more recently obtained records from horoszki duze e poland and lake yamozero nw russia the focus of the review is on pollen lithology and macrofossil and insect based temperature inferences the long records are further compared with recent proxy data from nearby terrestrial sites as well as with the rapidly accumulating high resolution proxy data from the ocean realm the comparison allows a re examination of the environmental history and climate evolution of the last interglacial glacial li g cycle mis 5 2 it shows that environmental and climate conditions during mis 5 ca 130 70 ka bp were distinctly different from those during mis 4 2 ca 70 15 ka bp mis 5 is characterized by three long forested intervals broadly corresponding to mis 5e 5c 5a both in temperate and northern boreal europe these mild periods were interrupted by two short relatively cold and dry intervals mis 5d and 5b with mountain centered glaciation in fennoscandia millennial scale climate events were superimposed upon these longer lasting climate fluctuations the time interval encompassing mis 4 2 shows open vegetation it is characterized by two glacial maxima mis 4 and 2 with sub continental scale glaciation over northern europe and dry conditions in strongly continental eastern european settings high amplitude climate oscillations of millennial duration characterized the climate variability of mis 3 mild climate conditions in early mis 3 caused large scale deglaciation of the fennoscandian ice sheet and ice free conditions with betula dominated vegetation including tree birch persisted over large parts of fennoscandia possibly interrupted by glaciation during major part of mis 3 till ca 35 ka bp overall mis 5 was mostly mild with warmest or peak interglacial conditions at the very start during mis 5e mis 4 2 was mostly cold with most extreme or peak glacial conditions in the closing phase during mis 2 this points to a subdivision of the last climate cycle into an early overall mild interglacial half and a late overall cold glacial half each with duration of ca 50 ka this review also shows that the climate variability in central and northern europe during the li g cycle was mostly in degrees of continentality with major shifts in winter temperature and precipitation values summer temperatures on the other hand remained largely unchanged it points to the waxing and waning of sea ice over the north atlantic ocean as a possible characteristic feature of the late pleistocene the present compilation based on long terrestrial sequences high resolution multi proxy data from the oceans and quantified paleo climate data strongly favors a definition of entire marine oxygen isotope stage 5 as the last interglacial similar as in the original marine stratigraphy and the stratigraphy at la grande pile in france the proxy based climate data places the start of the last glacial at the base of mis 4 and the northwest european pleniglacial it shows that the division between the eemian mis 5e and the early weichselian mis 5d a is not useful as not relevant from a climate point of view

ecosystems of eastern europe at the time of maximum cooling of the valdai glaciation 24 18 kyr bp inferred from data on plant communities and mammal assemblages abstract data on eastern european fossil mammal fauna and palaeoflora dated to the last glacial maximum 24 18 kyr bp have been summarized using paradox and arc view software palaeobotanical material from 54 sections 197 samples altogether was studied along with mammal fossils recovered from 55 localities this made it possible to compile a series of electronic maps for indicator mammal and plant species for the considered time interval an analysis of the spatial distribution of species belonging to different ecological groups enabled the identification of principal mammal assemblages and plant communities of the lgm the whole volume of data was then processed using a range of mathematical techniques the classes of the palynologically studied sections were analysed integrally with those of mammal localities both in the multidimensional axes space and in physical space described by their geographical coordinates mathematical processing of a considerable amount of palaeobiological data permitted the identification of individual groups of mammals and plants and to make a further comparison between them in this way palaeoenvironments of the coldest phase of the valdai glaciation for the territory of eastern europe were reconstructed for the first time by means of simultaneous analysis of theriological and palaeobotanical data using mathematical techniques

climatic implications of cirque distribution in the romanian carpathians palaeowind directions during glacial periods the many glacial cirques in the mountains of romania indicate the distribution of former glacier sources related to former climates as well as to topography in the transylvanian alps southern carpathians cirque floors rise eastward at 0 714 m km 1 and cirque aspects tend ene confirming the importance of winds from some westerly direction there is a contrast between two neighbouring ranges the fa ga ras where the favoured aspect of cirques is ene and the iezer where the tendency is stronger and to nne this can be explained by the iezer mountains being sheltered by the fa ga ras which implies precipitation bearing winds from north of west at times of mountain glaciation palaeoglaciation levels also suggest winds from north of west which is consistent with aeolian evidence from pleistocene dunes yardangs and loess features in the plains of hungary and south western romania in northern romania including ukrainian maramures the influence of west winds was important but sufficient only to give a northeastward tendency in cirque aspects this gave stronger asymmetry than in the transylvanian alps as the northward solar radiation incidence tendency in these marginally glaciated mountains was less diluted by wind effects cirque floors in northern romania are lower also in northeast facing cirques in general cirque aspects result from several factors and the mean tendency is not downwind but is displaced from poleward by wind and by minor effects copyright 2010 john wiley sons ltd

paleo climate of the central european uplands during the last glacial maximum based on glacier mass balance modeling during the last glacial maximum lgm glaciers existed in scattered mountainous locations in central europe between the major ice masses of fennoscandia and the alps a positive degree day glacier mass balance model is used to constrain paleo climate conditions associated with reconstructed lgm glacier extents of four central european upland regions the vosges mountains the black forest the bavarian forest and the giant mountains with reduced precipitation 25 75 reflecting a drier lgm climate the modeling yields temperature depressions of 8 15 c to reproduce past glaciers more severe cooling is required in the west than in the east indicating a strong west east temperature anomaly gradient

the last climatic cycle at kopais central greece thick lacustrine sequences from southern europe provide an opportunity to derive continuous records where the chronostratigraphical position of pre holocene stages can be determined with increased confidence here high resolution sediment and pollen analytical results from a 60 m core recovered from the kopais basin central greece spanning the interval from the last interglacial to the early holocene are presented the record shows distinct shifts between open vegetation periods of increased erosion with sediment inwashing and forest periods associated with calcite precipitation in the lake the sequence of major events of the last climatic cycle contained at kopais bears strong similarities to other records in greece but also reveals the presence of high frequency oscillations with higher amplitudes than previously seen at other sites

high resolution simulations of the last glacial maximum climate over europe a solution to discrepancies with continental palaeoclimatic reconstructions the analyses of low resolution models simulations of the last glacial maximum lgm 21 kyr bp climate have revealed a large discrepancy between all the models and pollen based palaeoclimatic reconstructions in general the models are too warm relative to the observations especially in winter where the difference is of the order of 10 c over western europe one of the causes of this discrepancy may be related to the low spatial resolution of these models to assess the impact of using high resolution models on simulated climate sensitivity we use three approaches to obtain high resolution climate simulations over europe first an atmospheric general circulation model agcm with a stretched grid over europe second a homogeneous t106 agcm high resolution everywhere on the globe and last a limited area model lam nested in a low resolution agcm with all three methods we have performed simulations of the european climate for present and lgm conditions according to the experimental design recommended by the palaeoclimate modeling intercomparison project pmip model results have been compared with updated pollen based palaeoclimatic indicators for temperature and precipitation that were initially developed in pmip for each model a low resolution global run was also performed as expected the low resolution simulations underestimate the large cooling indicated by pollen data especially in winter despite revised slightly warmer reconstructions of the temperatures of the coldest month and show results in the range of those obtained in pmip with similar models the two high resolution agcms do not improve the temperature field and cannot account for the discrepancy between model results and data especially in winter however they are able to reproduce trends in precipitation more closely than their low resolution counterparts do but the simulated climates are still not as arid as depicted by the data conversely the lam temperature results compare well with climate reconstructions in winter but the simulated hydrological cycle is not consistent with the data finally these results are discussed in regard of other possible causes for discrepancies between models and palaeoclimatic reconstructions for the lgm european climate

evolution of the danube deep sea fan since the last glacial maximum new insights into black sea water level fluctuations abstract the danube deep sea fan nw black sea is one of the most developed deep sea sediment depositional systems in europe although the morphology and the architecture have been widely described in the past years little is known about the stratigraphy of this depositional system for the late quaternary this results from the lack of significant stratigraphic markers the scarcity of radiocarbon ages and the difficulty in constraining reservoir ages recent robust quantification of reservoir ages has allowed the construction of a new stratigraphic framework for the black sea from the end of the last glacial period to the holocene thus giving the opportunity to correlate sedimentological and geochemical features previously described on the nw black sea margin with climatic events identified in the northern hemisphere based on this approach we propose an improved chrono lithostratigraphic framework for the danube deep sea fan channel levees since the last glacial maximum we show that the danube deep sea fan was active during the last glacial maximum until the younger dryas early holocene transition ca 11 700 cal a bp when the turbidite activity abruptly terminated in the whole system throughout this period the danube river was the main source of the deep depositional system except between ca 17 200 cal a bp and 15 700 300 cal a bp at that time the deposition of red turbidites in the deep basin concomitant with the deposition of the so called red layers onto the continental shelf and the upper slope emphasises the direct impact of the increased meltwater runoff of the dnieper river as far as the danube deep sea fan some significant changes in the location of the depocentre of the danube deep sea fan occurred through time the main change in depocentre location occurred at ca 28 000 cal a bp with the northward avulsion leading to the formation of the middle channel although the middle and northern channel became the preferential turbidite depocentres after this event the deposition of turbidites has persisted in the southern channel levee until 14 700 cal a bp indicating that the southern channel was definitely not abandoned after the upstream northward avulsion unsurprisingly water level fluctuations and river sediment flux acted as the main forcings on the evolution of the danube deep sea fan based on these results and on the morphology of the danube canyon we propose that i lowstand conditions 110 m prevailed during the last glacial maximum and possibly between 15 700 300 cal a bp and 14 700 cal a bp ii water level ranged from 110 and 70 m between 14 700 and 11 700 cal a bp and iii water level ranged from 70 and 30 m from 11 700 cal a bp and until the reconnection of the black sea lake with the global ocean at ca 9000 cal a bp

cover effect in bedrock abrasion a new derivation and its implications for the modeling of bedrock channel morphology the sediment load of a bedrock river plays an important role in the fluvial incision process by providing tools for abrasion the tools effect and by covering and thereby protecting the bed the cover effect we derive a new formulation for the cover effect in which the fraction of exposed bed area falls exponentially with increasing sediment flux or decreasing transport capacity and explore its consequences for the model of bedrock abrasion by saltating bed load erosion rates predicted by the model are higher than those predicted by earlier models in a closed system the maximum erosion rate is predicted to occur when sediment supply is equal to transport capacity for a flat bed by optimizing the channel geometry to minimize the potential energy of the stream and using representative values for both discharge and grain size we derive equations for the geometry of a bedrock river and explore how predictions for width slope and bed cover vary as functions of drainage area rock uplift rate and rock strength the equations predict a dependence of channel width on drainage area similar to the relations using a simple shear stress incision law the slope area relationship is predicted to be concave up in a log log regime with a curvature dependent on uplift rate however this curvature does not deviate sufficiently from a straight line to allow discrimination between models using empirical data dependence of channel width and slope on rock uplift rate can be separated into two domains for low uplift rates channel geometry is largely insensitive to uplift rate due to a threshold effect at high uplift rates there is a power law dependence bed cover is predicted to increase progressively downstream and to increase with increasing uplift rate in our model the width to depth ratio is a function of both tectonic and climatic forcing this indicates that the scaling between channel width and bed slope is neither a unique indicator of tectonic forcing at steady state nor a signature of transience or steady state we conclude that sediment effects need to be taken into account when modeling bedrock channel morphology

investigating the penultimate and last glacial cycles of the suttő loess section hungary using luminescence dating high resolution grain size and magnetic susceptibility data the loess paleosol record at sutt provides an excellent high resolution archive of climate and environmental changes loess deposits with a thickness of 20 m cover the travertine at sutt in the northern part of hungary next to the right bank of the danube river the loess sequence is intercalated with two greyish stratified horizons three brownish steppe like soils and a pedocomplex including a reddish brown paleosol covered by a chernozem like paleosol detailed infrared stimulated luminescence irsl dating was carried out revealing more or less continuous sedimentation from marine isotope stage mis 6 mis 2 sedimentological and paleomagnetic investigations have been performed to provide a high resolution study of the sutt loess paleosol sequence in order to reconstruct the paleoclimate and environmental changes during the penultimate and last glacial cycles grain size and magnetic susceptibility ms records of the sutt profile basically show similar patterns to those of other european loess sections however small differences are traced at sutt including more intensive deposition of coarser grained materials during mis 6 4 the loess record at sutt has a transitional position within the european loess belt as its sediment was deposited under an intermediate climate between the loess successions from the southern carpathian basin which accumulated under drier climate and the loess sequences from western europe which developed under wetter climate during the middle and late pleniglacial

responses of terrestrial ecosystems to dansgaard oeshger cycles and heinrich events a 28 000 year record of environmental changes from se hungary abstract according to the findings of a complex sedimentological geochemical malacological and pollen study implemented on a core sequence of an alkaline lake feher lake interstadials in the se great hungarian plain were characterized by increased boreal woodland cover during marine isotope stage 2 mis 2 29 700 14 500 cal bp these interstadials were dated to 26 420 27 970 23 185 24 880 and 18 810 20 770 cal bp and correlate well with the dansgaard oeschger do interstadials 2 and 3 and the post lgm warm interval seen in the greenland ice core oxygen isotope records intervening cold phases on the other hand were found between 24 880 26 420 and 20 770 23 185 cal bp correlating with heinrich event 2 and the lgm these data overall confirm that millennial scale climate variability during marine isotope stage 2 had profound effect on the terrestrial ecosystems in the continental interior of se europe leading to periodic boreal woodland expansions and contractions and wildfires

late pleistocene loess palaeosol sequences in the vojvodina region north serbia late pleistocene loess palaeosol sequences are widespread in the vojvodina region with thicknesses reaching a maximum of about 20 m our investigations include more than 40 of these loess sections geochronology of the last glacial loess palaeosol sequences based on lumines cence dating and amino acid racemisation provides correlations between upper pleistocene loess palaeosol sediments in vojvodina and comparable deposits at other european localities sedimentary logs of magnetic susceptibility grain size measurements and carbonate content combined with malacological evidence indicate two main relatively cold and arid phases during the last glacial period related to intensive accumulation of loess units l1l1 and l1l2 as well as many brief episodes of dry and windy climatic conditions suggesting a possible relationship with cold events recorded in the north atlantic region generally late pleistocene climate in the region was dry and relatively warm compared with glacial period sites in central europe and was characterised by sharp differences between glacial and interglacial modes new data and interpretations presented in this study emphasise the significance of loess palaeosol sequences in vojvodina for the reconstruction of the temporal and spatial evolution of late pleistocene palaeoclimate in this part of europe copyright 2007 john wiley sons ltd

synchronisation of palaeoenvironmental records over the last 60 000 years and an extended intimate event stratigraphy to 48 000 b2k the intimate protocol for the correlation of marine ice core and terrestrial records is here updated reflecting recent developments in palaeoclimate research originally focussed on last glacial to interglacial transition lgit 22 000 11 500 years b p the intimate group has now extended its study period back to 60 000 years as a first step the intimate event stratigraphy has now been extended to include 8000 48 000 b2k based on a combined ngrip and grip isotope profile against a gicc05 chronology and key tephra horizons from iceland and continental european volcanic sources in this lead article of this intimate special issue we introduce some of the recent achievements of the intimate community and discuss the challenges associated with extending the intimate approach back in time focussing in particular on the chronological problems inherent in comparing different proxy records the intimate approach has thus far been limited predominantly to the north atlantic and australasian regions and we also discuss the potential to extend the intimate protocol beyond these regions

a stratigraphic framework for abrupt climatic changes during the last glacial period based on three synchronized greenland ice core records refining and extending the intimate event stratigraphy due to their outstanding resolution and well constrained chronologies greenland ice core records provide a master record of past climatic changes throughout the last interglacial glacial cycle in the north atlantic region as part of the intimate integration of ice core marine and terrestrial records project protocols have been proposed to ensure consistent and robust correlation between different records of past climate a key element of these protocols has been the formal definition and ordinal numbering of the sequence of greenland stadials gs and greenland interstadials gi within the most recent glacial period the gs and gi periods are the greenland expressions of the characteristic dansgaard oeschger events that represent cold and warm phases of the north atlantic region respectively we present here a more detailed and extended gs gi template for the whole of the last glacial period it is based on a synchronization of the ngrip grip and gisp2 ice core records that allows the parallel analysis of all three records on a common time scale the boundaries of the gs and gi periods are defined based on a combination of stable oxygen isotope ratios of the ice 18o reflecting mainly local temperature and calcium ion concentrations reflecting mainly atmospheric dust loading measured in the ice the data not only resolve the well known sequence of dansgaard oeschger events that were first defined and numbered in the ice core records more than two decades ago but also better resolve a number of short lived climatic oscillations some defined here for the first time using this revised scheme we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the last glacial period that are represented in the greenland ice records the final product constitutes an extended and better resolved greenland stratotype sequence against which other proxy records can be compared and correlated it also provides a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations

high resolution x ray fluorescence core scanning analysis of les echets france sedimentary sequence new insights from chemical proxies the les echets sediment sequence has recently been the subject of a high resolution multi proxy study which revealed shifts in lake productivity linked to greenland stadials and interstadials over the last 40 ka wohlfarth et al 2008 rapid ecosystem response to abrupt climate changes during the last glacial period in western europe 40 16 ka geology 36 407 410 here we present new elemental data for this sequence as acquired using an x ray fluorescence core scanning system which provides in situ high resolution continuous multi element analyses it was found that the strength of associations between the studied elements ti rb k zr si ca sr mn and fe varied over time with changes in lake status which are ultimately driven by changes in climate increases in fine grained detrital input as indicated by ti rb k and zr rb overlap with independently established periods of lower lake productivity and are interpreted to represent more arid conditions several of these arid periods are coincident with low diatom concentrations and the timing of heinrich events h4 h3 and h2 the duration of the environmental impacts linked to the h events varied by proxy with elemental data ti and zr rb estimating shorter events than the diatom data periods of lower detrital input and coarser grain sizes agreed in time with periods of higher lake productivity the elemental data provide new insights into hydrological changes and related sediment processes within the catchment and highlight the need for multi element and multi proxy approaches when reconstructing climate change using lacustrine sediment sequences copyright 2011 john wiley sons ltd

dust deposition and climate in the carpathian basin over an independently dated last glacial interglacial cycle dust deposition and climate in the carpathian basin over an independently dated last glacial interglacial cycle

abrupt drainage cycles of the fennoscandian ice sheet continental ice sheets are a key component of the earth s climate system but their internal dynamics need to be further studied since the last deglaciation the northern eurasian fennoscandian ice sheet fis has been connected to the black sea bs watershed making this basin a suitable location to investigate former ice sheet dynamics here from a core retrieved in the bs we combine the use of neodymium isotopes high resolution elemental analysis and biomarkers to trace changes in sediment provenance and river runoff we reveal cyclic releases of meltwater originating from lake disna a proglacial lake linked to the fis during heinrich stadial 1 regional interactions within the climate lake fis system linked to changes in the availability of subglacial water led to abrupt drainage cycles of the fis into the bs watershed this phenomenon raised the bs water level by 100 m until the sill of the bosphorus strait was reached flooding the vast northwestern bs shelf and deeply affecting the hydrology and circulation of the bs and probably of the marmara and aegean seas

biotic responses to rapid climatic changes abstract qualitative and quantitative changes in fossil flora and fauna have been used in many studies to infer climatic change here we ask a different question how do flora and fauna respond to climatic changes such as rapid warming or cooling as an independent proxy for paleotemperature we take the ratio of oxygen isotopes in biogenically precipitated lake marl and in ostracod shells this introductory paper describes the project design and the five sites on an altitudinal transect from 600 m to about 2300 m asl in the western swiss alps as cases of climatic cooling and warming we use the beginning and end of the younger dryas as major changes and the gerzensee and preboreal oscillations as minor changes at the two sites of gerzensee and leysin these changes are recorded in stable isotope ratios and there the time scales can be derived by correlations to the grip ice core schwander et al 2000 von grafenstein et al 2000 biotic responses to climate changes are treated in individual papers using pollen wick 2000 plant macrofossils tobolski and ammann 2000 and remains of chironomids brooks 2000 beetles and other insects lemdahl 2000 and chydorid cladocera hofmann 2000 they are followed by a synthesis focusing on quantification of biotic responses ammann et al 2000 in addition a reconstruction of summer temperatures for the allerod and the younger dryas at gerzensee is provided by lotter et al 2000

eurasian permafrost instability constrained by reduced sea ice cover in order to specify potentially causal relationships between climate permafrost extent and sea ice cover we apply a twofold research strategy 1 we cover a large range of climate conditions varying from full glacial to the relatively warm climate projected for the end of the 21st century 2 we combine new proxy based reconstructions of eurasian permafrost extent during the lgm and climate model simulations we nd that that there is a linear relationship between the winter sea ice extent in the north atlantic and arctic oceans and the latitude of the southernmost permafrost limit in eurasia during the lgm extensive sea ice cover caused a zonal permafrost distribution with the southern margin extending w e and reaching 47 n contrasting with the present day nw se trending margin 66 52 n we infer that under global warming scenarios projected by climate models for the 21st century the arctic sea ice cover decline will cause widespread instability of mainly discontinuous permafrost in eurasian lowlands

new chronological constraints for middle palaeolithic mis 6 5 3 cave sequences in eastern transylvania romania abstract the middle to upper palaeolithic transition is one of the crucial periods of change in the prehistory of europe due to the full emergence continent wide of modern human lithic technologies and detrimental of neanderthal survival knowledge about the transition is growing however the evidence for cultural and technological developments for the middle palaeolithic in the carpathian lower danube basin is still rather sparse here we discuss latest findings arising from a chronological investigation of middle palaeolithic assemblages within the varghis karst eastern transylvania romania combining our first chronological results with information from previous excavations we can distinguish two main stages of habitation albeit middle palaeolithic lithics and faunal remains appear scattered throughout the investigated profile within the abri 122 rock shelter in order to augment the typological cultural considerations we applied direct radiocarbon dating on bones and charcoal from within the occupation layers radiocarbon dating of bones suggests that the middle palaeolithic sequence is older than the upper dating limit of the method whereas direct luminescence ages on the lowermost productive horizon and immediately above it indicate surprisingly old ages of ca 106 141 ka osl optically stimulated or 99 174 ka irsl infrared stimulated multiple protocol dating of charcoal found within the two habitation layers produced ages 38 14 c ka bp also suggesting that the lowermost lithic rich horizon pertains to the middle palaeolithic industries overall the recovered lithics currently forming one of the most significant collections for romania are fully consistent with two main habitation phases connected to middle palaeolithic cultural affinities the occurrence of a volcanic ash layer within ursului cave and originating from the ciomadul volcanic complex carpathians is first reported here recently dated to 43 50 ka it might represent an important marker horizon providing that it is identified within other palaeolithic cave assemblages