holocene ostracod and foraminiferal assemblages of the romanian black sea shelf abstract qualitative and quantitative study of the ostracod and foraminiferal assemblages were performed on two cores around 0 30 m depth bsf in thickness collected from the romanian black sea shelf the lithology of the studied cores is characterised by grey and black muds topped by a centimetre thick fluffy mud layer one of the cores mn 103 09 is placed on the romanian inner shelf at water depth of 17 80 m the sediments of this core contain very few and small bivalve fragments and no gastropods in this core the ostracod and foraminiferal assemblages are influenced by a quite high energy environment due to the sulina arm of the danube delta this feature is mirrored in the poor preservation and low abundance of the species as well as the mixed caspian and mediterranean character of the ostracod assemblages the other studied core mn 103 04 is situated on the romanian outer shelf at a water depth of 78 m its deposits commonly contain gastropods and bivalves as well as microfauna displaying a low diversity and a very high abundance the character of the ostracod assemblages is a mediterranean one overall the identified microfaunas of the two investigated cores reflect the environmental conditions of modern and or latest holocene sea floor assemblages and their relationships to salinity sediment input and water depth even the depositional time of the 30 cm cored interval in the two studied cores is quite different i e possibly several hundreds of years up to 1000 years on the inner shelf and several thousands from 3000 bp to the present in the outer shelf the results are indicative for modern black sea conditions a stable marine environment with a salinity around 17 18 comparable with the present one could be assumed for the whole cored interval of the romanian shelf besides the age structure i e the ratio between adults and juvenile taxa of ostracod population in the outer shelf indicates a moderate to high energy autochthonous thanatocoenosis with some post mortem disturbance by currents by contrast the ratio between adults and juvenile ostracod taxa in the inner shelf mirrored a taphocoenosis with post mortem disturbance sorting and transport this assemblage dominated mainly by disarticulated valves of juveniles does not represent the environment in which the ostracods lived

history and influence of the danube delta lobes on the evolution of the ancient harbour of orgame dobrogea romania on the coast of northern dobrogea south of the danube delta the greek settlement of orgame was founded in the mid 7th c bc probably by milesian colonists the ancient city was located on the cape dolojman which today overlooks a large lagoon complex we undertook a chronostratigraphic study to i understand coastal changes around cape dolojman since ca 5000 years bp in connection with the construction of the danube delta lobes and ii identify potential sediment impacts related to human occupation of the site three cores were extracted from the lagoon area sedimentological and biological analyses were undertaken to reconstruct the evolution of the coastal palaeoenvironments the results show a closure of the marine bay around 3500 cal bp and its transformation into a lagoon environment the first major environmental change was due to the construction of the lobe st george i and the formation of the barrier lupilor around 2000 cal bp the formation of an intra lagoonal lobe the dunavatz led to the gradual transformation of the lagoon into a fluvial dominated system paradoxically lagoon waters today still wash the ancient greek harbour environment which has not been totally infilled by alluvial sediments to understand this paradox in a context of coastal progradation we compared and contrasted the geomorphological data with the nearby city of istros histria which was already landlocked at this time the location of these two greek colonies relative to the coastal sediment cell and barriers partly explains their contrasting palaeoenvironmental evolution until 2650 cal bp the increase in charcoal and organic matter in sedimentary archives is interpreted as an anthropogenic signal for a more extensive use of the vegetation cover following the foundation of the city of orgame e g for domestic use and funeral rites

meltwater floods into the black and caspian seas during heinrich stadial 1 abstract deglaciation of the eurasian ice sheet dispensed vast amounts of meltwater laden with red brown clay into black and caspian sea s freshwater lakes between 16 350 and 15 400 calendar years bp the arriving sediment had a mineral composition and strontium neodymium isotope signatures 87sr 86sr and end consistent with the crystalline bedrock that lay beneath the ice sheet as opposed to sources from landscapes crossed by the rivers that carried meltwater to the lakes the magnitude and rapidity of the shifts of 87sr 86sr and 18o in shells of ostracods and mollusks an eight fold increase in sediment accumulation rate and a plunge of 1250 14c years in the radiocarbon reservoir age indicate a volume of meltwater sufficient to have replaced most or all of the pre existing lake water if the release of 25 000 km3 of water from the caspian into the black sea s new euxine lake was abrupt by judging the magnitude of erosion in the floor of the manych strait spillway this event qualifies as a megaflood deeply scoured furrows channel floor bars and swaths of mounds 5 20 km in length and 5 20 m in height are reminiscent of scabland landscapes the meltwater is coincident with heinrich stadial 1 when the alpine and eurasian ice sheets re advanced and temperatures of the black sea s lake surface remained cold sand grains within the red brown clay indicate they were transported by lake surface ice

numerical modeling of the morphodynamic response of a low lying barrier island beach and foredune system inundated during hurricane ike using xbeach and cshore abstract follet s island fi is a sediment starved barrier island located on the upper texas coast a stretch of coastline along the gulf of mexico that experiences on average four hurricanes and four tropical storms per decade during hurricane ike water levels and wave heights at fi exceeded the 100 year and 40 year return values respectively leading to significant overtopping and morphology changes of this low lying barrier island the physical processes governing the real time morphodynamic response of the beach and dune system during 96 h of hurricane impact were modeled using xbeach 2d and cshore 1d hydrodynamic boundary conditions were obtained from adcirc swan model runs validated with measured buoy and wave gauge data while lidar surveys provided pre and post storm measured topography xbeach displayed a decent model skill of 0 34 and provided numerical outputs of the entire 2d domain such as topography suspended sediment load and bed load which was very useful in visualizing erosion and deposition patterns cshore also displayed a decent model skill of 0 33 and was able to accurately predict the post storm beach slope and shoreline but was less effective at simulating the foredune morphology modeling results show that the complete morphodynamic response of fi to hurricane ike was governed by a sequence of impact regimes including swash collision overwash inundation and storm surge ebb

holocene sea level and climate change in the black sea multiple marine incursions related to freshwater discharge events abstract repeated marine invasions of the black sea during the holocene have been inferred by many eastern scientists as resulting from episodes of marine inflow from the mediterranean beneath a brackish outflow from the black sea we support this scenario but a fundamental question remains what caused the repeated marine invasions we offer an hypothesis for the repeated marine invasions of the black sea based on 1 the overall similarity of sea level curves from both tectonically quiescent and active margins of the black sea and their similarity to a sequence stratigraphic record from the us mid atlantic coast the similarity of the records from two widely separated regions suggests their common response to documented holocene climate ocean atmosphere reorganizations coolings 2 the fact that in the modern black sea freshwater runoff from surrounding rivers dominates over evaporation so that excess runoff might have temporarily raised black sea level although the black sea would have remained brackish following the initial invasion of the black sea by marine mediterranean waters through the marmara sea in the early holocene repeated marine incursions were modulated or perhaps even caused by freshwater discharge to the black sea climatic amelioration warming following each documented ocean atmosphere reorganization during the holocene likely shifted precipitation patterns in the surrounding region and caused mountain glaciers to retreat increasing freshwater runoff above modern values and temporarily contributing to an increase of black sea level freshwater to brackish water discharges into the black sea initially slowed marine inflow but upon mixing of runoff with more marine waters beneath them and their eventual exit through the bosphorus marine inflow increased again accounting for the repeated marine invasions the magnitude of the hydrologic and sea level fluctuations became increasingly attenuated through the holocene as reflected by black sea level curves

sr and nd isotope composition of late pleistocene sapropels and nonsapropelic sediments from the eastern mediterranean sea implications for detrital influx and climatic conditions in the source areas isotopic ratios of sr and nd from lithogenic components of three isochronous core sections recovered from an east west transect in the eastern mediterranean sea ems have been analyzed the data are used for a quantitative estimate of the temporal and spatial variation of detrital flux to the ems assuming saharan dust and aegean nile particulate matter as dominant end members it was established that the carbonate free saharan dust flux during deposition of the nonsapropel layers of marine oxygen isotope stage 5 4 mis 5 4 was similar to the present flux during the deposition of sapropels s5 and s6 however the saharan dust input was drastically reduced and was not balanced by a change in the riverine influx at this time denser vegetation cover during more humid conditions may have reduced physical erosion and sediment removal in the source area during marine oxygen isotope stage 6 2 mis 6 2 a pronounced increase of saharan dust and detrital influx from the aegean region is evident and implies more arid conditions in the southern and northern catchment areas during this period intersite variations are interpreted in terms of their geographic location relative to the seaways connecting the aegean sea and ems the width of the straits and hence the amount of sediment entering the eastern basins may have been affected by a low sea level that impeded interbasin sediment dispersal

abrupt changes of temperature and water chemistry in the late pleistocene and early holocene black sea new mg ca sr ca and published stable oxygen isotope and 87sr 86sr data obtained on ostracods from gravity cores located on the northwestern black sea slope were used to infer changes in the black sea hydrology and water chemistry for the period between 30 to 8 ka b p calibrated radiocarbon years the period prior to 16 5 ka b p was characterized by stable conditions in all records until a distinct drop in 18o values combined with a sharp increase in 87sr 86sr occurred between 16 5 and 14 8 ka b p this event is attributed to an increased runoff from the northern drainage area of the black sea between heinrich event 1 and the onset of the bolling warm period while the mg ca and sr ca records remained rather unaffected by this inflow they show an abrupt rise with the onset of the bolling allerod warm period this rise was caused by calcite precipitation in the surface water which led to a sudden increase of the sr ca and mg ca ratios of the black sea water the stable oxygen isotopes also start to increase around 15 ka b p although in a more gradual manner due to isotopically enriched meteoric precipitation while sr ca remains constant during the following interval of the younger dryas cold period a decrease in the mg ca ratio implies that the intermediate water masses of the black sea temporarily cooled by 1 2 c during the younger dryas the 87sr 86sr values drop after the cessation of the water inflow at 15 ka b p to a lower level until the younger dryas where they reach values similar to those observed during the last glacial maximum this might point to a potential outflow to the mediterranean sea via the sea of marmara during this period the inflow of mediterranean water started around 9 3 ka b p which is clearly detectable in the abruptly increasing mg ca sr ca and 87sr 86sr values the accompanying increase in the 18o record is less pronounced and would fit to an inflow lasting 100 a

diagenetic barium cycling in black sea sediments a case study for anoxic marine environments high resolution sedimentary records of major and minor elements al ba ca sr ti total organic carbon toc and profiles of pore water constituents view the mathml sourceso42 ch4 ca2 ba2 mg2 alkalinity were obtained for two gravity cores core 755 501 m water depth and core 214 1686 m water depth from the northwestern black sea the records were examined in order to gain insight into the cycling of ba in anoxic marine sediments characterized by a shallow sulfate methane transition smt as well as the applicability of barite as a primary productivity proxy in such a setting the ba records are strongly overprinted by diagenetic barite baso4 precipitation and remobilization authigenic ba enrichments were found at both sites at and slightly above the current smt transport reaction modeling was applied to simulate the migration of the smt during the changing geochemical conditions after the holocene seawater intrusion into the black sea based on this sediment intervals affected by diagenetic ba redistribution were identified results reveal that the intense overprint of ba and baxs ba excess above detrital average strongly limits its correlation to primary productivity these findings have implications for other modern and ancient anoxic basins such as sections covering the oceanic anoxic events which ba is frequently used as a primary productivity indicator our study also demonstrates the limitations concerning the use of baxs as a tracer for downward migrations of the smt due to high sedimentation rates at the investigated sites diagenetic barite fronts are buried below the smt within a relatively short period thus relict barite fronts would only be preserved for a few thousands of years if at all

further evidence of abrupt holocene drowning of the black sea shelf a 1999 survey of the black sea continental shelf off the north central turkish seaport of sinop using a side scan sonar small remotely operated vehicles and a series of dredge lowerings located inspected and sampled an exposed high energy paleoshoreline at a depth of 155 m radiocarbon dating of mollusk shells collected from this ancient beach revealed that the marine flooding of the black sea took place between 7460 and 6820 yr b p all ages are reported in radiocarbon years not calendar years without correction for reservoir age or dendro calibration changing it from a lacustrine to marine environment this relic surface remained in contact with the bottom waters of the black sea for a long period of time before being draped by a thin layer of sapropel mud wood samples recovered from this same location were very well preserved and yielded dates as old as 3580 yr b p q 2000 elsevier science b v all rights reserved

sediment transport on dissipative intermediate and reflective beaches abstract in this paper we review and synthesize field measurements of suspended sediment transport on the shoreface of dissipative intermediate and reflective beach states the morphodynamic beach state continuum was originally established in the 1970s but at the time only hydrodynamic processes and morphologies in these various states were described since the early 1980s when sensors capable of resolving suspended sediment concentration at intra wave time scale became available many studies have examined suspended sediment transport by waves and currents on the shoreface the synthesis of this work shows that the two end states in the morphodynamic continuum which are the dissipative and reflective states exhibit relatively small rates of cross shore sediment transport and weak gradients in that transport which both ensure that the nearshore morphology is relatively stable the intervening intermediate beach states typically exhibit prominent bar topographies and in these states strong morphodynamic feedbacks between hydrodynamic processes and morphology create locally large transport rates and sharp transport gradients which is the reason for the dynamic nature of these beach states transport processes driving sediment onshore and offshore within beach states are discussed as well as the transport processes responsible for state transitions

formation pathways of light hydrocarbons in deep sediments of the danube deep sea fan western black sea abstract we report on the geochemistry of light hydrocarbons and pore water in sediments down to 147 m below seafloor mbsf at two sites within the gas hydrate stability field of the danube deep sea fan black sea sediments were drilled with marum mebo200 and comprise the transition from limnic to the recent marine stage stable c n ratios mean 5 1 and 5 6 and 13c corg values mean 25 8 v pdb suggest relatively uniform bulk organic matter compositions in contrast pore water 2h and 18o values varied considerably from approx 120 to 30 v smow and from 15 to 3 v smow respectively these data pairs plot close to the global meteoric water line and indicate paleo temperature variations depletions of pore water in 2h and 18o below 40 mbsf indicate low temperatures and likely reflect conditions during the last glacial period s methane was much more abundant than the only other hydrocarbons found in notable concentrations ethane and propane c1 c2 c3 20 000 relatively constant 13c ch4 70 v pdb and 13c c2h6 52 v pdb values with depth indicate that methane and ethane are predominantly of microbial origin and that their formation was not limited by carbon availability in contrast 2h ch4 values varied in a large range approx 310 to 240 v smow with depth and positively correlated with trends observed for 2h h2o isotope separations 13c ch4 co2 2h ch4 h2o substantiate that microbial carbonate reduction cr is the prevalent methanogenic pathway throughout the sediments irrespective of their geochemical history remarkably in 13c ch4 2h ch4 diagrams widely used samples characterized by 2h ch4 values more negative than approx 250 plot out of the field assigned for pure cr we conclude that assignments of microbial methanogenic pathways based on classical interpretations of 13c ch4 2h ch4 pairs can lead to misinterpretations as severe 2h depletions of methane formed through microbial cr can result from 2h depletions of the pore water generated during low temperature climatic periods

late glacial to holocene climate and sedimentation history in the nw black sea abstract gravity cores from the continental slope in the northwestern black sea were studied using high resolution stable isotope grain size and xrf scanning data the measurements provide a 30 000 years ams 14c dated record of variations in the hydrological regime of the black sea and give insight into changing paleoenvironments in the surrounding areas stable climatic conditions during the last glacial maximum were followed by a series of meltwater pulses most likely originating from the scandinavian ice sheet between 18 000 and 15 500 yr bp 1 this meltwater input rose the level of the caspian sea to a point that caspian water could spill into the black sea via the manych depression north of the caucasian mountains high frequency oscillations in the xrf data during this period suggest a probable link to the arctic climate regime later during the bolling allerod and the early holocene prevailing high temperatures led to authigenic calcite precipitation through increased phytoplankton activity interrupted by the younger dryas and the 8200 yr bp cold event with dominant clastic sedimentation

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

late glacial to holocene paleoenvironmental evolution of the black sea reconstructed with stable oxygen isotope records obtained on ostracod shells high resolution stable oxygen isotope d 18 o on ostracod shells xrf scanning and bulk grain size data obtained on a transect of 6 gravity cores from the continental slope in the northwestern black sea give new insight into the hydrological evolution of the black sea since the last glacial maximum lgm stable climatic conditions during the lgm were followed by a series of meltwater pulses between 18 and 15 5 kyr bp that resulted in temporary isotopic depletion of the black sea waters subsequently steadily increasing d 18 o values in all cores are mainly caused by isotopically enriched precipitation at the onset of the allerod bolling warm period a comparison of the major trends in d 18 o at different water depths suggests evaporation driven deep water formation since 14 5 kyr bp while the two shallowest cores from 168 and 465 m water depth were under the influence of increased warming in the upper water column since 14 5 and 12 5 kyr bp respectively the core from 168 m depth seems to be additionally influenced by freshwater input of the danube this core provides a high resolution record from the younger dryas allerod boundary and suggests that a nao like climate mode was governing the interannual variability in the run off of the danube which implies that this climate mode has been a persistent climatic feature over central europe the inflow of saline mediterranean waters occurs between 9 and 8 kyr bp where a merging of all d 18 o records signals an initial homogenisation of the water column

chemical cycles in pliocene sapropel bearing and sapropel barren eastern mediterranean sediments abstract high resolution 3 4 cm investigations of major and minor elements were carried out on sediment cores from odp leg 160 sites 964 ionian basin 969 mediterranean ridge 967 and 966 northern slope and top of eratosthenes seamount south of cyprus at site 967 element al ratios display pronounced cyclic records that are related to astronomically forced climatic variations sediments from the top of eratosthenes seamount site 966 show a similar pattern to those from site 967 but they are more disturbed by bioturbation and also strongly influenced by long term variations in sediment dispersal sediments from site 969 display similar trends to those from site 964 i e they are characterized by higher mg al slightly higher k al and lower ti al ratios during sapropel formation higher ti al ratios at site 969 compared with sediments from site 964 may be explained by a westward transport of material from a source in the east where ti al ratios are highest sites 966 and 967 elevated mg al ratios at site 969 during sapropel intervals are due to river derived material transported through the kithira strait between peloponnesus and crete from the northwestern aegean sea which originates from ultramafic rocks a change in intermediate water currents current reversal during sapropel formation may explain the enhanced supply of mg rich and the relatively diminished supply of ti rich material we propose that during deposition of the reddish intervals at site 969 a change in circulation did not occur because a drastic decrease in ti al ratios is not evident in these sediments ba peaks indicative of former sapropels are not present ba enrichments in the same sapropel barren intervals at site 967 northern slope of eratosthenes seamount suggest that during such intervals the burn down process was more effective than during the sapropel bearing intervals mn contents in all investigated pliocene sediments correlate with the carbonate contents higher mn contents of the sapropel barren sediments suggest that during time intervals of sapropel formation either mn accumulation at the margins of the permanently oxic upper water column or mn export into the western mediterranean might have occured the latter could only be explained by sub or anoxic conditions in large parts of the water column

a post younger dryas black sea regression identified from sequence stratigraphy correlated to core analysis and dating the north western black sea shelf is the widest continental shelf of the black sea where the danube delta prodelta system includes important records on the black sea water level fluctuations this study integrates newly acquired high resolution single channel seismic reflection profiles and calypso piston cores recovered along a transect extending from the danube delta deep into its deep sea fan the correlated results provide information on the late quaternary architecture of the danube black sea shelf and on the role of global glacio eustatic fluctuations on the building of the danube delta prodelta the sedimentary sequences in the black sea are strongly affected by water level changes for the whole duration of late glacial holocene period the level of the black sea was controlled by the regional climate modifications rather than the global eustatic changes the seismic sequences recognized on a very high resolution seismic profile were dated by two calypso piston cores based on the obtained data during the last glacial maximum the black sea was a land locked lake with the level below 120 m in the course of the deglaciation the lake level rose up to 40 m which is confirmed by occurrence of the prodelta lobes formed after the rise in water level originated from the melt water following the younger dryas 11 000 8500 c 14 bp there occurred a new level lowering to the level of 100 m identified by the forced regression deposits recorded on the romanian shelf this last lowstand previously recognized by a pronounced shoreline with a characteristic beach profile and a belt of coastal dunes is also indicated by the prodelta at 100 m depth all these coastal features as well as the incised anastomosed channel system remained preserved on the shelf resulting from a rapid ultimate transgression starting immediately after 8500 c 14 bp c 2010 elsevier ltd and inqua all rights reserved

two dimensional time dependent hurricane overwash and erosion modeling at santa rosa island abstract a 2dh numerical model which is capable of computing nearshore circulation and morphodynamics including dune erosion breaching and overwash is used to simulate overwash caused by hurricane ivan 2004 on a barrier island the model is forced using parametric wave and surge time series based on field data and large scale numerical model results the model predicted beach face and dune erosion reasonably well as well as the development of washover fans furthermore the model demonstrated considerable quantitative skill upwards of 66 of variance explained maximum bias 0 21 m in hindcasting the post storm shape and elevation of the subaerial barrier island when a sheet flow sediment transport limiter was applied the prediction skill ranged between 0 66 and 0 77 in a series of sensitivity tests in which several hydraulic forcing parameters were varied the sensitivity studies showed that the variations in the incident wave height and wave period affected the entire simulated island morphology while variations in the surge level gradient between the ocean and back barrier bay affected the amount of deposition on the back barrier and in the back barrier bay the model sensitivity to the sheet flow sediment transport limiter which served as a proxy for unknown factors controlling the resistance to erosion was significantly greater than the sensitivity to the hydraulic forcing parameters if no limiter was applied the simulated morphological response of the barrier island was an order of magnitude greater than the measured morphological response

hydrothermal metallogenesis at the wilkes fracture zone east pacific rise intersection abstract two hundred and eight sediment samples from 25 gravity cores obtained in and around the wilkes fracture zone on the east pacific rise have been analysed in bulk for mn fe ni co pb zn cu ba al si and caco3 downcore metal variations suggest that apart from the present hydrothermal event which is more intense on the crest of the rise and in the western part of the fracture zone in the past two hydrothermal events occurred the end of the first event occurred about 121 000 yrs b p and that of the second event at about 85 000 yrs b p both events are recognized throughout the study area a third hydrothermal event is traced only on the crest of the rise and occurred at about 16 000 yrs b p generally in the last 90 000 years the eastern part of the wilkes fracture zone appears to have become less active in contrast to the western flank which has become more active geochemical partition analysis carried out on selected cores shows that the hydroxylamine hcl soluble fe mn ni cu and zn decrease while the proportion of these metals associated with the hcl soluble fraction increases with depth in the sediments in addition there is an increase in the proportion of the hydroxylamine hcl insoluble residue with depth from these data it is inferred that diagenetic transformation of phases occurs within the buried sediments leading to the formation of stable iron oxides and iron smectite the element partition variations are most pronounced in the upper 40 cm of the sediments and are probably associated with oxidation reduction reactions in which mn fe mn fe oxides and organic material are involved reduction of fe mn oxides may lead to the release of mn cu and zn which are subsequently incorporated in the newly formed goethite and smectite the transformation of the metalliferous sediment constituents to more stable phases increases away from the crest of the rise because the environmental conditions for the formation of smectite become more favorable i e lower temperature older sediments greater availability of al si and mg and greater physical contact between fe oxy hydroxides and sio2 in the narrow basins

geochemical and sedimentological patterns in the thermaikos gulf north west aegean sea formed from a multisource of elements surface sediment samples from thermaikos gulf were analysed for organic carbon cd pb cr cu zn mn ni co and fe and were subjected to grain size analysis the results showed that pb cu and zn had the same source of pollution in the following order of importance the sewage outfall the industrial zone and the axios river the concentration of these metals increased with decreasing mean grain size suggesting their association with the fine fraction of the sediments the clays and the organic matter cadmium was more loosely correlated with the metals of the previous group being derived from the community activities and also from the weathering of land based ophiolitic rocks iron cr ni co and mn are of natural origin the weathering of mafic and ultramafic rocks being responsible for their enrichment this was more apparent in the case of ni which was more enriched in the coarser and better sorted sediments near the delta of the river aliakmon

processes controlling the development of a river mouth spit abstract spits are among the most dynamic features in the coastal zones their stability is very often the result of a fragile equilibrium between the availability of sediments and the forcing hydrodynamics due to the complex interactions between the processes shaping such geomorphologic features the investigation is difficult and requires separate analysis for each of the processes a typical example of a spit is sahalin which emerged one century ago at the mouth of the danube delta s southernmost distributary and has continuously evolved through elongation and lateral migration in order to investigate and quantify separately each of the main processes shaping a spit we divide our research in two stages first wave induced sediment transports were simulated and analyzed using a complex processes based on a numerical model for an idealised spit this schematized spit was based on the shape of a number of spits secondly the findings were used in a similar approach for a real case the sahalin spit results show convergence of the wave fields towards the spit and large transport rates for the dominant wave directions the sediment budget derived from the predicted transport and the historical maps of the spit show that the evolution of the spit is the result of a continuous interaction between along and cross shore sediment transport furthermore a good match was obtained between the volumes of sediment supplied to the spit system and those feeding the expansion of the spit the final output is a conceptual model that includes four stages submarine accumulation emerging evolution and merging with the mainland of the spit based on the findings from the present study as well as on the findings of previous authors although the model was constructed to explain the evolution of sahalin spit it is suggested that it can be applied more generally for spits formed in wave dominated deltas in a microtidal environment and with a wave climate dominated by one direction

an abrupt drowning of the black sea shelf abstract during latest quaternary glaciation the black sea became a giant freshwater lake the surface of this lake drew down to levels more than 100 m below its outlet when the mediterranean rose to the bosporus sill at 7 150 yr bp 1 saltwater poured through this spillway to refill the lake and submerge catastrophically more than 100 000 km2 of its exposed continental shelf the permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of europe at that time

morphological changes beach inundation and overwash caused by an extreme storm on a low lying embayed beach bounded by a dune system nw mediterranean abstract the geomorphological evolution of a low lying micro tidal sandy beach in the western mediterranean pals beach was characterized using airborne light detection and ranging lidar data data were collected in prior to and six months after the impact of an extreme storm with a return period of approx 50 years with the aim of characterizing the beach s response to the storm the use of repeated high resolution topographic data to quantify beach geomorphic changes has allowed assessment of the accuracy of different proxies for estimating beach volume changes results revealed that changes in the shoreline position cannot accurately reproduce beach volume changes on low lying beaches where overwash processes are significant observations also suggested that volume estimations from beach profiles do not accurately represent subaerial volume changes at large profile distances on beaches with significant alongshore geomorphological variability accordingly the segmentation of the beach into regularly spaced bins is proposed to assess alongshore variations in the beach volume with the accuracy of the topographic data the morphological evolution of pals beach during the study period showed a net shoreline retreat 4 m and a significant sediment gain on the subaerial beach 7 5 m 3 m the net gain of sediment is mostly due to the impact of the extreme storm driving significant overwash processes that transport sediment landwards increasing volume on the backshore and dunes the increase of volume on the foreshore and the presence of cuspate morphologies along the shoreline also evidence post storm beach recovery observed morphological changes exhibit a high variability along the beach related to variations in beach morphology changes in the morphology and migration of megacusps result in a high variability in the shoreline position and foreshore volume changes on the other hand larger morphological changes on the backshore and larger inundation distances occur when the beach and the dunes are lower favouring the dominance of overwash the observed storm induced morphological changes differ from predicted beach storm impacts because of spatial and temporal variations in the beach morphology suggesting that detailed morphological parameters and indicators used for predicting beach vulnerability to storms should be regularly updated in order to represent the pre storm beach conditions finally observed morphological changes in pals bay evidenced a different behaviour between natural and urban areas with better post storm beach recovery on natural areas where the beach is not artificially narrowed

dynamic characteristics of the yellow river mouth the yellow river delta is dynamic because the river carries a heavy sediment load and serious siltation occurs in the area massive sediment transport brings fertile soil to the river mouth leading to its expansion by 20 25 km2 per year the dramatic reduction in runoff and sediment in the delta due to increasing water demand has extended the period of flow cut off the river changes its delta channel about once every ten years the channel shifts affect the upstream flood stages since the river shifted to the present delta channel in 1976 the shape of the delta has changed remarkably sediment laden flow has been building channels by depositing sediment in low velocity areas and has extended the river mouth into the sea for more than 40 km the velocity of sea currents is enhanced by the growth of the river mouth spit at a rate of 1 m s 1 per 10 km extension which results in high capacity of sea currents carrying sediment away from the mouth the new river mouth area was silted up by 14 m and the old river mouth area was eroded by 5 m siltation takes place in the low flow season and scouring occurs in the flood season scouring occurs during the rising limb of a flood and siltation occurs during the receding limb of a flood the roughness of the river changes largely following the increase in discharge the minimum manning roughness occurs at non siltation and non erosion discharge tidal influence in the river is restricted to a section extending over only a few kilometres unlike in many other coastal areas the river water with its high sediment concentration develops into density current and flows underneath the seawater during flood this mechanism contributes to sediment transportation in the delta copyright 2000 john wiley sons ltd

holocene litho and biostratigraphy of the nw black sea romanian shelf abstract detailed lithological and micropaleontological studies were performed on several cores from the romanian black sea shelf located in front of the danube delta in front of the razelm sinoe lagoonal complex close to the eforie beach as well as on the romanian inner shelf all the studied cores are situated at a water depth varying between 12 m and 67 m the purpose of the investigations was to reveal upper holocene lithological changes and the associated calcareous nannoplankton fluctuations in a very shallow marine setting such as the romanian black sea inner shelf the youngest holocene unit or shallow unit is composed of alternating sequences of mud silt clay and coquina layers containing marine mollusc faunas the upper part of the shallow unit contains blooms of the nannoplankton species emiliania huxleyi while its lower part yields besides common e huxleyi rare specimens of braarudosphaera bigelowii the shallow unit overlies a shell hash layer mainly made by coquinas containing mixing marine and brackish mollusc faunas towards the upper part of this level monospecific assemblages with b bigelowii were observed in a layer rich in carbonate acicular crystals the shallow unit partly corresponds to the unit 1 finely laminated coccolith ooze and unit 2 sapropelic sediments of slope and basinal settings of the black sea the layer rich in carbonate acicular crystals could be a shallower equivalent of the oldest layer of aragonite bands placed at the lower part of the unit 2 in deep parts of the black sea in the analyzed cores the oldest lithological unit unit 3 the muddy clay sediments deposited in a brackish to freshwater environment is characterized by the deposition of green yellowish clay devoid of any holocene calcareous nannoplankton species and containing brackish mollusc faunas based on nannofloral fluctuations an increasing salinity from the base towards the upper part of the shallow unit may be supposed together with the progressive establishment of a stable marine setting similar to today

holocene evolution of the danube delta an integral reconstruction and a revised chronology abstract the danube delta is one of the few large deltas in the world the evolution of which has involved numerous and varied episodes within a complex framework of interactivity between river sediment supply allochthonous sediments supplied by longshore currents marine dispersing forces vertical movements neotectonics sediment compaction and sea level the resulting complex morphology comprises diversified landscapes varying from labyrinthic net of channels and lakes fluvial delta to massive tracts of monotonous reed marshes large lagoons divided by barriers or beach ridge plains accommodating large transgressive dunefields maritime delta whilst previous studies have focused on various sectors of the danube delta the current paper proposes for the first time an integral reconstruction of delta evolution based on existing and new sedimentological and morphological analyses and absolute ages ams 14 c and osl enabling a comprehensive synthesis in terms of both evolutionary phases and growth patterns a chronological framework was established for all the deltaic lobes and beach ridge plains highlighting the relationship between formation timespan growth rates and the resultant morphology this work unveils the early stage of delta formation including the reconstruction of delta front advancement into danube bay old danube lobe prior to 7 5 5 5 ka and initial spit barrier development 6 7 6 5 5 8 ka inception of the bayhead delta started 1000 yr before the relative stabilization of sea level and of the initial spit formation the original fluvial delta plain topography is now buried at a depth of 4 6 m depth below the present topography representing the current stage of fluvial aggradation as a result of subsidence and sea level rise regarding the maritime delta six large open coast lobes developed in the last six millennia of which four were formed by the sf gheorghe branch attesting the long uninterrupted activity of this branch whereas the other two were created respectively by the sulina and the chilia branches the evolution of each lobe is derived from successive chronological shoreline positions and discussed in relation with changes in danube discharge special attention has been paid to their growth stages and progradation rates for the southern delta we bring in new arguments for an active southern distributary the dunav derived from the sf gheorghe branch that formed successive open coast lobes between 2 6 and 1 3 ka additionally we discuss the effects of modern anthropogenically driven fluvial sediment reduction on the morphology and morphodynamics of the active lobes of the danube

organic matter production and preservation and evolution of anoxia in the holocene black sea dating of sediments collected in gravity cores during leg 1 of the 1988 r v knorr expedition to the black sea suggests that the onset of water column anoxia at 7 5 ka was virtually synchronous across the basin over a depth range of 200 2250 m a finely laminated organic carbon oc rich sapropel unit ii was produced as a result of this anoxia the trigger for increased oc production and development of anoxia was the spillover of saline waters through the bosporus that probably began at 9 0 ka and peaked between 7 0 and 5 5 ka this spillover enhanced vertical mixing and nutrient cycling and caused a short term 2 3 kyr burst in surface water productivity during the early part of unit ii deposition continued incursion of saline waters enhanced vertical stability and inhibited mixing of nutrients into surface waters thus limiting primary production and decreasing the oc flux to sediments beginning 5 5 ka concentration accumulation rate and degree of preservation of organic matter all decreased in the upper part of unit ii as a result of decreasing productivity but anoxia persisted throughout most of the water column the end of unit ii sapropel deposition was synchronous across the black sea as the result of the first blooms of the coccolith emiliania huxleyi which presumably marked an increase in surface water salinity above 11 and the beginning of unit i deposition the high coccolith carbonate fluxes that occurred during deposition of unit i diluted the oc concentration in the sediments but oc accumulation rates are about the same as those in upper part of unit ii

sand suspension and transport during inundation of a dutch barrier island overwash and inundation of barrier islands transport large amounts of sediment landward which could potentially increase the aggradation of these islands in times of sea level rise however not much is known about the detailed processes of sediment suspension and transport during inundation here we analyze field data of suspended sediment water levels waves and currents which were collected during five inundation events on a barrier island in the netherlands we found that depth integrated suspended sand concentrations and cross shore sand transport showed high variability during and between inundation events at our location where 80 of the combined transport from all inundation events was completed before high tide this is primarily caused by variations in cross shore flow velocities which were strongest up to 1 2 m s onshore before high tide however episodically high depth integrated suspended sand concentrations defined as 2kg m2 were observed on infragravity time scales 20 200 s suggesting that the contribution of infragravity waves to the combined bed shear stresses of waves and currents was important high contributions of infragravity waves to the transport coincided with observed bore like wave shapes which might partly be attributed to higher short waves riding and suspending sediment at the position of the crest two transport regimes were thus found to govern the transport during inundation a flow driven regime when flow velocities were high 0 5 m s and the ratio of infragravity wave and current related shields numbers was below 0 11 and an episodic regime when this ratio exceeded 0 11

barrier island breach evolution alongshore transport and bay ocean pressure gradient interactions physical processes controlling repeated openings and closures of a barrier island breach between a bay and the open ocean are studied using aerial photographs and atmospheric and hydrodynamic observations the breach site is located on pea island along the outer banks separating pamlico sound from the atlantic ocean wind direction was a major control on the pressure gradients between the bay and the ocean to drive flows that initiate or maintain the breach opening alongshore sediment flux was found to be a major contributor to breach closure during the analysis period from 2011 to 2016 three hurricanes had major impacts on the breach first hurricane irene opened the breach with wind driven flow from bay to ocean in august 2011 hurricane sandy in october 2012 quadrupled the channel width from pressure gradient flows due to water levels that were first higher on the ocean side and then higher on the bay side the breach closed sometime in spring 2013 most likely due to an event associated with strong alongshore sediment flux but minimal ocean bay pressure gradients then in july 2014 hurricane arthur briefly opened the breach again from the bay side in a similar fashion to irene in summary opening and closure of breaches are shown to follow a dynamic and episodic balance between along channel pressure gradient driven flows and alongshore sediment fluxes

offshore transport of sediment during cyclonic storms hurricane ike 2008 texas gulf coast usa extreme storms can have a large impact on coastal sediment budgets and the character of strata preserved in the geologic record here we investigate the impact of a cyclonic storm surge flood and ebb on sediment transport in a microtidal beach barrier shelf system hurricane ike made landfall on the texas united states coast on 13 september 2008 the accompanying storm surge flooded galveston bay with up to 5 m of water above sea level the surge flood and ebb preferentially flowed over a low elevation bay fronting spit known as the bolivar peninsula destroying buildings and eroding sediments surge waters also flowed through bolivar roads tidal inlet the main passageway through the barrier system that separates the gulf and the bay bathymetry chirp data and samples were collected in bolivar roads tidal inlet 9 to 10 d after the storm and we compare them here to data collected 4 mo prior additional data were collected offshore of bolivar peninsula in october 2008 our results document the dominance of the storm surge ebb in forcing sediment transport through the inlet which is not considered in models of beach barrier evolution shoreface sands appear to have been incised by the storm and advected with beach barrier sediments sufficiently offshore by the storm surge ebb that they cannot be reincorporated indicating a significant loss to the barrier system9s sediment budget as a result of a single storm

young danube delta documents stable black sea level since the middle holocene morphodynamic paleogeographic and archaeological implications new radiocarbon and optical dates show that the holocene danube delta started to build out of a black sea embayment 5200 yr ago delta lobe development phases differ by as much as 5 k y from previously proposed ages the new chronology allows for a better understanding of the danube delta paleogeography includ ing the demise of istria the main ancient greek roman city in the region prior reconstructions of sea level in the black sea inferred fluctuations to 15 m in range however stratigraphy of beach ridg es in the delta shows that the relative black sea level for the past 5 k y was stable in the danube delta region within 2 m and 1 5 of the current level hydroisostatic effects related to a proposed catastrophic reconnection of the black sea to the world ocean in the early holocene may have been responsible for the sea level reaching the highstand earlier than estimated by models the new sea level data suggest that submergence at several ancient settle ments around the black sea may be better explained by local fac tors such as subsidence rather than by basin wide sea level fluctuations

observations of waves and currents during barrier island inundation overwash and inundation on barrier islands can transport sediment onshore leading to vertical accretion these processes could ensure barrier island growth in times of sea level rise but wave and current fields during overwash and inundation are not well understood field data of water levels waves and currents were collected on a barrier island in the netherlands to investigate the hydrodynamics during island inundation observations show that even in shallow water depths 0 5 m wave energy was not completely dissipated as waves propagated from the north sea onshore additionally locally generated wind waves entered the field area from the wadden sea and propagated offshore infragravity waves were an important part of the wave field particularly onshore of the beach crest they were observed to be onshore progressive and displayed a bore like shape when water depths were shallow wave breaking was the dominant dissipation mechanism for high frequency waves as well as for infragravity waves which is in agreement with prior research on infragravity wave energy dissipation on mild sloping closed boundary beaches a large scale offshore directed water level gradient between the wadden sea and the north sea side caused by elevated water levels in the wadden sea during the storms frequently drove an offshore flow if it was large enough to exceed the cross shore gradient due to wave setup in addition elevated water levels in the wadden sea decreased current velocities due to a decrease in water level gradients this study highlights the influence of back barrier processes on the hydrodynamics during inundation

reappraisal of the sequence boundary in time and space case and considerations for an su subaerial unconformity that is not a sediment bypass surface a time barrier or an unconformity abstract the sequence bounding unconformity bears the key defining traits of being a surface separating younger from older strata along which there is evidence of subaerial erosional truncation or subaerial exposure with a significant hiatus indicated van wagoner et al 1988 this subaerial component of sequence boundaries subaerial unconformity su is also broadly considered to form as a topographic surface of sediment bypass carved during relative sea level fall and buried by backfilling during relative sea level rise accordingly the su is commonly presumed to record an approximate time barrier which separates older from younger strata along its full length in this paper we show that regional composite scour rcs surfaces that are traditionally mapped as an integral component of the su were never a single subaerial topographic surface characterized by sediment bypass are not unconformities do not record an effective time barrier and form diachronously at the channel belt scale over the entire fall to rise of a base level cycle these rcs surfaces and by inference the su surfaces they comprise thus do not fully fit key defining characteristics embodied in the conceptual sequence boundary flume observations and field data show that the rcs is buried by fluvial sediment simultaneously as it is scoured accordingly the rcs is perennially covered with stored sediment during formation is only exposed as a subaerial topographic surface at the local place and time where it is undergoing active growth and forms over the duration of local marine drainage during a relative sea level cycle this cut and cover model differs greatly from more established bypass models which assume that the rcs was roughly sediment free and subaerially exposed for long durations of incision during regression and thus preserves a significant depositional hiatus upon later burial instead the rcs may commonly and locally record a hiatus more typical of a facies bounding diastem without a lacuna significantly greater than that of surfaces within the strata it binds fragments of fluvial strata may commonly and sporadically be preserved above the rcs that are older than underlying marine units overrun by this surface consequently the rcs is not an effective time barrier lateral planation by migrating and avulsing channels as the rcs expands laterally after nucleation can place younger fluvial strata over much older units which means that this surface is also composite and highly diachronous laterally at the scale of channel belts the cut and cover model has additional implications not captured by the bypass model first significant sediments may be stored within fluvial strata above the rcs during regression that are not available for contemporary falling stage and lowstand marine shorelines this can result in marine sediment starvation particularly of the sand fraction and in extreme cases can result in sand autodetachment and an absence of regressive marine reservoir sandstones second cutting of the rcs co generates a suprafluvial surface above the covering fluvial strata during regression that may be used as a mappable proxy for the conceptual maximum regressive surface mrs the mrs may be raised above this surface locally by low accommodation aggradation during lowstand normal regression but in either case preserves an approximate time line where not reworked during later transgression third valley development across the rcs does not exclusively form by landward knickpoint growth and may include complexly formed and potentially cross cutting buffer valleys su valley incision can be divided into four modes which include denudation structural buttress and buffer valley components which may work together locally and tend to have variable importance along the shore to hinterland profile although the rcs is not a good rock proxy for the conceptual sequence boundary it remains a very mappable surface which may separate facies of potentially very different origin and reservoir quality the rcs is also inseparable from the su and typically the only terrestrial erosional surface of extent in most short duration sequences its nullification as a sequence boundary would mean abandonment of depositional sequence stratigraphy as a correlation and interpretive tool within these sections an alternative to abandonment of the su as a sequence boundary is to loosen the definition of a sequence boundary to a discrete surface of erosional truncation carved landward of contemporary shorelines that is traceable beyond the scale of a single valley or comparable local system and its correlative surfaces of conformity and or non deposition and continue its use as before

sediment accumulation in the central western black sea over the past 5100 years the postdepositional particle flux accumulation rate over the last 5100 years was studied in the anoxic sediment units i and ii from the central western black sea deposition of unit ii sapropel in the deep black sea basin was divided further into two subunits the beginning of the deposition of the sapropel in the black sea 5100 3100 years b p subunit iib was characterized by higher organic carbon accumulation rates due largely to higher primary production accumulation rates of lithogenic matter were at a minimum compared to younger units during the subsequent 2100 years 3100 1000 years b p subunit iia organic carbon accumulation rates decreased considerably while accumulation rates of lithogenic matter increased to the present level at 1000 years b p unit i total mass accumulation rates increased by a factor of 3 this increase was largely a result of an increase in carbonate accumulation rates by a factor of 11 which was caused by the rapid appearance of emiliania huxleyi in the black sea higher carbonate accumulation rates in unit i are mainly the cause for the considerably lower organic carbon content compared to unit ii since the organic carbon accumulation rate in unit i did not decrease general correspondence of accumulation rates of lithogenic matter in different cores through time suggests overregional long term 100 year scale climatic effects on the terrigenous particle supply to the black sea

fluvial terrace formation and controls in the lower river danube se romania abstract the black sea climatically driven level change is the main control of the lower danube incision and aggradation in the long term subsiding setting of the eastern romanian plain the interglacial episodes of aggradation suggest a decreasing fluvial accommodation while t4 terrace fill partially buried the cut terrace t5 in the upstream part of the studied area lower danube arges d mbovi a younger deposition did not compensate the previous incisions black sea level fallings during glaciations were followed by lower danube incisions which propagated upward through knickpoints loess deposits can be correlated with these periods five episodes of incision were recognized based on terrace levels t5 to t1 their ages and of the covering loess were obtained through optically stimulated luminescence osl and were correlated with mis 6 mis 3 and classic glacial chronological events latest rissian middle wurmian the maximum limiting age of danube oldest terrace t5 in the studied area is 141 25 kyr while of the youngest t1 is 50 6 kyr the equivalent terraces on tributaries are younger the time delays between terrace incisions on the lower danube system were estimated the 32 7 15 9 kyr danube floodplain deposits and the 5 kyr forests buried up to 7 m under arges floodplain suggest that younger than 44 40 kyr terraces may be buried

the shelf to basin iron shuttle in the black sea revisited continental shelf sediments are a major source of iron fe for phytoplankton in surface waters in this study we investigate the mechanisms that control release of fe from shelf sediments and its lateral transport shuttling in oxic and hypoxic waters on the northwestern black sea shelf we find that at two coastal stations near the outflow of the danube river high input of organic matter drives strong reductive dissolution of fe oxyhydr oxides henceforth termed fe oxides in surface sediments supporting high rates of fe release to oxygenated bottom waters 0 36 mmol m 2 d 1 we suggest that bioirrigation plays a key role in the release of fe from these sediments at four stations further offshore organic matter deposition is lower resulting in limited mobilization of fe2 in the sediment and low benthic fluxes of fe 0 2 m in the lower part of the water column likely through repeated deposition and resuspension of fe oxides from surface sediments using synchrotron based x ray spectroscopy and sequential chemical extractions we demonstrate that the suspended matter and surface sediments are enriched in easily reducible fe oxides mostly ferrihydrite and fe associated with clay the mobilization of fe in the coastal zone and subsequent lateral transport of these fe bearing particles results in higher ratios of fe al in surface sediments at outer shelf stations ca 1 2 to 2 wt wt 1 than at coastal stations ca 0 5 to 0 9 wt wt 1 however below the sediment surface layer fe al ratios are similar at all stations indicating limited burial of the laterally transported fe our results highlight the critical role of organic matter input associated biological activity and riverine fe input as drivers of fe shuttling on continental shelves we also show that in shelf areas where sediments receive low inputs of organic matter physical transport controls the ultimate fate of the shuttled fe

danube river sediment input and its interaction with the north western black sea abstract the influence of the river danube is determinant to the sedimentation of the north western and western black sea area after 1970 following the building of the iron gates dam the danube river sediment discharge diminished to 30 40 of its previous value after a 12 000 year evolution marked by active progradation the danube delta has become mainly inactive over the last few decades partly due to interventions of man made origin the deficit of sediment influx has led to the intense erosional processes of the deltaic littoral on the black sea north western shelf two main areas with contrasting sedimentary processes have been identified the internal danube sediment fed shelf and the external sediment starved shelf the modern highstand sedimentary history of the north western black sea deep area is marked by the cessation of the danube deep sea fan active development the main depositional units within the north western black sea are described

holocene biostratigraphy and paleoenvironmental changes in the black sea based on calcareous nannoplankton in this study detailed micropaleontological analyses were carried out on 270 samples from eight piston cores collected in the black sea the primary goal was to elucidate the late quaternary evolution of the black sea specifically to refine its biostratigraphy and to explore the holocene paleoenvironmental changes three intervals were recognized in all the cores studied irrespective of whether they were from the basin or the shelf these intervals are characterized from old to young by the spotty occurrence the presence and the local acme of emiliania huxleyi respectively moreover the species braarudosphaera bigelowii is in contrast to the younger units absent in the oldest unit the co occurrence of the two marine species e huxleyi and b bigelowii suggests a shift from fresh brackish water to low salinity marine conditions in the black sea the spotty and very rare occurrence of e huxleyi in the lowermost unit is reported here for the first time two hypotheses are suggested the presence of reworked specimens from eemian outcrops or the presence of low salinity waters also during the lacustrine phase of the basin another feature observed in almost all the cores is the presence of a multi lamina aragonite level in the upper part of the ecozone 3 which functions as a marker for basin wide correlations the parallel study of water samples and surficial sediment assemblages demonstrates the presence of syracosphaera lamina in the surface water samples and its absence in the sediments suggesting dissolution in the water column on the other hand the occurrence of b bigelowii in all cores and its near absence in water and in recent sediment samples suggest a change in water conditions during recent times

barrier formation on an actively prograding delta system the red river delta vietnam abstract an extensive barrier spit system 20 to 30 km long developed on the delta front platform of the ba lat delta within a relatively short period 10 20 years however it was not evident whether the formation was related to river floods typhoons or calm weather conditions or to cross shore or alongshore sediment transport mechanisms therefore a process based numerical model that simulates sediment transport and morphologic changes by waves tides wind and river flow is used to analyze the processes that govern this barrier formation the mechanism that initiates the barrier formation is concluded to be onshore transport by wave asymmetry of sediment previously transported seaward in the buoyant river plume the main mechanism that counteracts the barrier formation is probably destruction of the barrier by river flow during the subsequent transformation from a subaqueous barrier into a sub aerial barrier spit system overwashes and alongshore sediment transport become increasingly important this spit system therefore appears to be dominated by alongshore processes even though its initial formation is more strongly regulated by cross shore processes the importance of cross shore processes results in a minor contribution of typhoons to the initial formation of these barriers typhoons are not very important to destruction of barriers as well because wave energy is gradually dissipated over the gentle offshore profile which in turn results from river plume sedimentation

clay mineral distribution in last glacial holocene sediment cores from the eastern marmara sea cinarcik basin izmit gulf transition nw turkey multisources and transport paths in a two way flow system abstract the regional variations in grain size xrd bulk and clay mineral distribution in 97 sediment samples from 6 gravity cores obtained from 20 to 300 m water depths have been investigated to reveal source and transportation patterns as well as the effects of climatic and sea level changes during the last 25 000 14 c bp in the eastern marmara sea ems nw turkey the major proportions of sediments in the ems consist of silt 20 83 and clay 17 90 whereas sand and gravel abundances rarely exceed 10 of the bulk minerals 10 a micas 23 55 and feldspars 17 55 dominate over quartz 10 21 and calcite 10 26 smectites 23 62 illite 18 36 chlorites 6 21 kaolinite 2 20 and 14s 14c mixed layer minerals 0 27 constitute the principal clay mineral assemblages both bulk and clay mineral assemblages in the ems are similar to those found in the izmit gulf on the southern marmara shelf at the marmara aegean approaches and the southern black sea this would suggest that there is no distinct source for mineral assemblages of the study area outside the marmara basin the concentrations of clay fractions and clay mineral assemblages tend to increase or decrease with depth in the cores but this is limited to some intervals and not to entire sections in the cores this distribution pattern therefore represents rather local sources of provenance and surrounding fluvial drainage basins together with dilution and distribution effects by current transport processes rather than the expected paleoclimatic features and sedimentary input by inflowing black sea and aegean sea water masses throughout the last glacial to holocene

controls on the age of vascular plant biomarkers in black sea sediments abstract transfer of organic carbon oc from the terrestrial to the oceanic carbon pool is largely driven by riverine and aeolian transport before transport however terrigenous organic matter can be retained in intermediate terrestrial reservoirs such as soils using compound specific radiocarbon analysis of terrigenous biomarkers their average terrestrial residence time can be evaluated here we show compound specific radiocarbon 14c ages of terrigenous biomarkers and bulk 14c ages accompanied by geochemical proxy data from core top samples collected along transects in front of several river mouths in the black sea 14c ages of long chain n alkanes long chain n fatty acids and total organic carbon toc are highest in front of the river mouths correlating well with bit branched and isoprenoid tetraether indices which indicates contribution of pre aged soil derived terrigenous organic matter the radiocarbon ages decrease further offshore towards locations where organic matter is dominated by marine production and aeolian input potentially contributes terrigenous organic matter average terrestrial residence times of vascular plant biomarkers deduced from n c29 31 alkanes and n c28 30 fatty acids ages from stations directly in front of the river mouths range from 900 70 years to 4400 170 years these average residence times correlate with size and topography in climatically similar catchments whereas the climatic regime appears to control continental carbon turnover times in morphologically similar drainage areas of the black sea catchment along transect data imply petrogenic contribution of n c29 31 alkanes and input via different terrigenous biomarker transport modes i e riverine and aeolian resulting in aged biomarkers at offshore core locations because n c29 31 alkanes show contributions from petrogenic sources n c28 30 fatty acids likely provide better estimates of average terrestrial residence times of vascular plant biomarkers moreover sedimentary n c28 and n c30 fatty acids appear clearly much less influenced by autochthonous sources than n c24 and n c26 fatty acids as indicated by increasing radiocarbon ages with increasing chain length and are thus more representative as vascular plant biomarkers

geochemical and micropaleontological characterisation of a mediterranean sapropel s5 a case study from core ban89gc09 south of crete several geochemical and micropaleontological proxies were studied in a well developed sapropel s5 from a core collected south of crete to investigate the causes and the mechanisms of its deposition to reconstruct the paleoenvironmental and paleoceanographical conditions at time of its formation and to detect the roles played by productivity and anoxia the geochemical proxies are also used to unravel the sediment provenance and therefore to help tracing water circulation patterns and freshwater sources the multiproxy approach reveals that the sapropel layer has high internal variability and five different depositional phases can be identified four within the visible sapropel layer an increase in temperature and the development of a deep chlorophyll maximum characterise the onset of the sapropel phase 1 with enhanced productivity being favoured by local riverine input not clearly ascribable to nile river freshwater discharge and by the shoaling of the pycnocline nutricline surface water stratification and productivity develop together with strong seafloor dysoxia anoxia phase 2 is characterised by lower stratification slightly lower temperature and or higher seasonal contrast and still high productivity phase 3 records high productivity high temperature and high stratification probably more sustained by the nile input a sudden partial re oxygenation takes place at the end of this phase changing the main features of the sapropel in the fourth phase productivity starts to decrease water stratification seems to be partially broken down and sediment oxygenation increases a transitional phase phase 5 occurs between the end of the visible sapropel and the normal pelagic post sapropel sedimentation where productivity is still high and oxygenation improves compared to the visible sapropel layer the massive occurrence of polysphaeridium zoharyi cyst of a red tide forming dinoflagellate also characterises this phase the geochemical proxies indicate that pre sapropel and post sapropel sediments are quite different from each other and the provenance shifts from a more mixed to a more markedly southern origin of sediments

carbon accumulation rates and the origin of the holocene sapropel in the black sea a detailed radiocarbon chronology obtained by accelerator mass spectrometry together with organic carbon and carbonate measurements on two black sea cores has been used to compare and contrast the burial fluxes of organic carbon in the holocene sapropel and the modern sediment at both deep water and eastern slope sites the sapropel is separated from the modern facies by a variable thickness of compositionally homogeneous sediment with low levels of organic carbon and anomalously old radiocarbon ages this homogeneous unit probably represents deposition by slumping or mudflow the age limits of the sapropel are 1600 6600 b p at the deep water site and 4000 6000 b p radiocarbon years before 1950 a d at the shallow water site the carbon accumulation rate in the deep water sapropel is higher than that in the modern deep water facies by a factor of 2 and is approximately the same as that in the modern sediment in shallow water the revised chronology of sapropel formation and the differences in the carbon accumulation rates probably indicate that the sapropel was formed by increased production during the transition from the premodern lake to the modern marine phases of the black sea this conclusion is consistent with the clear marine carbon isotope signal in the organic mattermore in the sapropel in both cores results to be reported elsewhere in contrast to the mixed source of carbon in the other facies less

geochemical study of sediments from northern euboekos bay greece with regard to the presence of submarine mineral deposits abstract chemical analyses of surface sediment cores from northern euboekos bay greece show that this area is markedly enriched in metals e g ni cr mn relative to aegean shelf sediments these enrichments are partly related to the presence of an fe ni ore body on the seafloor formed by the dumping of a metal rich slag and partly to natural geological processes in a zone on the northwestern coast of euboea island considerable enrichments of ni cr and mn are attributed to weathering of mafic and ultramafic rocks present on the island and probably extended onto the continental shelf it is suggested that the geological and oceanographic conditions in this area are favourable for the formation of placer mineral deposits similar and even greater enrichments of fe ni cr mn zn and cu identified in two older geological horizons are associated with coarse sediments and may be the result of the following processes 1 the weathering of ophiolitic rocks or fe ni deposits or both extending from onshore below the seafloor 2 the production of greater amounts of metal rich weathering products in the past due to climatic changes and 3 lowering of the sea level at times when metal rich horizons were being formed closer to the continent

environmental controls on paleo ph at mid latitudes a case study from central and eastern europe abstract here we present the first reconstruction of the black sea catchment soil ph evolution during the last glacial period and insights into its environmental controls the ph reconstruction is derived from the cbt index cyclization ratio of branched tetraethers brgdgts weijers et al 2007a a proxy based on the relative abundance of branched tetraethers applied in this study to a northwestern black sea sediment core since branched tetraethers are produced primarily in soils but also in aquatic environments we first evaluate the potential of the cbt proxy to reconstruct soil ph regarding the possible origins of brgdgts based on a previous study we propose a correction of the reconstruction to account for the increase in brgdgts derived from in situ production in the black sea paleo lake we also use the cbt ph record to track the soil signal of the black sea catchment as well as to investigate the internal i e soil parent material and external i e climatic controls on long term soil ph change at mid latitudes given that cbt ph was first proposed as a qualitative proxy of paleoprecipitation at lower latitudes we investigate in particular the influence of precipitation on our setting we show that in central and eastern europe soil ph evolution during the last glacial interglacial transition cannot be explained by precipitation amounts only but can be explained by i variations in the spatial source of brgdgts associated with that of soil parent material ii soil water balance and iii soil vegetation litter notably the cbt ph is significantly influenced by a spatial change of brgdgt sources during heinrich stadial 1 moreover the cbt ph record suggests a strong decrease in the soil moisture budget from the lgm towards the early holocene interrupted by an abrupt increase during the younger dryas our study stresses the importance of considering evapotranspiration in addition to precipitation shifts in order to better understand chemical changes of mid latitude soil under major climate change furthermore we suggest that mid latitude soil chemistry during the last glacial interglacial climate transition was more prone to and or more sensitive to vegetation cover changes through i the role of vegetation cover in evapotranspiration and thus in soil leaching and ii the different quality of vegetation litters whatever the latitude the cbt proxy appears useful as one of the only soil chemistry proxies to provide insights into the past hydrology of soil

submarine hydrothermal metallogenesis associated with the collision of two plates the southern aegean sea region abstract the geochemistry of sediments from the southern aegean sea demonstrates that the active tectonics in the hellenic arc trench system favor hydrothermal mineralization processes involving leaching of oceanic crust the distribution and geochemical behavior of mn fe cu zn p and ba indicate a hydrothermal influence i at plate boundaries such as the pliny and strabon trenches ii in fore arc basins such as maleas iraklion and karpathos iii on the island arc all fore arc basins having greater mn enrichments than the trenches are also characterized by higher heat flow values the greatest mn enrichments occur at maleas basin where a mn dispersion halo is recognized this basin is very tectonically active with the largest group of normal faults along the planes of which magmatic material was injected and the highest heat flow values in the sea of crete it also falls in the eastern mediterranean zone of high seismic activity because the fe mn sediments identified in the above geotectonic units are the end members of the hydrothermal fractionation sequence known from areas where leaching of oceanic crust occurs it is suggested that other members of the sequence such as metal sulfides may be found significant geochemical anomalies of pb and zn found in areas of high heat flow and on lines of normal faulting are considered to be traces of the presence of metal sulfides

intrawave sand suspension in the shoaling and surf zone of a field scale laboratory beach short wave sand transport in morphodynamic models is often based solely on the near bedwave orbital motion thereby neglec ting the e ect of ripple induced and surface induced turbulence onsand transport processes here sand stirring was studied using measurements of the wave orbital motion turbulence ripple characteristics and sand concentration collected on a eld scale laboratory beach underconditions ranging from irregular nonbreaking waves above vortex ripples to plunging waves and boresabove subdued bed forms turbulence and sand concentration were analyzed as individual events and ina wave phase averaged sense the frac tion of turbulence events related to suspension events is relativelyhigh 50 especially beneath plunging waves beneath nonbreaking waves with vortex ripples the sandconcentration close to the bed peaks right after the maximum positive wave orbital motion and shows amarked phase lag in the vertical although the peak in concentration at higher elevations does not shiftto beyond the positive to negative ow reversal under plunging waves concentration peaks beneaththe wavefront without any notable phase lags in the vertical in the inner surf zone bores the sandconcentration remains phase coupled to positive wave orbital motion but the concentration decreaseswith distance toward the shoreline on the whole our observations demonstrate that the wave drivensuspended load transport is onshore and largest beneath plunging waves while it is small and can alsobe o shore beneath shoaling waves to accurately predict wave driven sand transport in morphodynamicmodels the e ect of surface induced turbulence beneath plunging waves should thus be included

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

contrasted sediment processes and morphological adjustments in three successive cutoff meanders of the danube delta abstract since the 1980s intensive anthropogenic disturbances have affected the channel of the st george branch the southern distributary of the danube river the meander cutoff programme since 1984 1988 induced different hydrosedimentary impacts on the local distribution of river flow velocities discharge and sediment fluxes between the former meanders and the man made canals ichim and radoane 1986 popa 1997 panin 2003 this paper selects three large cutoff meander reaches of the st george branch the mahmudia dunav de sus and dunav de jos meanders noted here as m1 m2 and m3 respectively as an example to analyse the human impact in the danube river delta the diversion of the flow induces strong modifications by acceleration of the fluxes through the artificial canals combined with dramatically enhanced deposition in the former meander where it was observed in two cases m1 and m3 with slight modifications in m2 an exceptional flood that occurred in april 2006 offered a good opportunity for scanning different cross sections of the meander systems bathymetry flow velocity suspended load concentration and liquid and solid discharge data were acquired throughout several cross sections of both natural channels and artificial canals of the three cutoffs using acoustic doppler current profiler adcp technology in order to investigate the distribution of the flow and sediment and its impact on the hydrosedimentary processes in each channelized reach and adjacent former meander therefore the results obtained during the 2006 flood were referred to a long term evolution 1970 2006 analysed by gis techniques

observations of turbulence within a natural surf zone abstract here the reynolds stresses u w and w where u and w are the cross shore alongshore and vertical turbulence velocities respectively and the angle brackets represent time averaging are used to diagnose turbulence dynamics beneath natural breaking surf zone waves the data were collected at truc vert beach france during a 12 day period in 1 3 m water depth with strong cross shore and alongshore currents under high energy wave conditions offshore significant wave heights ranged between 2 and 8 m the u w term is predominantly negative increases with the ratio of wave height hs to water depth h degree of wave breaking and decreases in magnitude toward the bed this supports the view that the cross shore shear stress is due to breaking induced vortices that transport high speed cross shore flow downward and disintegrate close to the bed the occasional positive sign of u w within the lower 15 20 of the water column indicates that sometimes surface generated turbule

radiocarbon dating of danube delta deposits abstract the holocene history of the danube delta has been studied using 14c analyses of faunal material the principal phases of development include 1 initial letea caroarman spit 11 700 9800 yr b p in its central part 8800 5500 yr b p in its southern part 2 sf gheorghe i delta 8900 7200 yr b p 3 sulina delta 7200 2000 yr b p and 4 sf gheorghe ii delta chilia delta 2000 yr b p present other smaller scale features have also been dated including secondary deltas cosna and sinoe deltas and littoral bars age determinations carried out on whole samples were erratic and it was found that individual species had to be separated and dated in all cases the older dates were of transported material whereas the younger dates gave the true age of the formation

short term morphodynamics of non storm overwash abstract overwash is an important process in barrier island evolution and its effects on the barrier morphology and sedimentology have been widely studied however the short term sediment dynamics of overwash processes are not well known due to the lack of specific field studies this paper presents field data that clarify the sedimentary dynamics of overwash processes on different washover morphologies and determine the factors leading to non storm overwash occurrence two fieldwork campaigns were undertaken during overwash events go 1 winter of 2001 and go 3 winter of 2003 on western barreta island algarve portugal the fieldwork included measurements of oceanographic conditions overwash flows morphology variations mixing depth and sediment transport paths using tracers the sediment dynamics induced by overwash varied according to the washover morphology washover plain versus washover lobe the sediment transport inside the washover plain was different for the two fieldwork campaigns average mixing depth of 13 cm for go 1 and 6 cm for go 3 however it had similar main stages stage 1 crest accretion stage 2 onshore transport and stage 3 dynamic equilibrium the sediment transport inside the washover lobe can be characterised by one onshore flow stage with erosion of the mouth and channel and accretion on the washover fan the main factors governing the occurrence of non storm overwash in the study area were the combined occurrence of 1 typical winter waves 2 spring high tides 3 washover crest below the high tide level 2 m and 4 absence of prominent beach berm this study proved that when the proper conditions are generated non storm overwash has sediment transport comparable to storm overwash and therefore may be significant for barrier evolution further field studies of overwash are needed principally for more detailed overwash flow velocity measurements high frequency morphologic surveys and barrier groundwater measurements

response of wave dominated and mixed energy barriers to storms wave dominated and mixed energy barriers are extremely dynamic landforms responding to processes operating over a spectrum of time scales ranging from daily to monthly fluctuations related to storm and post storm conditions to century to millennium scale evolution driven by relative sea level change two types of storms are of particular relevance warm core tropical and cold core extratropical cyclones both are responsible for generating very large waves highly energetic surf zone dynamics and sediment transport elevated inshore water levels and extensive morphological responses all cyclones are affected by climate change which governs their frequency intensity and tracks barrier storm response is primarily governed by maximum storm runup and barrier morphology as conceptualised in abby sallenger s storm impact scale model sallenger 2000 this model defines four storm impact regimes and includes erosive as well as accretionary responses on the erosion side the swash regime drives bar and berm flattening the collision regime is marked by dune scarping and beach lowe the overwash regime leads to dune scouring and channel incision and the inundation regime may result in barrier destruction on the deposition side storm berms and beach ridges may form and accrete in the swash and collision regimes localised vertical beach and barrier accretion are associated with the collision and overwash regimes and washover deposition takes place in the overwash and inundation regimes site specific factors play a key role in moderating the morphological response and include storm characteristics type duration and track longshore sediment supply upwelling downwelling currents coastal setting and inner shelf topography the response of a barrier to a tropical or extratropical cyclone can however not be considered in isolation and has to be appreciated in a longer temporal context involving morphological preconditioning due to antecedent wave and water level conditions additionally a simple process response approach of the cause and effect type is inappropriate and a more complex conceptual framework involving thresholds feedbacks resilience and vulnerability will need to be adopted a useful way to visualise and conceptualise more complex storm behaviours and the longer term vulnerability of barriers is the resilience trajectory which maps out the changes in barrier geometry elevation and width over various time scales from weeks to years or even longer and under varying forcing conditions including changes in storminess and sea level rise an increased understanding of barrier response to storms and sequences of storms is required to better quantify long term barrier response to climate change high resolution and comprehensive decadal records of barrier response to storms are a prerequisite to achieve this ambition linking site specific coastal settings hydrodynamic drivers and morphological responses and allowing the recognition of recovery and impact dominated phases the enhanced insights in barrier response to extreme events must then be incorporated into improved coastal response models to help predict the impacts of future climate change on wave dominated and mixed energy barriers around the world 2013 elsevier b v

geodynamic and hydro geological constraints regarding the extension of the prospective archaeo cultural area within the northern romanian coastal zone abstract an obvious discrepancy is noticed between the very few archaeological sites discovered until now on the danube delta plain area and the large number of such sites whose ages range from the middle paleolithic to the middle ages and more recently identified on its higher topography surroundings the combined effects of the regional subsidence of the coast and delta area with amplitudes of 2 to 4 mm y and of the secular mean sea level rise 0 5 1 0 mm y continuously change the land mean sea level relative relationship placing the prospective archaeo cultural layer corresponding to the late prehistory antiquity period at a burial depth which now exceeds 4 5 m this situation partly explains the limited success of the archaeological research carried out until now within the danube delta plain area and recommends a systematic use of the geophysical investigation methods in future the integrated interpretation of the coastal zone bathymetry and sedimentology mappings and of the shoreline geomorphological evolution in time highlights the sedimentary processes that presently shape the littoral study zone allowing to divide it in sectors where either sediments accumulation or erosion processes prevail the study draws attention to the impu ita c sla v danei and cosna vadu littoral sectors where the intense marine erosion of the shoreline and the adjacent seabed also imminently endangers their prospective archaeo cultural load

flow and sediment processes in a cutoff meander of the danube delta during episodic flooding abstract this article analyzes the water and suspended solid fluxes through a straightened meander of the southern branch of the danube delta the st george branch during episodic flooding the mahmudia study site corresponds to a vast natural meander which was cut off in 1984 1988 by an artificial canal opened to shipping the meander correction accelerated fluxes through the artificial canal and dramatically enhanced deposition in the former meander after his formation the cutoff meander acted as sediment storage locations essentially removing channel and point bar sediments from the active sediment budget of the main channel increases in slope and stream power in reaches upstream and downstream have also occurred but to a lesser degree during the one hundred year recurrent flood in april 2006 bathymetry flow velocity and discharge data were acquired across several sections of both natural and artificial channels with an acoustic doppler current profiler adcp workhorse sentinel 600 khz teledyne rdi in order to investigate the distribution of the flow and sediment and his impact on sedimentation in a channelized reach and its adjacent cutoff the contrasting hydro sedimentary processes at work in both channels and bifurcation confluence nodal points are analyzed from the measured flux distribution morphological profiles and velocity and concentration patterns in the cutoff a diminishing of the intensity of the flow velocity c 50 and of the ssc was observed correlated with the aggradation of the river bed in the bifurcation confluence nodal points and in the artificial canal were observed the most intensive hydrodynamic activity high flow velocity ssc concentration degradation of the river bad both the event scale and long term morphological trends of the alluvial system are discussed analyzing the boundary shear stress and ssc variability excess boundary shear stress in the sub reaches directly affected by cutoffs resulted in scour that increased downstream bed material load these high sediment loads play a key role in driving morphological adjustments towards equilibrium in the cutoff channel the approach followed in this paper combines detailed episodic in situ adcp measurements and robust numerical 1d modeling in order to provide a practical comprehension of the relevant morphodynamical processes the 1d model reproduces robustly the continuity of hydrodynamical variables along the streamwise axes of the two channel network the simulated are used in the paper for highlighting reach scale morphological processes at both event and long term scales

wave climate coastal sediment budget and shoreline changes for the danube delta abstract since its formation approximately 12 000 years ago the coastal zone of the danube delta experienced alternating periods of accretion and erosion related to the natural process of lobe abandonment caused by river avulsion over the last 150 years the effects of human interventions modified these natural trends regulation of the danube river e g the iron gates barrages facilitating navigation and controlling river discharge construction and extension of the sulina entrance jetties and dredging of the sulina mouth bar for navigational purposes are examples of human interventions that influenced and still influence the actual state of the danube delta coastal zone most importantly these interventions diminished the quantity of sediments reaching the coast and consequently led to a severe retreat of the shoreline especially in the sulina sf gheorghe coastal sector to investigate and quantify the recent sediment budget and associated shoreline changes along the danube delta coastal zone we constructed a hindcast of the wave climate the alongshore transport capacity and the resulting sediment budget using a numerical coastline model on a local scale it was found that overwash plays an important role i e the observed evolution of sahalin spit island shows a cross shore landward migration that is much larger than could be explained by the calculated alongshore sediment transport gradients on a delta scale however the resulting alongshore sediment transport gradients and associated sediment budgets comply very well with the observations confirming the dominant role of wave induced alongshore transport and giving confidence in our predictions regarding the shoreline position for the next 25 and 50 years the results of this study indicate the potential for broader applicability of the model to other deltas especially those in wave dominated settings

the effect of tides and storms on the sediment transport across a dutch barrier island under natural conditions barrier islands might grow vertically and migrate onshore under the influence of long term sea level rise sediment is transported onshore during storm induced overwash and inundation however on many dutch wadden islands dune openings are closed off by artificial sand drift dikes that prevent the influx of sediment during storms it has been argued that creating openings in the dune row to allow regular flooding on barrier islands can have a positive effect on the sediment budget but the dominant hydrodynamic processes and their influence on sediment transport during overwash and inundation are unknown here we present an xbeach model study to investigate how sediment transport during overwash and inundation across the beach of a typical mesotidal wadden sea barrier island is influenced by wave tide and storm surge conditions firstly we validated the model xbeach with field data on waves and currents during island inundation in general the xbeach modelperformed well secondly we studied the long term sediment transport across the barrier island we distinguished six representative inundation classes ranging from frequently occurring low energy events to infrequent high energy events and simulated the hydrodynamics and sediment transport during these events an analysis of the model simulations shows that larger storm events cause larger cross shore sediment transport but the net sediment exchange during a storm levels off or even becomes smaller for the largest inundation classes because it is counteracted by larger mean water levels in the wadden sea that oppose or even reverse sediment transport during inundation when taking into account the frequency of occurrence of storms we concludethat the cumulative effect of relatively mild storms on long term cross shore sediment transport is much larger than that of the large storm events

inundation of a barrier island chandeleur islands louisiana usa during a hurricane observed water level gradients and modeled seaward sand transport large geomorphic changes to barrier islands may occur during inundation when storm surge exceeds island elevation inundation occurs episodically and under energetic conditions that make quantitative observations difficult we measured water levels on both sides of a barrier island in the northern chandeleur islands during inundation by hurricane isaac wind patterns caused the water levels to slope from the bay side to the ocean side for much of the storm modeled geomorphic changes during the storm were very sensitive to the cross island slopes imposed by water level boundary conditions simulations with equal or landward sloping water levels produced the characteristic barrier island storm response of overwash deposits or displaced berms with smoother final topography simulations using the observed seaward sloping water levels produced cross barrier channels and deposits of sand on the ocean side consistent with poststorm observations this sensitivity indicates that accurate water level boundary conditions must be applied on both sides of a barrier to correctly represent the geomorphic response to inundation events more broadly the consequence of seaward transport is that it alters the relationship between storm intensity and volume of landward transport sand transported to the ocean side may move downdrift or aid poststorm recovery by moving onto the beach face or closing recent breaches but it does not contribute to island transgression or appear as an overwash deposit in the back barrier stratigraphic record the high vulnerability of the chandeleur islands allowed us to observe processes that are infrequent but may be important at other barrier islands

suspended sediment transport and the role of infragravity waves in a barred surf zone abstract collocated optical backscatterance suspended solids sensors and electromagnetic flowmeters were deployed at stanhope lane beach p e i canada to assess the contributions of wind waves infragravity waves and mean currents to the cross shore flux of suspended sediment across a barred surf zone the local net transport of suspended sediment magnitude and direction was highly variable both spatially and temporally with respect to the relative magnitudes of the suspended sediment transport 1 that induced by quasi steady mean currents and oscillatory currents at both incident and infragravity frequencies were almost equal in magnitude when the total surf zone was averaged over the storm event 2 waves in the near infragravity band were quantitatively more important during the waning of the storm especially where when surf persisted well after the initial decay of the offshore wave field 3 incident waves were important where when the waves were not saturated i e during the early stages of the storm at all locations and persistently throughout the storm on the seaward slope of the bar where wave saturation was limited to a very short period with respect to the direction of net sediment transport 1 that attributable to mean currents was directed offshore in the inner surf zone probably reflecting the presence of an undertow while further seaward an onshore transport occurred probably resulting from mass transport induced by surf bores or drift velocities induced by the infragravity wave boundary layer 2 that induced by oscillatory currents at incident wave frequencies was generally onshore at any one location throughout the storm event in contrast oscillatory transport at low frequencies changed direction and also varied in magnitude at any given location in part these changes reflect the existence of significant oscillatory sediment transport at discrete infragravity frequencies the standing infragravity waves consistently transported suspended sediment towards antinodes in the water surface elevation

distribution of clay minerals in surface sediments of the aegean sea a compilation extensive published data sets and some new data on the clay mineral composition of surface sediments in the aegean sea northeastern mediterranean sea have been compiled in order to map the distribution patterns of clay mineral assemblages and to decipher source areas and transport paths we distinguished six provinces a northwest aegean province a marmara dardanelles province a west turkey province a southeast aegean province a kithira province and a central aegean province the clay mineral assemblages in the coastal and shelf areas carry the signature of the riverine sediment discharge from southeast europe and turkey respectively the southern aegean sea is probably influenced by the river nile discharge and transport of clay minerals by surface currents the clay minerals in the central aegean sea form a mixed assemblage comprising components of the other assemblages a dispersion and dilution of clay minerals by surface currents is obvious

the danube river inception evidence for a 4 ma continental scale river born from segmented paratethys basins before reaching the black sea the danube river passes through a string of para tethyan vienna pannonian and western and eastern dacian basins the key question is when and how did the danube river became a continental scale river with a drainage similar to present new data presented here show that the late miocene deep water strata in the black sea have a significant sediment source and depositional style change at about 4 ma however the presence of active miocene basins within the danube catchment raises questions about the timing of danube river inception and whether the upstream palaeogeography would have allowed or disallowed delivery of large sediment volumes to the deep water black sea stratigraphic analyses in the pannonian and dacian basins reveal a phase of coeval sedimentary fill of the basins along the danube at about 4 ma this multi basin observation points to a concurrent basin fill model rather than the basin fill and spill or messinian type lowstand models previously proposed for danube inception this article is protected by copyright all rights reserved

compositional trends through the holocene mud succession of the southwestern black sea shelf implications for sedimentary provenance and water level history abstract cores mar02 45 and mar05 03 were raised from 68 69 m water depth on the sw black sea shelf and indicate transgression and submergence beneath several tens of metres of water before 11 0 cal ka those who postulate a black sea lowstand below 100 m until the approximately 9 1 cal ka reconnection with the world ocean have suggested that sites like mar02 45 and mar05 03 must have been located in perched lakes on what is now the modern shelf however the silt and clay fraction mineralogy of samples from mar02 45 provides no evidence for a shift in provenance at 9 1 cal ka with earlier input from local rivers and later input from a broader region sedimentary abundances of sc fe co ce la th and y also show no significant downcore trends these elements likely reside in aluminosilicate mineral grains shed from terrestrial sources so negligible downcore variation suggests long term continuity in the composition of the detrital supply more critically the volume of pre 9 1 cal ka sediment around the mar02 45 and mar05 03 sites is 25 times the expected yield from local rivers over a 5000 year period so other more substantial sources are required the predominant silt size of the recovered sediments the configuration of late holocene currents in the western black sea and analogies with dispersal systems elsewhere suggest that the bulk of the fine grained muds at these sites likely came from the danube and kamchiya drainage basins where thick deposits of unconsolidated pleistocene loess have been strongly dissected to reach core sites on the sw black sea shelf this material must have been advected from the danube and kamchiya deltas by unobstructed marine currents only thin event beds tempestites of fine sand and silt in the lower part of cores mar02 45 and mar05 03 are interpreted to have a local source in the strandja mountains of thrace comparison of the palynology of surface samples from the danube delta and its associated coastal lagoons with the pre 9 1 cal ka sediments of core mar02 45 confirms that the hypothesis of deposition in a perched ancient lake is untenable

morphology and post chaudian late pleistocene evolution of the submarine danube fan complex the danube deep sea fan in the northwestem black sea has a lateral dimension of over 150 km and stretches from several hundred metres water depth down to the abyssal plain eight seismic sequences have been recognized in the fan complex each sequence consists of channel levee and overbank deposits as well as mass transport units the danube and the ukrainian rivers have aggraded two surficial channel levee systems which diverge and decrease in volume downfan the channels of these systems have a low sinuosity implying young age steep gradients and or limited sediment supply significant channel migration occurred in the course of fan development which could be largely controlled by relative sea level changes the six youngest sequences mapped have been correlated to sea level fluctuations from the post chaudian regression to the present day

seasonal interannual and mesoscale variability of the black sea upper layer circulation derived from altimeter data 1 topex poseidon and ers altimeter data comprising the period from may 1992 to may 1999 are assimilated into a shallow water model for providing a dynamically consistent interpretation of the sea surface height variations and estimation of the temporal and spatial characteristics of the upper layer circulation in the black sea these 7 year long observations offer a new capability for interpretation of major transient and quasi permanent features of the upper layer circulation the instantaneous flow fields involve a complex eddy dominated system with different types of structural organizations in which the eddies and the gyres of the interior cyclonic cell interact continuously among themselves and with meanders and filaments of the rim current the circulation possesses a distinct seasonal cycle whose major characteristic features repeat every year with some year to year variability an organized two gyre winter circulation system disintegrates gradually into a series of interconnecting eddies in the summer and autumn months which are also characterized by more pronounced and complex mesoscale activity in the peripheral flow system our analyses suggest a revised schematic circulation picture of the major quasi permanent and recurrent elements of the black sea

the impact of the late holocene coastal changes on the rise and decay of the ancient city of histria southern danube delta histria istros is one of the earliest milesian colonies founded on the black sea coast during the archaic period 7th c bc its remains are located within what is today the razelm sinoe lagoon system which forms the southern part of the danube delta during its 13 centuries of existence histria experienced an environment favourable for a prosperous economy e g fishery farming grazing pottery marine trades as indicated by numerous archeological finds from both in situ and elsewhere in the black sea and mediterranean sea basins moreover it benefited from a strategic position on an open coast which was easy to defend important environmental changes occurred both during and after the existence of the ancient city and the most significant are related to major shoreline displacement this study reports late holocene coastal landscape changes from the open coast stage to the present day lagoon system based on numerical age determination of the paleoshorelines stratigraphic records by cores in lagoons and beach ridges and topographic surveys a new chronological framework is established which reports younger ages than previously suggested for the coastal morphosedimentary units of the histria region further the findings shed new light upon the evolution of the southern part of the danube delta the results point to the development of an ancient deltaic lobe dunav lobe 2000 1300 bp associated with the southernmost danube distributary which was situated 10 20 km north of the settlement the lobe was subsequently reworked by waves providing sediments which were accumulated downdrift southward as a continuous beach ridge plain saele chituc in front of the city leading to its isolation from the sea the abandonment of histria 7th c ad coincides with the decoupling of the city from the open coast as a consequence of the shoreline progradation the new beach ridge plain saele chituc is affected by intense neotectonic movements which led to the recent drowning of its central part and the formation of sinoe lagoon the same processes affected the downdrift part of the dunav lobe and histria and nuntasi lakes the new sea level curve obtained for the histria region shows relative stability within the last four millennia with oscillations within 0 to 2 m of the current level this contradicts the concept of a marine regression phanagorian which is suggested to have occurred during the 1st millennium bc however a few areas containing archeological remains are currently below sea level owing to local neotectonics

cross shore sand transport by infragravity waves as a function of beach steepness two field data sets of near bed velocity pressure and sediment concentration are analyzed to study the influence of infragravity waves on sand suspension and cross shore transport on the moderately sloping sand motor beach 1 35 the local ratio of infragravity wave height to sea swell wave height is relatively small hig hsw 0 4 most sand is suspended during negative infragravity velocities and qig is offshore directed the infragravity contribution to the total sand flux is considerably larger and reaches up to 60 during energetic conditions on the whole hig hsw is a good indicator for the infragravity related sand suspension mechanism and the resulting infragravity sand transport direction and relative importance

holocene sedimentation in the southwestern black sea interplay between riverine supply coastal eddies of the rim current surface and internal waves and saline underflow through the strait of bosphorus abstract an extensive grid of high resolution huntec deep tow seismic reflection profiles 9150 line km complemented by 72 gravity cores and 25 piston cores reveals that the sedimentary architecture of the southwestern black sea above a prominent shelf crossing unconformity is characterized by three allostratigraphic units allounits 1b 1c 1d separated by two regional unconformities and their correlative conformities 1 and 2 a fourth allounit 1a occurs as patchy remnants between the unconformity and a deeper pleistocene erosional unconformity 0 the chronology is established using 56 radiocarbon dates in five key piston cores the unconformity developed as a ravinement surface during the transgression associated with the transition from the last glacial maximum to holocene thus defines the base of the holocene successions allounit 1b is bounded at its base and top by the and 1 unconformities correlative conformities it was deposited between 12 5 and 7 4 cal ka and shows a notably patchy but widespread distribution across the southwestern shelf allounit 1c is bounded at its base and top by the 1 and 2 unconformities correlative conformities it was deposited between 7 4 and 5 3 cal ka allounit 1d accumulated above the 2 unconformity correlative conformity and was deposited since 5 3 cal ka interpretation of radiometrically dated cores and several detailed regional maps reveal that the widespread occurrence of 12 5 7 4 cal ka deposits allounit 1b across the middle and outer shelf provides no possibility for a holocene evaporative drawdown to a lowstand elevation of 120 m at 9 4 cal ka as suggested by yanchilina et al 2017 instead the volume of detritus in allounit 1b can only be explained if base level was sufficiently high to allow major distant rivers in bulgaria and romania e g kamchiya danube to contribute mud through long distance marine transport along a submerged shelf there is no evidence in any cores which sample allounit 1b that the sites were located in limans rather than on a transgressed shelf which had been flooded by post glacial meltwater and enhanced river runoff as the climate became more humid in the early holocene a prolonged stillstand at the spill depth controlled by the sill in the strait of bosphorus is confirmed by the elevation of a drowned recurved spit downdrift from cape emine bulgaria the development of the subaqueous unconformities correlative conformities 1 and 2 was facilitated by storm induced wave erosion transport bypass and erosion under the rim current and its anticyclonic eddies and possibly breaking internal waves volumetrics based on isopach maps and pre industrial sediment discharge rates of various rivers entering the western and southwestern black sea suggest that the total sediment yields of bulgarian and turkish rivers can only account for 13 14 of the total holocene succession allounits 1b 1d and that major input from the danube river via along shelf long distance transport must have occurred through the entire holocene

combined organic and inorganic geochemical reconstruction of paleodepositional conditions of a pliocene sapropel from the eastern mediterranean sea layers of organic carbon rich sapropels in the sediment record of the mediterranean sea give evidence of repetitive changes in regional plio pleistocene climate results from biomarker molecule and major and trace element analyses of closely spaced samples are used to reconstruct the conditions leading to deposition of a pliocene sapropel at ocean drilling program odp site 969 on the mediterranean ridge organic carbon concentrations increase from 0 2 outside the sapropel and peak to more than 30 within it major and trace elemental composition and biomarker derived parameters indicate elevated productivity depletion of water column dissolved oxygen content and changes in sediment provenance in response to climatic changes budgets of rhenium thallium and other trace metals indicate that deep water exchange between the mediterranean subbasins and the atlantic ocean was not completely interrupted during sapropel formation enrichment factors of redox sensitive and sulfide forming trace metals as well as the presence of isorenieratene derivatives and high stanol sterol ratios point to an extended zone of anoxic water masses depth profiles of biomarker compositions sterols long chain alkenones alkandiols and ketols fatty acids indicate great floral diversity during deposition of a single sapropel and highlight the sensitive response of the marine community to variable environmental conditions changes in water mass circulation and eolian transport can be reconstructed by use of both lithogenic elements and average chain lengths of n alkanes acl index

sand spit dynamics in a large tidal range environment insight from multiple lidar uav and hydrodynamic measurements on multiple spit hook development breaching reconstruction and shoreline changes

linking danube river activity to alpine ice sheet fluctuations during the last glacial ca 33 17 ka bp insights into the continental signature of heinrich stadials abstract offshore archives retrieved from marine lacustrine environments receiving sediment from large river systems are valuable quaternary continental records in the present study we reconstruct the danube river activity at the end of the last glacial period based on sedimentological mineralogical and geochemical analyses performed on long piston cores from the north west black sea margin our data suggest that the danube river produced hyperpycnal floods throughout the ca 33 17 ka period four main periods of enhanced danube flood frequency each of 1 5 3 kyr duration are recorded at ca 32 5 30 5 ka equivalent to the first part of heinrich stadial hs 3 at ca 29 27 5 ka equivalent to greenland stadial 4 at ca 25 3 23 8 ka equivalent to hs 2 and at ca 22 3 19 ka based on mineralogical and geochemical data we relate these events to enhanced surface melting of the alpine ice sheet ais that covered 50 000 km2 of the danube watershed at the last glacial maximum lgm our results suggest that i the ais growth from the inner alps to its lgm position in the northern alpine foreland started from ca 30 5 ka ended no later than ca 25 3 ka and was interrupted by a melting episode ca 29 27 5 ka ii the ais volume drastically decreased from ca 22 3 to 19 ka as soon as summer insolation energy at the ais latitude increased and iii hss strongly impacted the ais mass balance through enhanced summer surface melt this together with evidence of severely cool winters and the rapid expansion of sea ice in the north atlantic implies strong seasonality in continental europe during stadials

methane derived carbonates and authigenic pyrite from the northwestern black sea abstract methane seeps in the northwestern black sea are accompanied by carbonate and pyrite precipitates sediments were sampled at locations on the romanian 120 m depth and ukrainian 180 200 m depth shelf and slope layered carbonate crusts are formed of i carbonate cemented siliciclastic sediment containing dreissenoid bivalves ii microcrystalline high mg calcite or aragonite and iii aragonitic cement the dreissena sediment is subrecent and was deposited during the freshwater phase of the black sea it has been affected by seepage of methane rich fluids which induced intergranular precipitation of authigenic carbonates the microcrystalline carbonates exhibit an intense autofluorescence high mg calcite contains 11 14 mol mgco3 the aragonitic cement 8300 9500 ppm sr forms either isopachous layers or botryoids microbial filaments about 10 20 m in diameter and up to 900 m in length are preserved within and on carbonate crusts the carbonates are depleted in 13c microcrystalline carbonate ranges from 27 to 41 pdb and botryoidal aragonite ranges from 26 to 38 pdb the 13c depletion indicates that the carbonates predominantly derive from the microbial oxidation of methane carbonate deposits do not project up into the oxic water column they are restricted to the anoxic water column and to anoxic sediments revealing the crucial role of anaerobic methane oxidation for carbonate precipitation 14c contents give apparent radiocarbon ages of 20 640 180 a bp for a sample of botryoidal aragonite and 19 110 180 a bp for a sample of microcrystalline carbonate compatible with minimum ages of carbon derived from a fossil hydrocarbon source the 18o values of methane derived carbonates show a narrow range from 1 2 to 0 2 pdb 87sr 86sr ratios of microcrystalline carbonate mean 0 70927 and aragonitic cement mean 0 70918 are indistinguishable from ambient seawater mean 0 70917 and thus indicate a shallow sr source higher 87sr 86sr ratios of the dreissena sediment mean 0 71005 are probably caused by sr derived from detrital mica carbonates are accompanied by blocks and crusts composed of pyrite the framboidal sulphide exhibits a palisade like fabric with framboids arranged to parallel pillars sulphur isotopic ratios 34s ranging from 16 8 to 19 7 cdt indicate that the sulphur derives not from the 34s depleted h2s of the water column or the uppermost sediment layers most likely pyrite formed in the lacustrine sediments after the first incursion of mediterranean seawater

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

prompt transgression and gradual salinisation of the black sea during the early holocene constrained by amino acid racemization and radiocarbon dating abstract the restricted environment of the black sea is particularly sensitive to climatic and oceanographic fluctuations owing to its connection with the mediterranean sea via the narrow bosphorus strait the exact mechanism and timing of the most recent connection between these water bodies is controversial with debate on the post glacial history of the black sea being dependent on radiocarbon dating for numerical ages here we present new 23 accelerator mass spectrometer ams radiocarbon ages on peat and bivalve molluscs supported by the first amino acid racemization aar dating of bivalve molluscs n 66 in the black sea these data indicate infilling of the black sea during the early holocene from an initial depth 107 m below sea level and 72 m below that of the bosphorus sill these data combined with a review of previous radiocarbon ages has enabled a unique perspective on the post glacial black sea a sea level curve based on conventional and ams radiocarbon ages on peat and ams based ages on dreissena sp shells indicate the water level in the earlier lake phase continued until the early holocene to be lower than the bosphorus sill after the younger dryas ended however the absence of ams dated mollusc ages from the shelves of this basin older than the younger dryas is suggestive of sub aerial exposure of the shelves and comparatively lower water levels when the younger dryas began thus post glacial outflow from the black sea occurred through a lowered or open bosphorus seaway basin wide radiocarbon ages on peat indicate a prompt increase in water level from that of the pre existing and unconnected palaeo lake during the earliest holocene 9600 9200 cal a bp mass colonisation of the black sea by mediterranean taxa did not occur until salinity had risen sufficiently a process which took 1000 a or more from the initial transgressive event this gradual change in salinity contrasts with the prompt transgression which would have taken 400 a to occur

late glacial to holocene benthic foraminifera in the marmara sea implications for black sea mediterranean sea connections following the last deglaciation benthic foraminifera were studied from four gravity cores that penetrated holocene marine sediments in the marmara sea morphogroup and assemblage analyses reveal that the holocene sea level rise did not result in a catastrophic flooding event as proposed by w b f ryan and others whereby well oxygenated saline mediterranean waters rapidly inundated a low lying low salinity black sea lake at v7 15 ka popularly known as the noah s flood hypothesis rather the benthic foraminiferal data confirm the hypothesis that the dardanelles sill was breached by the mediterranean at v12 ka allowing saline waters to penetrate the marmara sea these saline waters reached the level of the bosphorus sill at v9 5 ka but were unable to penetrate into the black sea until after v9 1 ka because of the persistent strong outflow of brackish to fresh water from the black sea the initial colonisation of the marmara sea by benthic foraminifera is essentially synchronous with the re establishment of marine connections through the dardanelles strait at v12 ka by v10 ka ammonia dominated faunas developed on the strait exit delta v1 at the southern end of the bosphorus and at v9 1 ka the appearance of fully marine species documents the establishment of a more stratified water column over v1 finally the increase in abundance of planktonic foraminifera at the southern exit of the bosphorus after v6 1 ka reflects a decreased volume of outflow water from the black sea quantitative analysis of benthic foraminiferal morphogroups reveals that the oxygen content of subhalocline water was low below v1 5 ml l throughout the holocene and the occurrence of sapropel sediment in the deeper part of the basin suggests bottom waters may have been anoxic at times after v4 5 ka an increase in benthic foraminiferal oxic morphotypes suggests a reduction in black sea outflow and weakening of the halocline the strong and persistent stratification of the water column in the marmara sea throughout the holocene is entirely incompatible with the noah s flood hypothesis 2002 elsevier science b v all rights reserved

insights into continental temperatures in the northwestern black sea area during the last glacial period using branched tetraether lipids abstract in the continental realm continuous quantitative temperature reconstructions spanning the last glacial are rare especially in central and eastern europe here we provide a reconstruction from the northwestern black sea catchment spanning 40 to 9 ka bp from a study of the relative distribution of branched glycerol dialkyl glycerol tetraethers brgdgts in black sea lacustrine sediments first the origins of brgdgts are discussed the comparison of geochemical proxies from the same core supports a dominant terrestrial origin for brgdgts during the last glacial and a strong decrease in the soil derived brgdgt proportion toward the holocene since the lowering of soil vs lacustrine derived brgdgts is prone to bias the temperature signal that is reconstructed using a soil calibration a correction for in situ production is applied the corrected signal is compared to independent discrete temperature records from the study area the brgdgt temperature relative evolution reconstructed in this work provides additional insight regarding millennial scale climate variability in central and eastern europe notably the imprints of heinrich event cold spells and lateglacial climatic oscillations are consistent with other regional paleorecords from the northern hemisphere

holocene coastal environmental changes and human occupation of the lower herault river southern france abstract sea level rise human impacts and climate change have deeply affected coastal environments during the holocene these forcing factors are studied using the lower herault valley which constitutes a very representative mediterranean case study because of i its very early intense and continuous land use since neolithic times and ii its sensitivity to sea level rise and mediterranean climate changes over a relatively small watershed 34 cores and 61 ams radiocarbon dates associated with biological and geochemical analyses have allowed us to precisely reconstruct the holocene evolution of the lower valley until 6500 cal yr bp a wave dominated morphology and retrogradational dynamics were reconstructed during this phase ephemeral channels and successive river mouths formed and were rapidly submerged by sea level rise the progradational phase began after 6500 cal yr bp and the alluvial plain gradually built seawards with the formation of a beachridge system outside the valley growth of the fertile alluvial plain was coeval with the development of neolithic agriculture this alluvial progradation gradually filled the estuary with advances of the mouths several shallow lagoons and sandbar the high density of information collected allows us to recognize for the first time a pronounced fluvial dominated deltaic morphology especially 3000 years ago during the bronze age lagoonal and coastal shores were continually inhabited human land use continually adapted to geomorphological and environmental changes around 300 years ago the delta shifted to a wave dominated system