a record of late quaternary continental weathering in the sediment of the caspian sea evidence from u th sr isotopes trace element and palynological data abstract this study presents combined mineralogical chemical isotopic 87sr 86sr and u th disequilibria series and palynological analyses on bulk sediments and on distinct mineral phases carbonates and clays from a 10 m long core drilled in the southern caspian sea and containing a late pleistocene and early holocene record the data allowed identifying 1 the main variations in sedimentation 2 the processes causing these variations 3 the modification of erosion vs weathering and 4 the influence of climatic and or caspian sea level changes in the region since the late pleistocene the chemical and mineralogical results allowed the division of the sedimentary sequence into three main units and a transition zone the lower unit unit u1 primarily consists of silicate and carbonate rich detritus sedimentation characteristics including observation of detritus in secular equilibrium are relatively constant within this unit and reflect mechanical erosion in a cold climate unit u1 probably corresponds to a glacial period when the vegetation cover was sparse and wind and river transport of pollen were strong subsequently global increase in temperatures has greatly modified the sedimentation in the caspian sea south basin biogenic sedimentation is higher in units u2 and u3 and detrital inputs varied from unit u1 variations in detrital input are likely to be caused by decreasing aeolian contribution and by relative changes in river volumes and origins the study of the bulk sediments clays and carbonates reflects an increase in chemical weathering since about 10 14c ka bp ago base of unit u2 in line with an increase in the vegetation cover our results suggest an evolution of continental weathering conditions in the catchment area of the caspian sea from dominantly mechanical physical erosion during the cold period to a continuous increase in weathering since the lateglacial period as climate improved which illustrates the strong relation between climate vegetation cover and weathering processes this paper also highlights how the u th disequilibrium series proxy combined with other geochemical and palynological studies could be a useful tool to record and constrain the modification of weathering regime in response to climatic and environmental changes at regional scale

late quaternary palynology in marine sediments a synthesis of the understanding of pollen distribution patterns in the nw african setting abstract after a review of the first steps in marine palynology we show that the understanding of the northwest african setting is crucial to evaluate the potential of marine palynological studies elsewhere we studied distribution patterns of pollen grains in recent marine sediments off nw africa and were able to clearly relate patterns to modern pollen source areas vegetation belts and operating transport systems wind belts and ocean currents in particular patterns of quercus artemisia chenopodiaceae amaranthaceae ephedra gramineae and wet forest trees are very indicative of the position of the vegetation belts on the adjacent continent aeolian pollen transport is carried out by the northeast trade winds and the african easterly jet aej in the rain forest belt transport of pollen and fern spores also occurs by rivers a detailed comparison between recent pollen rain samples from terrestrial and marine sites between 21 and 12 n showed that the latitudinal range of vegetation belts is clearly reflected in the pollen samples of both environments a migration of the southern border of the sahara is reflected by the changing ratio between chenopodiaceae amaranthaceae pollen from the desert and gramineae pollen from the savannah belt distribution patterns of pollen for 9000 and 18 000 14 c yr bp last glacial maximum time slices based on pollen records from eleven marine cores between portugal and the gulf of guinea show significant latitudinal migrations of vegetation belts but a stable position of the main wind trajectories the aej had a stable position around 21 n the belt with trade winds had a stable position from morocco southwards changing vigour of the trade winds is clearly reflected by the patterns of isopollen contours and by changes in pollen influx records

the palaeolimnology of the aral sea a review abstract formerly the fourth largest inland water body in the world the volume and area of the aral sea have decreased dramatically over the past 30 yr largely as a result of human actions throughout its approximately 2 million year history the fate of this water body has been intimately linked with that of its two main in flowing rivers the amu darya and the syr darya we present a review of the hydrological palaeontological and sedimentological evidence for the evolution of the aral sea based largely on russian literature although the structure of the aral basin can be traced back to the late neogene the sea has only existed in its present form for the past 8 10 ka and the holocene history has been shaped by regional climatic variations the development of the associated drainage system and anthropogenic forces past hydrological changes in the aral basin have led to systematic shifts in the level of the aral sea which are reflected sedimentologically through the deposition of transgressive and regressive sedimentary units and geomorphologically through the development of terraces all the above data are integrated to produced a late quaternary history of this important water body

late little ice age palaeoenvironmental records from the anzali and amirkola lagoons south caspian sea vegetation and sea level changes abstract two internationally important ramsar lagoons on the south coast of the caspian sea cs have been studied by palynology on short sediment cores for palaeoenvironmental and palaeoclimatic investigations the sites lie within a small area of very high precipitation in a region that is otherwise dry vegetation surveys and geomorphological investigations have been used to provide a background to a multidisciplinary interpretation of the two sequences covering the last four centuries in the small lagoon of amirkola the dense alder forested wetland has been briefly disturbed by fire followed by the expansion of rice paddies from ad1720 to 1800 on the contrary the terrestrial vegetation reflecting the diversity of the hyrcanian vegetation around the lagoon of anzali remained fairly complacent over time the dinocyst and non pollen palynomorph assemblages revealing changes that have occurred in water salinity and water levels indicate a high stand during the late little ice age lia from ad

atlas of modern dinoflagellate cyst distributions in the black sea corridor from aegean to aral seas including marmara black azov and caspian seas abstract we present the first comprehensive taxonomic and environmental study of dinoflagellate cysts in 185 surface sediment samples from the black sea corridor bsc which is a series of marine basins extending from the aegean to the aral seas including marmara black azov and caspian seas for decades these low salinity semi enclosed or endorheic basins have experienced large scale changes because of intensive agriculture and industrialisation with consequent eutrophication and increased algal blooms the bsc atlas data provide a baseline for improved understanding of linkages between surface water conditions and dinoflagellate cyst dinocyst distribution diversity and morphological variations by cross reference to dinocyst occurrences in sediment cores with radiocarbon ages covering the past c 11 700 years the history of recent biodiversity changes can be evaluated the seabed cyst samples integrate seasonal and multi year data which are not usually captured by plankton samples and the cyst composition can point to presence of previously unrecorded motile dinoflagellate species in the bsc results show the presence of at least 71 dinocyst taxa of which 36 can be related to motile stages recorded in the plankton comparison with sediment core records shows that five new taxa appear to have entered or re entered the region over the past century statistical analysis of the atlas data reveals the presence of four ecological assemblages which are primarily correlated with seasonal and annual surface water salinity and temperature correlation with phosphate nitrate and silicate nutrients chlorophyll a and bottom water oxygen is less clear but may be important for some taxa biodiversity indices reveal strong west east biogeographical differences among the basins that reflect the different histories of mediterranean versus ponto caspian connections the atlas data provide a standardised taxonomy and regional database for interpreting downcore cyst variations in terms of quantitative oceanographic changes the atlas also provides a baseline for monitoring further changes in the bsc dinocysts that may accompany the accelerating development of the region

quantitative estimation of holocene surface salinity variation in the black sea using dinoflagellate cyst process length reconstruction of salinity in the holocene black sea has been an ongoing debate over the past four decades here we calibrate summer surface water salinity in the black sea sea of azov and caspian sea with the process length of the dinoflagellate cyst lingulodinium machaerophorum we then apply this calibration to make a regional reconstruction of paleosalinity in the black sea calculated by averaging out process length variation observedatfourcore sites fromtheblack seawithhigh sedimentation rates anddatedbymultiple mollusk shell ages results show averygradual change of salinity from w14 0 91 psu around 9 9 cal ka bp to a minimum w12 3 0 91 psu around 8 5 cal ka bp reaching current salinities ofw17 1 0 91 psu around

river inflow and salinity changes in the caspian sea during the last 5500 years abstract pollen spores and dinoflagellate cysts have been analysed on three sediment cores 1 8 1 4 m long taken from the south and middle basins of the caspian sea a chronology available for one of the cores is based on calibrated radiocarbon dates ca 5 5 0 8 cal ka bp the pollen and spores assemblages indicate fluctuations between steppe and desert in addition there are some outstanding zones with a bias introduced by strong river inflow the dinocyst assemblages change between slightly brackish abundance of pyxidinopsis psilata and spiniferites cruciformis and more brackish dominance of impagidinium caspienense conditions during the second part of the holocene important flow modifications of the uzboy river and the volga river as well as salinity changes of the caspian sea causing sea level fluctuations have been reconstructed a major change is suggested at ca 4 cal ka bp with the end of a high level phase in the south basin amongst other hypotheses this could be caused by the end of a late and abundant flow of the uzboy river now defunct carrying to the caspian sea either meltwater from higher latitudes or water from the amu daria a similar later clear phase of water inflow has also been observed from 2 1 to 1 7 cal ka bp in the south basin and probably also in the north of the middle basin

environmental changes in shamei lagoon hainan island china interactions between natural processes and human activities abstract the sources and burial patterns of organic matter in shamei lagoon hainan china were investigated by analyzing the collected sediment cores in terms of the variations in total organic carbon toc total nitrogen tn stable carbon isotopic composition 13c and 15n and the ratio of total organic carbon to total nitrogen toc tn on such a basis the environmental evolution and primary productivity changes of the lagoon were revealed and the impacts of both natural environmental changes and human activities were identified downcore variation patterns of the parameters representing sources and burial flux of organic matter were predominantly related to natural evolution of the lagoon from 1800 to 1950 and they were increasingly affected by human activities afterwards in the period 1800 1900 the water exchange capacity of the lagoon declined substantially but it was still suitable for the growth of marine phytoplankton as is indicated by relatively high proportion and burial flux of organic matter originated from marine sources during 1900 1950 the lagoon was transformed into a freshwater environment after 1950 due to strong influence by human activities the local freshwater phytoplankton became the major source of buried organic matter at the same time marine lost its niche and its burial flux was much lower than that of its freshwater counterpart the large increment of buried freshwater organic matter also indirectly reflects the eutrophication trend since 1950

eolian sediments generated by anthropogenic disturbance of playas human impacts on the geomorphic system and geomorphic impacts on the human system abstract in many of the earth s arid and semiarid lands saline lakes playas and similar landforms are disturbed as a result of human activity diversion and or consumptive use of surface or groundwaters has created the effect of a climate change in numerous drainage basins resulting in the desiccation of lakes and reactivation of eolian processes at many locations playas are natural sites for extensive eolian activity because of the deposition of clastic and chemical sediments in basins by surface water via fluvial transport and groundwater via efflorescence wind erosion and deposition of playa sediments has had a major role in the development of landforms and sedimentary units in the present lunette fields worldwide simpson desert australia and geological past from the triassic mercia mudstone england to the quaternary lahontan basin and cima volcanic field usa anthropogenic disturbance or desiccation of playa systems has resulted in the eolian transport of sand e g lop nor china konya basin turkey rajasthan india kappakoola australia several sites in west africa and or dust e g aral sea kazakhstan uzbekistan old wives lake canada kara bogaz gol ex ussr lake texcoco mexico owens dry lake mono lake and other playas usa typically this is accomplished by abstraction of water and or removal of vegetation from terminal lake basins an extensive review of the literature documents many examples and or potential examples of such phenomena in numerous nations the reactivation of eolian processes from closed basins produces air pollution in the form of fugitive dust naturally occurring compounds released into the atmosphere by human actions and has significant environmental and economic impacts on human activities in the surrounding areas restoration or mitigation of degraded land on or surrounding playas has been accomplished at lake texcoco kara bogaz gol and the konya basin and is being actively implemented at mono lake owens dry lake and the aral sea

late pleistocene and holocene sea level change and coastal paleoenvironment evolution along the iranian caspian shore the authors published by elsevier b v this is an open access article under the cc by nc nd license http creativecommons org licenses by nc nd 4 0

a late pleistocene long pollen record from lake urmia nw iran abstract a palynological study based on two 100 m long cores from lake urmia in northwestern iran provides a vegetation record spanning 200 ka the longest pollen record for the continental interior of the near east during both penultimate and last glaciations a steppe of artemisia and poaceae dominated the upland vegetation with a high proportion of chenopodiaceae in both upland and lowland saline ecosystems while juniperus and deciduous quercus trees were extremely rare and restricted to some refugia hippophae rhamnoides constituted an important phanerophyte particularly during the late last glacial period a pronounced expansion in ephedra shrub steppe occurred at the end of the penultimate late glacial period but was followed by extreme aridity that favoured an artemisia steppe very high lake levels registered by both pollen and sedimentary markers occurred during the middle of the last glaciation and late part of the penultimate glaciation the late glacial to early holocene transition is represented by a succession of hippophae ephedra betula pistacia and finally juniperus and quercus the last interglacial period eemian slightly warmer and moister than the holocene was followed by two interstadial phases similar in pattern to those recorded in the marine isotope record and southern european pollen sequences

a two step expansion of the dinocyst lingulodinium machaerophorum in the caspian sea the role of changing environment dinoflagellate cyst assemblages were analysed in four short sediment cores collected in the south basin of the caspian sea for assessing environmental changes over the last few millennia two of these cores were dated by radionuclides the sedimentation rate of one of them was very high in the order of 20 mm per year the interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples a sharp increase in the concentration of the dinocyst occurs after 1967 especially owing to lingulodinium machaerophorum considering nine other cores covering parts or the whole of holocene it became clear that this species started to develop in the caspian sea only during the last three millennia by analysing instrumental data and collating existing reconstructions of sea level changes over the last decades we show that the main forcing for the recent increase of l machaerophorum percentages and concentration is global climate change especially sea surface temperature increase sea level fluctuations likely only have a minor impact we argue that the recent increase in l machaerophorum indicates that the caspian sea clearly is in the anthropocene

a full sea level cycle in 65 years barrier dynamics along caspian shores abstract the caspian sea being a closed basin shows much higher rates of sea level change up to 340 mm yr than the oceans it experienced a full sea level cycle with an amplitude of 3 m between 1929 and 1995 its coasts therefore present an attractive physical model to test predicted changes along oceanic coasts as a result of expected eustatic sea level rise and to validate sequence stratigraphical interpretations of ancient sediments along the wave dominated coasts with intermediate shore face slopes in dagestan low onshore bars were formed during the 1929 1977 sea level fall they represent minor short lived 1 2 years transgressive oscillations within the major regressional trend after the 1977 lowstand a prominent barrier lagoon system was formed which during the first phase of sea level rise 1977 1988 encroached landwards about 18 m each year by washover during storms continuous retreat between 1988 and 1995 however barrier size diminished lagoons widened and deepened apparently due to lack of coarse grained sediment supply discontinuous retreat the 1995 highstand prevented the barriers from being overstepped altogether sea level fall after 1995 again produced low bars without lagoons the caspian sea barrier coast demonstrates that for the formation of barrier lagoon complexes the combination of transgression and storms is essential barriers may show either continuous or discontinuous development at constant rate of sea level rise and constant offshore slope depending essentially on the availability of coarse grained sediments the rate of sea level rise as a factor in barrier behaviour cannot be viewed independently from barrier dimensions which in turn depend on wave base depth and maximum storm wave height relations between para sequence thickness and frequency and amplitude of sea level change in closed basins with an independent sea level regime may differ markedly from those in basins influenced by eustasy

natural and anthropogenic rapid changes in the kara bogaz gol over the last two centuries reconstructed from palynological analyses and a comparison to instrumental records abstract palynological analyses pollen and dinocysts of a sediment core taken in the kara bogaz gol have been used to reconstruct rapid and catastrophic environmental changes over the last two centuries chronology based on 210pb a natural cyclicity 65 years of water level changes in the caspian sea cs and in the kara bogaz gol kbg and anthropogenic factors building of a dam separating the cs and the kbg waters combine to induce rapid changes in water levels of the kbg in the salinity of its waters and in vegetation cover of its surroundings the impact of low water levels on the dinocysts is marked by a lower diversity and the survival of two species that are typical of the kbg the caspian sea species present in the kbg having disappeared during periods of higher water levels ad 1871 1878 the lake is surrounded by a steppe like vegetation dominated by artemisia whereas during periods of low water levels ad 1878 1913 and ad 1955 1998 the emerged shore are colonised by chenopodiaceae the period of ad 1913 1955 corresponding to decreasing water levels has an extremely low pollen concentration and a maximum of reworking of arboreal taxa during the last low level period humans responded by abandoning the shores of the bay what happened to the kbg can be used as an example of what may happen in the future for the aral sea a problem of reworking of tertiary dinocysts into modern deposits has been detected owing to the knowledge of the modern dinoflagellate assemblages recently made available through a water survey a comparison to modern surface pollen samples from central asia anzali caspian sea south and central basins aral sea lake balkhash lake issyk kul and the chinese tien shan range allows us to establish the potential reworking of at least five arboreal pollen taxa possibly by run off and dust storms

slope stability assessment of the helland hansen area offshore the mid norwegian margin abstract numerous large scale submarine slides affected the continental slope offshore mid norway during the holocene one of them the storegga slide is located south of the voring plateau stretching from the north sea fan to the helland hansen arch with a volume of 3200 km 3 and an influenced area of 95 000 km 2 the storegga slide which occurred about 8250 years before present bp represents one of the largest submarine slides worldwide the slope stability assessment concentrates on the northern sidewall helland hansen area where gas hydrates are suspected from the presence of a bottom simulating reflector bsr on reflection seismic data and where few slope stability investigations have been performed compared to the ormen lange area the limit equilibrium and finite element methods fem were used for the evaluation of static and dynamic seismic stabilities of the dipping seabed to account for the uncertainties in the soil parameters a probabilistic approach was applied by coupling the limit equilibrium model with the first and second order reliability methods form and sorm and the monte carlo simulation the finite element simulation for the seismic loading indicates that a strong earthquake 6 5 ms could be a potential trigger for slope failure but only down to 30 m subsurface obviously one needs a significant pore pressure build up and loosening of the sediments to explain the slide on such gentle slopes more critical preconditions to failure in the deeper sediments should exist to explain the thickness of the sliding slab knowing that the northern sidewall is approximately 150 m high cyclic loading due to a series of earthquakes could explain the slide affecting the shearing resistance in a marine clay unit weak layer by excess pore pressure generation drained conditions the degradation of undrained shear strength with cyclic loading plays a major role in the instability process

pollen plant macrofossil and charcoal records for palaeovegetation reconstruction in the mediterranean black sea corridor since the last glacial maximum new reconstructions of changing vegetation patterns in the mediterranean black sea corridor since the last glacial maximum are being produced by an improved biomisation scheme that uses both pollen and plant macrofossil data in conjunction changes in fire regimes over the same interval will also be reconstructed using both microscopic and macroscopic charcoal remains these reconstructions will allow a diagnosis of the interactions between climate fire and vegetation on millennial timescales and will also help to clarify the role of coastline and other geomorphic changes salinity and impacts of human activities in this region these new data sets are being produced as a result of collaboration between the palynology working group wg 2 within the igcp 521 project and the international palaeovegetation mapping project biome 6000 the main objective of this paper is to present the goals of this cooperation methodology including limitations and planned improvements and to show the initial results of some applications

late quaternary dinoflagellate cysts from the black marmara and aegean seas variations in assemblages morphology and paleosalinity abstract the link between sea surface salinity sss and dinoflagellate cyst morphology was studied quantitatively in cores of late quaternary mud from the black marmara and aegean seas where oxygen isotopic and planktonic foraminiferal data show salinities of about 5 19 15 22 and 36 39 ppt respectively in the black sea late glacial muds contain low diversity assemblages of the cruciform species spiniferites cruciformis and pyxidinopsis psilata with most s cruciformis cysts having expanded septal membranes form 1 circular outline form 2 irregular the assemblage is associated with surface salinities of in the northeast aegean core stenohaline species and morphotypes are rare occurring only as low percentages of s cruciformis forms 3 and 4 and o centrocarpum var truncatum in a mid holocene sapropel that was deposited during a period of high runoff and black sea water outflow marmara sea cores record surface salinities of 14 18 ppt during late glacial sapropel deposition and 20 22 ppt for the overlying marine sediments the sapropel is dominated by s cruciformis forms 1 and 2 and by p psilata with common l machaerophorum clavate and normal forms in surface sediments l machaerophorum is co dominant with o centrocarpum normal and truncate forms brigantedinium and spiniferites spp percentages of s cruciformis five forms and l machaerophorum two forms plotted against proxy salinity data however show no clear correlation indicating that morphological variation is not a simple function of salinity

from the allerod to the mid holocene palynological evidence from the south basin of the caspian sea pollen and dinoflagellate cysts have been analysed in a core from the south basin of the caspian sea providing a picture of respectively past vegetation and water salinity for the late pleistocene to middle holocene a relatively sharp lithological change at 0 86 m depth reflects a shift from detrital silts to carbonates rich fine silts from this depth upwards a holocene chronology is built based on ten radiocarbon dates on ostracod shells and bulk carbonates from the vegetation point of view the late pleistocene deserts and steppes were partially replaced in the most sheltered areas by an open woodland with pinus juniperus hippophae elaeagnus and even alnus quercus pterocarya and fraxinus related to the allerod palynozone this was interrupted by the younger dryas palynozone when artemisia reaches a maximum in a first instance followed by a very dry phase with only a slight return of pinus and quercus and the rare presence of ulmus zelkova from 11 5 to 8 4 cal ka bp an open landscape dominated by shrubs such as ephedra and progressively increasing quercus appeared the final spread of diverse evergreen and deciduous trees is delayed and occurs after 8 4 cal ka bp it is suggested that this delay is caused by an arid climate in the early holocene linked to high insolation and perhaps to a lake effect the dinocyst assemblages fluctuate between slightly brackish pyxidinopsis psilata and spiniferites cruciformis 7 psu and lower and more brackish impagidinium caspienense w13 psu in the lateglacial khvalynian highstand the assemblages remained dominated by relative low salinity taxa a late and brief increase of salinity occurred prior to 11 2 cal ka bp associated with the mangyshlak lowstand it is suggested that it was caused by a brief drop in meltwater flow from both the north and the southeast uzboy and a likely evaporation increase this lowstand occurs quasi at the same time as the end of a longer lowstand in the black sea the freshest waters are then inferred as having occurred between 8 4 and 4 4 cal ka bp linked to a connection with the amu darya and the melting glaciers on the pamir mountains

palynological evidence for climatic change anthropogenic activity and outflow of black sea water during the late pleistocene and holocene centennial to decadal scale records from the black and marmara seas abstract previous marine palynology studies of pollen and dinoflagellate cysts dinocysts in the black sea mediterranean corridor were made on short cores allowing only millennial century scale reconstruction of past climates we now describe pollen accumulation rates for 5 cores with eleven 14c ages over 30 000 years and new decadal scale data for a holocene core with fourteen 14c ages pollen influxes show pinus abies quercus forest steppe and deteriorating climate from 29 8 24 kyr bp then colder drier pre and post lgm conditions with artemisia cheno ams and ephedra that lasted through the bolling interstade deciduous oak returns by the younger dryas and rapidly expands followed by pistacia by 9 3 kyr bp foraminiferal 18o shows 4 c cooler than present late glacial summers and rapid holocene warming by 9 bp influxes from quercus cerris tilia fagus castanea ulmus shade ferns aquatics swamp plants and 18o indicate warm winters 5 c or more and year round precipitation 600 1000 mm not the dry conditions that would be required for black sea drawdown there is mid holocene expansion of carpinus evergreen quercus and pistacia walnut olive and cereal pollen suggest early cultivation attempts but no sustained farming before 4 5 kyr bp dinocyst assemblages show major changes traceable throughout the corridor variability in process length marks low diversity n 13 pleniglacial early holocene spiniferites cruciformis assemblages suggesting fluctuating salinity like the modern caspian sea with brackish to saline conditions 5 16 distributions of euryhaline cysts spiniferites mirabilis and spiniferites bentorii show the aegean and marmara seas were connected by 11 kyr bp and linked to black sea by 9 3 kyr bp there is no palynological evidence of either freshwater salinity

late pleistocene and holocene palaeoenvironments in and around the middle caspian basin as reconstructed from a deep sea core this article has been made available through open access by the brunel open access publishing fund

dinocyst records from deep cores reveal a reversed salinity gradient in the caspian sea at 8 5 4 0 cal ka bp abstract understanding the long term environmental forcings driving caspian sea cs water levels is of utmost importance not only owing to its large size or to the surrounding developing economies but also to improve global climate models and forecasts however late quaternary cs level changes and their amplitude are mostly documented from incomplete coastal sediment records because of the cs idiosyncrasies that behaves neither as a sea nor as a lake the methods used to reconstruct water levels in the global ocean or in freshwater lakes do not always apply here we propose a first step toward the use of dinoflagellate cysts records to reconstruct qualitative changes in water mass focusing on new and published deep water sedimentary sequences from the south and middle cs basins trends in water level changes are reconstructed on the relative proportions of dinocyst assemblages with different levels of brackishness a higher highstand than previously seen is reconstructed post mangyshlak lowstand a reverse water flow gradient from s to n not previously detected is identified at 8 5 8 to 4 cal ka bp a major turnover in dinocyst assemblage is found at 4 cal ka bp while the volga river is the main source of water nowadays we propose that the source of water to maintain the 8 5 8 to 4 cal ka bp highstand is the now disconnected drainage basin of the amu darya the cs was at that time most likely strongly influenced by low latitude climates with more precipitation over the karakum and perhaps even indirect monsoonal influence

high concentrations of biogenic barium in pacific sediments after termination i a signal of changes in productivity and deep water chemistry abstract high concentrations of barium have been found in sediments deposited on the chilean continental slope after glacial termination i when compared to independent proxies of paleoproductivity the pattern of biogenic barium accumulation does not match the changes in paleoproductivity in this region and cannot be explained by changes in the terrigenous supply of barium alone this leaves an increased concentration of dissolved barium in sea water as the most likely cause of the observed barium anomalies based upon the accumulation rate of biogenic barium and the paleoproductivity index which was calculated from the accumulation rates of organic carbon biogenic opal and carbonate the changes in the concentration of dissolved barium in the pacific ocean in the course of the last glacial and through the holocene could be modelled this model shows that barium concentrations in the pacific during the last glacial were comparable to today 150 nmol kg1 the highest dissolved barium concentrations were calculated for the early and middle holocene 190 nmol kg1 the resulting pattern of variations in the barium concentration in the seawater agrees well with ba ca ratios in benthic foraminifera published in the literature the observed changes are probably driven by the holocene shoaling of the pacific carbonate compensation depth which is assumed to have caused an increased flux of previously carbonate bound barium from the sediment to the deep ocean waters leading to the observed longstanding maximum of dissolved barium in the pacific during the holocene

strain degradation of saturated clay under cyclic loading soil degradation is studied from the point of view of cyclic axial strain through stress controlled triaxial tests on hangzhou normally consolidated clay different influence factors on strain such as cyclic stress ratio overconsolidation ratio and frequency are studied degradation index is redefined according to the tests a mathematical model for strain degradation is presented and verified key words cyclic loading saturated clay strain degradation mathematical model

cyclic water level oscillations of the karabogazgol caspian sea system abstract the karabogazgol kbg water level oscillations were reconstructed in the last 200 years using the geochemical evolution of the uppermost meter of its sedimentary infill high resolution studies of the mineralogical composition of the kbg sediments show alternating periods of high concentration brines followed by periods of more dilute waters the relative water level reconstruction was based on statistical models factor analysis fa correspondence analyses ca and detrended correspondence analyses dca whilst the chronological framework was established using the 210 pb technique this reconstruction was compared with the instrumental water level record of the caspian sea showing a high degree of correlation r 2 0 83 the agreement between the reconstructed and the measured water level oscillations of the caspian sea indicates that environmental changes can be reconstructed from closed lakes provided that an accurate chronological control of sedimentary processes is available the water level reconstruction shows that the caspian sea water level fluctuations follow a cyclical pattern rather than an erratic one as has been suggested in the literature two main periodicities of 62 5 and 38 46 years have been found

rapid evolution of coastal lagoons in response to human interference under rapid sea level change a south caspian sea case study this research is part of the phd of the first author entitled evaluation of sefidrud delta south west caspian sea during the last millennium which was funded by brunel university london grant no r85104 the publication is a contribution to the inqua quicklakeh project no 1227 and to the european project marie curie climseas pirses ga 2009 247512

holocene vegetation history and sea level changes in the se corner of the caspian sea relevance to sw asia climate the palynological investigation of core tm 27 7 m long taken in a dried out lagoon reveals both holocene vegetation history in the north eastern foothills of the alborz mountains and past water level changes of the caspian sea cs the delay in woodland expansion at the beginning of the holocene which is typical of eastern turkey the iranian plateau and recorded in the cs south basin is only weakly felt as the region is close to glacial refugia of trees the succession of the main trees out of their refugia has been established as deciduous quercus carpinus betulus parrotia persica and fagus orientalis pterocarya fraxinifolia presenting therefore close affinities to south european interglacials of the early pleistocene this suggests a similarity in climate a pterocarya decline is observed after ad 495 the studied region is close to the easternmost tree distribution this could explain why it has been affected earlier than elsewhere in the northern alborz and the caucasus in addition human activities during the sasanian empire and the subsequent drying of the climate contributed to weakening the spread of this tree a maximal sea level occurs in the first part of the holocene from 10 6 to 7 2 cal ka it is suggested that the cs levels were significantly influenced by the monsoon precipitations over the western himalayas via the uzboy inflow this is followed by low levels from 7 2 to 3 5 cal ka with a minimum at 3 9 cal ka the neocaspian period should be considered a biozone rather than a chronozone as the environmental conditions reconstructed from dinocyst assemblages are different in shallow shelf waters and in the deep basins