reconstructing biomes from palaeoecological data a general method and its application to european pollen data at 0 and 6 ka biome models allow the results of experiments with atmospheric general circulation models to be translated into global maps of potential natural vegetation the use of biome models as a diagnostic tool for palaeoclimate simulations can yield maps that are directly comparable with palaeoecological pollen and plant macrofossil records provided these records are biomized i e assigned to biomes in a consistent way this article describes a method for the objective biomization of pollen samples based on fuzzy logic pollen types taxa are assigned to one or more plant functional types pfts then affinity scores are calculated for each biome in turn based on its list of characteristic pfts the pollen sample is assigned to the biome to which it has the highest affinity subject to a tie breaking rule modern pollen data from surface samples reflecting present vegetation across europe are used to validate the method pollen data from dated sediment cores are then used to reconstruct european vegetation patterns for 6 ka the reconstruction shows systematic differences from present that are consistent with previous interpretations the method has proved robust with respect to human impacts on vegetation and provides a rational way to interpret combinations of pollen types that do not have present day analogs the method demands minimal prior information and is therefore equally suitable for use in other regions with richer floras and or lower densities of available modern and fossil pollen samples than europe

palynomorph distribution in recent sediments from the labrador sea surface sediments from the labrador sea and baffin bay have been examined for their palynomorph content pollen and spore assemblages reflect the vegetation zones of eastern canada although long distance atmospheric transport results in over representation of pinus and spores a linear decrease of pollen input is observed with distance from the source vegetation the abyssal domain receives less than 2 of the initial input the abundance of dinoflagellate cysts reflects a relatively high primary productivity in surface water masses which seems proportional to the benthic productivity as shown by the concentrations of organic linings of foraminifers the relative abundance of dinoflagellate cyst taxa and principal component analysis led to the definition of three assemblages that can be related to sea surface conditions and current pattern the modern distribution of dinoflagellate cysts was used to interpret assemblages recovered in five box cores from the deep labrador sea results reveal important ch

glacial hydrologic conditions in the black sea reconstructed using geochemical pore water profiles abstract chloride and 18 o compositions of interstitial water extracted from a long sediment core retrieved from the nw coast of the black sea allowed us to constrain the main hydrologic changes of the back sea during the late pleistocene and holocene prior to its reconnection with the mediterranean sea through the marmara sea at approximately 9000 calendar yr before present 9 ka cal bp the black sea has evolved as a fresh to brackish water lake at the time of reconnection hydrologic changes were drastic bottom water salinities changed from a few psu practical salinity unit to 22 psu since solutes in the interstitial water column within sediments are advected and diffused the measured concentrations do not reflect those of past bottom waters in order to reconstruct these former concentrations we used an advection diffusion model different scenarios of bottom water chloride and 18 o variations were accounted for in this model in order to simulate present day vertical profiles for concentrations of interstitial water in order to compare them to measured ones the comparison suggests that the glacial black sea was a homogeneous freshwater lake with a 18 o of 10 and a salinity of 1 psu modern hydrologic conditions would only have been reached at 2 ka cal bp concomitant with the onset of coccolith rich thin layers that characterize modern basin sediments such delayed salinization over 7000 yr in the basin may have been due to higher precipitation during the early holocene we also simulated the impact of a catastrophic reconnection and a smoother reconnection both salinity scenarios lead to undistinguishable modelled present day profiles indicating that the precise impact of the last reconnection was lost due to the advection diffusion processes

late quaternary history of the marmara sea and black sea from high resolution seismic and gravity core studies abstract lithologic and multi proxy paleoenvironmental data from 21 dated cores have been used to define three allostratigraphic units allounits within the late quaternary successions of the marmara sea and black sea allounits are bounded by unconformities and their correlative conformities in both regions allounit a extends from the seafloor downward to a 12 11 ka sequence boundary which is a major shelf crossing unconformity in water depths less than 100 110 m in deep basins of the marmara sea the lower part of allounit a designated subunit a2 is a laminated sapropel m1 on the shelf subunit a2 consists of backstepping delta lobes and early transgressive barrier islands and sand sheets allounit b has only been recovered in marmara sea cores collected at water depths greater than 90 m and represents basinal or prodeltaic deposition during the 23 12 ka late pleistocene lowstand during the last glacial maximum the shelves surrounding the marmara sea were subaerially exposed and deltas of allounit b accumulated along the present day shelf edge following the post glacial rise of global sea level to 75 m at 12 ka the marmara sea quickly became inundated and thereafter rose in synchroneity with the mediterranean by 10 ka the black sea rose to start spilling into the marmara sea leading to establishment of a brackish water lid that has persisted to the modern day the strongest black sea outflow began at 10 ka and persisted to 6 ka promoting the accumulation of sapropel m1 in the deep marmara sea and progradation of an overflow delta just south of the exit from the bosphorus strait allounit c is a laminated sapropel m2 in basinal cores dated at 30 23 ka like m1 it is believed that m2 accumulated during a period of increased brackish water input into the marmara sea mainly from the black sea in the black sea wave erosion kept the shelf stripped of unconsolidated sediments during the falling sea level associated with the last glaciation and subsequent early stages of the post glacial holocene transgression this erosion created a major unconformity shelf edge deltas of allounit b received their sediment during the last lowstand from small rivers that likely coalesced into a single system toward the shelf edge at modern water depths of 100 to 110 m these deltas were active until 11 10 5 ka subsequently sea level in the black sea rose to 40 m by 10 ka and a set of backstepping barrier islands developed on the shelf as part of the associated transgressive systems tract once water level reached 40 m continued sea level rise stalled until 9 ka as the black sea began to spill across the bosphorus strait into the marmara sea

the younger dryas in the eastern mediterranean abstract the younger dryas period is traced in pollen diagrams of the eastern mediterranean by means of radiocarbon dates the biostratigraphy in terms of pollen assemblages is compared with the absolute time scale the younger dryas as a pollen assemblage zone is at best vaguely visible in those parts that at present carry steppe or other open vegetation the part that nowadays carries forest produces pollen zones including the younger dryas which resemble those of parts of europe palynological developments in parts of the eastern mediterranean differ appreciably which implies that the vegetation developed differently also this suggests that the climatic development in the various parts of the region was not the same

palynostratigraphy and vegetation characteristics of neogene continental deposits interbedded with the cappadocia ignimbrites central anatolia turkey a palynological analysis of the late miocene and early pliocene successions of the cappadocian volcanic province central anatolia turkey has been carried out with the aim of reconstructing the palaeovegetation and palaeoclimatic conditions the samples are collected from outcrop sections from three different localities a akdag b bayramhacili and g guzeloz the pollen spectra reveals the existence of a steppe vegetation dominated by amaranthaceae chenopodiaceae and artemisia typical of present day arid and semi arid continental areas i e middle east and asteraceae asteroideae in the a section late miocene developed in arid climatic conditions the flora of the g early pliocene and lower part of the b late miocene sections reflects steppes on which asteraceae asteroideae was dominant this flora also indicates arid conditions the development of trees in the upper part of the b section was possibly related to local paleoenvironmental conditions rather than a climatic change this study provides the first palynological data to reveal the presence of an amaranthaceae chenopodiaceae and artemisia steppe already during the late miocene in turkey

first high resolution marinopalynological stratigraphy of late quaternary sediments from the central part of the bulgarian black sea area abstract spores pollen and dinoflagellate cysts of late pleistocene and holocene sediments were analyzed from giant gravity core 18 from the black sea continental slope recovered from a water depth of 971 m the investigated length of the core is 203 5 cm it includes 3 lithological units light grey clay sapropels and coccolith bearing ooze the core was sampled at 5 10 cm intervals sampling of the interval 141 5 126 cm was carried out at every cm ams radiocarbon dating of bulk organic carbon was performed on 18 selected sediment layers this chronological data allowed the first high resolution pollen stratigraphy of late quaternary sediments from the western black sea area to be presented the percentage spore pollen diagram is divided into 6 local pollen assemblage zones the trends in the vegetation dynamics and climate changes and the early history of migration of the majority of the arboreal taxa that nowadays occur in the eastern balkan range were traced out the palynological record suggests that open oak forests were spread in the eastern balkan range at the beginning of the holocene and shows early migration of the major temperate arboreal species such as quercus ulmus tilia and carpinus betulus this vegetation palaeosuccession continues with the spreading of mixed oak forests from 8950 until 2620 cal bp 8650 40 until 3120 35 14c bp followed by destructive changes due to human impact and climate deterioration a cooling of holocene climate that is well known in the north atlantic region as the 8200 yrs cold event is identified for the first time in marine records from the bulgarian black sea area the assemblages of dinoflagellate cysts and acritarchs were investigated to provide a reconstruction of surface seawater salinity and surface seawater temperature changes two main dinoflagellate cyst assemblages one dominated by fresh to brackish water species such as spiniferites cruciformis and pyxidinopsis psilata and a subsequent one that is characterized by euryhaline marine mediterranean species such as lingulodinium machaerophorum spiniferites belerius spiniferites bentorii operculodinium centrocarpum and acritarchs cymatiosphaera globulosa testified a change in sss from low salinity

aspects of carbon isotope biogeochemistry of late quaternary sediments from the marmara sea and black sea abstract the marmara sea is situated between the world s largest permanently anoxic basin the black sea and an enclosed marginal sea the aegean sea which experienced quasi periodic sapropel deposition since miocene time it is connected to the black sea and the aegean sea through the straits of bosphorus and dardanelles respectively sapropel m1 which contains from 1 to 2 total organic carbon was deposited in the marmara sea between 6 and 10 5 ka we inferred the carbon isotopic composition of dissolved inorganic carbon dic in the water column of the marmara sea before during and after the deposition of sapropel m1 from the carbon isotopic composition of a planktonic foraminifera turborotalita quinqueloba and individual hexadecanoic and octadecanoic fatty acids the period of sapropel deposition is marked by a depletion of 13 c in the water column dic contrary to what may be expected if sapropel deposition represents a period of enhanced primary productivity instead we propose that both the relative 13 c depletion of dic during sapropel deposition and the absolute values we estimated 13 c 13 to 14 are consistent with enhancement of the relative contribution of 13 c depleted respired carbon to the water column dic pool such enhancement possibly resulted from density stratification that existed during sapropel m1 deposition the existence of density stratification is also argued from palynological and other lines of evidence other papers in this issue and is believed to have resulted from the encroachment of black sea water into the sea of marmara before 10 000 yr ago thus sapropel m1 appears to have formed during periods of enhanced runoff and preservation and not enhanced primary productivity

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

pollen distribution in recent marine sediments eastern canada analysis of 90 samples from coastal and continental shelf areas off eastern canada between 42 and 69 n shows that quaternary pollen and spores are present in recent marine muds throughout this region pollen and spore concentrations range from 50 000 to 100 grains per cm3 and they decrease both offshore as a function of distance from vegetation sources and northwards as a function of lower vegetation density north of the summer arctic frontal zone isopercentage contours show that maximum relative abundances of most palynomorphs occur in marine sediments adjacent to their regions of highest vegetation representation onshore however pinus and picea pollen tend to increase in percentage abundance with distance offshore presence of these tree pollen in marine sediments off baffin island implies that wind transport is an important pathway by which bisaccate pollen types enter the ocean in addition to fluvial transport q mode factor analysis shows that four major factors account for 89 of the variance amo

modeling of cretaceous foreland basin parasequences utah with implications for timing of sevier thrusting computer modeling suggests that thrusting order can be discriminated on the basis of foreland basin geometry and parasequence stacking patterns the position of sequential thrust sheets relative to the basin affects the amount and distribution of subsidence source terrain elevation and distance from the shoreline and sediment transport into the basin for this study a forward numerical model was constructed to quantitatively simulate the interaction of geologic processes active in the foreland basin setting including thrusting and orogenic development lithospheric flexure orogenic denudation sediment transport across the coastal plain and nearshore deposition in order to isolate the effects of tectonics and sediment supply on nearshore deposition eustatic sea level is held constant model runs simulate two different thrusting sequences foreland stepping in sequence and hinterland stepping out of sequence when in sequence thrusting is modeled sediment is trapped in intra orogen basins because sediment is prevented from reaching the shoreline the basin is underfilled when out of sequence thrusting is modeled sediment is transported from the orogen to the shoreline episodes of thrusting result in subsidence and marine flooding surfaces and resulting accommodation space allows for parasequence development comparing model output to stratigraphy observed in eastern utah suggests that late cretaceous out of sequence uplift and thrust loading resulted in aggradational and progradational parasequence stacking in the campanian blackhawk formation this result supports the theory that the pavant thrust system was active prior to deposition of the blackhawk formation and that the location of thrust shortening shifted toward the hinterland prior to or during blackhawk formation deposition

vegetation and climate in southern hemisphere mid latitudes since 210 ka new insights from marine and terrestrial pollen records from new zealand abstract paleo vegetation records developed from marine sedimentary sequences offer considerable potential for examining changes in terrestrial climate beyond the range of 14 c dating because they can be independently dated by 18 o stratigraphy here we present the first pollen record of vegetation from a marine core site in the tasman sea tan0513 14 42 18 s 169 53 e 110 km west of new zealand s south island an independent chronology provided by correlating the globigerina bulloides 18 o record at tan0513 14 to a global isotope stack shows that the record extends back to 210 ka glacial to interglacial changes in palynomorph content are characterised by shrub and podocarp broadleaf forest taxa respectively and are correlated with similar changes in the ca 150 kyr long terrestrial pollen record from okarito pakihi bog 110 km to the south southeast both records are placed on the same timescale by matching variations in dacrydium cupressinum and fuscospora between sites with a unique tie point provided by the ca 25 4 ka kawakawa tephra our southern hemisphere mid latitude vegetation records show forest extent is greatest during periods of low ice volume high mean annual sea surface temperature masst and anti phased with local insolation intensity however there are several features not attributable to changes in mean annual temperature first a fundamental change in forest composition occurred at termination ii tii with a loss of southern beech nothofagus from the study area second the amplitude of masst change through mis 5 is not reflected in corresponding changes in forest extent suggesting other feature s of regional climate seasonality frostiness ice cover exert important controls over vegetation patterns at these latitudes

vegetation and climate of anatolia and adjacent regions during the last glacial period abstract reinterpretation of vegetation and climatic conditions of anatolia and neighboring regions during last glacial 30 15 cal ka bp have been done using a non quantitative biomization approach based on previously published plant functional types the results suggest that the climate was cold and humid before 25 cal ka bp and also during the period 23 19 cal ka bp except east anatolia forest vegetation was 80 90 of the land cover in the northwestern anatolia and black sea coast and 50 60 along the mediterranean coast at the same period during heinrich event 2 from 25 to 23 cal ka bp steppe vegetation dominated the anatolian region due to the sudden change to very cold and arid conditions approximately between 18 and 16 cal ka bp in the late glacial during heinrich event 1 a brief interval of cold and arid conditions resulted in weaker steppe vegetation over some part of anatolia around at 15 cal ka bp suitable climatic conditions for forest vegetation prevailed across a great part of anatolia except for eastern anatolia and western iran which are highlands

age palaeoenvironments and climatic significance of late pleistocene konya lake turkey abstract the konya basin a closed depression at the southern margin of the anatolian plateau contained a shallow but extensive lake during the late quaternary nearshore sands and gravels containing dreissena shells form prominent depositional terraces around the basin edges at elevations between 1005 and 1020 m and the highest has been dated at more than 30 000 yr b p the last major phase of limnic sedimentation occurred between 23 000 and 17 000 yr b p after which the lake fragmented into a number of subbasins or secondary depressions which evolved to become either marshes or playas a final expansion of these residual lakes has been dated to ca 11 000 yr b p in one secondary depression archaeological and other evidence indicate that only minor lake level fluctuations occurred during the holocene the dominant sedimentary process over the last 10 000 years has been alluviation at the basin margin the konya sequence confirms that the most recent period of high lake levels in the northern near east was of the last glacial age the palaeolakes of anatolia and iran were however more a product of reduced evaporation brought about by temperature depression than of changes in precipitation and thus belie their often used description as an indicator of pluvial climatic conditions

freshwater chlorophycean algae in recent marine sediments of the beaufort laptev and kara seas arctic ocean as indicators of river runoff freshwater chlorophycean algae are characteristic organic walled microfossils in recent coastal and shelf sediments from the beaufort laptev and kara seas arctic ocean the persistent occurrence of the chlorophycean algae pediastrum spp and botryococcus cf braunii in marine palynomorph assemblages is related to the discharge of freshwater and suspended matter from the large siberian and north american rivers into the arctic shelf seas the distribution patterns of these algae in the marine environments reflect the predominant deposition of riverine sediments and organic matter along the salinity gradient from the outer estuaries and prodeltas to the shelf break sedimentary processes overprint the primary distribution of these algae resuspension of sediments by waves and bottom currents may transport sediments in the bottom nepheloid layer along the submarine channels to the shelf break bottom sediments and microfossils may be incorporated into sea ice during freeze up in autumn and winter leading to an export from the shelves into the deep sea the presence of these freshwater algae in sea ice and bottom sediments in the central arctic ocean confirm that transport in sea ice is an important process which leads to a redistribution of shallow water microfossils

the distribution and relationship between palynomorphs in aerosols and deep sea sediments off the coast of northwest africa abstract palynomorphs in eolian dust and bottom sediments from the northeastern atlantic off the coast of northwest africa were studied primary examination was for terrestrial plant detritus pollen spores opal phytoliths and freshwater diatoms but observations about marine entities were also made three distinct geographic palynofloras were detected a northern palynoflora consisting of pollen derived primarily from the mediterranean basin a central or saharan palynoflora characterized by pollen derived from desert plants and a southern tropical equatorial palynoflora composed of pollen derived from tropical plants but including up to 50 allochthonous pollen from the drier interior of west africa palynomorph distributions are related closely to both source vegetation and to atmospheric and oceanic transport mechanisms and in many cases distribution patterns in bottom sediments and aerosols are complementary the quantity of pollen and spores per gram of bottom sediment ranges from greater than 2000 off the saharan coast in mauritania to less than 50 in deep ocean basins pollen and spores in mediterranean aerosols may exceed 40 per cubic meter of air during the summer and range between 4 to 6 for tropical aerosols during the winter tropical aerosols and bottom sediments contained the greatest abundance of fungal spores the distribution of opal phytoliths and freshwater diatoms in both aerosols and bottom sediments indicates that dust storms are a major transporting agent for these entities from the interior of west africa to the gulf of guinea these storms are also an important agent for the transport of pollen to the tropical atmosphere distances of transport may exceed 5000 km for mediterranean pollen and even greater distances for palynomorphs in eolian dust from interior west africa the abundance of dinoflagellates and microforaminifera in bottom sediments is directly related to the area of upwelling off the west african coast

holocene sedimentation in the tectonically active tekirdag basin western marmara sea turkey abstract the effects of various depositional conditions and active tectonics on the late holocene sedimentation in the tekirdag basin west of the marmara sea were investigated in 11 gravity cores and on 3 seismic profiles representing shelf to slope to deep basin floor environments except for the two coarser grained avg 60 sand and gravel and calcareous avg 25 caco 3 shelf cores sediments in the slope and basin floor cores constitute low calcareous avg 12 caco 3 and terrigenous mud 90 silt and clay the occurrences of relatively higher total organic carbon contents in sediments from the southern slope 1 14 1 38 compared to that from the northern slope 0 37 1 2 indicate significant input from the southern rivers the presence of silty sandy laminations within the mud matrix of the cores and chaotic and mounded reflection configurations on the seismic profiles from the slope and basin floor environments all suggest the effects of gravity mass movements of sediments slides slumps turbidites most likely due to seismotectonic events earthquakes however it was difficult to establish a basin wide correlation between the historical earthquake events in the region and the positions of silty sandy laminations in dated deep sea sediment cores due to complicated other events such as repeated river run off and floods increased sediment load and slope failure the water contents of sediments from the basin floor avg 10 30 are significantly lower than those from the slope sediments avg 32 46 the former can be explained by the influences of synsedimentation with tectonics and compaction between the north and south boundary sub faults of the naf system whereas the latter shows fluidization of slope sediments during sliding and slumping radiocarbon dated base sections from three cores revealed that sediment deposition at these sites commenced about 4700 bp when the late holocene depositional conditions changed from the formation of upper sapropels to the present state the increases of organic carbon contents at or near the base sections of the cores support this contention

dinoflagellate cysts freshwater algae and fungal spores as salinity indicators in late quaternary cores from marmara and black seas abstract seismic profiles and mollusks have been used to suggest that from 12 500 to 7000 yr bp the black sea was an isolated freshwater lake containing potable water and implying a surface salinity of 24 and that spiniferites cruciformis spiniferites inaequalis peridinium ponticum polykrikos spp and quinquecuspis concreta characterize the lower salinity of the marmara and or black seas the core top data and correlatable down core assemblage changes in time equivalent sapropelic and brown muds show that there is no evidence for differential aerobic decay of dinocysts in the study area the main acritarchs are sigmopollis psilatum concentricystes cf c rubinus and cf acritarch 8 of traverse 1978 all of which are absent from the aegean sea and decrease in abundance with increasing salinity the first two taxa have been reported previously as freshwater species fungal remains show a similar distribution pattern to the freshwater acritarchs indicating their origin from terrestrial environments freshwater chlorococcales are almost confined to the black sea but they have rare occurrences in the aegean indicating long distance transport microforaminiferal linings are abundant in the marmara sea but are absent in deep water of the black sea in the marmara sea mid late holocene assemblages

climate proxies for the last 17 3 ka from lake hazar eastern anatolia extracted by independent component analysis of μ xrf data abstract the elemental composition of lake sediment cores is often the result of several independent processes in this study we attempt to extract statistically independent climate related signals from xrf multi element data of a core drilled from lake hazar in eastern anatolia using the independent component analysis ica method in addition we analysed ostracod shells for oxygen and carbon isotopes the ica method has advantages over traditional dimension reduction methods such as principal component analysis or factor analysis because it is based on maximal statistical independence rather than uncorrelatedness where independence is a stronger property the hz11 p03 core which represents the last 17 3 ka was recovered from lake hazar which at times formed the headwaters of the tigris applying the ica method we selected two out of six independent components by measuring distance correlation similarity we propose that one of the selected components can be read as a proxy for temperature and the other for precipitation in this region our results indicate that the region was relatively cold and wet during the late glacial between 17 3 and 14 8 ka bp and wet and warm during bolling allerod the lake level dropped below today s level during the younger dryas stadial 12 49 and 11 76 ka bp forming a marked hiatus in the core s stratigraphic record during the beginning of the holocene while precipitation values were high the temperature gradually increased until 8 ka bp between 8 and 5 ka bp the region was warm but extremely dry after 5 ka bp around 3 5 ka bp temperatures suddenly fell and three abrupt dry phases are observed around 3 5 ka and 2 8 ka and 1 8 ka bp

oscillating quaternary water levels of the marmara sea and vigorous outflow into the aegean sea from the marmara sea black sea drainage corridor abstract detailed interpretation of single channel air gun and deep tow boomer profiles demonstrates that the marmara sea turkey experienced small amplitude 70 m fluctuations in sea level during the later quaternary limited in magnitude by the sill depth of the strait of dardanelles moderate subsidence along the southern shelf and quaternary glacio eustatic sea level variations created several stacked deltaic successions separated by major shelf crossing unconformities which developed during the transitions from global glacial to interglacial periods near the strait of dardanelles a series of sand prone deposits are identified beneath an uppermost holocene transparent mud drape the sandy deposits thicken into mounds with the morphology and cross sectional geometries of barrier islands sand waves and current generated marine bars all cross stratification indicates unidirectional flow towards the dardanelles prior to the deposition of the transparent drape which began 7000 years bp in strong support of the notion that the marmara sea flowed westwards into the aegean sea through the dardanelles at times of deglaciation in northern europe the global sea level curve shows that at 11 000 and 9500 years bp sea level rose to the sill depths of the straits of dardanelles and bosphorus respectively the effect from 11 000 to 9500 years bp was seawater incursion into the marmara sea drowning and formation of algal serpulid bioherms atop lowstand barrier islands and transgression of shelves and lowstand deltas at 9500 years bp glacial meltwater temporarily stored in the black sea lake developed into a vigorous southward flow toward the aegean sea forming west directed sandy bedforms in the western marmara sea and initiating deposition of sapropel s1 in the aegean sea this strong outflow persisted until 7000 years bp after which a mud drape began to accumulate in the marmara sea and euryhaline mediterranean mollusks successfully migrated into a progressively more saline black sea where sapropel deposition began most eastern mediterranean sapropels from s1 to s11 appear to correlate with periods of rising sea level and breaching or near breaching of the bosphorus sill these events are believed to coincide with times of vigorous outflow of low salinity fresh surface waters transiting the black sea marmara sea corridor and ultimately derived from melting of northern european ice sheets

late glacial holocene climate variability at the south eastern margin of the aegean sea abstract new micropaleontological palynological and geochemical results from a relatively shallow 500 m sediment core ns 14 in the south eastern aegean sea provide a detailed picture of the regional expression of sapropel s1 formation in this sub basin of the eastern mediterranean sea specifically freshwater input during 10 6 10 0 ka bp has preceded the deposition of s1 further decrease in surface water salinity is evidenced between 10 0 and 8 5 ka bp at the lower part of s1a which in respect to s1b is featured by warmer 19 5 c and more productive surface waters associated with dysoxic bottom conditions a series of coolings detected within the s1 depositional interval may be linked to outbursts of cold northerly air masses and relevant pulses in the deep intermediate water ventilation that caused the s1 interruption between 7 9 and 7 3 ka bp and culminated during the deposition of s1b with the decline of deep chlorophyll maximum dcm at 6 5 ka bp the climate instability and the relevant absence of anoxia weakened the organic matter preservation in the shallow south eastern aegean margin during the s1 times ns 14 record provides evidence for a distinct mid holocene warm up to 25 c and wet phase associated with the deposition of the sapropel like layer smh sapropel mid holocene between 5 4 and 4 3 ka bp the smh layer could represent evidence of on going albeit weak african monsoon forcing only expressed at the south eastern edge of the aegean sea its end is associated with the 4 2 ka bp northern hemisphere mega drought event and the termination of the african humid period at 3 8 ka bp

pollen stratigraphy of late quaternary cores from marmara sea land sea correlation and paleoclimatic history marine pollen analysis is an important tool for paleoclimatic reconstruction of regions like the eastern mediterranean and near east where few onshore sites provide long pollen records first a compilation was made of core top data from the eastern mediterranean to blackseas to map regional variations in modern marine pollenspore concentrations these data show a strong linkbetween pollen spore concentrations and sea surface salinity with minima of 5 grains g in the southern mediterranean and maxima of 160 000 grains g in the blacksea despite under representation of some forest and herbaceous vegetation indicators e g fagus and pistacia variations in species composition of the marine assemblages correspond closely with the distribution of regional vegetation zones and can be used as proxies for spatial differences in seasonal and total temperature and rainfall pollen spore assemblages in five cores from the marmara sea with multiple ages ranging from 33 550 to 1990 yr bp and one holocene core from southeastern blacksea were used to compile a late quaternary marine pollen stratigraphy these data were then compared with eastern mediterranean onshore reference sites in order to reconstruct a vegetation and paleoclimate history for the blacksea aegean corridor from the pleniglacial interval to present five marine pollen zones are recognized pz 5 v33 6 24 ka corresponds to the late wu rm pleniglacial pz 4 v24 13 ka spans the late glacial maximum lgm pz 3 v13 10 2 ka includes the allero d younger dryas glacial interglacial transition pz 2 10 2 4 ka marks the early holocene interglacial warm wet interval and pz 1 covers the latest holocene colonization phase which may also have been cooler and drier using the steppe forest index of traverse 1975 it is shown that the only intervals of severely dry conditions occurred briefly during the lgm and its transition during most of the pleniglacial and all of the postglacial time precipitation versus evaporation rates were sufficiently high to permit persistence of oro mediterranean forest vegetation furthermore there is no evidence for environmental conditions in the blacksea marmara region that would have encouraged pastoral or agricultural settlement in the littoral region prior to the bronze age commencing 4600 years ago crown copyright a 2002 elsevier science b v all rights reserved

organic geochemical and palynological evidence for terrigenous origin of the organic matter in aegean sea sapropel s1 abstractorganic geochemistry and micropaleontology are used to determine the origin of sapropel s1 in the aegean sea low molecular weight c 15 c 17 and c 19 n alkane data show that net primary productivity npp increased from 14 000to 10 000 yr bp at the glacial interglacial transition but the onset of s1 at 9600 yr bp marks a sharp decline in npp whichremained low until 8200 yr bp the start of sapropel deposition is marked by increased total organic carbon toc and pollen spore concentrations together with increased high molecular weight c 27 c 29 c 31 and c 33 n alkanes pollenassemblages show large in ux of tree pollen from central northern european forests increases in high molecular weightn alkanes suggest greater in ux of fresh vascular plant material at the start of s1 although the amount is small comparedto other insoluble organic matter palynological studies showed that most of this insoluble organic matter are ocksof dark brown amorphous kerogen typical of terrigenous humic compounds from 8200 yr bp to the top of s1at 6400 yr bp there is a decline in high molecular weightn alkanes and terrigenous kerogen and an increase inlow molecular weightn alkanes suggesting that npp recovered during the later deposition of s1 in the aegean sea theincrease in low molecular weightn alkanes coincides with the recovery of coccolithophores and dino agellates suggestingthat these phytoplankton are primarily responsible for the low molecular weightn alkane variations these data from theaegean sea support the model for sapropel deposition resulting from increased in ux of toc during times of stagnantbottom water but disagree with mediterranean models prescribing a large increase in marine productivity 1999 elsevierscience b v all rights reserved keywords sapropel s1 aegean sea fatty acids n alkanes palynology

late quaternary pollen transport processes western north atlantic data from box models cross margin and n s transects abstract surface pollen assemblages in coastal and neritic sediments of the western north atlantic compare well with eastern north american vegetation zones and late quaternary pollen in marginal marine sediments clearly correlate with changes in terrestrial vegetation and paleoclimates in contrast offshore assemblages are strongly affected by differential adaptation of pollen to long distance transport by wind and water marine pollen transport processes were studied by measuring air and water inputs to a coast shelf box model and by study of surface samples from cross margin transects in three different climatic and oceanographic regions at approximately 38 45 and 55 n latitude the box model shows that aerial transport is the main process by which pollen moves across the continental margin off nova scotia two clear seabed distribution patterns were found betula quercus and herb pollen decrease rapidly offshore in abundance grains per cubic centimetre and in relative abundance percentage pinus and picea have abundance peaks on the continental margin but percentages increase further offshore distributions of the main pollen and spore taxa were compared for late wisconsinan glacial oxygen isotopic stage 2 12 28 ka terminal pleistocene 10 12 ka and holocene sediments at 5 continental margin and 3 deep sea sites the largest changes were found in percentages of pinus picea and herb pollen during the late wisconsinan glacial and terminal pleistocene intervals at subpolar latitudes these data can be related to shifts in paleo vegetation winds and hydrology that accompany global climate change

mediterranean vegetation lake levels and palaeoclimate at the last glacial maximum the apparent conflict between pollen evidence for widespread artemisia steppe1 6 implying semi arid conditions and geomorphological evidence for high lake levels4 7 11 has produced controversy about the ice age palaeoclimate of the mediterranean region here we use a water balance model12 to predict catchment runoff and a biome model13 to predict vegetation type to reconstruct the palaeoenvironment around lake loannina a type locality for the northern mediterranean region we show that both sets of evidence are compatible with a summer dry winter wet regime with seasonal temperature anomalies similar to those predicted by atmospheric model simulations of the last glacial maximum14 18 the drying effect of the cold north atlantic ocean may have been counteracted in winter by increased storm frequency under a southward shifted jet stream as shown by several atmospheric models16 18

last glacial holocene paleoceanography of the black sea and marmara sea stable isotopic foraminiferal and coccolith evidence multi proxy data and radiocarbon dates from several key cores from the black sea and marmara sea document a complex paleoceanographic history for the last v30 000 yr the marmara sea was isolated from both the black sea and the aegean sea during glacial periods when global sea level lowering subaerially exposed the shallow sills at the straits of bosphorus and dardanelles i e lake stage and reconnected through both straits during interglacial periods when rise of global sea level breached the shallow sills i e gateway stage micropaleontological data show that during the lake stage the surface water masses in both the marmara sea and black sea became notably brackish however during the gateway stages there was a low salinity surface layer and normal marine water mass beneath two sapropel layers are identified in the marmara sea cores sapropels m2 and m1 were deposited between v29 5 and 23 5 ka and v10 5 and 6 0 ka respectively micropaleontological and stable isotopic data show that the surface water salinities were reduced considerably during the deposition of both sapropel layers m2 and m1 and calculation using planktonic foraminiferal transfer functions shows that sea surface temperatures were notably lower during these intervals the presence of fauna and flora with black sea affinities and the absence of mediterranean fauna and flora in sapropels m1 and m2 strongly suggest that communication existed with the black sea during these times a benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the marmara sea rapidly followed the establishment of fully marine conditions at v11 10 5 ka and are attributed to black sea outflow into the marmara sea since 10 5 ka these suboxic conditions have persisted to the present the data discussed in this paper are completely at odds with the flood hypothesis of ryan et al 1997 and ryan and pitman 1999 crown copyright 2002 elsevier science b v all rights reserved

hydrology in the sea of marmara during the last 23 ka implications for timing of black sea connections and sapropel deposition 1 sediments deposited under lacustrine and marine conditions in the sea of marmara hold a late quaternary record for water exchange between the black sea and the mediterranean sea here we report a multiproxy data set based on oxygen and strontium isotope results obtained from carbonate shells major and trace elements and specific organic biomarker measurements as well as a micropaleontological study from a 14c dated sediment core retrieved from the sea of marmara pronounced changes occurred in 18o and 87sr 86sr values at the fresh and marine water transition providing additional information in relation to micropaleontological data organic biomarker concentrations documented the marine origin of the sapropelic layer while changes in n alkane concentrations clearly indicated an enhanced contribution for organic matter of terrestrial origin before and after the event when compared with the black sea record the results suggest that the black sea was outflowing to the sea of marmara from the last glacial maximum until the warmer bolling allerod the first marine incursion in the sea of marmara occurred at 14 7 cal ka b p however salinification of the basin was gradual indicating that black sea freshwaters were still contributing to the marmara seawater budget after the younger dryas which is associated with a high input of organic matter of terrestrial origin both basins were disconnected resulting in a salinity increase in the sea of marmara the deposition of organic rich sapropel that followed was mainly related to enhanced primary productivity characterized by a reorganization of the phytoplankton population

interglacial variability mis 5 and mis 7 and dinoflagellate cyst assemblages in the bay of biscay north atlantic the interglacial periods of the late quaternary are frequently investigated as they constitute potential analogues for our modem climate and may shed light on the key questions of natural climate variability and future developments the aim of this work is to reconstruct the paleoenvironmental history of marine isotope stages mis 5 and 7 in deep sea sediments of the northern bay of biscay north east atlantic ocean on the basis of a multiproxy compilation including analysis of dinoflagellate cyst assemblages we discuss the nature of the paleoenvironmental and paleoclimate changes that took place in this region recurrent successions of species marking the beginning and the termination of the interglacial complexes mis 5 and mis 7 revealed a coherent scheme of water mass migration during these key transitional periods moreover our data extend knowledge about the ecology of several dinoflagellate taxa in particular we discuss the ecology of spiniferites septentrionalis and note that this species can be used as a biostratigraphical tracer in north atlantic quaternary sediments until a major event of iceberg calving occurred during mis 6 dated to around 150 ka bp the dinocyst spinferites mirabilis appears to be an important proxy for recognizing warm intervals within interglacial complexes during mis 5e the last interglacial this species is represented by the highest percentages ever recorded in sediments from the north atlantic region peak occurrence of this species during mis 7 indicates that substage mis 7c the second warm interval of the penultimate interglacial represents the climatic optimum during the mis 7 interglacial complex

depth dependent viscosity and mantle stress amplification implications for the role of the asthenosphere in maintaining plate tectonics summary boundary layer theory is used to derive scaling relationships for plate stresses in a mantle convection system with a low viscosity asthenosphere the theory assumes a plate tectonic like mode of mantle convection withflow driven by an active upper boundary layer the theory predicts that the confinement of horizontal mantle flow within a low viscosity sublithospheric channel can lead to an increase in plate stress compared to the case lacking a channel even if the absolute viscosity of the sublithosphere mantle does not change between the two cases thetheoryfurtherpredictsincreasingshearstresswithdecreasinglow viscositychannelthickness if the thickness of tectonic plates is determined dominantly by a dehydrated chemical lithosphere then the plate normal stress is predicted to also increase with decreasing channel thickness we use 3 d spherical shell simulations of mantle convection with temperature depth and stress dependent rheology to test scaling trends the simulations and theoretical scalings demonstrate that a low viscosity layer asthenosphere can amplify convective stresses if the level of convective stress plays a role in maintaining and or reactivating plate boundaries this suggests that a relatively thin low viscosity layer may help to maintain plate tectonics the numerical simulations support this suggestion as they show that an increase in the thickness of a low viscosity channel can cause the system to transition from an active lid modeofconvectiontoastagnantlidstate collectively thesimulationsandtheoreticalscalings lead to the conclusion that the role of the asthenosphere in maintaining plate tectonics does not come principally from a basal lubrication effect associated with a low absolute asthenosphere viscosity but instead from a mantle flow channelization effect associated with a high viscosity contrast from the asthenosphere to the mantle below

sea land correlation of pollen records in the eastern mediterranean for the glacial interglacial transition biostratigraphy versus radiometric time scale abstract pollen diagrams based on marine cores from the eastern mediterranean and arabian seas and land cores from greece turkey the levant and western iran during the last deglaciation reveal a similar succession of conspicuous pollen abundance maxima an early phase with chenopodiaceae signaling the highest aridity a late phase with pistacia and gramineae in the mediterranean domain and tropical humid taxa in the arabian sea domain indicating conditions of mildest winter and wettest summer between these two phases the record for deciduous oak in the mediterranean and near east shows a continuous increase that points to rising moisture the chronology of this succession and its exact relationship with the marine isotopic record of global climate are established using marine cores the marine records dated by the ams 14 c method show that the chenopodiaceae phase correlates with the younger dryas chronozone globally dated 11 000 to 10 000 bp during which the climate reversed to quasi glacial conditions at least in the northern hemisphere they also show that the pistacia phase during which the mediterranean climate reached its seasonal optimum occurred from 9000 to 6000 14 c years bp boreal and early atlantic chronozones defined in nw europe in the first half of the holocene the oak pollen abundance increases rapidly from 10 000 to 9000 bp preboreal chronozone thus in terms of climate the younger dryas chronozone is regionally expressed by wide spread desert conditions as a cold and arid period during the pistacia phase the climate was most favourable both for plants that require frost free winters such as the mediterranean pistacia and those that need spring summer moisture such as gramineae at low annual moisture level seasonally 300 mm and deciduous oak at higher levels 600 mm all year without summer drought during the brief intermediary phase the climate changed drastically through an increase of winter temperature and of spring summer moisture the chronologies of the land cores however based on few 14 c dates show significant discrepancies with the marine based time frame these discrepancies imply a lack of coherence in the climate history of this mediterranean irano turanian region we propose using the chronology derived from the marine records for the entire region the local 14 c dates generally appear too old perhaps because of geological contamination of the material by older carbon

late glacial holocene paleoclimatic and paleoceanographic evolution of the aegean sea micropaleontological and stable isotopic evidence abstract late glacial to holocene paleoclimatic and paleoceanographic changes are examined using records of calcareous and organic walled marine microfossils pollen and terrestrial spores and oxygen isotope data in cores from the aegean sea basins planktic foraminiferal coccolith and dinoflagellate data show that the late glacial holocene transition in the region was associated with a large warming of surface water mediterranean based paleotransfer functions for planktic foraminifera show a 5 10 c increase in surface water temperature from 14 000 to 9600 yr b p estimates of surface water oxygen isotopic composition 18 o w derived from planktic foraminiferal oxygen isotopic and transfer function data indicate that this warming was associated with a 2 0 to 2 5 reduction in 18 o w transfer function results indicate corresponding 1 0 to 1 5 salinity reductions for this tim ca 6400 9600 yr b p throughout the aegean sea pollen dinoflagellate and isotopic data show that the early holocene excess fresh water originated from rapid melting of the northern european and siberian ice sheets supplied primarily from the black sea by the opening of bosphorus and dardanelles channels during the post glacial sea level rise and supplemented by major rivers entering the aegean sea continuous outflow of fresh water into the aegean sea provided a low salinity surface lid preventing the ventilation of the deep water benthic foraminifera shows a major turn over that indicates low dissolved oxygen however bottom waters were not anoxic sapropel level s1 resulted from a combination of stagnant deep water in isolated depressions increased terrigenous organic matter and periods of high primary productivity as indicated by pollen and dinocysts respectively the surface water temperature and salinity reached present day values at 6400 yr b p with little subsequent change despite the major deforestation onshore