lake level and climate records of the last 90 ka from the northern basin of lake van eastern turkey abstract sedimentary geochemical and mineralogical analyses of the icdp cores recovered from the northern basin nb of lake van provide evidence of lake level and climatic changes related to orbital and north atlantic climate system over the last 90 ka high lake levels are generally observed during the interglacial and interstadial periods which are marked by deposition of varved sediments with high total organic carbon toc total inorganic carbon tic low detrital influx high ca f and high 18o and 13c values of authigenic carbonate during the glacial and stadial periods of 71 58 ka bp marine isotope stage 4 mis4 and end of last glaciation deglaciation 30 14 5 ka bp mis3 relatively low lake levels prevailed and grey homogeneous to faintly laminated clayey silts were deposited at high sedimentation and low organic productivity rates millennial scale variability of the proxies during 60 30 ka bp mis3 is correlated with the dansgaard oeschger d o and holocene abrupt climate events in the atlantic these events are characterized by laminated sediments with high toc tic ca fe 18o and 13c values the lake van nb records correlate well in the region with the climate records from the lakes zeribar and urmia in iran and the sofular cave in nw anatolia but are in general in anti phase to those from the dead sea basin lake lisan in the levant the relatively higher 18o values 0 to 0 4 for the interglacial and interstadial periods in the lake van nb section are due to the higher temperature and seasonality of precipitation and higher evaporation whereas the lower values 0 8 to 2 during the glacial and stadial periods are caused mainly by relative decrease in both temperature and seasonality of precipitation the high 18o values up to 4 2 during the younger dryas together with the presence of dolomite and low toc contents supports evaporative conditions and low lake level a gradual decrease in the 18o values from an average of 0 4 during the humid early holocene to an average of 3 5 during the more arid late holocene suggests an increasing contribution of winter precipitation the changes in the seasonality of precipitation in eastern anatolia are probably caused by changes in the temperatures of north atlantic and mediterranean and in the strength of siberian high

mercury radar imaging evidence for polar ice the first unambiguous full disk radar mapping of mercury at 3 5 centimeter wavelength with the goldstone 70 meter antenna transmitting and 26 antennas of the very large array receiving has provided evidence for the presence of polar ice the radar experiments conducted on 8 and 23 august 1991 were designed to image the half of mercury not photographed by mariner 10 the orbital geometry allowed viewing beyond the north pole of mercury a highly reflective region was clearly visible on the north pole during both experiments this polar region has areas in which the circular polarization ratio pt was 1 0 to 1 4 values 0 1 are typical for terrestrial planets such high values of have hitherto been observed in radar observations only from icy regions of mars and icy outer planet satellites

evidence of lateglacial and holocene climatic change and human impact in eastern anatolia high resolution pollen charcoal isotopic and geochemical records from the laminated sediments of lake van turkey annually laminated sediments from lake van spanning about 13000 varve years were sampled for stable isotopic geochemical pollen and charcoal analyses in order to find evidence of past regional climatic changes and human impact in the semi arid region of eastern anatolia turkey the lateglacial period was cold and dry with steppe vegetation and saline lake water during the younger dryas the lake level dropped dramatically and the vegetation turned to a semi desert geochemical and isotopic records indicate a strong increase in moisture at the onset of the holocene and artemisia chenopod steppes were partly replaced by grass steppe and pistachio scrub a delay of about 3000 years in the expansion of deciduous oak woodlands and high steppe fire frequencies suggest dry spring and summer weather during the early holocene at 8200 yr bp a shift in the regional climate regime facilitated the transport of more moisture into the interior areas of the taurus mountains and caused a change in the seasonal distribution of precipitation the steppe forests dominated by quercus advanced and reached their maximum extention at about 6200 yr bp all the proxy data indicate optimum climatic conditions low water salinity and high lake level between 6200 and 4000 yr bp after 4000 yr bp aridity increased again and the modern climatic situation was established human impact in the catchment of lake van started at 3800 yr bp and was intensified during the last 600 years

stability of polar frosts in spherical bowl shaped craters on the moon mercury and mars following svitek martian water frost control of global distribution by small scale processes ph d thesis california institute of technology 1992 analytic solutions are presented for the effective albedo the effective emissivity and the radiative equilibrium temperature in the shadowed portions of a spherical bowl shaped crater the model assumes that the surface is a lambert scatterer with visual albedo and infrared emissivity each independent of wavelength across their respective spectral ranges absorption emission and multiple scattering from the walls of the crater are treated rigorously to all orders for airless bodies whose surfaces are in radiative equilibrium all shadowed portions of any individual crater have the same temperature whose value depends on four quantities the insolation product of the solar constant and the sine of the solar elevation angle the depth diameter ratio of the crater the visual albedo and the infrared emissivity as long as the crater is deep enough to have shadows the lowest temperatures are for the shallowest crater those with the smallest depth diameter ratio the model is applied first to the moon and mercury using a depth diameter ratio of 0 2 which is typical of the lunar highlands according to pike geophys res lett 1 291 294 1974 in impact and explosion cratering roddy et al eds pp 489 509 pergamon new york 1977 for mercury and the moon temperatures in shadows in polar craters are below 102 k so the sublimation rate of water ice calculated according to the model of watson et al j geophys res 66 3033 3015 1961 is less than 1 cm per byr the latitudinal extent of the cold zone on the moon is greater than that on mercury although temperatures at the poles of the two planets are similar the other application is to polar frosts on mars illuminated water frosts in radiative equilibrium grow rougher because the average temperature of a depression is greater than that of flat ground subliming co 2 frosts which are always at the same temperature grow rougher at low solar elevation angles because the heat flux absorbed by a depression is greater than that for a flat surface at high insolation rates high sun near perihelion the average heat flux to a depression is less than for a flat surface the latter evaporates faster which makes the average surface smoother and leads to a high average albedo this behavior helps explain the fact that the south co 2 cap which receives its greatest insolation near perihelion has a higher effective albedo and therefore can survive the summer whereas the north co 2 cap has a lower effective albedo and disappears each year around summer solstice

mercury full disk radar images and the detection and stability of ice at the north pole the first full disk radar images of mercury were obtained on august 8 and 23 1991 these images were constructed using the very large array vla in socorro new mexico to receive and map radar flux at 3 5 cm x band which was continuously transmitted from the 70 m jet propulsion laboratory deep space network antenna at goldstone california approximately 77 of the surface was imaged at resolutions as good as 150 km about half of the hemisphere photographed by mariner 10 was imaged as well as most of the hemisphere which has not previously been photographed at the time of the observations the north pole was visible and the feature with the highest same sense ss circular reflectivity in the images is near the nominal polar position the peak ss reflectivity of this feature was 7 9 and the circular polarization ratio throughout much of the feature is 1 our best estimate of the size of the feature is that its diameter is 350 km we interpret the feature to be indicative of the presence of ices because of the signal strength and polarization characteristics the ices must be very clean and were thus probably deposited in a relatively short time period the most likely place to find these ices is in any permanently shadowed areas in the polar regions which would be very cold in comparison to absolute reflectivities of other icy bodies and regions in the solar system the reflectivity of the north polar feature is slightly depressed this is probably because the ices do not fill an observational resolution cell i e there is incomplete areal coverage or are covered by a layer of dust or soil which absorbs some of the incoming and outgoing radar energy or both a covering layer would also protect any ices from erosion by energetic sources other prominent features on the unphotographed hemisphere correspond to positions where atmospheric sodium enhancements have been measured from earth this may indicate that these locations are large basins similar to the caloris basin where an atmospheric potassium enhancement has been measured which may be the result of increased degassing in the disrupted surface and near surface direct comparison of the radar echoes from our features with those from the caloris basin are hard to make as caloris was not imaged by us in a favorable geometry features on the photographed hemisphere are smaller and mostly associated with craters and crater complexes most notably the kuiper crater and its environs

a 600 000 year long continental pollen record from lake van eastern anatolia turkey abstract lake van is the fourth largest terminal lake in the world 38 5 n 43 e volume 607 km 3 area 3570 km 2 maximum water depth 460 m extending for 130 km wsw ene on the eastern anatolian high plateau turkey the sedimentary record of lake van partly laminated obtains a long and continuous continental sequence that covers multiple interglacial glacial cycles promoted by the potential of the sedimentary sequence for reconstructing the paleoecological and paleoclimate development of the near east a deep drilling operation was carried out in 2010 supported by the international continental scientific drilling program icdp the 219 m long continental pollen record presented here is based on a well dated composite profile drilled on the so called ahlat ridge in water depth of 360 m encompassing the last 600 000 years it is the longest continuous continental pollen record of the quaternary in the entire near east and central asia obtained to date the glacial interglacial cycles and pronounced interstadials are clearly reflected in the vegetation development based on millennial scale time resolution in general the glacial stadial vegetation is characterized by dwarf shrub steppe and desert steppe whereas the climax vegetation of past interglacials can be described as oak steppe forest similar to the present interglacial in this sensitive semi arid region between the black caspian and mediterranean seas by comparing the lake van pollen record with other western asian and southern european long continental pollen sequences as well as marine and ice core records the regional variability of the climate signals is also discussed

formation of the upper pleistocene terraces of lake van turkey sedimentological and geomorphological studies of terraces around lake van 1647 m provided a preliminary framework for lake level variations the elevations of terraces and past lake level were measured with a differential global positioning system a chronology is developed using 234 u 230 th dating of travertines 39 ar 40 ar dating of pyroclastites and 14 c dating of organic matter facies and stratigraphic correlations identify four transgressions c1 0 c 1 00 c 2 0 and c2 00 each followed by a regression which ended with low lake levels that caused river incision and terrace formation evidence of the oldest transgression c1 0 is found in the uppermost reaches of valleys up to 1755 m an altitude higher than the present lake threshold 1736 m this c1 0 transgression may be related to pyroclastic flows which dammed an outlet located in the western part of the lake basin and which is dated to before 105 ka after 100 ka a second transgression c1 00 reached 1730 1735 m possibly related to a younger ignimbrite flow in association with high water inflow warm and or wetter conditions the two younger transgressions reached 1700 1705 m the first one c2 0 is dated to 26 24 5 cal ka bp and the second one c2 00 to 21 20 cal ka bp available data suggest that the long term lake level changes responded mainly to climate oscillations additional events such as river captures caused by volcanic falls filling valleys tectonism erosion and karstic diversion may have impacted these long term lake level changes copyright 2010 john wiley sons ltd

early to mid holocene lake level and temperature records from the terraces of lake sunnet in nw turkey abstract lake sunnet a freshwater landslide dammed lake in nw anatolia comprises a10 m thick widespread of early to mid holocene deltaic sediments paleo environmental interpretation of these deposits coupled with a high resolution data 18 yrs sample of stable o and c isotopes magnetic susceptibility and total organic and carbonate contents allows an understanding of the nature of the mid holocene climatic transition as well as the short duration extreme events in relatively humid nw turkey detailed sedimentological logging showed that four phases of progradation of deltaic sand bodies over pro delta muds occurred it is suggested that they correspond to phases of increased precipitation a sudden vertical transition from lacustrine muds to subaerial colluvial facies at 5 9 ka cal bp is considered to be due to lake level drop related to water deficit oxygen isotope data suggest that the mid holocene transition with high mean summer temperatures initiated at 7 3 ka cal bp and continued until the end of the section with an interruption by a humid event between 6 8 and 6 0 ka cal bp centennial extreme events characterized by sharp 18o positive shifts 1 2 permil are also encountered at 9 2 8 9 8 2 and 7 6 ka cal bp a comparison of the lake sunnet record with previous aegean and sea of marmara palynological and sea surface temperature data shows a good fit in terms of the timing and nature of mid holocene transition and early holocene cold events the lake sunnet stable isotope record particularly suggests gradually increasing summer temperatures and hence continentality during the mid holocene cooling in the mediterranean

craters hosting radar bright deposits in mercury s north polar region areas of persistent shadow determined from messenger images 1 radar bright features near mercury s poles were discovered in earth based radar images and proposed to be water ice present in permanently shadowed areas images from messenger s one year primary orbital mission provide the first nearly complete view of mercury s north polar region as well as multiple images of the surface under a range of illumination conditions we find that radar bright features near mercury s north pole are associated with locations persistently shadowed in messenger images within 10 of the pole almost all craters larger than 10 km in diameter host radar bright deposits there are several craters located near mercury s north pole with sufficiently large diameters to enable long lived water ice to be thermally stable at the surface within regions of permanent shadow craters located farther south also host radar bright deposits and show a preference for cold pole longitudes thermal models suggest that a thin insulating layer is required to cover these deposits if the radar bright material consists predominantly of long lived water ice many small 10 km diameter and low latitude extending southward to 66 n craters host radar bright material and water ice may not be thermally stable in these craters for 1 gy even beneath an insulating layer the correlation of radar bright features with persistently shadowed areas is consistent with the deposits being composed of water ice and future thermal modeling of small and low latitude craters has the potential to further constrain the nature source and timing of emplacement of the radar bright material

modelling flanking structures using deformable high axial ratio ellipses insights into finite geometries flanking structures develop locally around material inhomogeneities the evolution of these structures is investigated here by modelling peturbations around a deformable ellipse using a 2d analytical solution non unique instantaneous and finite geometries are predicted and it is shown that in terms of slip and curvature complex histories are possible under simple shear whereas under pure shear instantaneous geometries map directly into finite state geometries single flanking structures are of limited use in kinematic analysis but can help constrain the kinematics when interpreted in conjunction with other structural features flanking structures exhibiting a range of ce cross cutting element orientations have more potential as kinematic indicators flanking structures serve as an excellent example of the role that material homogeneity can play in locally producing complex structures in a relatively simple bulk flow field

mercury evidence for anorthosite and basalt from mid infrared 7 3 13 5 μm spectroscopy abstract spectroscopic observations 7 3 13 5 m of three locations on the surface of mercury are reported the observed spectral radiance emanated from equatorial and low latitude regions between 12 and 32 mercurian longitude on 8 december 1990 from the longitudinal region 22 44 on 10 december 1990 and from the longitudinal region 110 130 on 12 july 1992 all locations are primarily intercrater plains spectra indicate compositional differences among these three locations the emissivity maximum or christiansen emission peak occurs at 8 1 m in the 8 december 1990 spectra but at shorter wavelengths in the data of 10 december 1990 and 12 july 1992 emission peaks near 8 m indicate rocks of intermediate or mafic composition spectra from 22 to 44 longitude resemble spectra of terrestrial basalt and diorite with sio2 content between 49 and 55 the christiansen feature in spectra from near 110 130 longitude strongly suggests the presence of plagioclase in particular labradorite while the overall spectrum resembles anorthosite the spectra from all three locations on mercury show distinct and recognizable features the principal christiansen emission peak being the most prominent but they also contain features that we have not yet identified the general indication from the spectra is that mercury s surface consists of minerals more depleted in oxidized iron than those on the moon we also explore the theoretical and observational complexities of ground based mid infrared spectroscopy of airless bodies in general and mercury in particular a spectroscopic study of quartzite in both reflectance and emittance illustrates the practical spectral validity of kirchhoff s law

eastern mediterranean hydroclimate over the late glacial and holocene reconstructed from the sediments of nar lake central turkey using stable isotopes and carbonate mineralogy there is a lack of high resolution records of hydroclimate variability in the eastern mediterranean from the late glacial and early holocene more knowledge of the speed of climate shifts and the degree to which they were synchronous with changes in the north atlantic or elsewhere is required to understand better the controls on eastern mediterranean climate using endogenic carbonate from a sediment sequence from nar golu a maar lake in central turkey dated by varve counting and uranium thorium methods we present high resolution 25 years oxygen 18o and carbon isotope records supported by carbonate mineralogy data spanning the late glacial and holocene 18ocarbonate at nar golu has been shown previously to be a strong proxy for regional water balance after a dry period i e evaporation far exceeding precipitation in the younger dryas the data show a transition into the relatively wetter early holocene in the early holocene there are two drier periods that appear to peak at 9 3 ka and 8 2 ka coincident with cooling events seen in north atlantic records after this and as seen in other records from the eastern mediterranean there is a millennial scale drying trend through the mid holocene transition the relatively dry late holocene is punctuated by centennial scale drought intervals at the times of 4 2 ka event and late bronze age societal collapse overall we show that central turkey is drier when the north atlantic is cooler throughout this record and at multiple timescales thought to be due to a weakening of the westerly storm track resulting from reduced cyclogenesis in the north atlantic however some features such as the mid holocene transition and the fact the early holocene dry episodes at nar golu are of a longer duration than the more discrete events seen in north atlantic records imply there are additional controls on eastern mediterranean hydroclimate

the thermal stability of water ice at the poles of mercury recent radar observations of mercury have revealed the presence of anomalous radar reflectivity and polarization features near its north and south poles thermal model calculations show that despite mercury s proximity to the sun the temperatures of flat low reflectivity surfaces at mercury s poles are not expected to exceed 167 kelvin the locations of the anomalous polar radar features appear to be correlated with the locations of large high latitude impact craters maximum surface temperatures in the permanently shadowed regions of these craters are expected to be significantly colder as low as 60 kelvin in the largest craters these results are consistent with the presence of water ice because at temperatures lower than 112 kelvin water ice should be stable to evaporation over time scales of billions of years

evaluation of the plio quaternary tectonic stress regime from fault kinematic analysis in the lake van basin eastern anatolia abstract we focus on the neogene quaternary tectonic evolution of the lake van basin located within the turkish iranian plateau to better understand the complex tectonic history of the region and determine the paleostress patterns we investigate and report on the geometric structural and kinematic characteristics of the basin based on field observations of fault slip orientations which are classified according to radiometric ages of the basin stratigraphy the analysis of large scale structures and fault kinematics indicate that three different deformation phases prevailed in the lake van basin during the neogene quaternary periods phase 1 is characterized by nw se extension and ne sw contraction that gave rise to the development of strike slip faults with thrust or normal components during the late miocene deforming the fluvial sediments which expose at east northeast of the basin phase 2 is characterized in fluvial and lake deposits of the middle pleistocene deformed by dominant contraction stress regime effective along nw se direction the late pleistocene tectonic regime phase 3 consists of transpressional deformation that develops under nnw sse compression and ene wsw extension according to our analysis the present day deformation pattern of the lake van basin is dominated by compression at east while at the northern part is transtensional

displacement length relations of thrust faults associated with lobate scarps on mercury and mars comparison with terrestrial faults the displacement dand length lof thrust faults associated with lobate scarps on mercury and mars are estimated from topographic and planimetric measurements dranges from 0 29 to 3 58 km for mercurian thrust faults n 10 and from 0 27 km to 2 90 km for martian thrust faults n 13 the d lrelationship between thrust fault populations analyzed on mercury and mars is very similar mercury 6 5 3 2 10 3 mars 5 9 2 0 10 3 and about an order of magnitude lower than terrestrial thrust faults the difference is probably dominated by the contrast in tectonic setting between terrestrial thrust faults and those on mercury and mars the similarity in morphology and the d lrelationship of the mercurian and martian thrust faults may be due to the similarity in mechanical properties of the deformed materials and the acceleration due to gravity of the two planets

the tempo of holocene climatic change in the eastern mediterranean region new high resolution crater lake sediment data from central turkey this study presents results from a multi proxy analysis of cores taken in a crater lake sequence from eski acigol in central turkey which cover the period from pre c 16000 cal yr bp to the present the sediments comprise an upper unit of generally non laminated banded to massive silts and peats of mid to late holocene age overlying a laminated unit of late pleistocene to early mid holocene age the laminae comprising mainly aragonite amorphous silica diatom frustules and organic matter were formed in a relatively deep dilute meromictic lake pollen data indicate an abrupt replacement of artemisia chenopod steppe by grass oak terebinth parkland during the period of laminae deposition marking the start of the holocene a gradual increase in tree pollen during the early holocene came to an end c 6500 cal yr bp u series and adjusted c 14 timescale when mesic deciduous taxa declined at the same time as lake levels fell human impact on regional vegetation is inferred from a sharp decline in oak around 4500 4000 cal yr bp diatom isotopic and mineralogical data indicate that during the second half of the holocene the lake became relatively shallow and oscillated between fresh and brackish evaporated water conditions the contrast between wetter early and drier late holocene climatic conditions is matched by other eastern and central mediterranean proxy climate data while the eski acigol sequence resembles holocene hydroclimatic changes in the saharo arabian zone and was also apparently linked to orbital forcing it is unlikely to have had the same direct cause i e an expansion and subsequent retreat of monsoon rainfall

radar mapping of mercury full disk images and polar anomalies a random code technique has been used at arecibo to obtain delay doppler radar images of the full disk of mercury anomalously bright features were found at the north and south poles the north polar feature is oblong 4 by 8 and offset from the pole the smaller south polar feature is mostly confined to the floor of the crater chao meng fu the polar locations and radar properties of these features indicate that they may be produced by volume scattering in ice the images also reveal a variety of more subdued reflectivity features ranging in size from hundreds to thousands of kilometers some of these appear to have an impact origin

thrust faults and the global contraction of mercury 1 lobate scarps on mercury are the surface expression of thrust faults and are generally thought to be the result of global contraction our analysis indicates that these thrust faults are not uniformly distributed and exhibit non random patterns on the imaged hemisphere the greatest area normalized cumulative length of the faults occurs in the southern hemisphere below 50 s the thrust faults in this region dip to the north indicating a broad zone where the crust has been displaced to the south widespread thrust faulting may not have initiated before the emplacement of calorian smooth plains well after the emplacement of pre tolstojan intercrater plains our observations suggest that regional scale tectonic stresses on mercury dominated over stresses resulting from global contraction

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

palynology of lake arin eastern anatolia turkey deposits and its relation with water level change of lake van preliminary findings palynological and lithological investigations of lake arin indicate mid late holocene lake level fluctuations both in lake arin and lake van pollen diagram and lithological features of sediments suggest unstable conditions during last 6 kyr bp for lake arin climatic changes and human impact have been both effective for destroying uppermost sediments of the lake semi arid steppe vegetation dominance has been identified for early holocene around lake arin

topography of lobate scarps on mercury new constraints on the planet s contraction lobate scarps are landforms on mercury that appear to have formed by thrust faulting and are thought to reflect global contraction due to cooling of the planet s interior topographic data for 10 mercurian lobate scarps derived from mariner 10 images using photoclinometry and digital stereoanalysis indicate a range in maximum relief of 0 1 to 1 5 km and a range in horizontal shortening of 0 3 to 3 2 km assuming fault plane dips of 25 previous estimates of cumulative compressional strain recorded in the lobate scarps suggest a decrease in mercury s radius of 1 to 2 km our estimate of compressional strain based on these new topographic measurements is 0 056 25 this suggests that mercury s radius decreased by 1 km

recalibrated mariner 10 color mosaics implications for mercurian volcanism recalibration of mariner 10 color image data allows the identification of distinct color units on the mercurian surface we analyze these data in terms of opaque mineral abundance iron content and soil maturity and find color units consistent with the presence of volcanic deposits on mercury s surface additionally materials associated with some impact craters have been excavated from a layer interpreted to be deficient in opaque minerals within the crust possibly analogous to the lunar anorthosite crust these observations suggest that mercury has undergone complex differentiation like the other terrestrial planets and the earth s moon

climatically induced lake level changes at lake van turkey during the pleistocene holocene transition sediment core k10 from lake van eastern turkey provides a continuous varve record back to 14 570 calendar years b p before present 1950 the longest unbroken and non floating lake varve sequence yet described the underlying sediment is unvarved and hard changes in the aragonite calcite ratio the presence of protodolomite and magnesite in certain profile sections the annual record of the sedimentation rate the water content of the sediment the concentrations of organic carbon and opal and the texture of the sediments from this core provide a record of the lake level history the new chronology enabled us to redate the old pollen profile van zeist and woldring 1978a b and to establish an accurate timescale for the reconstructed lake level change carbon 14 dates show that the highest lake terrace corresponds to high lake level at around 19 000 years b p during the last glacial 70 m above its present level before 15 000 years b p the lake must have been completely dry marking a reduction of lake level by 500 m in maximum 4000 years beginning at 14 600 years b p and ending at 12 040 years b p the lake level recovered by 250 m to fall again during the next 1400 years by 10 600 years b p the lake began to rise and reached following another regression between 9000 and 8100 years b p the holocene highstand by about 7500 years b p dropping to today s level at about 3000 years b p

holocene climate variability although the dramatic climate disruptions of the last glacial period have received considerable attention relatively little has been directed toward climate variability in the holocene 11 500 cal yr b p to the present examination of similar to50 globally distributed paleoclimate records reveals as many as six periods of significant rapid climate change during the time periods 9000 8000 6000 5000 4200 3800 3500 2500 1200 1000 and 600 150 cal yr b p most of the climate change events in these globally distributed records are characterized by polar cooling tropical aridity and major atmospheric circulation changes although in the most recent interval 600 150 cal yr b p polar cooling was accompanied by increased moisture in some parts of the tropics several intervals coincide with major disruptions of civilization illustrating the human significance of holocene climate variability c 2004 university of washington all rights reserved

a revised control network for mercury an improved control net for mercury has been completed by utilizing images acquired during the three mariner 10 flybys in 1974 1975 relative positional errors within the net are 1 km on average and absolute locations are estimated to be better than 25 km the analytical triangulation resulted in new values for focal lengths camera a 1493 6 mm camera b 1500 1 mm w0 329 548 and camera orientation angles for 811 images acquired during all three flybys of mercury

holocene climate variability and cultural evolution in the near east from the dead sea sedimentary record abstract a comprehensive record of lake level changes in the dead sea has been reconstructed using multiple well dated sediment cores recovered from the dead sea shore interpreting the lake level changes as monitors of precipitation in the dead sea drainage area and the regional eastern mediterranean palaeoclimate we document the presence of two major wet phases 10 8 6 and 5 6 3 5 cal kyr bp and multiple abrupt arid events during the holocene the arid events in the holocene dead sea appear to coincide with major breaks in the near east cultural evolution at 8 6 8 2 4 2 3 5 cal kyr bp wetter periods are marked by the enlargement of smaller settlements and growth of farming communities in desert regions suggesting a parallelism between climate and near east cultural development

radar mapping of mercury s polar anomalies ground based radar observations of mercury have revealed unusually strong highly depolarized echoes from the north1 2 and south2 poles these anomalous echoes have been cited as evidence of polar ice deposits1 5 thermal studies3 5 suggest that the permanently shaded floors of large polar craters are cold enough to preserve water ice in a stable state over aeons in spite of mercury s proximity to the sun here we present high resolution radar maps of mercury s polar regions derived from delay doppler measurements we have resolved the north and south polar anomalies into numerous crater sized features and we have been able to identify the source craters for many of these features after making small corrections to the pole positions on the mariner 10 images the coincidence with crater locations together with other properties of the radar features are consistent with the polar ice hypothesis

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

the late holocene climate change vegetation dynamics lake level changes and anthropogenic impacts in the lake urmia region nw iran two short 100 and 175 cm long sediment cores from the southwestern corner of lake urmia provide a record of vegetation dynamics lake level changes and the role of climate and humans in shaping the landscape around lake urmia over the last 2550 years relatively low values of arboreal pollen ap and substantial values of artemisia pollen from 2550 to 1500 cal bp indicate the prevalence of steppe vegetation and relatively arid climate in the area however a prominent peak of riella spores may indicate a short lived lake level rise for the period 1900 2000 cal bp the next period 1500 550 cal bp is characterized by substantial rise in ap particularly quercus and a sharp decline of artemisia chenopodiaceae amaranthaceae and wetland pollen types suggesting the expansion of oak forests under a rather moist climate and or a decline in agro sylvo pastoral practices in the area agricultural activity in the area can be inferred from sporadic occurrences of vitis ricinus and juglans pollen from the beginning of the record the rise of saline habitat pollen types between 1100 and 800 cal bp along with increased values of magnetic susceptibility and organic matter suggest a lower water level and the subaerial exposure of saline mud flats which could favour the re colonization of chenopods and other halophytes around the margins of the lake thus the medieval climatic anomaly seems to be warmer than present in the lake urmia region from 450 to 150 cal bp the decline in quercus and high values of artemisia along with higher lake levels and high magnetic susceptibility values could be associated with the little ice age since 500 cal bp quercus and riella steadily decline and fade out towards the surface of the core whereas pollen types attributable to steppe and desert vegetation increase a prominent increase in organic matter in the uppermost part of the record could be associated with a lower lake level and the expansion of wetland vegetation in the recent past our findings suggest that the regional forest coverage in the highlands of zagros and azerbaijan has reached its minimum during recent decades while urmia s lake level dropped dramatically increasing its water salinity most likely as a function of extensive anthropogenic activities and general climate aridification c 2015 elsevier ltd and inqua all rights reserved

late pleistocene holocene sedimentary records of climate and lake level changes in lake hazar eastern anatolia turkey abstract the sedimentary record of lake hazar has been documented by detailed seismo and chronostratigraphic analyses using high resolution seismic profiles and sediment cores in this study two main seismic stratigraphic units can be confidently correlated with sediment cores using lithology and physical properties as a result of radiocarbon ams dating these sedimentary units presumably cover the period from the late pleistocene to holocene the holocene sequence of the lake infills can be subdivided into five subunits each subject to distinctive hydrological and sedimentological processes due to fluctuating lake level the elevations of these deposits including coastal paleo terraces provide history of the lake level changes in lake hazar the maximum lowstand lake level occurred during the transition from the younger dryas to holocene when the 73 m wave cut terrace was formed as the main shelf crossing unconformity surface the beginning of the holocene was associated with a abrupt lake level rise and resultant deepening analysis of the lake hazar terraces has the potential to provide complementary data on the chronology of past lake level and lake volume changes and their link to past climate change the continued rising lake level during beginning of the holocene was modulated by stillstands at 63 m and 56 m as indicated by broad coastal paleo terraces across the northern shelf the main shelf margin sedimentary system for the holocene period is composed of three distinct buried deltaic complexes that were presumably sourced from the kurkcayi river the largest input into lake hazar the 3rd millennium crisis at around 3 14c ka bp is recorded in the seismic and core data when the cold and dry climatic condition gave rise to a significant lake level drop

palynological analysis of the late pleistocene terrace deposits of lake van eastern turkey reconstruction of paleovegetation and paleoclimate paleovegetation and paleoclimate reconstruction of a late pleistocene terrace of lake van northern part of lake ercis celebibagi region was based on pollen analysis from continuous laminated sediments according to the pollen analysis nap pollen values are predominantly abundant chenopodiaceae artemisia and poaceae were the prevailing plants and chenopodiaceae was the dominant paleoflora element during late pleistocene pollen data indicate halophyte vegetation climate was colder and drier

paleovan international continental scientific drilling program icdp site survey results and perspectives lake van is the fourth largest terminal lake in the world volume 607 km 3 area 3570 km 2 maximum depth 460 m extending for 130 km wsw ene on the eastern anatolian high plateau turkey the sedimentary record of lake van partly laminated has the potential to obtain a long and continuous continental sequence that covers several glacial interglacial cycles ca 500 kyr therefore lake van is a key site within the international continental scientific drilling program icdp for the investigation of the quaternary climate evolution in the near east paleovan as preparation for an icdp drilling campaign a site survey was carried out during the past years we collected 50 seismic profiles with a total length of similar to 850 km to identify continuous undisturbed sedimentary sequences for potential icdp locations based on the seismic results we cored 10 different locations to water depths of up to 420 m multidisciplinary scientific work at positions of a proposed icdp drill site included measurements of magnetic susceptibility physical properties stable isotopes xrf scans and pollen and spores this core extends back to the last glacial maximum lgm a more extended record than all the other lake van cores obtained to date both coring and seismic data do not show any indication that the deepest part of the lake tatvan basin ahlat ridge was dry or almost dry during past times these results show potential for obtaining a continuous undisturbed long continental palaeoclimate record in addition this paper discusses the potential of paleovan to establish new results on the dynamics of lake level fluctuations noble gas concentration in pore water of the lake sediment history of volcanism and volcanic activities based on tephrostratigraphy and paleoseismic and earthquake activities c 2009 elsevier ltd all rights reserved