holocene climate variability in the levant from the dead sea pollen record abstract the dead sea located at the deepest place on continent and between the subtropical mediterranean zone and the desert reflects in its water composition and levels and sedimentary records the hydrological conditions in the southern levant region temporal variations in rainfall and temperatures of the holocene levant are reconstructed here from pollen data recovered from a sediment core drilled at the ein gedi shore applying a novel biome model based on bayesian statistics our results suggest that the region was arid and warm in the early holocene period 10 6 5 ka cal bp wetter and colder in the mid holocene 6 3 3 3 ka cal bp and drier and warmer in the late holocene 3 2 ka cal bp to present these periods comprise multi centennial climate cycles that are characterized by rapid changes in temperature and precipitation reflecting sea surface temperature sst and atmospheric conditions over the atlantic ocean the pollen record responds within a short time interval to the climate conditions and marks rapid shifts from mediterranean to desert environmental conditions and back in the southern levant region we also evaluate our results in the light of possible disturbances of the natural vegetation e g the possibility of forest decrease since the neolithic

sea ice motion in response to geostrophic winds it is an old rule of thumb that sea ice moves with a speed of about 2 of the surface wind and about 45 to the right of the wind a similar relationship between the ice velocity and the geostrophic wind is examined here it is found that only about half of the long term several month average ice motion is directly related to the geostrophic wind the other half being due to the mean ocean circulation on shorter time scales and in all seasons more than 70 of the variance of the ice velocity in the central arctic ocean is explained by the geostrophic wind within about 400 km of the coasts the geostrophic wind is less successful in explaining the ice motion the spatial variations in ice velocity are also partly explained by the geostrophic wind about half of the variance in the large scale ice vorticity and shear are accounted for on the other hand none of the large scale ice divergence can be explained by the wind the long term average ocean current is estimated by subtracting the share of the ice motion caused by the wind from the total ice motion

thin section and s e m textural criteria for the recognition of cement dissolution porosity in sandstones cement porosity relationships are described from the lower triassic sherwood sandstone group and the middle jurassic ravenscar group in the united kingdom calcite cemented sandstones display a variety of replacement textures with preferential replacement of grains and of overgrowth faces with high free surface energy dolomite and siderite cemented sandstones display similar textures but replacement is less specific and euhedral overgrowth surfaces are commonly embayed by carbonates examination of the more porous sandstones with the scanning electron microscope reveals a range of pitting and embayment textures in authigenic overgrowths and in detrital grains these range from small v shaped notches and pits through regular and irregular shaped embayments into large depressions these textures appear to be morphologically similar to the quartz surfaces seen in thin sections of carbonate cemented sandstones and are interpreted to have been formed by the dissolution of pore filling and grain replacive authigenic carbonates this is confirmed by examination of experimentally exhumed overgrowth surfaces from carbonate cemented sandstones these textures indicate that part of the intergranular porosity in these sediments is secondary in origin and has been generated by the dissolution of carbonate cements the identification of such textures may lead to a more confident interpretation of the nature of intergranular porosity in the subsurface

estimating sea ice area flux across the canadian arctic archipelago using enhanced amsr e 1 enhanced resolution advanced microwave scanning radiometer amsr e imagery is used to estimate daily sea ice area fluxes between the canadian arctic archipelago and the arctic ocean and baffin bay for the period september 2002 to june 2007 over the period amundsen gulf and m clure strait exported 54 103 km2 of sea ice area or roughly 77 km3 of sea ice volume each year into the arctic ocean export import into the arctic ocean through the queen elizabeth islands is small and uncertain since no estimates for july and august could be made due to atmospheric attenuation of the microwave signal lancaster sound exported 68 103 km2 of sea ice area or roughly 102 km3 of ice volume into baffin bay this produced a net loss of sea ice area of about 122 103 km2 or roughly 174 km3 a 1 which is presumed to be generated from within the archipelago itself mainly through the stationary and transient polynyas and leads that form each winter daily ice area fluxes for amundsen gulf ag and lancaster sound ls were as high as 2500 km2 d 1 and were event driven depending on synoptic scale atmospheric circulation and the mobility of the sea ice mean sea level pressure difference across each gate is moderately correlated with daily sea ice area fluxes despite the fact that free ice drift conditions are not always met in the region cross gradient and daily sea ice area flux for lancaster sound show a large number of counter gradient ice flux occurrences suggesting that local mesoscale winds nongeostrophic and perhaps ocean currents play a role in transporting sea ice through this gate monthly ice fluxes for the ag and ms gate were positively correlated with the ao index indicating that a strong beaufort sea high pressure and gyre correspond to more export into the beaufort sea monthly fluxes for the ls gate were positively correlated with the nao index indicating that strong southerly atmospheric circulation over baffin bay increases ice export into baffin bay from lancaster sound

rapid entrenchment of stream profiles in the salt caves of mount sedom israel rock salt is approximately 1000 times more soluble than limestone and thus displays high rates of geomorphic evolution cave stream channel profiles and downcutting rates were studied in the mount sedom salt diapir dead sea rift valley israel although the area is very arid mean annual rainfall 50 mm the diapir contains extensive karst systems of holocene age in the standard cave profile a vertical shaft at the upstream end diverts water from a surface channel in anhydrite or clastic cap rocks into the subsurface route in the salt mass balance calculations in a sample cave passage yielded downcutting rates of 0 2 mm s 1 during peak flood conditions or about eight orders of magnitude higher than reported rates in any limestone cave streams however in the arid climate of mount sedom floods have a low recurrence interval with the consequence that long term mean downcutting rates are lower an average rate of 8 8 mm a 1 was measured for the period 1986 1991 in the same sample passage quite independently long term mean rates of 6 2mm a 1 are deduced from 14c ages of driftwood found in upper levels of 12 cave passages these are at least three orders of magnitude higher than rates established for limestone caves salt cave passages develop in two main stages 1 an early stage characterized by high downcutting rates into the rock salt bed and steep passage gradients 2 a mature stage characterized by lower downcutting rates with establishment of a subhorizontal stream bed armoured with alluvial detritus in this mature stage downcutting rates are controlled by the uplift rate of the mount sedom diapir and changes of the level of the dead sea passages may also aggrade these fast developing salt stream channels may serve as full scale models for slower developing systems such as limestone canyons

late quaternary environmental and human events at en gedi reflected by the geology and archaeology of the moringa cave dead sea area israel abstract the moringa cave within pleistocene sediments in the en gedi area of the dead sea fault escarpment contains a sequence of various pleistocene lacustrine deposits associated with higher than today lake levels at the dead sea basin in addition it contains chalcolithic remains and 5th century bc burials attributed to the persian period cemented and covered by late holocene travertine flowstone these deposits represent a chain of late pleistocene and holocene interconnected environmental and human events echoing broader scale regional and global climate events a major shift between depositional environments is associated with the rapid fall of lake lisan level during the latest pleistocene this exposed the sediments providing for cave formation processes sometime between the latest pleistocene ca 15 ka and the middle holocene ca 4500 bc eventually leading to human use of the cave the chalcolithic use of the cave can be related to a relatively moist desert environment probably related to a shift in the location of the northern boundary of the saharo arabian desert belt the travertine layer was u th dated 2 46 0 10 to 2 10 0 04 ka in agreement with the archaeological finds from the persian period together with the inner consistency of the dating results this strongly supports the reliability of the radiometric ages the 2 46 2 10 ka travertine deposition within the presently dry cave suggests a higher recharge of the judean desert aquifer correlative to a rising dead sea towards the end of the 1st millennium bc this suggests a relatively moist local and regional climate facilitating human habitation of the desert

salt cave cross sections and their paleoenvironmental implications salt caves respond rapidly to environmental changes direct measurement and 14c dating show that complex cross sections may develop in a few hundred years two basic forms are discussed 1 ingrowing vadose canyons where changing width may correspond to changing discharge 2 wide low passages with flat ceilings developed by upward dissolution which may indicate rising base level some cross sections are deformed by holocene tectonics

sea ice response to an extreme negative phase of the arctic oscillation during winter 2009 2010 3 the long term annual mean arctic slp field features an anticyclone centered over the northern beaufort sea known as the beaufort sea high bsh and a trough of low pressure extending from the icelandic low northeastward into the kara sea associated surface winds drive the clockwise beaufort gyre ice motion and the transpolar drift stream tds representing ice motion from the siberian coast across the arctic and then into the north atlantic through fram strait when the winter ao is in its positive mode slp over the icelandic low region and extending into the arctic is anomalously low and the bsh is weak promoting a cyclonic counter clockwise sea ice circulation anomaly this is expressed as decreased ice transport from the beaufort sea westward across the dateline into the chukchi sea increased ice transport out of the arctic ocean through fram strait and increased transport of ice away from the siberian coast leaving open water areas that foster new iceformation rigoretal 2002 bypromotingmorethinice in spring the positive ao sets the stage for negative summer ice extent anomalies conversely during a negative ao phase slp is above normal over the arctic most prominent in the vicinity of the icelandic low ice motion tends to have an anticyclonic clockwise anomaly ice flow through fram strait is reduced and the beaufort gyre is stronger leading to enhanced ice transport from the western to the eastern arctic where ice thickens by ridging and rafting against the siberian coast the stronger beaufort gyre also sequesters and thickens ice in the canada basin collectively these processes favor survival of sea ice through summer

role of ice dynamics in anomalous ice conditions in the beaufort sea during 2006 and 2007 1 a new record minimum in summer sea ice extent was set in 2007 and an unusual polynya formed in the beaufort sea ice cover during the summer of 2006 using a combination of visual observations from cruises ice drift and satellite passive microwave sea ice concentration we show that ice dynamics during preceding years included events that preconditioned the beaufort ice pack for the unusual patterns of opening observed in both summers intrusions of first year ice from the chukchi sea to the northern beaufort and increased pole ward ice transport from the western arctic during summer has led to reduced replenishment of multiyear ice older than five years in the western beaufort resulting in a younger thinner ice pack in most of the beaufort we find ice younger than five years melts out completely by the end of summer south of 76n the 2006 unusual polynya was bounded to the south by an ice tongue composed of sea ice older than 5 years and formed when first year and second year ice melted between 76n and the older ice to the south in this paper we demonstrate that a recent shift in ice circulation patterns in the western arctic preconditions the beaufort ice pack for increased seasonal ice zone extent

soil erosion in relation to land use changes in the sediments of amik lake near antioch antique city during the last 4 kyr the amik basin in the eastern mediterranean region occupied since 6000 7000 bc has sustained a highly variable anthropic pressure culminating during the late roman period when the antioch city reac

baffin bay ice drift and export 2002 2007 1 multiyear estimates of sea ice drift in baffin bay and davis strait are derived for the first time from the 89 ghz channel of the amsr e instrument uncertainties in the drift estimates assessed with envisat ice motion are 2 3 km day a persistent atmospheric trough between the coast of greenland and baffin island drives the prevailing southward drift pattern with average daily displacements in excess of 18 20 km during winter over the 5 year record the ice export ranges between 360 and 675 103 km2 with an average of 530 103 km2 sea ice area inflow from the nares strait lancaster sound and jones sound potentially contribute up to a third of the net area outflow while ice production at the north water polynya contributes the balance rough estimates of annual volume export give 500 800 km3 comparatively these are 70 and 30 of the annual area and volume exports at the fram strait

comparing l and c band synthetic aperture radar estimates of sea ice motion over different ice regimes abstract estimating sea ice motion from synthetic aperture radar sar imagery at c band is the most reliable approach because of its high spatial resolution and ever increasing temporal resolution given the multiple current and upcoming sar platforms however there is still uncertainty in sar derived sea ice motion depending on the ice type and its thermodynamic state there have been suggestions mostly theoretical that use of l band sar and its inherent longer wavelength 15 30 cm and subsequent increased penetration capability could be beneficial for estimating sea ice motion especially during the melt season here we estimate and analyze sea ice motion for 9 pairs of c and l band sar imagery from radarsat 2 palsar 1 and palsar 2 located in the canadian arctic over a variety of sea ice types at different thermodynamic states results show that the increased signal penetration of l band sar into multi year ice myi during the melt season facilitates the detection of more motion vectors with stronger cross correlation coefficients compared to c band sar over newly formed ice and dry first year ice the reduced sensitivity to surface scattering and richer texture from l band sar imagery facilitates the detection of more motion vectors with stronger cross correlation coefficients compared to c band sar over dry myi l band provided stronger cross correlation coefficients but c band detected more motion vectors with a more representative spatial distribution with arctic sea ice continuing shift from a multi year to first year dominated icescape coupled with an increasing melt season length l band sar s ability to provide improved sea ice motion estimates during both the melt and freeze up time periods could prove even more useful in the coming decades

genesis and shape of natural solution cavities within salt deposits 1 since the genesis and shape of natural deep seated cavities within a salt body are insufficiently understood the current study tries to shed some light on this topic to this end freshwater was pumped slowly through a horizontal borehole in rock salt cores owing to fast halite dissolution kinetics high solubility and slow inflow rate halite dissolution took place only in the inflow of the rock salt cylinder the shape of the created cavities is an approximately symmetrical half cone with a horizontal base facing upward a conceptual model is presented that is inspired by the experimental results and based on theoretical hydraulic geochemical considerations as well as on field observations it proposes that triangular prism or conically shaped cavities develop within salt under confined conditions where aggressive water flows upward along a fracture conduit from an insoluble aquifer into the soluble stratum such cavity enlargements may cause land subsidence and structure collapse

holocene environmental change and its impact on sediment dynamics in the eastern mediterranean abstract investigators have studied past environmental change in the eastern mediterranean region from a number of perspectives while climate reconstructions and palynological research have focused on forces that drive the geomorphologic system many researchers have attempted to use sediment archive studies to identify periods of change in sediment dynamics due to the large variability in environmental parameters and the variety of landscapes present in the eastern mediterranean region research has focused on sediment archives ranging from small colluvial sites to deltas of large rivers on the mediterranean coast as the cultural record for the region is extremely rich the main goal of palaeo environmental research in the eastern mediterranean has been to identify the relative importance of human impact on the landscape nevertheless sediment archives have significant limitations chronological control for many palaeo environmental records is highly uncertain and rates of landscape change are oftentimes difficult to assess most palaeo environmental research has been conducted on or near archeological sites where direct human impact may obscure the indirect impact on sediment dynamics through land use changes quantification and modeling of sediment dynamics in the eastern mediterranean environment offer one solution when erosion and sediment transport rate analyses are incorporated periods of relatively important change can be identified using multiple approaches the relative importance of the main driving forces climate and land use become distinguishable since field based data from the actual sediment archives remain vital an overview of numerous studies in the eastern mediterranean is provided in order to draw a general picture for different time periods and the relative scale of regional landscape development during the holocene a comparison of sediment dynamics with the record of driving forces indicates that while climate was the main driver of the geomorphic system during the early holocene at some point human impact became widespread and began to dictate sediment dynamics to a large extent from the byzantine period onward soil properties seem to play an increasingly important role as the hillslope soil reservoir in the eastern mediterranean was progressively depleted during the late holocene

diagenesis and reservoir quality in high resolution sandstone sequences an example from the middle jurassic ravenscar sandstones yorkshire coastuk abstract a section of the middle jurassic ravenscar sandstones exposed between cloughton wyke and burniston bay was studied to understand fine scale variation in reservoir quality that can affect flow properties at the reservoir scale the study has identified two 3rd order depositional sequences consisting of twelve 4th order high resolution sandstone sequences deposited mostly in a lower delta plain although these sandstones exhibit a narrow range in porosity values however a sharp disparity exists in their permeability which can have implications at the scale of reservoir development diagenetic studies have revealed that mechanical compaction produced the same effect for most of these sandstones however dissolution and cementation vary hence are mostly responsible for the sharp contrast in their reservoir quality the distributary channel sandstones developed during normal regression of the area in the fs9 sequence are considered the best reservoir sand bodies however these lst sandstones are compartmentalised by authigenic illite quartz and kaolin into two reservoir segments the upper portion lacks illite with resultant higher permeability values above 1100 md ave 2217 md and classified as reservoir group 4 in contrast the lower part contains illite with relatively lower permeability values in the range of 300 1100 md ave 879 md and classified as reservoir group 3 together with the transgressive crevasse channel sandstones in the fs11 sequence the presence of illite cement in these sandstones is linked to the occurrence of k feldspar hence facilitated illitization of kaolin in contrast to group 4 which lacks this mineral the other transgressive sandstones deposited in interdistributary bay crevasse delta back barrier lagoon lagoon and estuarine environments which form reservoir groups 1 and 2 have permeability values in the range of 0 50 md ave 6 md and 50 300 md ave 184 md respectively these sandstones have complex styles of diagenetic cement with variable higher volumes of total authigenic cement consisting of quartz kaolin illite chlorite and calcite than reservoir groups 3 and 4 hence have significantly reduced their reservoir potential therefore for effective reservoir development of these sandstone reservoirs in the north sea and elsewhere in the world with a similar geological setting detailed reservoir characterisation involving linking lithofacies sequence stratigraphy and diagenesis at high resolution are essential for understanding the distribution of reservoir flow properties

asymmetry and basin migration in the dead sea rift the dead sea depression sensu stricto forms the deepest continental part of the dead sea rift a transfer which separates the levanthine and arabian plates it is occupied by three distinct sedimentary bodies deposited in basins whose depocenters are displaced northward with time they are the continental red beds of the hazeva formation miocene the bira lido gesher marls and the exceptionally thick rocksalt of the sedom formation pliocene early pleistocene and the successive amora lisan and dead sea evaporites and clastics early pleistocene recent lengthwise and crosswise asymmetries of these sedimentary basins and their respective depocenters are due to leftlateral shear combined with anticlockwise rotation of the arabian eastern plate steeper faulting of the crustal eastern margin than of the western sedimentary margin and modification of depositional pattern by twice filling up of basins by hazeva red beds during late miocene pause of shear and by sedom rocksalt during pliocene marine ingression

recent changes in the exchange of sea ice between the arctic ocean and the canadian arctic archipelago 1 sea ice is exchanged between the arctic ocean and canadian arctic archipelago caa but has not been quantified over long time periods the corresponding mechanisms responsible for recent variability and change also remain unidentified to address this we estimated the sea ice area flux between the arctic ocean and the m clure strait and queen elizabeth islands qei from 1997 to 2012 for the months of may to november over the period there was a mean flux of 1 103 km2 21 103 km2 at the m clure strait and mean flux of 8 103 km2 8 103 km2 at the qei positive and negative flux signs correspond to arctic ocean ice inflow and outflow respectively the m clure strait had a mean flux of 5 103 km2 from may to september and a mean flux of 7 103 km2 from october to november the qei gates had a mean flux of 4 103 km2 from august to september with negligible ice exchange from may to july and october to november more frequent high sea level pressure anomalies over the beaufort sea and canadian basin since 2007 have reduced arctic ocean multiyear ice myi inflow into the m clure strait the presence of myi in the caa originating from the arctic ocean has been maintained by inflow at the qei which has increased since 2005 these recent increases in arctic ocean myi inflow into the qei can be attributed to increased open water area within the caa that have provided more leeway for inflow to occur

structural control on drainage network and catchment area geomorphology in the dead sea area an evaluation using remote sensing and geographic information systems in the wadi zerka ma in catchment area jordan the geology of jordan is characterized by fault systems with three major trends 1 nw se the oldest 2 wnw ese and 3 nnw sse the youngest the drainage network of the wadi zerka ma in catchment area located in the middle of the dead sea rift parallels these structural orientations a regional transtensive fault with embedded normal faults bounds the lower and middle part of the catchment area the topographic profile of the zerka ma in river exhibits two major knickpoints where it crosses two major embedded normal faults the second major knickpoint developed as a result of the dramatic lowering of the lisan lake water level a lake that pre dates the dead sea the decreased water level triggered river incision into the clastic sandstone units of wadi zerka ma in we performed a morphotectonic analysis study to investigate how the rock structures control the drainage network and the catchment area geomorphology according to the transverse topographic symmetry factor t the catchment area is highly asymmetric the major basin asymmetry trend is se oriented parallel to the oldest set of fault systems the catchment area displays a convex hypsometric curve indicating a very recent stage in the geomorphologic cycle our study indicates that the lisan lake catchment area shrinkage and structures growth controlled and shaped the wadi zerka ma in catchment area geomorphology the combined use of a geographic information system gis and remote sensing was shown to be very efficient in unraveling the evolution of the drainage network and catchment area geomorphology

characteristics of the beaufort sea high abstract characteristics of the arctic ocean s beaufort sea high are examined using fields from the ncep ncar reanalysis at a 2 hpa contour interval the beaufort sea high appears as a closed anticyclone in the long term annual mean sea level pressure field and in spring in winter the beaufort sea region is influenced by a pressure ridge at sea level extending from the siberian high to the yukon high over northwestern canada as assessed from 6 hourly surface winds the mean frequency of anticyclonic surface winds over the beaufort sea region is fairly constant through the year while for all seasons a strong closed high can be interpreted as the surface expression of an amplified western north american ridge at 500 hpa there is some suggestion of a split flow where the ridge linked to the surface high is separated from the ridge to the south that lies within the main belt of westerlies the aleutian low in the north pacific tends to be deeper than normal when there is a strong beaufort sea high in

seasonal ice loss in the beaufort sea toward synchrony and prediction the seasonal evolution of sea ice loss in the beaufort sea during 1979 2012 is examined focusing on differences between eastern and western sectors two stages in ice loss are identified the day of opening doo is defined as the spring decrease in ice concentration from its winter maximum below a value of 0 8 areal concentration the day of retreat dor is the summer decrease below 0 15 concentration we consider three aspects of the subject i e i the long term mean ii long term linear trends and iii interannual variability we find that in the mean doo occurs earliest in the eastern beaufort sea ebs owing to easterly winds which act to thin the ice there relative to the western beaufort sea wbs where ice has been generally thicker there is no significant long term trend in ebs doo although wbs doo is in fact trending toward earlier dates this means that spatial differences in doo across the beaufort sea have been shrinking over the past 33 years i e these dates are becoming more synchronous a situation which may impact human and marine mammal activity in the area retreat dates are also becoming more synchronous although with no statistical significance over the studied time period finally we find that in any given year an increase in monthly mean easterly winds of 1 m s during spring is associated with earlier summer dor of 6 15 days offering predictive capability with 2 4 months lead time

a review of palaeoclimates and palaeoenvironments in the levant and eastern mediterranean from 25 000 to 5000 years bp setting the environmental background for the evolution of human civilisation abstract the southern levant has a long history of human habitation and it has been previously suggested that climatic changes during the late pleistocene holocene stimulated changes in human behaviour and society in order to evaluate such linkages it is necessary to have a detailed understanding of the climate record we have conducted an extensive and up to date review of terrestrial and marine climatic conditions in the levant and eastern mediterranean during the last 25 000 years we firstly present data from general circulation models gcms simulating the climate for the last glacial maximum lgm and evaluate the output of the model by reference to geological climate proxy data we consider the types of climate data available from different environments and proxies and then present the spatial climatic picture for key climatic events this exercise suggests that the major northern hemisphere climatic fluctuations of the last 25 000 years are recorded in the eastern mediterranean and levantine region however this review also highlights problems and inadequacies with the existing data

role of sediment in speleogenesis sedimentation and paragenesis although the effects of sedimentation in caves have been recognised for many years its role in speleogenesis is frequently overlooked influxes of sediment into a cave system fundamentally alter the way cave passages develop either by alluviation in a vadose environment forcing lateral corrosion and the development of notches or by upwards dissolution in a phreatic environment through a process known as paragenesis sediment influxes affect the hydrological functioning of a karst aquifer by changing the way conduits behave and subsequently develop both in plan and long section here we give an overview of the mechanisms of cave sedimentation and describe how the process of alluviation and paragenesis affect speleogenesis a characteristic suite of meso and micro scale dissolutional features can be used to recognise paragenetic development which is reviewed here in a vadose environment these include alluvial notches whilst in a phreatic environment half tubes anastomoses and pendants bedrock fins and paragenetic dissolution ramps result using these to identify phases of sedimentation and paragenesis is crucial for reconstructing denudation chronologies from cave deposits we suggest that sedimentation and paragenesis are most likely to occur in certain geomorphological situations such as ice marginal and periglacial environments beneath thick residual soils and where rivers can transport fluvial sediment into a cave either via stream sinks or back flooding

changes in arctic melt season and implications for sea ice loss the arctic wide melt season has lengthened at a rate of 5 days decade 1 from 1979 to 2013 dominated by later autumn freezeup within the kara laptev east siberian chukchi and beaufort seas between 6 and 11 days decade 1 while melt onset trends are generally smaller the timing of melt onset has a large influence on the total amount of solar energy absorbed during summer the additional heat stored in the upper ocean of approximately 752 mj m 2 during the last decade increases sea surface temperatures by 0 5 to 1 5 c and largely explains the observed delays in autumn freezeup within the arctic ocean s adjacent seas cumulative anomalies in total absorbed solar radiation from may through september for the most recent pentad locally exceed 300 400 mj m 2 in the beaufort chukchi and east siberian seas this extra solar energy is equivalent to melting 0 97 to 1 3 m of ice during the summer

determining the exposure age of a karst landscape an extensive salt karst system has developed in mount sedom salt diapir israel during the holocene multilevel vadose caves were14c dated using wood fragments embedded in alluvial deposits the oldest date of each cave is used to constrain the age of the salt exposure the upper portion of the southeastern escarpment was the first to rise above base level 7100 yr b p caves in the surrounding area indicate gradual landscape exposure around this initial karstified area between 7000 and 4000 yr b p the northern part of the mountain experienced a similar exposure history lagging some 3000 yr after the southern part this lag may be attributed to the narrow width of the diapir in the north which increases viscous drag at the borders of the rising diapir

recent changes in sea ice area flux through the beaufort sea during the summer over the annual cycle sea ice is sequestered from the canadian basin and transported through the beaufort sea toward the chukchi sea in recent years the beaufort sea has experienced considerable ice loss during the summer which may be indicative of recent changes to this process in order to investigate this we quantify the sea ice area flux using radarsat from 1997 to 2014 at three gates in beaufort sea the canadian basin entrance mid beaufort midpoint and chukchi exit there was a mean annual flux of 42 56 103 km2 at the canadian basin gate 94 92 103 km2 at the mid beaufort gate and 83 68 103 km2 at the chukchi gate positive and negative flux signs correspond to ice inflow and outflow respectively the majority of ice transport in beaufort sea was found to occur from october to may providing replenishment for ice lost during the summer months the cross strait gradient in sea level pressure explains 40 of the variance in the ice area flux at the gates remarkably the mean july october net sea ice area flux at the chukchi gate decreased by 80 from 2008 to 2014 relative to 1997 2007 and became virtually ice free every year since 2008 this reduction was associated with younger thinner ice that was unable to survive the summer melt season when either being sequestered from the canadian basin and transported through beaufort sea during the melt season 2008 2011 or remaining immobile and present in the vicinity of the chukchi gate during the melt season 2012 2014

late pleistocene palaeoclimatic and palaeoenvironmental reconstruction of the dead sea area israel based on speleothems and cave stromatolites abstract calcite speleothems are a hitherto hardly documented occurrence in the nowadays arid to hyper arid rain shadow dead sea area of eastern israel speleothem ages u th from two caves on the dead sea fault escarpment and two caves from arid rain shadow areas surrounding the dead sea span the last three glacial cycles from ca 354 to 12 ka and suggest episodic moist local palaeoclimate mainly during glacial periods of marine isotopic stages mis 6 and 4 to 2 previously reported u th ages of stromatolites deposited in the late pleistocene lake lisan and preserved in caves of the dead sea fault escarpment suggest that regional relatively moist climate affected the lake catchment area during the late part of relatively warm mis 3 lasting until middle cold mis 2 as well as at the mis 5 to 4 interglacial glacial transition speleothem deposition periods spanning the 38 4 0 5 to 16 4 0 3 ka time interval i e late mis 3 to early mis 2 representing moist periods in the lake area are coeval to regional moist conditions inferred by the stromatolite record a direct connection is thus implied between local and regional climate at the latest pleistocene based on correlation between two independent data sets this connection implies that glacial climate has generally been moister than interglacial climate during the last glacial interglacial cycle at both local and regional scales around the dead sea and its predecessors

a discussion of alluvial sandstone body characteristics related to variations in marine influence middle jurassic of the cleveland basin uk and the implications for analogous brent group strata in the north sea basin

on the record reduction in 1998 western arctic sea ice cover during summer 1998 record reductions in ice cover occurred in the beaufort and chukchi seas open water formed earlier than in prior years and september ice extent in this region was 25 percent less than the previous minimum for 1953 1997 seven percent of the arctic basin that had been perennially ice covered was ice free in 1998 this reduction in western arctic ice extent can be attributed in part to preconditioning by light ice cover in autumn 1997 and to atmospheric circulation patterns during the following winter through autumn that favored southerly and easterly winds such decreases in northerly winds and the associated weakening or displacement of the beaufort gyre is found to be typical of winters that precede years with below normal ice extent in the western arctic

sinkholes and caves related to evaporite dissolution in a stratigraphically and structurally complex setting fluvia valley eastern spanish pyrenees geological geomorphological and environmental implications abstract evaporite karst and sinkhole development is analysed in a geologically complex area of ne spain including four evaporite units with different characteristics and affected by compressional and extensional tectonic structures the exposed paleosinkholes including remarkable early pleistocene paleontological sites provide valuable information on the subsidence mechanisms and reveal the significant role played by interstratal karstification in the area these gravitational deformation structures including hectometre scale bending folds and oversteepened normal faults strongly suggest that the present day compressional regime inferred in previous studies may be largely based on the analysis of non tectonic structures two gypsum caves ca 1 km long show that passages with restricted cross sectional area may produce large breccia pipes and sinkholes thanks to the removal of breakdown boulders by high competence episodic floods moreover the upward progression of cave ceilings by paragenesis and condensation dissolution contributes to increase the probability of sinkhole occurrence an inventory of 135 sinkholes together with their geological and geomorphological context has been developed this data base has been used to infer several properties of the sinkholes with practical implications a magnitude and frequency scaling relationship spatial distribution patterns dominant controlling factors and risk implications

high resolution geological record of historic earthquakes in the dead sea basin a 2000 year paleoseismic record of the dead sea area was recovered from a lacustrine sedimentary section the section is being exposed at the ze elim terrace on the shores of the dead sea due to the fast retreat of the lake the section consists of laminated detrital and chemical mainly aragonite sediments that were deposited in the holocene paleo dead sea eight layers in the section show deformed sedimentary structures and are identified as seismites their chronology was determined by radiocarbon dating on organic remains the seismite ages are well correlated with the historically documented earthquakes of 64 and 31 b c and 33 363 1212 1293 1834 and 1927 a d the few historically documented earthquakes that have no correlatives in the ze elim seismite record occurred in times of sedimentary hiatuses at this site e g 749 a d based on modern analogues and the association of similar disturbed layers with syndepositional faults the ze elim terrace seismites indicate m 5 5 earthquakes the average recurrence interval is estimated as 100 300 years and represents slip events on different faults in the dead sea area the ze elim section provides a unique opportunity to correlate two independent and extensive data sets the historical and sedimentary records this study opens the way for better understanding of spatial and temporal distribution of earthquakes along the dead sea transform and elsewhere

interdecadal changes in snow depth on arctic sea ice snow plays a key role in the growth and decay of arctic sea ice in winter it insulates sea ice from cold air temperatures slowing sea ice growth from spring to summer the albedo of snow determines how much insolation is absorbed by the sea ice and underlying ocean impacting ice melt processes knowledge of the contemporary snow depth distribution is essential for estimating sea ice thickness and volume and for understanding and modeling sea ice thermodynamics in the changing arctic this study assesses spring snow depth distribution on arctic sea ice using airborne radar observations from operation icebridge for 2009 2013 data were validated using coordinated in situ measurements taken in march 2012 during the bromine ozone and mercury experiment bromex field campaign we find a correlation of 0 59 and root mean square error of 5 8 cm between the airborne and in situ data using this relationship and icebridge snow thickness products we compared the recent results with data from the 1937 1954 1991 soviet drifting ice stations the comparison shows thinning of the snowpack from 35 1 9 4 to 22 2 1 9 cm in the western arctic and from 32 8 9 4 to 14 5 1 9 cm in the beaufort and chukchi seas these changes suggest a snow depth decline of 37 29 in the western arctic and 56 33 in the beaufort and chukchi seas thinning is negatively correlated with the delayed onset of sea ice freezeup during autumn

holocene stratigraphy of the dead sea correlation of high resolution seismic reflection profiles to sediment cores the northern basin of the dead sea is occupied by a 300 m deep lake a series of cores in the deep water part of the lake provide information about the top 365 cm of the sediments the cores were correlated with high resolution 3 5 khz seismic profiles from this area and provide lithologic and age constraints for the high resolution seismic reflection data visual comparison of the two data sets shows that strong surface and shallow subsurface reflectors a and b correlate to the massive salt at the seafloor surface and the indurated salt at the base of the cores respectively calculations of an average seismic velocity based on the interval between these reflectors and the corresponding sedimentary thickness yield an average 3500 m s velocity this agrees closely with velocities determined from direct measurements of compressional velocities for sediment samples ultrasonic wave velocity measurements of salt samples from the cores and dry rock salt cores from the southern basin of the dead sea indicate that wave velocities are independent of the burial depth at shallow depths however velocities show strong dependence on porosity at low hydrostatic pressure a reduction in porosity as well as closure of microcracks in the crystals cause an increase in the velocities this increase disappears at higher stress levels synthetic seismograms of the upper 3 ms and the entire 25 ms penetrated by the seismic profiles reinforce the lithologic and seismic stratigraphic correlation and confirm that prominent reflectors in the basin represent the top boundary of halite layers which are separated by laminated sequences of evaporites and elastics the salt in the upper salt sequence is deposited at a very fast rate of more than 20 mm yr however at shallow depths considerable compaction takes place variations in appearance and velocities of the upper salt sequence and middle salt sequence indicate that the porous granular and fine grained precipitates of the surface salts are diagenetically altered to a coarse and compact crystalline aggregate by re solution and crystallization with burial the sedimentary sequences recovered in the cores suggest that significant lake level fluctuations took place in the past in response to climatic changes the detailed correlation of the cores and seismic profiles makes it possible to extrapolate climatic data from earlier periods beneath the maximum core penetration by analyzing the seismic stratigraphic sequences of the seismic reflection data

decline in arctic sea ice thickness from submarine and icesat records 1958 2008 1 the decline of sea ice thickness in the arctic ocean from icesat 2003 2008 is placed in the context of estimates from 42 years of submarine records 1958 2000 described by rothrock et al 1999 2008 while the earlier 1999 work provides a longer historical record of the regional changes the latter offers a more refined analysis over a sizable portion of the arctic ocean supported by a much stronger and richer data set within the data release area dra of declassified submarine sonar measurements covering 38 of the arctic ocean the overall mean winter thickness of 3 64 m in 1980 can be compared to a 1 89 m mean during the last winter of the icesat record an astonishing decrease of 1 75 m in thickness between 1975 and 2000 the steepest rate of decrease is 0 08 m yr in 1990 compared to a slightly higher winter summer rate of 0 10 0 20 m yr in the five year icesat record 2003 2008 prior to 1997 ice extent in the dra was 90 during the summer minimum this can be contrasted to the gradual decrease in the early 2000s followed by an abrupt drop to 55 during the record setting minimum in 2007 this combined analysis shows a long term trend of sea ice thinning over submarine and icesat records that span five decades

natural and human induced dissolution and subsidence processes in the salt outcrop of the cardona diapir ne spain the cardona diapir in ne spain with a salt outcrop about 0 9 km2 in area has a well developed endokarstic system that used to discharge into the cardener river underground mining for potassium salt carried out from 1930 to 1990 caused significant changes in the topography and hydrology of the diapir the accumulation of two halite slag heaps totalling around 10 million tons locally dammed the surface drainage creating closed depressions and preferential zones of water recharge the waters that infiltrated in one of these depressions largely derived from uncontrolled sewage disposal led to the generation of a 335 m long human induced cave excavated in one of the slag heaps moreover the inflow of freshwater from the surrounding sandstone aquifer caused by the excavation of a ventilation gallery resulted in the generation of a 280 m long cave in march 1998 the interception of a phreatic conduit by a halite mine gallery 50 m deep caused dramatic changes in the hydrology and geomorphology of the diapir including a a sudden decline in the piezometric level of the karstic aquifer b the inflow of freshwater and debris from the cardener river into the endokarstic system and the mine galleries a tunnel had to be constructed to divert the river flow from the salt outcrop c massive dissolution of salt creating new cavities and enlarging the pre existing ones including both mine galleries or cave passages the 4 300 m long salt meanders cave was largely generated by the inrush of water from the cardener river into the mine galleries and d the generation of a large number of sinkholes in the vicinity of the cardener river an inventory of 178 sinkholes has allowed us to estimate minimum probability values of 4 7 and 8 sinkholes km2 year for time intervals previous and subsequent to the 1998 mine flood event respectively

outflow of arctic ocean sea ice into the greenland and barents seas 1979 2007 abstract twenty nine years of arctic sea ice outflow into the greenland and barents seas are summarized outflow is computed at three passages fram strait between svalbard and franz josef land s fjl and between franz josef land and severnaya zemlya fjl sz ice drift at the flux gates has been reprocessed using a consistent and updated time series of passive microwave brightness temperature and ice concentration ic fields over the record the mean annual area outflow at the fram strait is 706 113 103 km2 it was highest in 1994 95 1002 103 km2 when the north atlantic oscillation nao index was near its 29 yr peak the strength of the transpolar drift stream tds was high during the late 1980s through the mid 1990s there is no statistically significant trend in the fram strait area flux even though there is a positive trend in the gradient of cross strait sea level pressure the outflow has not increased because of a negative trend in ic seasonally the area outflow during recent sum

evidence for holocene environmental changes in the northern fertile crescent provided by pedogenic carbonate coatings abstract holocene environmental changes in the northern fertile crescent remain poorly understood because of the scarcity of local proxy records in the region in this study we investigated pedogenic soil formed carbonate coatings on stones at the pre pottery neolithic site gobekli tepe as an indicator of local early mid holocene environmental changes the 14c ages and stable isotopic composition of carbon and oxygen in thin 0 2 0 3 mm thick pedogenic carbonate lamina indicate two main periods of coating formation the early holocene ca 10000 6000 cal yr bp and the mid holocene ca 6000 4000 cal yr bp during the first period there was an inverse relationship between 13c and 18o curves a decrease in 13c values coincide with an increase in 18o values for this period a trend towards higher temperatures is suggested in the mid holocene the mean rate of coating growth was 2 3 times higher than in the early holocene both 13c and 18o reached their maximum values during this time and the direction of changes of the 13c and 18o curves became similar the combination of data suggests that this period was the most humid in the holocene and on average warmer than the early holocene at ca 4000 cal yr bp secondary accumulation of carbonate ceased presumably reflecting a shift to a more arid climate

sea ice motion tracking from sequential dual polarization radarsat 2 images a new sea ice motion tracking algorithm that operates with two sequential synthetic aperture radar sar radarsat 2 scansar images is presented the feature tracking approach is based on the combination of the phase correlation and cross correlation methods an algorithm for selecting control points a matching technique an approach for filtering out error vectors and a confidence levels setting for output drift vectors were specifically developed in order to increase the system s robustness and accuracy we evaluated ice motion tracking results derived from hh and hv channels of radarsat 2 scansar imagery and formulated a condition where the hv channel is more reliable than the hh channel for ice tracking furthermore we found that the ice motion tracking from the hv channel is not affected by noise floor stripes which are prominent in the cross polarization radarsat 2 scansar images the developed sea ice tracking technology was implemented at the canadian ice service environment canada for operational use the system was successfully run to provide operational support of field work in the arctic ocean in compliance with the united nations convention on the law of the sea in the spring of 2010

variability of fram strait ice flux and north atlantic oscillation we estimate the winter sea ice export through the fram strait using ice motion from satellite passive microwave data sea ice motion october may is obtained by tracking the displacement of common features in sequential 85 and 37 ghz brightness temperature fields the average winter area flux over the 18 year record 1978 1996 is 670 000 km2 7 of the area of the arctic ocean the winter area flux ranges from a minimum of 450 000 km2 in 1984 to a maximum of 906 000 km2 in 1995 the daily monthly and interannual variabilities of the ice area flux are high there is an upward trend in the ice area flux over the 18 year record the average winter volume flux over the winters of october 1990 through may 1995 is 1745 km3 ranging from a low of 1375 km3 in the 1990 flux to a high of 2791 km3 in 1994 the sea level pressure gradient across the fram strait explains more than 80 of the variance in the ice flux over the 18 year record we use the coefficients from the regression of the time series of area flux versus pressure gradient across the fram strait and ice thickness data to estimate the summer area and volume flux the average 12 month area flux and volume flux are 919 000 km2 and 2366 km3 we find a significant correlation r 0 86 between the area flux and positive phases of the north atlantic oscillation nao index over the months of december march correlation between our 5 years of volume flux estimates and the nao index gives r 0 56 during the high nao years a more intense icelandic low increases the gradient in the sea level pressure by almost 1 mbar across the fram strait thus increasing the atmospheric forcing on ice transport correlation is reduced during the negative nao years because of decreased dominance of this large scale atmospheric pattern on the sea level pressure gradient across the fram strait

holocene earthquakes inferred from a fan delta sequence in the dead sea graben abstract the holocene sequence of the fan delta of nahal darga in israel records deformation associated with earthquakes related to the dead sea transform in general and to the jericho fault in particular the fan delta sequence is well exposed and 20 radiocarbon ages help to date the earthquakes that are inferred from a displacement along faults b liquefaction features associated with 11 separate sandy and silty layers and c slumped allocthonous bodies of sediments located directly above one of the main splays of the jericho fault on average an earthquake larger than m 5 5 has occurred approximately every 600 years this estimate is based on the earthquake record of the complete stratigraphic sequence with erosional hiatuses omitted from the calculations the most recently deformed layer is related to the 1927 jericho m l 6 2 earthquake this layer provides a modern analog for the style of soft sediment deformation associated with earthquakes in the late pleistocene and holocene silty sand beds of the fan delta complexes of the dead sea and its predecessor lake lisan

authigenesis of titania minerals and the mobility of ti new evidence from pro deltaic sandstones cretaceous scotian basin canada titania tio2 minerals are minor diagenetic phases in many sandstone shale successions but the conditions of ti mobility and titania authigenesis are poorly known here new modes of occurrence of authigenic titania minerals filling pores and replacing phytodetritus are documented from lower cretaceous prodeltaic sandstones in the offshore scotian basin of southeastern canada textural relationships suggest that titania minerals formed at the same time as kaolinite most commonly below lowstand sequence boundaries related to flux of meteoric water such authigenic titania is most abundant in thin bedded sandstones interbedded with thick prodeltaic mudstone in which fine grained detrital ti rich minerals are concentrated textures in titania that has replaced uncompacted phytodetritus suggest microbial mediation in near surface eodiagenesis eogenetic titania is enriched in phosphorus 0 6 p2o5 and may co occur with authigenic fluorapatite and crandallite crystals such titania resulted from prolonged flow of meteoric water that dissolved p from apatite and feldspar thereby enhancing ti solubility in basins with supply of immature sediment from granitic terranes and important diagenesis by meteoric water the assumption that ti is an immobile element and that rutile or other titania minerals are exclusively of detrital origin may not be valid probable mesodiagenetic titania has low p content suggesting that ti mobility under these conditions was facilitated by some other agent probably organic acids the results of this study illustrate that even in cases where titania minerals are volumetrically insignificant their microtextures and trace element chemistry can provide important insights into the character of fluid flow during diagenesis of siliciclastic rocks

the 2017 reversal of the beaufort gyre can dynamic thickening of a seasonal ice cover during a reversal limit summer ice melt in the beaufort sea during winter 2017 the semi permanent beaufort high collapsed and the anticyclonic beaufort gyre reversed the reversal drove eastward ice motion through the western arctic causing sea ice to converge against banks island and halted the circulation of multiyear sea ice via the gyre preventing its replenishment in the beaufort sea prior to the reversal an anomalously thin seasonal ice cover had formed in the beaufort following ice free conditions during september 2016 with the onset of the reversal in january 2017 convergence drove uncharacteristic dynamic thickening during winter by the end of march despite seasonal ice comprising 97 of the ice cover the reversal created the thickest roughest and most voluminous regional ice cover of the cryosat 2 record within the beaufort sea previous work has shown that winter ice export can precondition the region for increased summer ice melt but that a short reversal during april 2013 contributed to a reduction in summer ice loss hence the deformed ice cover at the end of winter 2017 could be expected to limit summer melt in spite of this the beaufort ice cover fell to its fourth lowest september area as the gyre re established during april and divergent ice drift broke up the pack negating the reversal s earlier preconditioning our work highlights that dynamic winter thickening of a regional sea ice cover for instance during a gyre reversal offers the potential to limit summer ice loss but that dynamic forcing during spring dictates whether this conditioning carries through to the melt season

response of sea ice to the arctic oscillation abstract data collected by the international arctic buoy programme from 1979 to 1998 are analyzed to obtain statistics of sea level pressure slp and sea ice motion sim the annual and seasonal mean fields agree with those obtained in previous studies of arctic climatology the data show a 3 hpa decrease in decadal mean slp over the central arctic ocean between 1979 88 and 1989 98 this decrease in slp drives a cyclonic trend in sim which resembles the structure of the arctic oscillation ao regression maps of sim during the wintertime january march ao index show 1 an increase in ice advection away from the coast of the east siberian and laptev seas which should have the effect of producing more new thin ice in the coastal flaw leads 2 a decrease in ice advection from the western arctic into the eastern arctic and 3 a slight increase in ice advection out of the arctic through fram strait taken together these changes suggest that at least part of the thinning of sea ice recently observed ov

historic dead sea level fluctuations calibrated with geological and archaeological evidence abstract the dead sea the holocene terminal lake of the jordan river catchment has fluctuated during its history in response to climatic change biblical records calibrated by radiocarbon dated geological and archaeological evidence reinforce and add detail to the chronology of the lake level fluctuations there are three historically documented phases of the dead sea in the biblical record low lake levels ca 2000 1500 b c e before common era high lake levels ca 1500 1200 b c e and low lake levels between ca 1000 and 700 b c e the biblical evidence indicates that during the dry periods the southern basin of the dead sea was completely dry a fact that was not clear from the geological and archaeological data alone

deterioration of perennial sea ice in the beaufort gyre from 2003 to 2012 and its impact on the oceanic freshwater cycle time series of ice draft from 2003 to 2012 from moored sonar data are used to investigate variability and describe the reduction of the perennial sea ice cover in the beaufort gyre bg culminating in the extreme minimum in 2012 negative trends in median ice drafts and most ice fractions are observed while open water and thinnest ice fractions 0 3 m have increased attesting to the ablation or removal of the older sea ice from the bg over the 9 year period monthly anomalies indicate a shift occurred toward thinner ice after 2007 in which the thicker ice evident at the northern stations was reduced differences in the ice characteristics between all of the stations also diminished so that the ice cover throughout the region became statistically homogenous the moored data are used in a relationship with satellite radiometer data to estimate ice volume changes throughout the bg summer solid fresh water content decreased drastically in consecutive years from 730 km3 in 2006 to 570 km3 in 2007 and to 240 km3 in 2008 after a short rebound solid fresh water fell below 220 km3 in 2012 meanwhile hydrographic data indicate that liquid fresh water in the bg in summer increased 5410 km3 from 2003 to 2010 and decreased at least 210 km3 by 2012 the reduction of both solid and liquid fresh water components indicates a net export of approximately 320 km3 of fresh water from the region occurred between 2010 and 2012 suggesting that the anticyclonic atmosphere ocean circulation has weakened

perennial pack ice in the southern beaufort sea was not as it appeared in the summer of 2009 1 in september 2009 we observed a much different sea icescape in the southern beaufort sea than anticipated based on remotely sensed products radarsat derived ice charts predicted 7 to 9 tenths multi year my or thick first year fy sea ice throughout most of the southern beaufort sea in the deep water of the canada basin in situ observations found heavily decayed very small remnant my and fy floes interspersed with new ice between floes in melt ponds thaw holes and growing over negative freeboard older ice this icescape contained approximately 25 open water predominantly distributed in between floes or in thaw holes connected to the ocean below although this rotten ice regime was quite different that the expected my regime in terms of ice volume and strength their near surface physical properties were found to be sufficiently alike that their radiometric and scattering characteristics were almost identical

evidence for rapid thinning of sea ice in the western arctic ocean at the end of the 1980s examination of springtime ice drafts obtained from submarine profiles in a narrow band of the western arctic ocean from offshore alaska to 89 n indicates that the mean ice draft decreased 1 5 m between the mid 1980s and early 1990s no similar trend was evident in ice drafts near the north pole the 1980s drafts were composed largely of ice exceeding 3 5 m while the early 1990s drafts contained more ice in thinner categories the differences in drafts between the two periods appear to be related largely to ice dynamics effects associated with the presence and strength of the beaufort gyre which weakened considerably in the early 1990s

a high resolution late holocene landscape ecological history inferred from an intramontane basin in the western taurus mountains turkey abstract late holocene vegetation and geomorphological history is reconstructed from a 800 cm long high resolution palynological and sedimentological record sampled from bereket a 6 3 km 2 semi arid to sub humid intramontane basin in the western taurus mountains southwest turkey the well dated bereket record provides from cal 360 bc to cal ad 400 a unique record of biennial to decadal landscape changes caused primarily by intensive human impacts against a background of global climate variations during this period land clearance with multiple fire episodes intensive agricultural practices and grazing pressure profoundly altered the pre existing warm mixed forest increasing moisture availability since cal 280 bc has acted as a trigger to crop cultivation and mountain adapted arboriculture starting with juglans regia during the beysehir occupation phase pollen from olive groves have been recorded above 1400 m a s l only at cal 23 bc and have disappeared definitively at cal ad 294 during this phase the sediment accumulation rate was extremely high reflecting landscape instability from cal ad 450 to recent times the area has mainly recorded pasture and minor cultivation activities reflected in stable soils and thin colluvial depths

arctic sea ice conditions in spring 2009 2013 prior to melt 1 measurements from nasa icebridge airborne surveys in march april 2009 2013 over the western arctic ocean are presented in the context of previous observations to assess changes in the characteristics of the sea ice cover during the last decade taking into account spatial and temporal limitations in the available data following a precipitous drop in the amount and thickness of multiyear my ice in 2007 2008 the characteristics of the ice cover have remained largely consistent through march 2013 the central arctic continues to be dominated by my ice with mean and modal thicknesses of 3 2 m and 2 4 m respectively the southern beaufort and chukchi sea region is a complex mixture of 75 first year ice and 25 my ice icebridge observations indicate that the mean thickness in the beaufort and chukchi seas may have decreased from 2 5 m to as low as 1 6 m over the 5 year period

rates of cave and landform development in the yorkshire dales from speleothem age data uranium series ages have been obtained for 87 speleothems collected from nine major cave systems in the craven district of northern england large systems such as ease gill caverns the west kingsdale caves and gaping gill ingleborough cave which contain relict high level tunnels are found to be older than 350 000 years the limit of the 230th 234u dating method there is little evidence to indicate a significant enlargement of these passages since this time estimates of the age of victoria cave from 234u 238u isotopic ratios suggest that the cave has been fully relict for more than 500 000 years ages of in situ speleothems immediately adjacent to local base level cave streams show that mean maximum downcutting rates in limestone channels are about 2 to 5 cm 1000 yr these rates are significantly lower than those obtained from direct measurements on limestone bedrock in stream channels but are comparable to areal denudation rates based on solute budgets using the present elevation of caves with respect to adjacent valley floor levels mean maximum valley entrenchment rates are found to range between 5 cm ky and 20cm ky which corresponds to 6 m to 24 m of lowering per glacial interglacial cycle these rates suggest that upper beds of the limestone were incised to form the yorkshire dales between 1 and 2 million years ago the results indicate that the erosional effects of individual glaciations are not as severe as previously proposed in the literature

geochemical and petrographical characteristics of a domed bog nova scotia a modern analogue for temperate coal deposits a freshwater domed bog in nova scotia canada was investigated for its petrographic mineralogical and geochemical characteristics three cores were taken from the lagg zone margin and centre to examine different stages of evolution in a fen to domed bog sequence based on this study a model was developed which shows the relationship between factors controlling peat geochemistry and petrography all of them being dependent on trophic conditions the bog may represent a modern analogue for temperate coal deposits and thus can be used to help understand spatial variability within coal beds rheotrophic conditions in the early stages of mire development result in the formation of high ash highly humified carex dominated peat while the evolution toward ombrotrophic conditions is reflected in a progressive replacement by low ash and well preserved sphagnum dominated peat the associated decrease in ph reflects a decrease of groundwater influence which is also supported by the mineralogical assemblage and petrographic data decrease in reflectance and change in maceral composition except for cl br i and se which are associated with the organic fraction variations in elemental composition can be explained in terms of mineral matter abundance i e decrease upward and with increasing distance from the margin sea spray is the most probable origin for halogen enrichment in the peat

palaeo climate controlled diagenesis of the westphalian c d fluvial sandstones in the campine basin north east belgium the westphalian c and d fluvial sandstones in the campine basin north east belgium are potential reservoirs for the sequestration of co2 and interesting analogues of the hydrocarbon reservoirs in the southern north sea although these sandstones were deposited in a relatively short period of time their reservoir properties and mineralogical compositions are very different a petrographic study complemented with stable isotope analyses fluid inclusion microthermometry and x ray diffraction analyses of the clay fractions of the sandstones which were sampled from deep boreholes 1000 m in the campine basin revealed that these differences are related mainly to the climate at the time of deposition the most important eogenetic processes affecting the westphalian sandstones were the generation of a pseudomatrix by physical compaction of al silicates and lithic fragments that were strongly altered by extensive meteoric leaching kaolinitization of unstable silicates and precipitation of siderite these processes had a detrimental influence on the reservoir properties of westphalian c sandstones but their impact on the westphalian d sandstones was minimal the difference is assumed to be related to the climate at the time of deposition which changed from tropical humid in the westphalian c to semi arid arid during the late westphalian d both the westphalian c and d sandstones were affected by similar mesogenetic processes mesogenetic quartz cementation resulted from chemical compaction and illitization of kaolinite k feldspar and smectitic clays illitization of kaolinite was controlled by the available quantities of co existing kaolinite and k feldspar and mainly affected the westphalian d sandstones illitization of k feldspar was controlled by the k feldspar content it had a much larger impact on the reservoir properties of the westphalian d as in these sandstones k feldspar was less affected by eogenetic alteration the illitization of smectitic clays resulted in illite quartz and ankerite cementation in both reservoirs this process had a more important impact on the westphalian c reservoir since cementation here also resulted from smectite to illite conversion in the interbedded and underlying shales the effect of mesogenetic alterations on the reservoir properties was much less drastic than the impact of eodiagenesis mesogenetic alterations do exert a significant control on the properties of the westphalian d the vast impact of eodiagenesis on the westphalian c sandstones made them less susceptible to mesogenetic alteration the effect of telogenetic processes on the porosity and permeability of the westphalian sandstones was small and restricted to the top reservoir intervals that directly underlie the cimmerian unconformity no significant telogenetic alterations related to the variscan unconformity were observed

sinkholes collapse structures and large landslides in an active salt dome submerged by a reservoir the unique case of the ambal ridge in the karun river zagros mountains iran abstract ambal ridge covering 4 km2 is a salt pillow of gachsaran formation with significant salt exposures in direct contact with the karun river zagros mountains the highly cavernous salt dome is currently being flooded by the gotvand reservoir second largest in iran geomorphic evidence including the sharp deflection of the karun river and defeated streams indicate that ambal is an active halokinetic structure probably driven by erosional unloading around 30 of the salt dome is affected by large landslides up to ca 50 106 m3 in volume slope oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor a total of 693 sinkholes have been inventoried 170 sinkholes km2 for which a scaling relationship has been produced the depressions occur preferentially along a belt with a high degree of clustering this spatial distribution is controlled by the proximity to the river slope gradient and halite content in the bedrock a large compound depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by water table rise forming a lake the impoundment of the reservoir has induced peculiar collapse structures 220 280 m across expressed by systems of arcuate fissures and scarps rapid subsurface salt dissolution is expected to generate and reactivate a large number of sinkholes and may reactivate landslides with a significant vertical component due to lack of basal support

geochemical variability induced by entrainment sorting quantified signals for provenance analysis abstract a substantial part of the mineralogical and chemical heterogeneity of clay poor sands at the bed scale results from tractive redistribution of the grains in the bedload since coarse and light particles are more easily entrained than denser and smaller heavy minerals the latter commonly concentrate in grain scale lags that alternate with sand depleted in these minerals when sampled and analysed at the centimetre scale this primary heterogeneity translates into nice geochemical covariations between the minor trace elements that concentrate in some heavy minerals zr ti p cr v y ce among others regressing these variations allow us to derive two chemical fingerprints of the sand one records the proportions between some heavy minerals the other the average composition of framework grains i e a sand composition corrected from the contribution of heavy minerals both relate to provenance and allow different sand beds to be compared in appropriate spider diagrams the construction of these diagrams their potential use and their limitations are discussed using two contrasting examples continental channel sandstones from the ravenscar group middle jurassic yorkshire uk illustrate how these geochemical fingerprints vary from the local to the group scales and how robust they are against diagenetic overprint at ravenscar the zr vs ti v cr covariations record the presence of ti oxides and magnetite together with zircon and of volcanic lithoclasts at the deposition stage despite a high degree of diagenetic alteration overbank sandstones lateral to channels from the deep marine gres d annot formation eocene oligocene alps illustrates how apatite and monazite delivered by a dominantly granitic source generate covariations between zr and p y ce and th contents with characteristically steep slopes

tephra in caves distal deposits of the minoan santorini eruption and the campanian super eruption abstract tephra deposits in caves are not only significant as stratigraphic markers the comparatively sheltered position of cave environments protected from rainfall may preserve original distal tephra deposition features unlikely to have survived in the open landscape most reported findings of tephra in caves are from the campanian super eruption which originated in the area of naples italy these findings facilitate evaluation in different caves of facies variability and modes of tephra deposition derived from the same eruption the campanian volcanic event about 40 000 years ago was the largest eruption in europe and the mediterranean region during the late pleistocene another major volcanic event during the quaternary was the more recent santorini eruption in the eastern mediterranean aegean sea during the late minoan cultural period approximately 3600 years ago this was the largest holocene eruption in the region but tephra deposits in caves from this event appear to be very rare we present here the first ever finding of a visible tephra layer from the minoan santorini eruption in a cave the pure tephra situated in the pelekita cave in eastern crete near kato zakros has a thickness of up to 9 cm geochemistry analyses of major elements by electron probe micro analysis epma and trace elements by laser ablation inductively coupled plasma mass spectrometry la icp ms prove the tephra to be derived from the minoan santorini eruption radiocarbon dating also fits the time frame of this eruption our findings indicate that the tephra layer in the pelekita cave is an air fall deposit the lower boundary of the tephra layer is sharp and wavy draping over the underlying irregular cave surface particle size distribution of the tephra is bimodal and typical for suspended aeolian transport the consistently smaller size of heavier feldspar particles adjacent to larger but lighter volcanic glass particles in thin sections of undisturbed samples corroborate emplacement of the tephra inside the pelekita cave from high altitude fallout

a holocene coral algal reef at mavra litharia gulf of corinth greece structure history and applications in relative sea level change a holocene coral algal reef at mavra litharia south central coast of gulf of corinth greece is exposed from ca 2 to 9 3 m above sea level on an uplifting footwall associated with the eliki fault the reef lacks sea level critical species but its coralline algal assemblage indicates a ca 10 m water depth reef frame components date from 9280 8730 years bp to 6343 5993 years bp so the reef frame grew between ca 10 000 and 6000 years bp the youngest dated shells 1860 305 years bp from the site are accessory organisms collected from the lowest 2 m of outcrop one of which dendropoma grew at sea level stiros s c and pirazzoli p 1998 late quaternary coastal changes in the gulf of corinth greece tectonics earthquake archaeology guidebook for the gulf of corinth field trip patras university greece patras september 14 16 1998 reef history has four phases a growth and lithification of reef b development of smooth walled dissolution pipes and caves in the reef c colonisation of dissolution surfaces by mn fe crusts that may be bacterially formed barnacles serpulid worms and rock boring bivalves and d uplift to present position where much of the reef is eroded sea level history after 11 500 years bp when rising post glacial sea level overtopped the rio sill and returned the gulf of corinth to a marine environment is reconstructed calculations of interplay between sea level rise and tectonic uplift suggest that between 11 500 and 10 000 years bp sea level rose very quickly associated with deglaciation at the close of the younger dryas mwp 1b at a maximum of 25 6 mm year broadly consistent with other studies then slowed to ca 4 4 mm year until 6000 years bp when sea level was ca 3 m below modern after which sea level rose at ca 0 5 mm year to modern day tectonic uplift rate of maximum 3 mm year slower than sea level rise means that the reef could not catch up to sea level until recent times explaining its fossil assemblage the pipe cave system is interpreted as having formed when the reef top was emerged but much dissolution occurred beneath sea level because of insufficient time to allow uplift and resubmergence intense rainfall during the mid holocene pluvial phase ca 6000 years bp for the eastern mediterranean which affected large areas of the mediterranean is suggested as the mechanism and timing of submarine dissolution

a younger thinner arctic ice cover increased potential for rapid extensive sea ice loss 1 satellite derived estimates of sea ice age and thickness are combined to produce a proxy ice thickness record for 1982 to the present these data show that in addition to the well documented loss of perennial ice cover as a whole the amount of oldest and thickest ice within the remaining multiyear ice pack has declined significantly the oldest ice types have essentially disappeared and 58 of the multiyear ice now consists of relatively young 2 and 3 year old ice compared to 35 in the mid 1980s ice coverage in summer 2007 reached a record minimum with ice extent declining by 42 compared to conditions in the 1980s the much reduced extent of the oldest and thickest ice in combination with other factors such as ice transport that assist the ice albedo feedback by exposing more open water help explain this large and abrupt ice loss

diagenesis of quartz in the upper proterozoic kaimur sandstones son valley central india abstract the upper proterozoic kaimur sandstones in central india are quartz sublithic and lithic arenites cemented by quartz illite and hematite diagenetic quartz occurs in five modes syntaxial overgrowths fracture healings aggregates of small euhedral crystals quartz resulting from the alteration of detrital silicates and from the recrystallization of quartz intergranular pressure dissolution is suggested as the main source of silica with smaller contribution from other sources such as silica dissolved in meteoric waters stylolitization clay mineral diagenesis and the alteration of detrital silicates studies on the fluid inclusions and oxygen isotopes of diagenetic quartz suggest that meteoric water modified by diagenetic reactions has mediated the quartz cementation

exchange of sea ice between the arctic ocean and the canadian arctic archipelago 1 first estimates of sea ice exchange between the arctic ocean and the canadian arctic archipelago caa are obtained using six years 1997 2002 of radarsat ice motion over the period the mean annual flux of sea ice area from the amundsen gulf ag m clure strait ms and queen elizabeth islands qei are 85 26 103 20 24 103 and 8 6 103 km2 positive negative sign indicates arctic outflow inflow overall net sea ice area is exported from the caa rough estimates suggest a mean annual volume flux of 102 km3 into the canada basin ice types are largely seasonal near the ag flux gate mixed seasonal and multiyear at the ms gate and primarily multiyear at the qei gates sea ice at the qei flux gates remains land fast for most of the year cross strait gradient in sea level pressure explains more than 50 of the variance in the area flux at these passages the role of ice exchange during the anomalous decrease in multiyear ice coverage in the sverdrup basin during september 1998 is examined

stable isotopes of a subfossil tamarix tree from the dead sea region israel and their implications for the intermediate bronze age environmental crisis article i nfo n values calibration using modern tamarix stable isotopes in various climatic settings in israel shows direct relationship between isotopic enrichment and climate deterioration particularly rainfall decrease the subfossil tamarix probably reflects an environmental crisis during the intermediate bronze age which subsequently killed the tree 1930 bce this period coincides with the largest historic fall of the dead sea level as well as the demise of the large regional urban center of the 3rd millennium bce the environmental crisis may thus explain the archaeological evidence of a shift from urban to pastoral culture during the intermediate bronze age this was apparently the most severe long term historical drought that affected the region in the mid late holocene

the petrology and diagenesis of middle jurassic clastic sediments ravenscar group yorkshire the petrology of non marine clastic sediments from the middle jurassic ravenscar group was investigated to identify and to assess the significance of possible controls on diagenesis diagenetic modifications took place in three broad regimes within the depositional groundwater eogenesis during burial mesogenesis and during uplift and erosion telogenesis eogenesis involved the initial interaction of the original sedimentary assemblage with its depositional pore waters eogenetic processes were influenced strongly by bacterial degradation of organic matter present in the finer grained sediments this bacterial activity caused a lowering of pore water ph and subsequently reduced eh feldspar dissolution and alteration of muscovite to kaolinite occurred quartz overgrowths and vermiform kaolinite precipitated in sands with oxygenated and mildly acidic pore waters whereas chlorite and quartz overgrowths formed in sands with anoxic and neutral pore waters this caused complete reduction of porosity in both finer grained and texturally less mature floodplain facies sandstones channel facies sandstones were cemented only with a thin veneer of quartz overgrowths creating a rigid but still porous quartzose framework bacterial ferric iron reduction throughout the water table subsequently established more ubiquitous conditions raised ph and caused rhombic siderite cementation within the remaining porosity mesogenetic modifications of the mineralogy formed at the surface occurred when pore water composition changed during burial bicarbonate saturated solutions migrated through the surviving porosity precipitating replacive poikilotopic ferroan calcite carbonate dissolution occurred subsequently carbonate dissolution was possibly caused by the same solutions which then precipitated dickite and further authigenic quartz telogenetic modifications took place during uplift and exposure groundwater reactions and subaerial exposure probably caused further carbonate and feldspar dissolution as well as alteration of chlorite to interstratified chlorite vermiculite it is concluded that the diagenesis of these non marine clastic sediments reflects various factors the complex interrelationship of which precludes the identification of any single factor as wholly controlling their diagenesis eogenetic modifications involved the interaction of the sediments and their pore waters as a result of the metastability of the mineral assemblage established at this time these modifications can still be recognized despite the sediments subsequent history

changes in the thickness and circulation of multiyear ice in the beaufort gyre determined from pseudo lagrangian methods from 2003 2015 we combine eulerian ice draft observations from moored ice profiling sonars with buoy and satellite derived ice drift data to obtain lagrangian observations of changes in the thickness distribution of sea ice circulating the beaufort sea we examine repeat measurements of ice draft by identifying events where buoys or pseudobuoys made repeat overpasses within 30 km of ice profiling sonar equipped beaufort gyre exploration project moorings comparison of ice draft distributions from each overpass indicates that summertime melt rates are related to drift track with more melt occurring in the southern beaufort sea than to the north additionally we find that ice surviving summer in the beaufort sea since 2007 is similar in thickness to surrounding first year sea ice by the end of the following winter these findings are supported by continuous ice thickness data from ice mass balance buoys by examining plumes of pseudobuoys originating at each mooring location we identify anomalous northward transport of ice in the southern beaufort sea in 2007 that likely contributed to the record breaking reduction in sea ice extent that year we also find that repeat overpasses have been much rarer since 2007 due to reduced summertime sea ice extent in the beaufort gyre and possible changes in ice drift patterns these changes contribute to diminished replenishment of multiyear sea ice volume in the arctic

evolution of salt diapir and karst morphology during the last glacial cycle effects of sea level oscillation diapir and regional uplift and erosion persian gulf iran abstract marine fluvial and cave sediments and karst phenomena were studied and dated by 14 c u series and osl methods to determine the evolution of the namakdan diapir and the world s longest salt cave 3n cave during the holocene and the last glacial sea level oscillations the uplift rate of the diapir and its surroundings and erosion are the main factors influencing the diapir morphology although the diapir uplift rate has been constant for the last 50 kyr 4 mm yr at a distance 600 m from the diapir edge the uplift rate decreases with the distance from the diapir center drag induced host rock deformation extends for 300 m from the outside edge of the diapir and host rocks in this zone have an uplift rate of 0 4 0 6 mm yr which is 2 3 times greater than the regional uplift rate based on known sea level oscillations radiometric dating and geological evidence the namakdan diapir was repeatedly flooded by sea water between 130 and 80 kyr bp submarine residuum composed mainly of gypsum and dolomite formed cap rock on the diapir after 80 kyr bp surficial drainage network and karst development started blind valleys and their corresponding cave systems evolved continuously for 20 30 kyr between 9 and 6 cal kyr bp the rate of sea level rise exceeded the namakdan diapir uplift rate by the factor of 3 as a consequence upward incision of cave streams paragenetic trend occurred and blind valleys near the seashore were filled with gravels cave passages now accessible on the namakdan and hormoz diapirs started to form 3 6 cal kyr bp when sea level stabilized and downward stream incision began older cave levels are still preserved but are filled with sediments and salt precipitates a comparison of the namakdan diapir evolution with data from the hormoz and larak diapirs shows that the evolution of diapir morphology is strongly affected by the differences in uplift rates and geological settings the general scheme of the evolution of the namakdan diapir is believed to be partly applicable to many other diapirs in coastal settings

the palaeoflood record of a hyperarid catchment nahal zin negev desert israel the palaeohydrology of nahal zin a 1400 km2 catchment in the hyperarid negev desert is inferred from slackwater deposits and palaeostage indicators in a canyon near its lower end the palaeoflood record augmented by the instrumental and historical records of the last decade includes 28 floods ranging from 200 to 1500 m3s 1 over the last 2000 years this helps to reanalyse the frequency of floods in this drainage system the clusters of floods around 1000 years bp and again during the last 60 years are characterized by high flow magnitudes periods with many floods correspond well to periods with high dead sea levels and are probably relatively wet periods while periods with few floods correspond well to low dead sea levels indicating a drier climate fluctuations in the frequency of floods are typical of periods of transition from one climate regime to another copyright 2000 john wiley sons ltd

the coal bearing cenozoic as pontes basin northwestern spain geological influence on coal characteristics lignite deposits in the cenozoic as pontes strike slip basin northwestern spain were formed as a function of specific paleoclimatic conditions and tectonic evolution of the basin during the early evolutionary stages the presence of active normal faults and thrusts inside the basin resulted in two subbasins with distinct differences in sedimentary records with respect to lignite seam occurrence thickness area1 extent and lithotype development in contrast during the late evolutionary stages the basin was not split and a more homogeneous sedimentary record in terms of coal seam occurrence and lithotype characteristics developed a total of 26 lignite samples distributed along the basin infill were analyzed by organic petrography and geochemistry all are lignite b astm the lignites deposited during lower basin infill sedimentation units 1 and 2 are dark matrix rich mainly huminitic brown coals with minor bright liptinitic rich coal lithotypes the dark huminitic coals in these units show sedimentological and paleontological evidence of lacustrine influence persistent relatively moderate to low tissue preservation index tpi values and high average gelification index gi values are characteristic of these limno telmatic coals lignites in the upper basin infill unit 4 are almost exclusively matrix rich huminitic brown coals persistent widespread low tpi values and variable but low average gi values are also characteristic of these telmatic coals the overall coal petrological data trend tpi gi and widespread development or absence of liptiniteenriched lignite layers recorded from the lower to the upper basin infill units agrees with the stratigraphic and sedimentological data which show a trend of increasingly drier conditions development of bright liptinite enriched lignite layers was widespread during the early basin evolutionary stages and was influenced by punctuated water table oscillations sedimentological petrological and organic geochemical data point to the conclusion that although the paleoenvironments where peat deposition took place did not undergo dramatic changes they were affected by distinguishable

the holocene climatic record of the salt caves of mount sedom israel mount sedom is a salt diapir on the southwestern shore of the dead sea which has been rising above the local base level throughout the holocene karst development within the salt body has kept pace with the rise forming subhorizontal cave passages with vertical shafts wood fragments found embedded in flood sediments that were deposited in the cave passages yielded 14c ages ranging from c 7100 to 200 bp a palaeoclimatic sequence was constructed based on parameters that include relative abundance of plant types or floral communities the elevations of the corresponding cave passages and the ratio of their width to present passage width the results were correlated to the holocene sedimentary sequence of the dead sea basin and other features associated with shifting lake levels moister climatic stages are indicated by relatively abundant wood remains by wide cave passages and by elevated outlets indicating high dead sea level arid periods are marked by a scarcity of wood remains by narrow cave pa

depositional and compositional controls on sandstone diagenesis the tetori group middle jurassic early cretaceous central japan abstract the tetori group is a representative middle jurassic to lower cretaceous deposit in the northern central part of honshu japan the tetori group is divided into the kuzuryu itoshiro and akaiwa subgroups with decreasing age it consists mainly of a marine sequence in the lower part kuzuryu subgroup and non marine sequence in the upper part akaiwa subgroup with transitional sequence in the middle part itoshiro subgroup diagenesis of tetori group sandstones comprises compaction cementation and replacement early diagenetic events include mechanical compaction and pore filling cementation of calcite siderite dolomite and formation of kaolinite late diagenesis includes formation of quartz cement and albitization of feldspar and formation of illite chlorite calcite ankerite and pyrite among the diagenetic minerals carbonate forms the major cement in tetori group sandstones calcite of each subgroup is subdivided into two or three types based on cathodoluminescence tetori group sandstones of marine fresh water and mixed depositional environments are characterized by distinct chemical compositions of early diagenetic calcites late diagenesis seems to have been mainly influenced by detrital compositions of the sequence burial temperatures and partially hydrothermal processes especially late diagenetic carbonate and authigenic clay minerals seem to have formed mainly from ions released from clay mineral transformations in the adjacent shales based on the illite crystallinity ic the kuzuryu subgroup exhibits higher diagenetic grades than the overlying itoshiro and akaiwa subgroups indicating that the diagenesis of the tetori group was mainly affected by depth of burial

rock magnetism of greigite bearing sediments from the dead sea israel summary detailed magnetostratigraphic investigations were carried out on five sediment cores obtained from three sites on the northwestern shore of the dead sea israel the sediments are heterogeneous composed of fine clastic layers alternating with authigenic aragonite the magnetic remanence is carried by ti magnetite and greigite reflecting a detrital as well as an authigenic phase directions of the characteristic remanent magnetization were obtained from stepwise af demagnetization of the natural remanent magnetization and subsequent principle component analysis the acquisition of a gyroremanent magnetization in a noticeable amount of the samples could be linked to core disturbances the depth age models based on ams 14c datings on plant remains yielded an age of 10 04 ka cal bp for the base of the longest profile from site ein gedi a continuous lacustrine sediment sequence the profiles from the two other sites representing near shore sedimentation are interrupted by a hiatus in sedimentation comparison of the inclination and declination records from all dead sea cores and nearby sited lakes suggest that low frequency variations documented in the dead sea sediments are likely of geomagnetic origin

vegetation and climate changes in the south eastern mediterranean during the last glacial interglacial cycle 86 ka new marine pollen record the eastern mediterranean located at the meeting between the mediterranean vegetation of the eurasian continent and the desert vegetation of the saharan arabian desert belt is ideal for tracking changes in regional vegetation as function of climate changes reconstruction of these changes in the south eastern mediterranean during the last 86 ka is based on a palynological record from deep sea core 9509 taken by r v marion dufresne off the southern israeli coast the chronological framework is based on the correlation of d 18 o records of planktonic foraminifera with the high resolution well dated u th speleothem record from the soreq cave israel and the occurrence of sapropel layers several cycles of humid dry periods were documented during the last 86 ka the record starts with the moderate humid and warm sapropel s3 marking the end of marine isotope stage mis 5 the climate during the last glacial period 75 5e16 2 ka was cold and dry with low arboreal pollen ap levels and high values of semi desert and desert vegetation e g artemisia sagebrush the driest and coldest period during the last 86 ka corresponds to mis 2 27 1e16 2 ka characterized by the lowest tree cover along the sequence and the dominance of steppe vegetation some slightly more humid fluctuations were identified during the period of 56 3 and 43 5 ka with its peak between 56 0 and 54 4 ka the most pronounced climate change started at the beginning of the deglaciation 16 2e10 ka and continued throughout the holocene last 10 ka notwithstanding some short fluctuations high ap levels were dominated by quercus callipprinos evergreen oak suggesting that the mediterranean forest was more extensive in the area and the climate was wet sapropels s3 and s1 were clearly recognized here by the high concentrations and good state of preservation of pollen because of the development of anoxia in the bottom water that may be related to more extensive nile discharge coinciding with high insolation values at 65

holocene evolution of halite caves in the cordillera de la sal central atacama chile in different climate conditions abstract geomorphological studies have been carried out in rapidly evolving salt caves related to small watersheds in the san pedro de atacama area chile radiocarbon ages of bones and wood from cave deposits combined with the presence of large salt caves geomorphological and sedimentological observations and the results of micrometer measurements outside and in some of the caves suggest a period of speleogenesis in the cordillera de la sal during the onset of the holocene during which the large halite cave systems developed followed by an early holocene hyperarid period most smaller caves i e lechuza del campanario most probably formed at the start of the wetter mid holocene period 5 4 4 ka when precipitation was never intense enough to entrain large amounts of sediments but enough to trigger cave development a diamicton in lechuza del campanario cave radiocarbon dated at ca 4 4 ka shows that at least one high intensity rainfall event occurred in this recharge basin during the mid holocene wet interval a wet period with lower intensity rainfall events followed between 4 0 and 2 5 ka causing the 4 4 kyrs old diamicton in lechuza del campanario cave to be entrenched and the alluvial fan at the downstream end of palacio del sal cave to be covered with windborne sediments dated by osl at around 3 6 ka at ca 2 ka there was a high intensity rainfall event documented by the age of a twig stuck in the ceiling of the palacio del sal cave followed by a period with lower intensity rain events until ca 1 3 ka when another intense flood produced a mudflow that deposited a second diamicton in lechuza del campanario cave from then on clustering of radiocarbon ages for wood and bone recovered from caves indicates increased rainfall intensity in the period ca 0 9 0 5 ka followed by no registered events until a minor flood at ca 0 13 ka the four centuries long wetter time interval 0 9 0 5 ka corresponding to the medieval climate anomaly has been an archeologically important period in the atacama desert tiwanaku culture the observations and a detailed review of paleoclimate literature from this key area have allowed the development of a landscape evolution model related to changing climate conditions during the late holocene

hydrology and denudation rates of halite karst salt karst terrains exist mainly in arid climates where rock salt outcrops may escape complete destruction by dissolution such is the case with mount sedom on the sw shore of the dead sea one of the most arid parts of israel many small catchments developed over the relatively insoluble cap rock which overlies the highly soluble rock salt the catchments were surveyed and classified some 57 of the surface area is drained by an underground karst system water samples from various points in the system were analysed and water development was inferred waters in cave conduits do not reach saturation during flood flow unless the water is ponded for at least several hours based on the available evidence regional karst denudation is tentatively estimated to be about 0 5 0 75 mm year 1 occurring mainly within the rock salt

floodplain degradation and settlement history in wadi al wala and wadi ash shallalah jordan this study investigates a mid holocene cycle of stream aggradation and incision in wadi al wala and wadi ash shallalah western jordan aggradation took place sometime between 7 ka and 6 ka followed by stability as evidenced by a floodplain soil that was mantled by colluvial deposits between 4 6 and 4 ka stream incision around or after 4 ka eroded the floodplains a second cycle of aggradation and incision occurred in the late holocene but this cycle is not synchronous between the two streams causes of the stream incision around 4 ka are hypothesized in the context of local geomorphological and hydrological characteristics regional climatic change dead sea level changes and cultural landscape changes interpreted from archaeological and pollen records in the context of available local and regional evidence this study discusses the relation between early bronze age settlement and stream degradation

sea ice convergence along the arctic coasts of greenland and the canadian arctic archipelago variability and extremes 1992 2014 after the summer of 2013 a convergence induced tail in the thickness distribution of the ice cover is found along the arctic coasts of greenland and canadian arctic archipelago prompted by this a normalized ice convergence index ici is introduced to examine the variability and extremes in convergence in a 23 year record 1992 2014 of monthly ice drift large scale composites of circulation patterns characteristic of regional convergence and divergence are examined indeed the ici shows the june 2013 convergence event to be an extreme i e ici 2 furthermore there is a cluster of 9 months over a 17 month period with positive icis i e 1 following the record summer minimum ice extent smie in 2012 the imprint of ice dynamics from this cluster of positive icis likely contributed to higher smies in 2013 and 2014 the impact of convergence on smie is discussed and the increase in arctic ice volume in 2013 is underscored