sulphuric acid speleogenesis and landscape evolution montecchio cave albegna river valley southern tuscany italy abstract montecchio cave grosseto province tuscany italy opens at 320 m asl in a small outcrop of jurassic limestone calcare massiccio fm close to the albegna river this area is characterised by the presence of several thermal springs and the outcropping of travertine deposits at different altitudes the montecchio cave with passage length development of over 1700 m is characterised by the presence of several sub horizontal passages and many medium and small scale morphologies indicative of sulphuric acid speleogenesis sas the thermal aquifer is intercepted at a depth of about 100 m below the entrance the water temperature exceeds 30 c and sulphate content is over 1300 mg l 1 the cave hosts large gypsum deposits from 40 to 100 m below the entrance that are by products of the reaction between sulphuric acid and the carbonate host rock the lower part of the cave hosts over 1 m thick calcite cave raft deposits which are evidence of long standing probably thermal water in an evaporative environment related to significant air currents sulphur isotopes of gypsum have negative 34 s values from 28 3 to 24 2 typical of sas calcite cave rafts and speleogenetic gypsum both yield young u th ages varying from 68 5 ka to 2 ka bp indicating a rapid phase of dewatering followed by gypsum precipitation in aerate environment this fast water table lowering is related to a rapid incision of the nearby albegna river and was followed by a 20 30 m fluctuation of the thermal water table as recorded in the calcite raft deposits and gypsum crusts

amplified erosion above waterfalls and oversteepened bedrock reaches erosion rate at the upstream end of the flow acceleration zone above a waterfall fr is the froude number at this setting and n ranges between 0 5 1 7 this amplification expression suggests that erosion at the lip could be as much as 2 5 times higher relative to erosion at a normal setting with identical hydraulic geometry utilizing this erosion amplification expression in numerical simulations we demonstrate its impact on reach scale morphology above waterfalls amplified erosion at the lip of a waterfall can trigger the formation of an oversteepened reach whose length is longer than the flow acceleration zone provided incision wave velocity vi at the upstream edge of the flow acceleration zone is higher than the retreat velocity of the waterfall face such an oversteepened reach is expected to be more pronounced when vi increases with increasing slope the simulations also suggest that oversteepening can eventually lead to steady state gradients adjacent to a waterfall lip provided vi decreases with increasing slope flow acceleration above waterfalls can thus account at least partially for prevalent oversteepened bedrock reaches above waterfalls using the cosmogenic isotope cl 36 we demonstrate that incision wave velocity upstream of a waterfall at the dead sea western escarpment is probably high enough for freefall induced oversteepening to be feasible

paleoclimate and location of the border between mediterranean climate region and the saharo arabian desert as revealed by speleothems from the northern negev desert israel speleothem bearing karstic caves of the northern negev desert southern israel provides an ideal site for reconstructing the paleoclimate and paleo location of the border between mediterranean climate region and the saharo arabian desert major periods of speleothem deposition representing humid periods were determined by high resolution 230 th u dating and corresponding studies of stableisotopecompositionwereusedtoidentifythesourceofrainfallduringhumidperiodsandthevegetationtype majorhumidintervals

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

potential use of the deep aquifers in the negev desert israel a conceptual model abstract the deep aquifers jurassic paleozoic 1 5 km deep underlying the negev desert israel contain brackish to saline water 800 120 000 ppm cl and have been penetrated by only 47 wildcat oil drillings the objective of this study was to evaluate the water potential of these aquifers for irrigation and for industrial consumption as well as their potential for serving as host rocks for hazardous wastes we developed a special methodology for constructing a conceptual model for the thick sequence of layers in which these aquifers are found it seems that although these aquifers have different lithologies they may be hydraulically connected statistics of the distribution of the aquifer system s parameters of state and analysis of their variance are used to aggregate individual formations into a few large hydrologic units we employed regression analysis to supplement missing data and to evaluate estimation errors based on this methodology a model consisting of three aquifers was defined the consistency of the conclusions of the model is confirmed by our studies of pressure permeability salinity temperature and isotopic distribution wherever data were scarce we estimated hydraulic parameters by linear regression according to our study the lower aquifer in the northern negev contains only brines and is hydrologically separated from the two aquifers above it the lower aquifer could therefore be considered as a possible site for toxic waste disposal or at suitable locations for hydrocarbon exploration hydrological continuity probably exists between the upper and middle aquifers in the eastern and central negev where brackish water is found in both aquifers the methodology used here is suitable for constructing a conceptual model of any complex geohydrologic system in an area with scarce data

the syrian arc system an overview abstract a comparison between the ne directed negev and palmyra foreland monoclines of the syrian arc shows strong similarity in both their statigraphy and late mesozoic and cenozoic tectonic history a first phase of simple folding in the senonian was followed by a phase of reverse faulting in the miocene and ended with a phase of post miocene uplift in the style of fault bend fold this triple deformation of the north arabian subplate was contemporaneous with the thrusting of the tauros zagros zone the ne sw direction of the syrian arc as well as many other structures on the african and arabian plates are an inherited ancient feature predating any contact with the eurasian plate the continental drift proposed for turkey and arabia is reviewed and rejected for both the amounts of horizontal displacement of the dead sea rift and the east anatolian fault are estimated to be 45 and 27 km respectively it is suggested that the stress system upon the levant has been nw directed since the late cretaceous to the present time the dead sea rift n s stress direction is a local post miocene response to limited regional shift and to intense uplift

fission track analysis of basement apatites at the western margin of the gulf of suez rift egypt evidence for synchroneity of uplift and subsidence fifty six apatite fission track ages and 52 horizontal confined track length measurements are reported from precambrian crystalline rocks along the western margin of the gulf of suez egypt ages fall in the range of ca 11 385 m y and older ages often occur within very close geographic proximity to younger ones indicating non uniform uplift the wide range in ages is accompanied by a systematic variation in the distribution of horizontal confined fission track lengths on the basis of apatite fission track ages and their length distributions data fall into three distinct groups group i ages ranging from 43 to 385 m y length distributions are all positively skewed and with decreasing age become progressively broader with shorter mean track length group ii ages ranging from 23 to 31 m y length distributions are negatively skewed with either a distinct tail or a small peak of short tracks group iii ages ranging from 11 to 20 5 m y length distributions are al unimodal narrow negatively skewed and have the longest mean lengths among samples studied apatite ages from groups i and ii are interpreted as mixed ages as a result of cooling during uplift from different levels within the apatite partial track annealing zone ages from group iii are interpreted as cooling ages due to uplift from the apatite total track annealing zone with minor partial annealing correcting the ages of the two oldest samples in this group for track length reduction yields ages of21 2 2and23 1 5m y it is proposed that the onset of rift flank uplift in the gulf of suez northern red sea area occurred between 21 and 23 m y ago fission track analysis in combination with subsidence data from the gulf of suez basin indicate that commencement of basement uplift postdate the start of rifting and is interpreted as evidence for passive rifting at the gulf of suez furthermore this uplift is contemporaneous with and is directly related to the process of extension and subsidence at the gulf of suez

corrosion morphology and cave wall alteration in an alpine sulfuric acid cave kraushohle austria abstract whereas most karstic caves worldwide are formed by carbonic acid a small but significant number of sub surface cavities are the product of sulfuric acid speleogenesis sas in the eastern alps no cave has so far been attributed to this type in this multidisciplinary study we demonstrate that kraushohle in northern styria was indeed formed by sas the cave pattern shows individual chambers 3d mazes and blind galleries as well as typical sas morphologies such as cupolas gypsum replacement pockets corrosion notches and convection niches ceiling pendant drip holes are described here for the first time and these corrosion features are fully consistent with the sas model other features of kraushohle include thick gypsum deposits with strongly depleted 34 s values and other minerals mostly sulfates indicating highly acidic conditions we also studied acid rock interaction processes giving rise to widespread corrosion and concomitant replacement by gypsum petrographic and geochemical analyses reveal the presence of a distinctive alteration layer of highly increased porosity at the interface between the host limestone and the secondary gypsum dissolution and replacement of the limestone was fast enough to prevent the development of c and o isotopic alteration halos but resulted in selective leaching of elements this stable isotope signal is thus different from the pronounced isotope gradient commonly observed in co 2 dominated hypogenic caves petrographic observations reveal that the limestone gypsum replacement was a nearly constant volume process

sea rain lake relation in the last glacial east mediterranean revealed by δ18o δ13c in lake lisan aragonites we investigated the sea rain lake relation during the last glacial holocene in the east med iterranean region by comparing the 18 o and 13 c records of authigenic aragonite deposited in lake lisan the dead sea mediterranean foraminifera and speleothems the lisan formation data display long and short term variations of 18 o representing steady state conditions of the lake e g 5 6 0 5 and 4 5 1 in the upper and lower members of the lisan formation respectively and short term excursions reflecting large floods and droughts the long term steady state 18 o values of the lisan aragonites show similarity to the corresponding time equivalent records of the eastern mediterranean foraminifera and judea mountain speleothems the last glacial deposits are in all of them 2 3 heavier than the holocene ones we interpret this similarity as reflecting the significance of the source effect on the long term behavior of isotopic reservoirs speleothem 18 o is strongly influenced by the marine reservoir that contributes its vapor to rain formation the lake 18 o is dominated by the composition of the inflowing water short term variations in the isotopic composition of rainfall are dominated by the amount effect and the temperature and those of the lake s upper water mass by the lake s water balance 13 c values are more variable than 18 o in the same lisan sequences e g 13 c in the lower member is 1 0 1 7 whereas 18 o is 4 6 0 7 and are 1 to 1 5 higher in the upper member than in the lower and middle members of the lisan formation these variations reflect significant increase in primary productivity of the lake and algal bloom activity it appears that the hypersaline saline lakes were not as dead as the dead sea is and that algal activity had an important impact upon the geochemistry of lake lisan the 18 o data combined with independent geochemical and limnologic information e g level fluctuations indicate that lisan time was characterized by high precipitation high lake stands high atmospheric humidity whereas the holocene dead sea shows the opposite behavior this paleoclimatic reconstruction is consistent with independent evidence for significantly wetter conditions in the east mediterranean region during the last glacial period copyright 2005 elsevier ltd

late neogene rift valley fill sediments preserved in caves of the dead sea fault escarpment israel palaeogeographic and morphotectonic implications evaporitic lagoonal marl and dolomite laminar fill sediments are preserved in relict dry caves of the dead sea fault escarpment israel which has been tectonically active since the late neogene the hosting caves are located within turonian massive carbonate bedrock and at higher altitudes than previously documented fill sediments of the dead sea depression based on the relative altitudes of the cave sediments the reversed stratigraphy of the dead sea depression fill sediments possible partial correlation of the cave sediments with other fill sedimentary units of the depression and sedimentary geochemical and mineralogical characteristics it is concluded that i the cave sediments are among the oldest of the depression fill and ii the deposition of the cave sediments took place in hypersaline dolomite precipitating water bodies of late neogene age during the initial morphotectonic stages of the depression formation variable and relatively low sr ca and 34s ratios of the cave sediments assuming precipitation from sea water suggest variable fresh water input into the depositional brine the present altitudes of the cave sediments reflect late neogene levels of water bodies in the depression modified by vertical post late neogene tectonic movements within the still active fault escarpment according to these altitudes a 50 to 250 m uplift of the western margins of the depression since the late miocene to early pliocene is inferred

the yarkon taninim groundwater basin israel hydrogeology case study and critical review abstract the late albian turonian judea group carbonate aquifer is one of the most important resources of fresh groundwater in the northern negev and in the central part of israel over three decades ago various hydrological hydrochemical hydrometeorological and geological aspects of this aquifer were thoroughly investigated and served to build up the professional background and data base for the management of this resource notwithstanding the accumulating structural hydrogeological and hydrochemical evidence the conceptual hydrogeological model of the yarkon taninim basin which constitutes the western part of the judea group aquifer has neither been questioned nor updated therefore the existing and accepted model of this basin should in the best case only depict general features and trends the present review critically examines the main hitherto accepted hydrogeological conventions points out puzzling and contradictory phenomena and emphasizes questionable issues although the present review deals with problems related to a specific groundwater basin the methods and effort for breaking long established conventions may serve as an example for similar situations in other places in which water resources are managed according to long established concepts and traditions without being periodically revised and reassessed in view of accumulating knowledge

10be dating of neogene halite direct radioactive dating of ancient halite formations is difficult because this mineral typically lacks conventionally datable material we describe an attempt to date neogene halite using the cosmogenic isotope 10 be t1 2 1 39 ma we dated marine derived salt deposits from the sedom and amora the hebrew forms of sodom and gomorrah formations dead sea basin israel to verify whether be is incorporated into marine halite we measured the stable isotope 9 be 7 be the short lived cosmogenic brother of 10 be having t1 2 53 3 d and 10 be in evaporation pans of sea salt production plants the data suggest that seawater beryllium is incorporated into the halite with a halite brine distribution coefficient kd of about unity a 10 be 9 be decay curve constructed for sedom formation halite yielded an age that lies in the range of 2 6 ma the 10 be decay curve constructed for sedom formation halite yielded an age that lies in the range of 3 5 ma this age is consistent with previous estimates of the sedom formation age furthermore this age lies in the same range of 10 be in situ ages obtained on the lacustrine erq el ahmer formation located in the northern jordan valley this may imply that during the mid pliocene the sedom lagoon the water body that deposited the sedom formation might have been already disconnected from the open sea 2013 elsevier ltd all rights reserved

evolution of isolated caves in porous limestone by mixing of phreatic water and surface water at the water table of unconfined aquifers a model approach summary when water from the surface e g from a lake flows through porous carbonate rocks down along some region with high hydraulic conductivity and encounters the water table of a phreatic aquifer both waters mix by diffusion along their boundary in a carbonate aquifer where both surface and phreatic waters are saturated with respect to calcite mixing corrosion causes renewed dissolution of the carbonate rock in the diffusional mixing zone extending from the boundary separating the phreatic water from the surface water encountering it a numerical model is presented from which the initial change of porosity in such a diffusional mixing zone is obtained the initial change of porosity d dt 0 is proportional to m x y 2 and d2 ceq m dm2 m x y is the spatial distribution of the mixing ratio m vsur vsur vphr and the vs assign the corresponding volumes of surface and phreatic water d2 ceq dm2 is the second derivative of ceq the renewed dissolution capacity of the mixed solution it has been calculated for three geochemical scenarios with differing co2 concentrations of surface and phreatic water by use of phreeqc 2 the spatial distribution m x y is obtained by using modflow and mt3dms in a modeling domain with constant hydraulic conductivity for various flow velocities of the phreatic aquifer from the results the time scale of cave evolution is estimated passages of dimensions of about one meter in width and several 10 cm in height extending in length along the border line where surface and phreatic water meet can be created in time scales of 10 000 years these caves are horizontal with blind ending passages and resemble closely to the isolated caves observed in central west florida for more realistic modeling we have used a geostatistical local distribution of hydraulic conductivities in the modeling domain for a correlation length of 1 of the length of modeling domain the spatial distribution extends deeper into the flow direction when the correlation length is increased by a factor of 10 flow focusing distorts the diffusional mixing zone and enhances the creation of porosity

lithofacies and cyclicity of mohilla evaporite basins on the rifted margin of the levant in the late triassic makhtesh ramon southern israel marine connected basins with evaporites occur beneath most extensional continental margins that originated at low latitudes and often are of major economic significance cyclicity in the evaporite lithofacies reflects the degree of restriction of the basin overprinted by sea level changes and caused by structural movements in the barrier region whether by fault block rotation footwall uplift or hanging wall subsidence in both extensional and compressional basins the upper triassic evaporites of the ramon section in southern israel model cyclic sedimentation in such environments the mohilla formation is a carbonate evaporate siliciclastic succession of carnian age that fills a chain of basins extending along the levant margin from southern israel to jordan and syria the basins developed in half grabens adjacent to normal faults that formed during a period of regional extension evaporites of this formation are well exposed in outcrops at makhtesh ramon the southernmost of these basins the m2 member of the mohilla formation is composed of 42 sub metre cycles of alternating dolostone gypsum and calcareous shales field and microfacies analysis showed these cycles to conform mostly to restricted shallow and marginal marine environments spatially limited by the uplifted shoulders of the half graben systems a total of 10 facies types belonging to six depositional environments have been identified from stacking patterns and analysis of bed to bed change cycles can be categorized into three groupings i low frequency exposure to exposure cycles that developed under eustatic or climate control ii high frequency deepening shallowing upward cycles characterized by gradual transitions due to short term sea level or runoff event oscillations possibly referable to orbital forcing and iii high frequency shallowing upward cycles characterized by abrupt transitions attributable to sporadic tectonic events affecting accommodation space or barrier effectiveness the way facies and cycling of the sedimentary environments was deciphered in the mohilla evaporite basin can be used to unravel the genesis of many other evaporite basins with barriers of tectonic origin

petroleum migration pathways and charge concentration a three dimensional model petroleum migration pathways through a basin are determined by the three dimensional distribution of discontinuous sealing surfaces which are usually parallel to bedding the petroleum migrates below the sealing surface taking the structurally most advantageous route the three dimensional distribution of migration pathways within the petroleum system can be modeled on a personal computer using a program based on the parameters discussed in this paper application of the model to the paris and williston basins demonstrates that a good correlation between predicted pathways and discovered accumulations can be made using simple models pathways form a dense network overlying generating areas in the central parts of basins toward the basin margins these routes commonly become increasingly focused into discrete pathways by the sealing surface morphologies eventually these pathways may reach the surface as seepages it is important to integrate surface outcrops of migration routes surface seepages into migration modeling deflection of the pathways from the structurally most advantageous route below the sealing surface may be caused by lateral sealing barriers due to facies variation in the carrier rock below the seal fault juxtaposition or cross formational seals such as salt intrusions deflection of pathways also occurs where there are hydrodynamic conditions in response to topography driven groundwater flow zones of vertical migration are associated with facies changes along the horizon of the sealing surface into a nonsealing facies or juxtaposition to nonsealing strata by faults vertical migration from either normally or abnormally pressured strata is most likely to occur into normally or lesser pressured strata at intrabasinal highs where hydrocarbons can be stored and transferred at times of temporary seal rupture reverse modeling of individual pathways from fields and seepages to potential sources is a powerful exploration tool it assists in predicting the boundaries of the leaking accumulations or areas of petroleum expulsion

alteration of magnetic minerals and its effect on the nrm of deccan trap flows of the narmada region india magnetic and geochemical investigations have been carried out on suites of deccan lava flows from both sides of the river narmada multidomain magnetite is more abundant in the flows on the southern side than among the northern ones flows from south of the river seem to have absorbed more water than those on the northern side possibly well after their emplacement multidomain magnetite bearing samples shattered often into pieces when standard cores of these were heated to a temperature beyond 570 k and several such samples lost their primary nrm direction

unraveling rift margin evolution and escarpment development ages along the dead sea fault using cosmogenic burial ages abstract the dead sea fault dsf is one of the most active plate boundaries in the world understanding the quaternary history and sediments of the dsf requires investigation into the neogene development of this plate boundary dsf lateral motion preceded significant extension and rift morphology by 10 ma sediments of the sedom formation dated here between 5 0 0 5 ma and 6 2 2 1 inf ma yielded extremely low 10be concentrations and 26al is absent these reflect the antiquity of the sediments deposited in the sedom lagoon which evolved in a subdued landscape and was connected to the mediterranean sea the base of the overlying amora formation deposited in the terminal amora lake which developed under increasing relief that promoted escarpment incision was dated at 3 3 0 8 0 9 ma burial ages of fluvial sediments within caves 3 4 0 2 ma and 3 6 0 4 ma represent the timing of initial incision initial dsf topography coincides with the earliest red sea morb s and the east anatolian fault initiation these suggest a change in the relative arabian african plate motion this change introduced the rifting component to the dsf followed by a significant subsidence margin uplift and a reorganization of relief and drainage pattern in the region resulting in the topographic framework observed today

early development of karst systems 2 turbulent flow a simulation model developed to explore patterns of fracture enlargement within incipient limestone karst aquifers has been extended to turbulent flow in contrast to the highly selective passage enlargement that occurs early in cave network development under laminar flow the transition to turbulent flow results in more general passage enlargement leading to maze networks when initial fractures are large and hydraulic gradients are high these results support previously published hypotheses for the development of maze patterns including formation within structural settings that have created initially large fractures or within flow systems periodically inundated by flooding maze development is also favored under turbulent flow when passages are entirely water filled and where the groundwater flow system is long lived by contrast branched patterns are most common when passages become free surface subterranean streams because depression of the piezometric surface along main passages downcutting along main passages and possible infilling with sediment of side passages limit the sharing of discharge among interconnected fractures or bedding planes that promote maze development

the fault pattern in the northern negev and southern coastal plain of israel and its hydrogeological implications for groundwater flow in the judea group aquifer abstract on the basis of a broadly expanding data base the hydrogeological properties of the judea group sequence in the northern negev and southern coastal plain of israel have been reassessed the updated subsurface model is based on data derived from water and oil wells and on recent large scale geophysical investigations a new regional pattern of the reassessed geological through the subsurface of the study area has been revealed in view of the reassessed geological and hydrological subsurface setting it appears that the judea group aquifer should not be regarded as one continuous and undisturbed hydrological unit owing to the occurrence of regional faults its subaquifers are locally interconnected these subaquifers which contain mainly high quality water are juxtaposed as a result of faulting against kurnub group sandstones containing brackish paleowater the latter group is faulted against late jurassic formations containing highly saline groundwater in the beer sheva area the judea group aquifer is vertically displaced against the senonian and eocene mt scopus and avdat groups which also contain brackish and saline water in the southern coastal plain major faults locally dissect also the pleistocene kurkar group facilitating inflow of mg rich groundwater deriving from judea group dolomites the new geological evidence and its hydrogeological implications provide new solutions for previously unexplained salinization phenomena

possible atmospheric origin of the 7 may 2007 western black sea shelf tsunami event 1 the paper examines the possibility that tsunami event recorded in the western black sea on 7 may 2007 was triggered by a traveling atmospheric disturbance as meteotsunamis are favored by specific synoptic conditions we inspected available ground and sounding observations european centre for medium range weather forecasts reanalysis fields and satellite based products and compared them to the documented mediterranean meteotsunamis we found an atmospheric disturbance traveling toward 30 nne with amplitude of 2 3 hpa and propagation speed of about 16 m s passing through few tens of kilometers wide pathway over the region affected by the tsunami this disturbance occurred in the lower troposphere but it was capped by instable convective cell that preserved gravity disturbance s coherence over a region at least 150 km long an ocean modeling study showed that such a disturbance is capable of generating large tsunami waves and strong currents over the shallow regions following the observations over the region where maximum sea level oscillations have been documented therefore this event has a potential to be classified as a meteotsunami the first of such kind in the black sea

sulfuric acid speleogenesis sas close to the water table examples from southern france austria and sicily caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate settings from arid regions to mid latitude and alpine areas h2s is generally formed at depth by reduction of sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers in tectonically disturbed areas major fractures eventually allow these h2s bearing fluids to rise to the surface where oxidation processes can become active producing sulfuric acid this extremely strong acid reacts with the carbonate bedrock creating caves some of which are among the largest and most spectacular in the world production of sulfuric acid mostly occurs at or close to the water table but also in subaerial conditions in moisture films and droplets in the cave environment these caves are generated at or immediately above the water table where condensation corrosion processes are dominant creating a set of characteristic meso and micromorphologies due to their close connection to the base level these caves can also precisely record past hydrological and geomorphological settings certain authigenic cave minerals produced during the sulfuric acid speleogenesis sas phase allow determination of the exact timing of speleogenesis this paper deals with the morphological geochemical and mineralogical description of four very typical sulfuric acid water table caves in europe the grotte du chat in the southern french alps the acqua fitusa cave in sicily italy and the bad deutsch altenburg and kraushohle caves in austria

transition from arid to hyper arid environment in the southern levant deserts as recorded by early pleistocene cummulic aridisols abstract the time at which deserts established their current arid or hyper arid conditions remains a fundamental question regarding the history of earth cosmogenic isotope exposure ages of desert pavement and welded calcic gypsic salic reg soils that developed on relatively flat alluvial surfaces 2 ma ago in the negev desert indicate long geomorphic stability under extremely dry conditions over a short interval during their initial stage of development between 1 2 ma these cumulative soils are characterized by calcic soils reaching maximum stage iii of carbonate morphology this interval is the only period when calcic soil horizons formed on stable abandoned alluvial surfaces in the southern negev desert since 1 ma pedogenesis changed toward more arid soil environment and the formation of gypsic salic soil horizons that were later followed by dust accumulation the dichotomy of only moderately developed calcic soil stages ii iii during a relatively long time interval 105 106 years indicates an arid environment that does not support continuous development but only occasional calcic soil formation the very low 18o and relatively high 13c values of these early pedogenic carbonates support soil formation under arid climatic conditions such an environment was probably characterized by rare and relatively longer duration rainstorms which occasionally allowed deeper infiltration of rainwater and longer retention of soil moisture this in turn enabled the growth of sparse vegetation that enhanced deposition of pedogenic carbonate at 1 ma these rare events of slightly wetter conditions ceased and less atmospheric moisture reached the southern negev desert leading to deposition of soluble salts and dust deposited in the soils the combination of long term hyperaridity scarcity of vegetation and lack of bioturbation salts cementation dust accumulation and tight desert pavement cover has protected the surfaces from erosion forming one of the most remarkably stable landscapes on earth a landscape that essentially has not eroded but accumulated salt and dust for more than 106 yr

the cave of the letters sediments indication of an early phase of the dead sea depression abstract the highest aquatic sediments along the shoulders of the dead sea depression have been found in the cave of the letters nahal hever israel the cave has acted as a sediment trap preserving autogenic dolomite and detritic deposits the dolomitic sediment may correlate with late miocene dolomites within the rift valley the morphostratigraphic setting of the sediment implies deposition within an early topographic low that existed in the dead sea region since 10 to 7 ma

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

sulfuric acid speleogenesis of carlsbad cavern and its relationship to hydrocarbons delaware basin new mexico and texas sulfur isotope data and ph dependence of the mineral endellite support the hypothesis that carlsbad cavern and other caves in the guadalupe mountains were dissolved primarily by sulfuric acid rather than by carbonic acid floor gypsum deposits up to 10 m thick and native sulfur in the caves are significantly enriched in 32 s isotope 34 s values as low as 25 8 per mil cdt indicate that the cave sulfur and gypsum are the end products of microbial reactions associated with hydrocarbons a model for a genetic connection between hydrocarbons in the basin and caves in the guadalupe mountains is proposed as the guadalupe mountains were uplifted during the late pliocene pleistocene oil and gas moved updip in the basin the gas reacted with sulfate anions derived from dissolution of the castile anhydrite to form h 2 s co 2 and castile limestone the hydrogen sulfide rose into the capitan reef along joints forereef carbonate beds or bell canyon siliciclastic beds and there reacted with oxygenated groundwater to form sulfuric acid and carlsbad cavern a sulfuric acid mode of dissolution may be responsible for large scale porosity of some delaware basin reservoirs and for oil field karst reservoirs in other petroleum basins of the world

late holocene lake levels of the dead sea this work presents a high resolution lake level record of the late holocene dead sea a hypersaline terminal lake whose drainage basin encompasses both mediterranean and hyperarid climatic zones the lake level curve reflects the regional hydrologic variations in the drainage basin which in turn represent the levant paleoclimates the curve is based on 46 radiocarbon ages of organic remains from well exposed sedimentary sequences along the dead sea shores these sequences record fluvial and lacustrine depositional environments the paleolakeshores are marked by shore ridges coarse sand units and aragonite crusts in the modern dead sea such features indicate the exact elevation of the shore the late holocene dead sea level fluctuated within the range of 390 to 415 m below sea level mbsl for most of the time the lake was below the topographic sill 402 mbsl separating the northern and southern basins of the dead sea and was confined to the deep northern basin nevertheless short term rises in the late holocene dead sea level caused the flooding of the shallow and flat southern basin highstands occurred in the second and first centuries b c and the fourth century a d during the roman and early byzan tine periods respectively in the eleventh and twelfth centuries a d during the crusader period and at the end of the nineteenth century a d the rises mark a significant change in the annual rainfall in the region which likely exceeded the instrumentally measured modern average the curve also indicates drastic drops that exposed the sedimentary sequences to erosion the oldest and probably deepest drop in the lake level culminated during the fifteenth and fourteenth centuries b c after a retreat from a higher lake stand the longest lowstand occurred after the byzantine period and continued at least until the ninth century a d this arid period coincided with the invasion of moslem arab tribes into the area during the seventh century a d the dramatic fall of the dead sea level during the twentieth century is primarily artificial and has been caused by the diversion of runoff water for the drainage basin but the magnitude is not considered exceptional for the late holocene although the past drops in the lake never exceeded the modern artificial drop rates they do represent extreme arid conditions that occurred frequently over the past several thousand years

styles and rates of long term denudation in carbonate terrains under a mediterranean to hyper arid climatic gradient abstract carbonate minerals unlike silicates have the potential to dissolve almost completely and with high efficiency thus in carbonate terrains denudation rate and style the governing process of denudation mechanical or chemical should be more sensitive to climatic forcing using 36 cl measurements in 39 carbonate bedrock and sediment samples we calculate long term denudation rates across a sharp climatic gradient from mediterranean to hyper arid conditions our samples were collected along the arugot watershed which drains the eastern flank of the judea range central israel to the dead sea and is characterized by a pronounced rain shadow denudation rates of flat lying bedrock outcrops sampled along interfluves differ by an order of magnitude from 20 mm ka 1 in the mediterranean zone to 1 3 mm ka 1 in the hyper arid zone these rates are strongly correlated with precipitation and thus reflect the importance of carbonate mineral dissolution in the overall denudation process in contrast denudation rates of steep bedrock surfaces depend on the hillslope gradient but only in the hyper arid climate zone indicating that mechanical processes dominate the overall hillslope denudation within this zone the dominance of slope dependent mechanical erosion in the hyper arid zone is also reflected by an increase in spatially average denudation rates from 17 19 mm ka 1 in the mediterranean semi arid zones to 21 25 mm ka 1 in the hyper arid zone these higher rates are attributed to clast contribution from steep slopes under arid climate this suggests an increased importance of mechanical processes to the overall denudation in the hyper arid zone we demonstrate that the transition between chemically dominated denudation to mechanically dominated denudation occurs between 100 and 200 mm of mean annual precipitation long term denudation rates across the judea range indicate that between mediterranean and hyper arid climates chemical weathering rates are limited by precipitation nevertheless in more humid climates chemical weathering rates are apparently limited by the rates of carbonate mineral dissolution this study demonstrates that carbonate terrains have the capacity to shift between mechanically and chemically dominated denudation in response to changes in precipitation similar transitions in response to changes in temperature or the level of tectonic activity have been previously reported we suggest that the abrupt nature of such transitions can be primarily attributed to the efficiency of carbonate dissolution processes and the competition between surface and subsurface drainage systems in carbonate terrains

occurrence of hypogenic caves in a karst region examples from central italy the caves of the umbria and marche regions in central italy are made up of three dimensional maze systems that display different general morphologies due to the various geological and structural contexts at the same time the internal morphologies of the passages galleries and shafts present some similarity with solutional galleries characterized by cupolas and blind pits anastamotic passages roof pendants and phreatic passages situated at different levels some of these caves are still active as is the case for frassassi gorge parrano gorge and acquasanta terme with galleries that reach the phreatic zone where there is a rising of highly mineralized water rich in hydrosulfydric acid and with erosion of limestone walls and the formation of gypsum elsewhere there are fossil caves such as monte cucco and pozzi della piana where large speleothems of gypsum are present 500 m or more above the regional water table in all of these important karst systems it is possible to recognize basal input points through fracture and intergranular porosity networks at the base of the oxidizing zone in the core of the anticline where mineralized water rises up from the triassic evaporitic layers in small hydrogeological circuits different underground morphologies can derive from the presence of a water table related to an external stream or from the confined setting of the carbonate rocks underlying low permeable sedimentary cover where artesian conditions can occur

the chemical evolution of kurnub group paleowater in the sinai negev province a mass balance approach abstract the chemical evolution of the kurnub group paleowater was studied starting from rainwater in recharge areas of the sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer this was achieved by investigating the chemical composition of groundwater ionic ratios degrees of saturation with common mineral species normative analysis of dissolved salts and by modeling of rock water interaction and mixing processes occurring along groundwater flow paths the initial groundwater composition used is from the nakhel well in sinai it evolves from desert rainwater percolating through typical kurnub group lithology in sinai this rainwater dissolves mainly gypsum halite and dolomite together with smaller amounts of marine aerosol and k feldspar at the same time it precipitates calcite sio 2 smectite and degasses co 2 between the area of nakhel and the northern negev the chemistry of kurnub group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas small amounts of feldspars and of dolomite cement in sandstones eroded from the arabo nubian igneous massif of sinai and organic degradation derived co 2 concomitantly there is precipitation of calcite smectite sio 2 and probably analcime characteristic of sediments in continental closed basins north of the negev the kurnub group fluids are diluted and altered by mixing with judea group aquifer groundwaters on the e there is mixing with residual brines from the water body ancestral to the dead sea prior to discharge into the arava valley rock water interaction indicated by netpath and phreeqc modeling is in agreement with lithology and facies changes previously observed in the kurnub group sequence

stromatolites in caves of the dead sea fault escarpment implications to latest pleistocene lake levels and tectonic subsidence abstract a varied assemblage of algal stromatolites was encountered in caves along the northern section of the dead sea fault escarpment the caves are situated at the lower part of the escarpment at altitudes 310 to 188 m relative to mean sea level m s l i e ca 110 230 m above the present dead sea level the cave stromatolites are mainly composed of aragonite yielding u th ages of 75 17 ka the altitude mineralogy and ages as well as comparison with previously documented stromatolite outcrops in the area ascribe the cave stromatolites to the aragonite precipitating hypersaline lake lisan the late pleistocene predecessor of the dead sea the stromatolites are used as a lake level gauge based on the algae being reliant upon the light of the upper water layer preservation of the original structure and aragonite mineralogy of the stromatolites suggests a closed system regarding the radioactive elements enabling reliable u th dating a curve of lake lisan levels is constructed based on the stromatolite ages and cave elevations the following points are noted 1 lake levels of 247 m relative to m s l are recorded at 75 72 5 ka 2 relatively high lake levels above 220 m relative to m s l are achieved at 41 5 ka and are still recorded at 17 ka 3 the peak level is 188 m relative to m s l at 35 5 29 5 ka these results indicate lake stands up to 80 m higher than previously accepted for large parts of the lake lisan time span this difference is explained by tectonic subsidence of up to 2 2 m ka within the dead sea depression since the latest pleistocene this subsidence rate is in the same order of magnitude with previously calculated subsidence rates for the dead sea depression begin z b zilberman e 1997 main stages and rate of the relief development in israel geological survey of israel report jerusalem unlike previous lake lisan level estimations the new curve is measured at the relatively stable shoulders of the dead sea depression

the sulfur system in anoxic subsurface brines and its implication in brine evolutionary pathways the ca chloride brines in the dead sea area abstract important elements in the evolutionary history of saline groundwater might be overlooked when they involve both sulfate removal through reduction and input of sulfate via dissolution these two simultaneous and apparently contrasting processes can result in a negligible net effect on the sulfate concentration isotopic composition of sulfur in sulfate and sulfide can be applied to identify the bacterial sulfate reduction bsr though the extent of the process is difficult to quantify saturation with respect to gypsum may suggest that gypsum dissolution also occurs however a more definite identification of these processes and their quantification can be achieved through the use of ammonium concentration in the anoxic brines this approach assumes that the ammonium is derived only from the oxidation of organic matter through bsr and it requires that the c n ratio in the oxidized organic matter be known a minimum estimate for the sulfate reduction can be obtained when the redfield c n ratio 106 16 is assumed several calculation methods are presented to identify the extent of sulfate reduction prior to concomitant with or following gypsum dissolution that are based on combining sulfur isotopic compositions rayleigh distillation equation and calculated gypsum saturation indices the required assumptions are presented and their validation is discussed the subsurface hypersaline ca chloride brines in the vicinity of the dead sea are taken as a case study here sulfur isotope compositions of sulfate and sulfide and high ammonium concentrations indicate bsr occurs in the subsurface the sulfur isotopic composition of the sulfate makes it possible to distinguish between two major groups of brine and their recent evolutionary histories 1 the qedem shalem thermal brines 34 s so4 21 24 which emerge as springs along the shores and are slightly undersaturated with respect to gypsum 2 dsif tappuah brines 34 s so4 30 60 which are found in shallow boreholes and are saturated to oversaturated with respect to gypsum calculations based on their ammonium content suggest that both groups of brine require apparent unreasonably high oversaturations with respect to gypsum prior to the onset of the reduction this implies that the groundwater systems were open with respect to sulfate and that the sulfate reservoir was replenished continuously or intermittently during the bsr the dsif tappuah brines continue to dissolve gypsum during their bsr the dissolving sulfate is derived from relatively isotopically enriched gypsums 34 s so4 20 such as found in the lisan formation these brines approach the steady state isotopic composition 34 s ss dictated by the combination of the 34 s of the dissolving gypsum and the fractionation factor accompanying bsr the sulfur isotopic composition of the qedem shalem brines implies that most of their ammonium content is derived from an earlier phase of bsr and that the last phase of bsr takes place during the brines rapid ascent to the surface prior to this stage they evolved through either 1 dissolution of gypsum with 34 s so4 20 which occurred after the main bsr in the subsurface 2 a previous phase in which the brines were part of a lake and later percolated to the subsurface as such their isotopic composition and ammonium content were determined by the combined effect of freshwater sulfate input to the lake and bsr in the stratified lake

continental oxygen isotopic record of the last 170 000 years in jerusalem abstract a long radiometrically dated oxygen isotopic record of continental climatic variations since the penultimate glaciation was obtained from a stalagmite deposited in a sealed cave in jerusalem this record shows that speleothems have the potential of assigning dates to long and short term climatic events with possible refining of milankovitch tuning of ice and marine records which themselves are not datable short term 1000 yr events are very significant in the region reaching 50 of glacial interglacial fluctuations the mediterranean sea was the most probable source of local precipitation throughout the last glacial cycle

geological evolution of the afro arabian dome abstract the afro arabian dome includes the elevated continental regions enclosing the red sea gulf of aden and the ethiopian rift system and extends northwards as far as jordan it is more than an order of magnitude larger than other african uplifts both the structures and the igneous rocks of the dome appear to be products of the superimposition of two perhaps three semi independent generating systems initiated at different times but all still active a strain pattern dominated by nw trending basins and rifts first became established early in the cretaceous by the end of the oligocene much of the extensional strain had been taken up along the red sea and gulf of aden axes which subsequently developed into an ocean palaeogene trap volcanism of mildly alkaline to transitional character was related to this horizontal extension rather than to doming further west the east sahara swell has a history of intermittent alkaline volcanicity which began in the mesozoic and was independent of magmatism in the afro arabian dome volcanicity specifically related to doming began in the miocene along a n s zone of uplift extending from ethiopia to syria this elongated swell forms the northern termination of the east african system of domes and rifts characterized by episodic vertical uplift but very little extension superimposition of epeirogenic uplift upon structures formed by horizontal extension took place in the neogene volcanicity related to vertical tectonics is mildly alkaline in character whereas transitional and tholeiitic magmas are found along the spreading axes

cross formational rising groundwater at an artesian karstic basin the ayalon saline anomaly israel it is proposed that a geothermal artesian karstic system at the central part of the yarkon taninim aquifer creates the ayalon saline anomaly asa whose mechanism has been under debate for several decades a 4 year long detailed groundwater monitoring was carried out at 68 new shallow boreholes in the ayalon region accompanied by a comprehensive survey of karstic voids results indicate the rising of warm brackish groundwater through highly permeable swarms of karstic shafts serving as an outflow of the artesian geothermal system the asa area contains hot spots where groundwater contrasts with normal water hundreds of meters away the asa temperature reaches 30 8 c w5 8c warmer than its surroundings chloride concentration reaches 528 mg l 50 100 mg l in the surrounding h2s concentration reaches 5 6 mg l zero all around and ph value is 7 0 compared with 7 8 around subsequently the hydrothermal water flows laterally of at the watertable horizon through horizontal conduits mixing with normal fresh water which had circulated at shallow depth following rainy seasons maximal watertable rise is observed in the asa compared to its surroundings regional hydrogeology considerations suggest that the replenishment area for the asa water is at the samaria mountains east of the asa the water circulates to a great depth while flowing westward and a cross formational upward flow is then favored close the upper sub aquifer s confinement border

too low δ18o of paleo meteoric low latitude water do paleo tropical cyclones explain it abstract isotopic analysis of rock samples showed anomalously 18 o depleted reconstructed isotopic composition of paleo meteoric water over southern israel between the late cretaceous and the early miocene with 18 o w as low as 14 smow this range is significantly lighter than the expected values for rain at the relevant paleo latitudes 8 n to 25 n it is similar or lighter than areas with meteoric water at the present climate in which rainfall contribution from tropical cyclone tc is significant rainfall from tcs is 18 o depleted because of the recirculation of the vapor into repeated precipitation or distillation cycles a paleo geographic reconstruction of the region shows that throughout the period there was a warm ocean to the east and southeast of the relevant area thus tcs formed over the ocean and made landfall on the coastline at a distance of 300 to 400 km to the east the reconstructed composition of the rainwater implies dominance of tcs at these times furthermore the combination of warmer seas and lighter rainwater than at present suggests that the tcs were more dominant than in the most tc prone coastal areas at the present climate the results of the present study suggest that climate during the relevant time periods was very different from the present with tc activity similar or exceeding the most tc prone locations in the world at the present climate this might also hint that warmer sea waters in the geological past were conducive to greater tc activity than in the present climate answering this question requires additional research

early pleistocene lake deposits and lower paleolithic finds in nahal wadi zihor southern negev desert israel abstract an early pleistocene fluvio lacustrine sequence from the extremely arid southern negev desert israel indicates that climatic conditions during that period were humid enough to support the formation of a lake lake zihor there the lacustrine sediments were deposited in a tectonic valley that developed along the zihor tectonic line after the deposition of the pliocene arava formation they intercalate with fluvial sediments that contain several horizons of reddish calcic paleosols the lacustrine sequence comprises three sedimentary cycles each starts with a dark clay layer overlain by a white limestone unit both of which contain abundant freshwater fauna and terminates with a green detrital limestone that contains only one type of brackish water ostracod the top of each green limestone unit is characterized by pedogenic features and microrelief indicating desiccation of the lake and soil development isotope data support the hypothesis that the white limestone was deposited in an open freshwater lake the incision of the present channel of nahal wadi zihor in the lacustrine sediments is manifested by a series of rock cut and fluvial terraces q1 q4 capped by gypsic salic soils which reflect the onset of the present extremely arid climate over 100 find spots and larger occurrences of prehistoric artifacts assigned to the lower paleolithic were discovered near lake zihor on the basis of techno typological and stratigraphic considerations these assemblages are divided into two groups the first of which may be contemporaneous with the lake while the second is found mainly on the younger q1 and q2 terraces it is estimated that the lake existed for more than 100 000 years the climate during this period was probably semiarid but water budget calculations suggest that in addition to surface runoff seepage of groundwater along the zihor line contributed a considerable amount of water to the lake

the nubian sandstone aquifer in the central and northern negev israel delineation of the hydrogeological model under conditions of scarce data abstract the cl content of ground water in the central and northern negev ranges between 250 mg 1 1 in the beer sheva area and 1600 mg 1 1 near the egyptian border where the water is also thermal with high concentrations of sulphates and iron during the last few years groundwater resources in the heavily populated beer sheva area have become endangered by a continuing process of salinization in the course of the present work it was found that in the study area ground water flows through a multiple aquifer system including the jurassic lower cretaceous kurnub group and the upper cretaceous judea group aquifers because of the absence of impermeable beds at the boundary between the two groups brackish ground water flows from the kurnub group into the overlying judea group aquifer moreover numerous faults discovered in the subsurface facilitate lateral inflow of kurnub ground water into the judea aquifer by interpreting new lithostratigraphic data from the kurnub group and seismic surveys made in the study area it is shown that the kurnub aquifer extends far beyond the hitherto known boundaries and contains an additional estimated volume of 51 10 9 m 3 of paleowater the limiting factors of its exploitability are groundwater depth and salinity the rational exploitation of the kurnub paleowater may prevent salinization of the overlying judea group aquifer

the interaction of two major old water bodies and its implication for the exploitation of groundwater in the multiple aquifer system of the central and northern negev israel abstract in the beer sheva region of the negev desert the only significant fresh groundwater is contained within the judea group carbonate aquifer it is found that this aquifer holds two distinctly different old water bodies one such groundwater body has evolved in equilibrium with the carbonate aquifer rocks after being recharged during the holocene in the hebron mountains north of the study area at present modern recharge as denoted by the tritium and radiocarbon contents is very minor a subtle piston effect generated by contemporary replenishment is discussed in representative hydrographs in beer sheva wells another groundwater body identified in the judea group aquifer derives from the underlying kurnub group aquifer the regional artesian kurnub group aquifer nubian sandstone contains an older and brackish groundwater body which has been recharged in sinai during pleistocene pluvials faulting in the beer sheva region facilitated hydrologic contact between the two aquifers exploitation of the judea group has released confining pressures and resulted in the intrusion of kurnub group water into the overlying judea group carbonate aquifer this process is most significant in those wells drilled close to major faults where salinity increases with pumping the intruding water originating from the kurnub group sandstone aquifer has not yet equilibrated chemically with the carbonate host the low ph and high temperatures that have been encountered indicate continuing and very recent intrusion in the beer sheva area in the absence of direct significant modern recharge as determined from tritium and 14 c values all waters should be considered as paleowaters that are being mined a complete revision of the hydrologic concept by which the multiple aquifer system can be exploited is required to take into account the fact that the fresh judea group groundwater is actually an old holocene water body intruded by brackish and older pleistocene water along fault zones

the transformation of southern israel from a swell to a basin stratigraphic and geodynamic implications for intracontinental tectonics abstract the history of southern israel during the 100 myr period between the cretaceous and the eocene is an example of epeirogenic movements which were controlled by magmatism and heating initially this region was uplifted and became a local swell then it subsided more than its surroundings and became a local basin this study analyzes the subsidence history of the region during its cooling for two purposes first to understand the relations between the tectonic pattern of subsidence and the resulting stratal geometry and second to constrain the volume of magmatism that intruded the lithosphere and perturbed the isostatic equilibrium our results show that lateral changes in the intensity of the tectonically driven subsidence are not always expressed by simple corresponding changes in the thickness of sedimentary units the most prominent example of this was found in the cenomanian section which thickens northward in absolute contrast with the tectonic pattern of subsidence during its deposition the reason for this discrepancy lies in lateral differences in the compactibility of the substrate upon which these sediments were deposited the two most important factors controlling the compactibility of the substrate are the thickness of previously existing sediments and their history of uplift since sediments that are reburied after an uplifting phase do not compact significantly until they reach their previous maximal depth we emphasize the need to reveal the amount of exhumation from the amount of erosion hidden in unconformities our second aim was achieved only in part because we cannot distinguish the subsidence caused by midlithospheric intrusions from secondary factors one possible scenario that satisfies the observations is a combination of midlithospheric intrusions equivalent to a 15 km thick sill plus thermal thinning of the lithosphere of the same order

groundwater flow along and across structural folding an example from the judean desert israel abstract the considerable influence of the geological structure on groundwater flow regime is exhibited in the thick carbonate aquifer beneath the judean desert israel groundwater flow is diverted from the general steep hydraulic gradient creating a subsurface river like meandering flow pattern the structure of the extensive folded anticlinorium forces groundwater flow through synclinal axes in the upper aquifer and in places it overflows from one to an adjacent syncline groundwater outflows are at tsukim kane samar and en gedi springs near the dead sea shore and by sub surface flow across the graben faults towards the dead sea in this study all available data are integrated and processed first ever to form a complete representation of the three dimensional hydrostratigraphy and hydrogeology using numerical modeling modflow we analyzed quantitatively the flow regime leakage rates between upper and lower sub aquifers and between adjacent sub basins the groundwater mass balance and aquifer hydraulic properties this study has practical implications regarding recent groundwater management future possibilities of groundwater development for the benefit of both israelis and palestinians residing in the area and conservation of nature reserves located along the dead sea

the sources and evolution of sulfur in the hypersaline lake lisan paleo dead sea d 34 s values in gypsum are used to evaluate the fate of sulfur in the hypersaline lake lisan the late pleistocene precursor of the dead sea 70 14 ka bp and applied as a paleo limnological tracer the ca chloride lake lisan evolved through meromictic periods characterized by precipitation of authigenic aragonite and holomictic episodes characterized by enhanced gypsum precipitation the lake deposited two major gypsum units the blower gypsum unitq deposited at 56 ka showing d 34 s values of 18 20x and the bupper gypsum unitq deposited at 17 ka displaying significantly higher d 34 s values of 26 28x laminated and disseminated gypsum residing within the aragonite exhibit d 34 s values in the range of 26x to 1x the isotopic composition of the gypsum was dictated by freshwater sulfate input that replenished the upper layer of the lake the mixolimnion bacterial sulfate reduction bsr that occurred under the anoxic conditions of the lower brine the monimolimnion and mixing between these two layers during meromictic periods the sulfate reservoir in the lower brine was replenished by precipitation of gypsum from the upper layer and its subsequent dissolution due to sulfate deficiency induced by bsr activity this process describes a bsulfur pumpq mechanism and its effect on d 34 s in the water can be modeled by a modified rayleigh distillation equation steady state d 34 s values 40x were reached in the lower brine after long meromictic periods following overturn episodes induced by diminishing freshwater input and lake level decline large quantities of d 34 s enriched gypsum precipitated the negative d 34 s values in laminated and disseminated gypsum provide evidence for bsr activity in the lower brine that removed isotopically depleted sulfides from the water column causing significant isotopic enrichment of remaining sulfate following the lake desiccation the sediments were exposed and the latter sulfides oxidized and re crystallized as gypsum d 2005 elsevier b v all rights reserved

morphogenesis of hypogenic caves abstract hypogenic speleogenesis is the formation of solution enlarged permeability structures by waters ascending to a cave forming zone from below in leaky confined conditions where deeper groundwaters in regional or intermediate flow systems interact with shallower and more local groundwater flow systems this is in contrast to more familiar epigenic speleogenesis which is dominated by shallow groundwater systems receiving recharge from the overlying or immediately adjacent surface hypogenic caves are identified in various geological and tectonic settings formed by different dissolutional mechanisms operating in various lithologies despite these variations resultant caves demonstrate a remarkable similarity in patterns and meso morphology which strongly suggests that the hydrogeologic settings were broadly identical in their formation hypogenic caves commonly demonstrate a characteristic suite of cave morphologies resulting from rising flow across the cave forming zone with distinct buoyancy dissolution components in addition to hydrogeological criteria hydrostratigraphic position recharge discharge configuration and flow pattern viewed from the perspective of the evolution of a regional groundwater flow system morphogenetic analysis is the primary tool in identifying hypogenic caves cave patterns resulting from ascending transverse speleogenesis are strongly guided by the permeability structure in a cave formation they are also influenced by the discordance of permeability structure in the adjacent beds and by the overall hydrostratigraphic arrangement three dimensional mazes with multiple storeys or complex 3 d cave systems are most common although single isolated chambers passages or crude clusters of a few intersecting passages may occur where fracturing is scarce and laterally discontinuous large rising shafts and collapse sinkholes over large voids associated with deep hydrothermal systems are also known hypogenic caves include many of the largest by integrated length and by volume documented caves in the world more importantly hypogenic speleogenesis is much more widespread than it was previously presumed growing recognition of hypogenic speleogenesis and improved understanding of its peculiar characteristics has an immense importance to both karst science and applied fields as it promises to answer many questions about karst porosity especially as deep seated settings are concerned which remained poorly addressed within the traditional epigenetic karst paradigm

the rate of flushing as a major factor in determining the chemistry of water in fossil aquifers in southern israel abstract issar a 1981 the rate of flushing as a major factor in determining the chemistry of water in fossil aquifers in southern israel in w back and r letolle guest editors symposium on geochemistry of groundwater 26th international geological congress j hydrol 54 285ndash 296 a parallel trend has been found to exist between the isosalinity lines and the isopiezo metric lines in the fossil aquifers of the nubian sandstones in southern israel and the central sinai the flow pattern in these aquifers determines the rate of mixing between paleo seawater and paleo meteoric water this flowpattern is determined by the spatial relations between the nubian sandstone outcrops in the central sinai and the major fault lines of the dead sea and suez rift valleys a cumulative chemical composite diagram in which 18o stable isotope data were plotted makes it possible to classify the water and to trace the ratios in the mixture

middle late quaternary paleoclimate of northern margins of the saharan arabian desert reconstruction from speleothems of negev desert israel abstract speleothems in arid and hyper arid areas of negev desert israel are used in paleoclimate reconstruction of northern margins of saharan arabian desert focused on the following objectives 1 precise u th dating of the timing of speleothem growth as an indicator of periods of humid climate i e positive effective precipitation 2 the origin of rainfall using the speleothem 18 o and changes in spatial pattern of speleothem deposition and speleothem thickness along a north south transect 3 changes of vegetation cover based on speleothem 13 c variations during the last 350 ka major humid periods referred to herein as negev humid periods nhp occurred in the central and southern negev desert at 350 310 ka nhp 4 310 290 ka nhp 3 220 190 ka nhp 2 and 142 109 ka nhp 1 nhp 4 nhp 2 and nhp 1 are interglacial events whereas nhp 3 is associated with a glacial period during nhp 1 2 and 3 the thickness and volume of the speleothems decrease from the north to the south and in the most southern part of the region only a very thin flowstone layer formed during nhp 1 with no speleothem deposition occurring during nhp 2 and 3 these data imply that the eastern mediterranean sea was the major source of the rainfall in northern and central negev more negative speleothem 18 o values relative to central parts of israel soreq cave are attributed to rayleigh distillation because of the increasing distance from the mediterranean sea speleothem deposition during the nhp 4 in the southern negev was more intensive than in most of the central negev suggesting the prominence of the tropical rain source decrease in speleothem 13 c during nhp events indicates growth of the vegetation cover nevertheless the ranges of 13 c values show that the vegetation remained semi desert c4 type throughout the nhps with an additional significant carbon fraction coming from the host rock and the atmosphere these observations together with small thickness of the speleothem layers favor that nhp events consisted of clusters of very short humid episodes interspersed with long droughts nhp events were contemporaneous with climate periods with monsoon index of 51 cal cm 2 day and with the formation of sapropel layers in the mediterranean sea such simultaneous intensification of the monsoon and atlantic mediterranean cyclones is probably related to the weakening of the high pressure cell above sub tropical atlantic ocean which enabled more rainfall to penetrate into the saharan arabian desert from the north and south the contemporaneous occurrence of the nhp events and the increased monsoon rainfall could have opened migration corridors creating climatic windows of opportunity for dispersals of hominids and animals out of the african continent

paleoclimate reconstruction in the levant region from the geochemistry of a holocene stalagmite from the jeita cave lebanon dated oxygen and carbon isotopic profiles from a holocene stalagmite 11 9 1 1 ka from the jeita cave lebanon are compared to variations in crystallographic habit stalagmite diameter and growth rate the profiles show generally high 18o and 13c values during the late glacial period low values during the early holocene and again high values after 5 8 ka on the basis of the good correlation between the morphological and crystallographic aspect of the stalagmite and its isotopic records as well as the isotopic response of speleothems from central and northern israel we relate high 18o and 13c values to drier conditions between 6 5 and 5 8 ka an increase in isotopic values a decrease in growth rate and stalagmite diameter suggest a transition from wet conditions in the early holocene towards drier conditions in the mid holocene the transition occurred in two steps first a progressive change to drier conditions started at 6 5 ka but was interrupted by a short 100 years return to wetter conditions followed by an equally rapid 200 years change to drier conditions

morphometry and distribution of isolated caves as a guide for phreatic and confined paleohydrological conditions isolated caves are a special cave type common in most karst terrains formed by prolonged slow water flow where aggressivity is locally boosted the morphometry and distribution of isolated caves are used here to reconstruct the paleohydrology of a karstic mountain range within a homogenous karstic rock sequence two main types of isolated caves are distinguished and each is associated with a special hydrogeologic setting maze caves form by rising water in the confined zone of the aquifer under the mt scopus group israel confinement while chamber caves are formed in phreatic conditions apparently by lateral flow mixing with a vadose input from above

pliocene pleistocene climate of the northern margin of saharan arabian desert recorded in speleothems from the negev desert israel abstract the middle late pliocene climate was 2 3 c warmer than today but with similar levels of atmospheric co2 this period reflects climate conditions expected in the near future and is therefore an important target for current data modeling studies this study reconstructs the pliocene quaternary evolution of arid conditions on the northern margin of the saharan arabian desert using radiometrically u pb dated periods of speleothem deposition from three caves of the negev desert israel speleothem growth started between 3 75 and 3 ma at the end of the first significant tectonic uplift of the western shoulder of the dead sea rift major speleothem deposition indicating wet conditions occurred during the pliocene around 3 1 ma with subsequent aridity during the last 3 myr punctuated by short wet episodes the pleistocene negev humid periods nhp the oldest dated nhp occurred between 1 7 and 1 25 ma and other short humid episodes continued intermittently later speleothem 18o values 6 9 to 11 2 show that the humid episodes were associated with periods of low global ice volume and warm temperatures after correction for rainfall 18o changes associated with ice volume and temperature effects the observed relative constancy of speleothem 18o values from pliocene to late pleistocene indicates rainfall was from a common source most probably the eastern mediterranean sea the humid pliocene conditions could be generated by more southerly position of the mediterranean coast allowing the access of mediterranean precipitation to the negev as well as by warmer atlantic sea surface temperatures that weakened the azores high pressure cell maximum amounts of precipitation were 500 600 mm a during the pliocene and 300 mm a during pleistocene nhp the pliocene and the earliest pleistocene nhp are associated with formation of lakes in the negev low 87sr 86sr ratios of 0 7078 in the pliocene speleothems are indicative of low dust supply low water residence time in the vadose zone and relatively high weathering rates of the cave host rock increase of 87sr 86sr ratios to 0 7082 0 7083 in the pleistocene suggest an increased supply of desert dust high water residence time in the vadose zone and reduced host rock weathering

permanent quaternary hyperaridity in the negev israel resulting from regional tectonics blocking mediterranean frontal systems although various episodes of wet quaternary climates have been suggested in studies of the negev desert here we demonstrate that reg soils developed on flat alluvial surfaces and sensitive to minor changes in precipitation indicate that the southern negev has been permanently hyperarid at least since the middle pleistocene the wetter episodes were restricted to the northern negev currently mildly arid gypsic saline reg soils that de veloped on stable surfaces during 200 k y in the southern negev are cumulative and polygenetic but none exhibits even the weakest development of calcic horizons under current climate conditions in the negev calcic soils are widespread in areas with rainfall 80 mm yr 21 the fact that the hyperarid 50 mm yr 21 southern negev lacks any calcic horizons indicates that it never experienced an average rainfall of 80 mm yr 21 during the middle late pleistocene whereas the northern negev was wetter this negev dichotomy is explained by the main physical features controlling rainfall over the negev i e the southward decreasing depth of the atmospheric boundary layer with distance from the mediterranean and the altitude of the central negev highland 1000 m the interaction between these two features often prevents the passage of rain clouds into the southern negev the holocene and pleistocene gypsic salic soil distribution across the negev closely matches the current circumstances we suggest that hyperaridity has prevailed over the southern negev since the last stages of the uplift of the central negev highland in the late pliocene early pleistocene

relation between continental rifting and uplifting evidence from the suez rift and northern red sea abstract the suez rift and the northern red sea are flanked by high standing shoulders with elevations often exceeding 2 km and with a structural relief reaching 4 5 km in this area pre rifting erosion was small not more than a few hundred meters there is no evidence that a precursory uplift formed along the site of future rifting uplifting and erosion began essentially at the same time as rift faulting and magmatism in late oligocene and early miocene limes in the gebel serbal area sinai where the uplifting history is resolved best the tectonic relief reached about 800 m by the end of the early miocene and a similar amount of tectonic uplifting developed in later times other parts of the rift shoulders probably had a similar uplifting history but the total uplifting was often less considerable erosion in places more than 3 km occurred mainly since middle miocene times and caused considerable isostatic rebound this magnified the uplifting and caused the structural and topographic relief to be considerably greater than the tectonic uplifting initial uplifting and contemporaneous magmatic activity were probably caused by rising of deep hot material which thinned the lithosphere and heated it such deep seated processes probably continued to operate also during the later stages of tectonic uplifting though igneous activity no longer occurred on the surface stretching of the lower lithosphere under the rift shoulders could have also contributed to their uplifting the features of uplifting history of the studied region may well be typical of other active rifts

the rotation of arabia and the levant fault system abstract we establish the kinematics of the rotation of arabia with respect to africa and show that the rotation rate of africa increased by a factor of about four in late serravallian time about 12 13 ma ago we discuss evidence that oceanic accretion started simultaneously in the gulf of aden and in the red sea at this time it is also at this time that the levant and anatolian fault systems were initiated our initial reconstruction of the red sea rift in late oligocene early miocene time approximately superposes the present shore lines which coincide with the mid point of the zones of rapid crustal thinning the future continental slopes the amount of extension during the early phase of continental rifting is obtained by assuming that the total volume of continental crust is conserved during extension and by checking these estimates through closure around the sinai triple junction in the late miocene the southern evant fault zone was a zone of distributed shear deformation through counterclockwise block rotation extending soul h ward within the northernmost red sea since the early pliocene the shear motion has been localized within the gulf of aqaba changing the tectonic pattern in the northern red sea

tracing end member fluid sources in sub surface iron mineralization and dolomitization along a proximal fault to the dead sea transform shear faults in upper cretaceous limestones of the central negev desert adjacent to the dead sea transform dst feature extensive ferruginous mineralization and dolomitization this has been related to topographically driven flow of metalliferous groundwaters through an underlying clastic nubian sandstone aquifer and rise of the fluids up the fault zones the present study combines pb and sr isotope measurements with detailed sampling and petrography at the eastern end of the paran fault menuha ridge in order to identify the types of groundwater and the sources of enriched elements in this regional scale sedimentary mineralization ferroan and non ferroan dolomitization along the paran fault caused significant enrichment of several elements mg cu mn ni v zn pb and u and 87 sr 86 sr values that are significantly higher than the upper cretaceous limestone country rock the non ferroan dolomite and the ferroan dolomite sampled at three sites along the menuha ridge have similar 87 sr 86 sr values 0 7076 0 7089 and 0 7077 0 7086 respectively additionally there is a positive correlation between mg content of the dolomites and their 87 sr 86 sr values the isotopic composition of sr and pb of dolomite corresponds to the mineralogical type identified in the mineralized rock non ferroan dolomite simple zoned ferroan dolomite and complex zoned ferroan dolomite the 207 pb 204 pb and 206 pb 204 pb ratios of fe oxides and dolomites from the three sites plot on a straight line where the simple zoned ferroan dolomite values are at the non radiogenic end of the line and the complex zoned ferroan dolomites at the radiogenic end both 206 pb 204 pb and 207 pb 204 pb ratios in dolomites and to a lesser degree in fe oxides suggest that a mixing between two end members controls the behavior of pb in the mineralization products along the paran fault rather than a single fluid source the study indicates that two types of metalliferous groundwaters were involved in the dolomitization and mineralization along the paran fault the first and hitherto undocumented fluid source is the mg rich dead sea rift brine migrating in the sub surface before dolomitizing the carbonate bedrock migration of the brines took a deep path to the site of mineralization with temperatures reaching 75 c based on the geological history of the region this probably took place in the late miocene early pliocene interval the second type of groundwater acquired its high solute concentrations from leaching igneous rocks and clastic sediments in the sub surface and infiltrated along the paran fault precipitating fe rich minerals and caused the first stage of dolomitization this groundwater flowed at shallower depth than the dsr brines and at lower temperatures t 6 50 c the study shows that sedimentary mineralization in faults adjacent to active transform fault zones may arise from the combination of several different fluid flow regimes

desert speleothems reveal climatic window for african exodus of early modern humans one of the fi rst movements of early modern humans out of africa occurred 130 100 thousand years ago ka when they migrated northward to the levant region the climatic conditions that accompanied this migration are still under debate using high precision multicollector inductively coupled plasma mass spectrometry mc icp ms u th methods we dated carbonate cave deposits speleothems from the central and southern negev desert of israel located at the northeastern margin of the saharan arabian desert speleothems grow only when rainwater enters the unsaturated zone and this study reveals that a major cluster of wet episodes the last recorded in the area occurred between 140 and 110 ka this episodic wet period coincided with increased monsoonal precipitation in the southern parts of the saharanarabian desert the disappearance at this time of the desert barrier between central africa and the levant and particularly in the sinai negev land bridge between africa and asia would have created a climatic window for early modern human dispersion to the levant

occurrence of secondary gypsum veins in joints in chalks in the negev israel abstract beds fissures and joints filled with coarse sparitic gypsum were found associated with the upper layers of chalks of eocene age in the beer sheva region in southern israel the average34s so4 value of the gypsum is 15 which signifies an evaporitic origin field observations show that the veins are connected with the loess soil cover of upper pleistocene age which overly the chalks the deposition of the gypsum is suggested to be through a process of leaching from the loess during a more humid period its concentration possibly by roots of sulfate tolerant trees and its deposition from groundwater which became over saturated with caso4 the high contents of sulfate in the loess is explained by the special climatic conditions which prevailed during the uppermost pleistocene and which were characterized by sulfate rich dust and rainstorms

deep confined karst detection analysis and paleo hydrology reconstruction at a basin wide scale using new geophysical interpretation of borehole logs summary deep karst voids can be identified by a new method of geophysical interpretation of commonly used borehole logs in deeply confined carbonate aquifers we show that deep buried karst voids can be characterized by combining this geophysical interpretation together with geological and hydrological data and with known speleological constraints we demonstrate how this characterization can reveal past hydrological regimes and allow mapping of karst distribution on a basin wide scale a combined analysis of geophysical geological hydrological and speleological data in the confined yarkon taninim aquifer israel led us to reconstruct past groundwater levels at different relief and sea levels with the karst voids as a marker for long term flow close to the water table paleo canyons along the mediterranean sea shoreline strongly affected the region s paleo hydrology by serving as major outlets of the aquifer during most of the cenozoic we conclude that intensive karstification was promoted by flow periods of longer duration and or higher flux and flow velocities close to the aquifer s past and present outlets in addition we suggest that karst voids found under shallow confinement were developed by renewed aggressivity due to hypogene water rising in cross formational flow becoming mixed with fresh lateral water flow from the east

last glacial warm events on mount hermon the southern extension of the alpine karst range of the east mediterranean abstract this study focuses on warm last glacial episodes in the southernmost extension of the alpine karst range of the eastern mediterranean levant region through the study speleothems in mizpe shelagim cave located in mt hermon the alpine karst range extends from turkey through syria and lebanon reaching its southern limit in mt hermon at an elevation of more than 2000 m under present day conditions southern mt hermon receives 1000 2000 mm precipitation mostly as snow that originates in the eastern mediterranean sea speleothems deposition in this high altitude region was continuous during interglacials but during the last glacial growth only occurred when average annual temperatures exceeded 3 c as inferred from the study of speleothem fluid inclusions warming episodes occurred at 65 ka 56 ka 54 5 ka 52 5 51 ka 49 ka 42 ka and 36 ka and are coincident with maximum insolation at 65 n the main depositional period from 56 ka to 51 ka coincides with dansgaard oeschger interstadial 15 and 14 and warming in the northeastern basin of the mediterranean sea warming in the southern alpine karst range of the eastern mediterranean was manifested by vegetation development together with significant snow melting that resulted in the drainage of large amount of water to the dead sea rift valley

depositional environments and facies of the late triassic abu ruweis formation jordan abstract the abu ruweis formation is composed of carbonates evaporites and mudstones with some locally developed pelletic oolitic and stromatolitic limestones the lateral persistence of bedding the purity of the evaporite rocks the alternating arrangement of marine carbonates and evaporites indicates periodic deposition in subaqueous conditions salina petrographic investigations x ray diffraction analysis as well as chemical analysis have shown that the outcropping evaporite beds are mainly composed of secondary gypsum with rare anhydrite relics five microfacies of gypsum were recognized according to their fabrics porphyroblastic and granoblastic gypsum showing polarization texture gypsum pseudomorph after anhydrite laths and satin spar gypsum the textures they display indicate a hydration origin of precursor anhydrite which is in turn rehydrated from primary gypsum some of these anhydrites were formed as a result of replacement processes of the carbonate sediments associated with the evaporites as evidenced from the textural relationships of the carbonate and sulfate minerals the o18 content ranges from 1 45 to 8 38 pdb and the c13 content ranges from 1 52 to 4 73 pdb trace elements analysis has shown that the abu ruweis dolomites are rich in strontium up to 600 ppm and sodium up to 835 ppm the isotope composition and trace elements content as well as the petrographic characteristics point to a penecontemporaneous hypersaline dolomitization origin for the abu ruweis dolomites the evaporites were deposited during a regressive lowstand systems tract whereas the carbonates were deposited under shallow water marine conditions during a highstand systems tract the abu ruweis succession represents a relatively stable arid climate within a rapidly subsiding basin restricted conditions were provided by the development of beach barriers

distinction between epigenic and hypogenic maze caves abstract certain caves formed by dissolution of bedrock have maze patterns composed of closed loops in which many intersecting fractures or pores have enlarged simultaneously their origin can be epigenic by shallow circulation of meteoric groundwater or hypogenic by rising groundwater or production of deep seated solutional aggressiveness epigenic mazes form by diffuse infiltration through a permeable insoluble caprock or by floodwater supplied by sinking streams most hypogenic caves involve deep sources of aggressiveness transverse hypogenic cave origin is a recently proposed concept in which groundwater of mainly meteoric origin rises across strata in the distal portions of large flow systems to form mazes in soluble rock sandwiched between permeable but insoluble strata the distinction between maze types is debated and is usually based on examination of diagnostic cave features and relation of caves to their regional setting in this paper the principles of mass transfer are applied to clarify the limits of each model to show how cave origin is related to groundwater discharge dissolution rate and time the results show that diffuse infiltration and floodwater can each form maze caves at geologically feasible rates typically within 500 ka transverse hypogenic mazes in limestone to enlarge significantly within 1 ma require an unusually high permeability of the non carbonate beds generally 10 4 cm s large discharge and calcite saturation no greater than 90 which is rare in deep diffuse flow in sedimentary rocks deep sources of aggressiveness are usually required the origin of caves by transverse hypogenic flow is much more favorable in evaporite rocks than in carbonate rocks

pleistocene paleoclimate of the arid region of israel as recorded in calcite deposits along regional transverse faults and in veins abstract the 18o and 13c values of the calcites associated with e w and ne sw transverse faults in the negev israel indicate that calcite was deposited from meteoric water a regional change in the 18o and 13c values was observed the 18o content in the calcite increases from the southwestern 18 o 17 8 to the northeastern 18 o 2 9 part of the region the 13c values show the opposite trend of the 13c content decrease from 2 in the south to 10 in the northeast these trends had to reflect changes in regional paleoclimate suggesting a change in the isotopic composition of the solution from which the calcite was deposited in different periods the variations in the 18o values reflect shifts in the 18o values of precipitation and are associated with a change in the source of moist air masses which came from the equatorial atlantic in the early pleistocene and from the mediterranean during a later period variations in 13c values reflect changes from humid to arid conditions two modes of calcite deposition are suggested 1 precipitation of calcite minerals in the unsaturated zone following the dissolution in the soil or 2 calcite deposition that occurred as co2 was lost during emergence of paleogroundwater from lower cretaceous and jurassic aquifers

paleoclimate and vegetation of the last glacial cycles in jerusalem from a speleothem record a speleothem isotopic record taken from jerusalem is used to reconstruct regional climate over the last 170 000 years glacial periods in jerusalem were generally cooler and wetter than the present climate stage 5e in the desert margin of jerusalem was extremely unstable dry and warm and instability persisted throughout the transition to glacial conditions the climate after stage 5e became gradually cooler and wetter over a 20 000 year interval and did not recover to interglacial conditions in stages 5c and 5a the 13 c varied by up to 12 from glacial stages 6 4 3 2 values of 10 to 12 that reflect dense c 3 vegetation above the studied cave and up to 0 in early stage 5 when there was probably complete loss of vegetation the climatic instability during interglacial periods is much larger than during glacial periods and glacial interglacial transitions do not behave the same in each climatic cycle in this region