seasonality of holocene hydroclimate in the eastern mediterranean reconstructed using the oxygen isotope composition of carbonates and diatoms from lake nar central turkey a positive shift in the oxygen isotope composition 18o of lake carbonates in the eastern mediterranean from the early to late holocene is usually interpreted as a change to drier reduced p e conditions however it has also been suggested that changes in the seasonality of precipitation could explain these trends here holocene records of 18o from both carbonates and diatom silica from lake nar in central turkey provide insights into palaeoseasonality we show how 18olakewater the difference between spring and summer reconstructed 18olakewater was minimal in the early holocene and for most of the last millennium but was greater at other times for example between 4 100 1 600 years bp we suggest that increased 18olakewater could have been the result of relatively more spring summer evaporation amplified by a decline in lake level in terms of change in annual mean 18o isotope mass balance modelling shows that this can be influenced by changes in seasonal p e as well as inter annual p e but lake level falls inferred from other proxies confirm there was a mid holocene transition to drier climatic conditions in central turkey

elevated pore pressure and anomalously low stress in regions of low frequency earthquakes along the nankai trough subduction megathrust 1 recent seismic reflection and ocean bottom seismometer obs studies reveal broad regions of low seismic velocity along the nankai subduction plate boundary megathrust offshore sw japan these low velocity zones lvz s extend 55 km landward from the trench corresponding to depths of 10 km below sea floor here we estimate the in situ pore pressure and stress state within these lvz s by combining p wave velocities obtained from the geophysical surveys with new well constrained empirical relations between p wave velocity porosity and effective mean stress defined by laboratory deformation tests on drill core samples of the incoming oceanic sediment we document excess pore pressures of 17 87 mpa that extend 55 km into the subduction zone indicating that trapped pore fluids support 45 91 of the overburden stress along the base of the upper plate and surrounding major fault zones the resulting effective stresses in the lvz are limited to 1 3 of the values expected for non overpressured conditions these low effective stresses should lead to a mechanically weak and predominantly aseismic plate boundary the region of lowest effective stress coincides with precisely located very low frequency earthquakes providing the first quantitative evidence linking these anomalous slip events to low stress and high pore pressure

holocene climatic changes in the western mediterranean from south east france to south east spain abstract holocene climatic changes along coastal regions from south east france to south east spain were studied using pollen ratios comparing modern pollen rain vegetation and climate along selected transects from the atlantic ocean to the mediterranean we obtained threshold values of two different ratios corresponding to the different climatic conditions along the transects these pollen ratios and threshold values were employed to characterize the holocene climatic changes from nine mediterranean coastal sites the results were compared with data from marine and continental pollen sequences distributed in the western mediterranean basin and with additional regional data independent of human activity lake level fluctuations alpine glacier advance and retreat chronology 14 c anomaly and cooling phases in eastern france and central europe the role of anthropogenic activities and climate on the changes in vegetation is discussed six major changes in vegetation cover were identified they correspond to aridification phases that occurred around 9500 9000 yr bp 10 900 9700 cal bp 7500 7000 yr bp 8400 7600 cal bp 4500 4000 yr bp 5300 4200 cal bp 3700 3300 yr bp 4300 3400 cal bp 2600 1900 yr bp 2850 1730 cal bp and 1300 1000 yr bp 1300 750 cal bp these arid episodes were regional responses to more global climatic changes and determined the changes in the vegetation cover humans undoubtedly enhanced the vegetation changes but none the less had to adapt to these new climatic conditions

adriatic deep water formation during the holocene implication for the reoxygenation of the deep eastern mediterranean sea under modern conditions the reoxygenation of eastern mediterranean deep water is the result of the formation of dense bottom water in the southern adriatic sea oxygen isotopic records of planktonic foraminfera used as a paleosalinity tracer show that po river and or the alpine glaciers meltwater are not directly responsible of the inhibition of the deep water formation in the adriatic during sapropel s1 formation at 9 000 years b p sedimentological evidence indicates that fully oxygenated conditions in the deep adriatic occurred only by 1 650 100 years b p a long time after the total reoxygenation of the deep eastern mediterranean organic carbon content and isotopic ratio indicate that persistence of a reduced sediment phase until 1 650 years b p does not result from increased primary productivity or large input of terrestrial organic matter

first evidence of a distal early holocene ash layer in eastern mediterranean deep sea sediments derived from the anatolian volcanic province article i nfo a hitherto unknown distal volcanic ash layer has been detected in a sediment core recovered from the southeastern levantine sea eastern mediterranean sea radiometric stratigraphic and sedimentological data show that the tephra here termed as s1 tephra was deposited between 8970 and 8690 cal yr bp the high silica rhyolitic composition excludes an origin from any known eruptions of the italian aegean or arabian volcanic provinces but suggests a prevailing central anatolian provenance we compare the s1 tephra with proximal to medial distal tephra deposits from well known mediterranean ash layers and ash fall deposits from the central anatolian volcanic field using electron probe microanalyses on volcanic glass shards and morphological analyses on ash particles we postulate a correlation with the early holocene dikkartin dome eruption of erciyes dag volcano cappadocia turkey so far no tephra of the central anatolian volcanic province has been detected in marine sediment archives in the eastern mediterranean region the occurrence of the s1 tephra in the south eastern part of the levantine sea indicates a wide dispersal of pyroclastic material from erciyes dag more than 600 km to the south and is therefore an important tephrostratigraphical marker in sediments of the easternmost mediterranean sea and the adjacent hinterland

late quaternary paleoclimate in the eastern mediterranean region from stable isotope analysis of speleothems at soreq cave israel abstract the eastern mediterranean continental paleoclimate during the past 25 000 years was determined by a high resolution petrographic stable isotopic and age study of speleothems from soreq cave israel 18o 13c trends indicate that all speleothems older than 7000 yr formed under conditions that differ from those of today the period from 25 000 to 17 000 yr b p was characterized by the highest 18o and 13c values which indicate deposition at temperatures of 12 16 c annual rainfall of 300 450 mm and vegetation typical of a mixed c3 c4type from 17 000 to 10 000 yr b p deglaciation in northern europe 18o values dropped progressively correlative with warming 2 3 c and a gradual increase in precipitation a simultaneous decrease in 13c gives a range expected for c3 type vegetation this period also shows significant 18o and 13c spikes which are correlatable with global events e g heinrich events and the younger dryas stade the speleothems that grew between 10 000 and 7000 yr b p have a unique petrography showing irregular thin laminae of various colors and much detritus they have the lowest 18o corresponding to 1000 mm rain coupled with the highest 13c caused by flooding events which stripped the soil cover from 7000 to 1000 yr b p conditions became closer to those of today this study demonstrates that global events which were recognized in northern europe and north africa are also evident in the eastern mediterranean and are reflected principally by large changes in the rainfall rate

modern and early middle holocene shells of the freshwater mollusc unio from catalhoyuk in the konya basin turkey preliminary palaeoclimatic implications from molluscan isotope data carbon and oxygen isotope ratios in the shells of the freshwater unio mollusc yield information on the isotopic composition of the water in which the shell was formed which in turn relates to climatic conditions prevailing during the bivalves life span here we analysed shells from one modern unio from a modern lake shore in anatolia and 4 subfossil unio shells from catalhoyuk dated between 7200 bc and 5000 bc neolithic and chalcolithic periods sequential carbon and oxygen isotope analysis along the surface of the shells provides information on seasonal or shorter term variability of lake waters during the lifetime of the organisms 18o values of the modern shell are consistent with it being collected from a dammed portion of the seyhan river that does not undergo intensive summer evaporation this is in contrast to many of the surface water bodies in anatolia which suffer extensive evaporation in the arid summers 18o values of the subfossil shells from the catalhoyuk middens indicate that the bivalves came from lakes which evaporated extensively during the summer months but were replenished by high winter rainfall suggesting that the subfossil shells lived in relatively small lakes or ponds stable isotope analysis along the growth of freshwater bivalves is one of the few methods for investigating seasonal water fluctuations in the past these results may alter current interpretations on the environment of catalhoyuk during the neolithic although more work is needed to confirm these initial findings

multicomponent analysis of ftir spectra quantification of amorphous and crystallized mineral phases in synthetic and natural sediments abstract the study of weathering and erosion processes requires the establishment of a mass balance of minerals from the soils towards the sedimentation area this calls for the development of quantitative tools that can be applied to mixtures of finely divided and sometimes poorly crystallized minerals found in soils and sediments we present here the use of fourier transform infrared ftir absorbance spectroscopy in the mid infrared as a method to calculate mineral modes for such materials samples were prepared using the kbr disc method this ensures that lambert beer s law is valid a quantitative determination of the mineral content from various blends was performed by making a multicomponent analysis of the experimental spectrum using the spectra of each component in the mixture to check the validity of the procedure the multicomponent analysis was performed on spectra from synthetic mixtures of standard minerals quartz kaolinite gibbsite amorphous silica good agreement between actual and computed wt was obtained in the range 1315 315 cm 1 this application of ftir spectroscopy was used to quantify the mineral components of a lacustrine sediment cored at salitre minas gerais brazil the major phases are organic matter kaolinite gibbsite quartz anatase and amorphous silica phytoliths and sponge spicules fifty three samples were analyzed quantitative results from ftir spectroscopy were compared to chemical analyses to assess the validity of the method for the natural sediments phases with no sharp diagnostic spectral features such as anatase or amorphous silica were quantified using the multicomponent analysis the variations of the main mineral phases along the core reflect the mechanisms of transfer from the surrounding soils to the sediment area and the role of the vegetal cover over the drainage area

abrupt post glacial climate events in west asia and north africa monsoon domains regions beyond the present or past penetration of the indian and african monsoons have experienced several large and abrupt climatic fluctuations over the past 13 14c kyr pollen and lake records from west asia western tibet and rajasthan east africa ethiopia and west africa western sahara sahel and subequatorial africa were selected on the basis of chronological control sensitivity of both site and environmental indicators to climate change the continuity of the record and interdisciplinary control of the palaeoclimatic interpretation conditions wetter than those of today prevailed during the early mid holocene period but major dry spells are recorded at all sites during the intervals 11 0 9 5 kyr bp 8 7 kyr bp and 3 4 kyr bp several records also suggest dry events of minor amplitude around 6 kyr bp potential boundary forcings of insolation and sea surface and tropical land surface conditions are discussed the solar radiation accounts for the general envelop of the post glacial monsoon fluctuations but explains neither the timing nor the amplitude of the short term changes in spite of apparent covariation between fluctuations in sea surface conditions in the north atlantic and the monsoon record no direct mechanism could be found relating the intensity of the oceanic thermohaline conveyor belt to the monsoon strength changes in tropical land surface conditions soil moisture negative feedback and changes in ch4 production from wetlands provide a more satisfactory hypothesis for explaining abrupt reversal events

oxygen isotopes in lacustrine carbonates of west china revisited implications for post glacial changes in summer monsoon circulation five lakes in the qinghai tibet plateau and north xinjiang have provided oxygen isotope records covering the past 17 11 cal kyr bp the modern lakes are first presented within the major atmospheric circulation and climate patterns of china with the climate related isotope composition of input water equations used to extract hydrological and climatic information from 18o in carbonates are then given after a discussion on potential causes for 18o changes each of the five isotope profiles is interpreted in the light of its specific environmental data the most significant event observed in all records occurred at 12 11 cal kyr bp an abrupt intensification of summer rainfall associated with an extremely rapid 1000 1500 km westward migration of the monsoon fronts the monsoon regime weakened in stages after 8 7 cal kyr bp holocene maximal aridity is recorded at all sites between about 4 5 and 3 5 cal kyr bp long term changes in monsoon strength as inferred from our isotopic interpretation are in good agreement with climate model reconstructions in the tibet qinghai plateau while observed hydrological changes in north xinjiang are not simulated by the models also the non linearity of the holocene monsoon variations cannot be accounted for by orbital forcing

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

facies changes and high calorific peat formation in a quaternary maar lake central anatolia turkey the possible role of geothermal processes in a closed lacustrine basin abstract the sedimentary infill of the acigol maar lake one of the volcanic centres in the cappadocia district of anatolia contains unusual high calorific sub recent peat deposits of which the origin is attributed to geothermal processes the sedimentary facies record is analyzed to reconstruct the lake s depositional history and to disentangle the combined signal of climatic and geothermal factors the facies succession comprises a lake fringe clastic apron shed from the maar walls early stage coarse grained tuffaceous deposits of the lake proper intercalated with brecciated mudstones and limestones and final stage fine grained tuffaceous deposits of the lake proper intercalated with peats and plant bearing clastics and with some terminal travertines the closed lake was highly dependent on climate particularly precipitation and the depositional conditions were further controlled by a connective hydrothermal system which itself was driven by the input of meteoric water the associated heat flow played an important role by creating a microclimatic niche where even the impoverished late quaternary cold regional climate vegetation could flourish and form substantial peats the varying hydrological budget of the lake was the main switching mechanism for the peat forming conditions with two water depth thresholds involved if the lake level rose too high the low vegetation was drowned and hemipelagic clastic sedimentation prevailed if the lake level fell too low the vegetation was killed and formation of travertine took place the heat flow through the pore water and clastic sediments was crucial to the high maturation of the peat deposits

mid to late holocene climate change in central turkey the tecer lake record the mineralogy and grain size distribution of sediments from tecer lake in central anatolia provides a 6000 year record of mid to late holocene climate trends and events correspondences between k

fluid induced rupture experiment on fontainebleau sandstone premonitory activity rupture propagation and aftershocks 1 a 14 porosity fontainebleau sandstone sample diameter 40 mm length 88 mm was loaded tri axially under 100 mpa confining pressure and 240 mpa differential stress in drained conditions and under constant load pore pressure water was raised until failure was triggered during the experiment elastic wave velocities and permeability were monitored while more than 3000 acoustic emissions ae were located prior and after failure ae locations show that macroscopic fracture propagated from a large nucleation patch at speeds comprised between 0 1 and 4 m s number of ae hits per second followed omori s law with exponents of 0 92 and 1 18 pre and post failure respectively no quiescence was observed post failure except where rupture initially nucleated from fast depressurization of the pore space induced secondary aftershocks located within the fracture plane possibly indicating a heterogeneous fault geometry after rupture of lower permeability that compacted during the release of pore pressure

a calendar age estimate of the younger dryas holocene boundary at krakenes western norway the younger dryas holocene transition yd h in the sediments of krakenes lake western norway is well marked both lithologically and palaeobiologically at 756 5 cm in the investigated core a ser

palaeoclimate interpretation of stable isotope data from lake sediment archives the isotope composition of authigenic and biogenic carbonates and diatom silica are commonly used as palaeoclimate proxies from lake sediments this article reviews the controls on the isotope composition of lacustrine skeletal and non skeletal deposits and illustrates how stable isotope studies contribute to an understanding of changes in temperature precipitation patterns evaporation and the carbon cycle it highlights the differences in the palaeoclimate potential of a wide range of lakes ranging from open to closed lake basins a large number of the case histories but not all are drawn from studies of temperate lakes from europe large closed lake systems in the tropics and elsewhere lose water predominantly through evaporation and contain sediments with variable and generally high 18o values fluctuations in the isotope composition of authigenic or biogenic minerals are mainly a function of long term changes in the precipitation evaporation ratio in contrast small open lakes which have a degree of through flow typically contain sediments with 18o values that vary by no more than a few these variations are generally ascribed to variations in temperature or the isotope composition of precipitation p from which either an annual or seasonally specific signal can be gained these types of lakes are common in northern europe and at high altitudes the interpretation of isotope data from a lacustrine succession requires a knowledge of the local processes that might control and modify the signal their effects need to be quantified and a robust calibration using the modern lake system is necessary to establish the relationship between the measured signal the isotopic composition of the host waters and climate

earthquakes induced by water injection at 3 km depth within the rongchang gas field chongqing china 1 unwanted water amounting more than 1 million m 3 has been injected intermittently at a pumping pressure of 2 1 2 9 mpa over hydrostatic at 2 6 2 9 km depth within the rongchang gas field western chongqing china since july 1988 the injections have induced more than 32 000 surface recorded earthquakes including 2 of m l 5 14 of m l 4 and more than 100 of m l 3 up until the end of 2006 we examined the epidemic type aftershock sequence etas model and the temporal evolution of several statistics of the earthquake sequence the random component in the etas model can be considered as an indicator of fluid driven activity while the rate of omori law type aftershocks indicates stress triggering of the preceding earthquakes we observed three distinct seismic activity phases that were coincident with different injection periods phase i corresponds to initial injections with low injection rate long time interval and shows a vast majority of omori type events and only 8 externally forced activity phase ii corresponds to a period of high injection rates and shows intense earthquake activity characterized by a high percentage 45 of fluid driven earthquakes phase iii demonstrates decreasing seismicity as a result of a lowering in the injection rate more than 70 of earthquakes occurred randomly over time indicating the dominance of external triggering the physical mechanism that induced the rongchang earthquake sequence was a change in coulomb s failure stress caused by pore pressure diffusion and transformed from seismic slip of preceding earthquakes a pressure increase of 2 1 2 9 mpa at the injection well is more than sufficient to induce failure within the local formations

u series isochron dating a generalized method employing total sample dissolution the age of a sedimentary deposit can be determined by measuring 238u 234u 232th and 230th in two or more samples of the deposit with the requirement that these samples have different u th ratios but an identical 230th232th ratio when deposited this paper presents the theoretical and experimental aspects of the dating method the latter involves techniques for securing samples of varied u th ratios from the same deposit plotting isochrons of the radiochemical data obtained on totally dissolved samples for age analysis and estimating the errors involved although applications to impure carbonates and lacustrine evaporite sediments are given as examples in this paper the method potentially can be generalized for dating a variety of authigenic deposits such as rock varnish peat opal sulfate minerals and marine phosphorites

positive feedback fracture process induced by nonuniform high pressure water flow in dilatant granite during forced water infiltration into a dry granite rock in the dilatant state migration of a water front and a clear positive feedback between acoustic activity and water flow into microcracks were revealed by means of ae hypocenter locations and velocity tomography water was injected into a cylindrical granite sample subjected to 40 mpa confining pressure and constant axial stress equal to about 70 of short term dry strength the injection water pressure was held constant at 17 mpa until failure occurred soon after water injection into the bottom end of the sample ae hypocenters began near the bottom end subsequently they moved up with a strong preference for the region where a weak concentration of ae events had been observed during a steady state creep stage before the water injection the p wave velocity structure was determined in the section parallel to the loading axis and crossing the cluster of ae hypocenters the velocity structure reconstructed by seismic tomography showed a nonsymmetric distribution of the velocity with regard to the loading axis during the injection the strong concentration of ae hypocenters suggests that water flow channels are preferentially formed in a very limited region in the dilatant rock the concentration of ae events and formation of these water channels marks a positive feedback process in which the local strength of the rock is reduced by the decrease of the effective confining pressure caused by increasing pore pressure which in turn triggers more microfracturing

sedimentology dating and palaeoclimatic interpretation of a 76 3 ka record from lago grande di monticchio southern italy abstract detailed sedimentological and microstratigraphical investigations of lacustrine sediments from lago grande di monticchio southern italy provide a time scale based on rates of sedimentation obtained from annual laminations although not annually laminated throughout a time scale covering the last 76 3 ka is available by interpolation of sedimentation rates results of this chronology agree with radiocarbon dates and with ar ar dates on tephra layers from the same lacustrine sediment sequence occurrence of varves in combination with physical and geochemical properties are related to variations in the trophic state of the lake and to changing runoff both controlled by palaeoclimatic conditions water depth was relatively shallow with dominating bioturbation and only few varves preserved for most of the pleniglacial a marked increase in precipitation and related runoff characterises the early last glacial maximum when water depth reached a maximum and clastic varves were deposited subsequently water depth was shallower again a drastic change towards nutrient rich conditions occurred at the pleistocene holocene transition during the holocene organic varves were deposited two periods with higher organic productivity were recognised prior to the last glacial maximum around 50 ka and 73 ka these intervals are interpreted as the result of interstadial conditions the oldes of the two events shows laminations comparable to those at the glacial holocene transition the periods with increased minerogenic influx may be characterised as stadial conditions lasting from 14 40 ka and from 50 73 ka

postglacial connection of the black sea to the mediterranean and its relation to the timing of sapropel formation the opening of the connection between the mediterranean and black seas as sea level rose above the bosporus sill has long been associated with the formation of the most recent holocene sapropel deposit s1 in the eastern mediterranean but the mechanism has remained elusive we present a model for the opening of the black sea based on hydraulics arguments which demonstrates that increased freshwater flux out of the black sea began 500 1000 years after sea level reached sill depth and that the timescale for the increased freshwater flux that drained the freshwater reservoir of the black sea is about 2500 3500 years we argue that the increased freshwater discharge out of the black sea would lead to decreased deep water formation and higher productivity in the surface waters in the eastern mediterranean two conditions generally associated with sapropel formation the delay in increased freshwater flux after the opening of the black sea and the period of increased freshwater discharge appear to match the onset and duration of sapropel deposits in the eastern mediterranean

active post depositional oxidation of the most recent sapropel s1 in sediments of the eastern mediterranean sea abstract over a wide area of the eastern mediterranean basin two mn rich layers have been observed above the most recent sapropel s1 one immediately above the sapropel top and one a few centimetres closer to the sediment surface different mechanisms have been proposed to explain the occurrence of these two mn peaks either both peaks have a diagenetic origin in which case the upper mn peak is actively forming or the lower peak is actively forming and the upper peak has a different formation mechanism high resolution porewater including a gel sampler used for the first time in marine sediments and solid phase data are now used to demonstrate that the oxidation front is located at the level of the lower mn peak which therefore is presently being formed a barium organic carbon relationship is used to calculate the initial organic carbon profile of the s1 sapropel the palaeoproductivity profiles generated by this method demonstrate that the original sapropel unit was bounded by the upper mn peak this implies that the interval between the two mn peaks where a low organic carbon content is now observed was originally part of the sapropel the initially deposited organic carbon has been oxidised by a progressive downwards moving oxidation front the penetration depth of this oxidation front i e the distance between the two mn peaks is mainly determined by the organic carbon content the sediment accumulation rate and the bioturbation depth the upper mn peak appears to have formed as a result of either mn precipitation upon oxygenation of previously anoxic eastern mediterranean deep water or preservation of a surficial mn peak at the end of the high productivity episode in either case the upper mn peak marks the end of sapropel formation as indicated by the ba profiles this means that formation of the s1 sapropel ceased more recently than is indicated by radiocarbon dating of the visible top of s1

speleothem evidence for late holocene climate variability and floods in southern greece abstract we present stable isotope data 18o 13c from a detrital rich stalagmite from kapsia cave the peloponnese greece the cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave using a combination of u th and 14c dating to constrain a site specific correction factor for 232th 238u detrital molar ratio a linear age model was constructed the age model shows that the stalagmite grew during the period from ca 950 bc to ca ad 830 the stable oxygen record from kapsia indicates cyclical changes of close to 500 yr in precipitation amount with rapid shifts towards wetter conditions followed by slowly developing aridity superimposed on this signal wetter conditions are inferred around 850 700 500 and 400 100 bc and around ad 160 300 and ad 770 and driest conditions are inferred to have occurred around 450 bc ad 100 150 and ad 650 detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 bc 70 bc and ad 450 the stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities

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

holocene water level changes inferred from a section of fluvio lacustrine sediments in the southeastern mu us desert china abstract a natural exposure of fluvio lacustrine sediments the dsgl section on the left bank of salawusu river located at the southeastern margin of the mu us desert in north china was studied in order to reconstruct holocene water level changes a chronology was established based on 11 ams 14c dates and variations in the lithology and grain size c m variations were used to assess the forcing factors of local hydrological changes during the holocene a lake swamp environment with high hydrodynamic energy occurred from 9 6 to 9 2 ka cal yr bp which was succeeded by a full lake environment at around 9 6 ka cal yr bp however an interval of sand deposits and peat sediments from 9 2 to 8 6 ka cal yr bp indicates unstable hydrodynamic conditions the salawusu paleo lake reached its maximum level between 8 4 and 6 5 ka cal yr bp and gradually shrank thereafter after 1 2 ka cal yr bp a shallow lake environment returned indicating a humid phase which may be correlative with the relatively warm and moist medieval warm period mwp after 0 68 ka cal yr bp broadly coeval with the little ice age lia a fluvial environment appeared the variations in water level were mainly triggered by the east asian monsoon however site specific factors may have also have been important

u series dating of impure carbonates an isochron technique using total sample dissolution abstract u series dating is a well established technique for age determination of late quaternary carbonates materials of sufficient purity for nominal dating however are not as common as materials with mechanically inseparable aluminosilicate detritus detritus contaminates the sample with extraneous th we propose that correction for contamination is best accomplished with the isochron technique using total sample dissolution tsd experiments were conducted on artificial mixtures of natural detritus and carbonate and on an impure carbonate of known age results show that significant and unpredictable transfer of radionuclides occur from the detritus to the leachate in commonly used selective leaching procedures the effects of correcting via leachate residue pairs and isochron plots were assessed isochrons using tsd gave best results followed by isochron plots of leachates only

acoustic emission induced by pore pressure changes in sandstone samples an understanding of microseismicity induced by pore pressure changes in stressed rocks is important for applications in geothermal and hydrocarbon reservoirs as well as for co 2 sequestrations we have studied the triggering mechanisms of microseismicity or acoustic emission in the laboratory as a function of triaxial stress conditions and pore pressure changes in investigating the spatiotemporal distribution of acoustic emission activity in water saturated triaxially stressed flechtingen sandstone samples subjected to changes in pore pressure we assumed that acoustic events were triggered by pore pressure increase to estimate pore pressure changes in the sample we used an analytical solution of the 1d diffusion equation a theoretical analysis of the spatiotemporal distribution suggested that for initially insignificantly stressed samples acoustic events were triggered by the migration of a critical pore pressure level through the sample the critical level was controlled by the applied pore press

hydrogeology and mechanics of subduction zone forearcs fluid flow and pore pressure at subduction zones fluid flow pore pressure and tectonic processes are tightly interconnected excess pore pressure is driven by tectonic loading and fluids released by mineral dehydration and it has profound effects on fault and earthquake mechanics through its control on effective stress the egress of these overpressured fluids which is in part governed by the presence of permeable fault zones is a primary mechanism of volatile and solute transport to the oceans recent field measurements new constraints gained from laboratory studies and numerical modeling efforts have led to a greatly improved understanding of these coupled processes here we summarize the current state of knowledge of fluid flow and pore pressure in subduction forearcs and focus on recent advances that have quantified permeability architecture fluxes the nature and timing of transience and pressure distribution thus providing new insights into the connections between fluid metamorphic mechanical and fault slip proc

slow earthquakes coincident with episodic tremors and slow slip events we report on the very low frequency earthquakes occurring in the transition zone of the subducting plate interface along the nankai subduction zone in southwest japan seismic waves generated by very low frequency earthquakes with seismic moment magnitudes of 3 1 to 3 5 predominantly show a long period of about 20 seconds the seismicity of very low frequency earthquakes accompanies and migrates with the activity of deep low frequency tremors and slow slip events the coincidence of these three phenomena improves the detection and characterization of slow earthquakes which are thought to increase the stress on updip megathrust earthquake rupture zones

fission track dating obsidians in central and northern anatolia twenty obsidian samples from central and north anatolia were dated by the fission track method split samples analyzed in two different laboratories give consistent results data presented refer to three volcanic fields and are summarized as follows orta sakaeli northern anatolia obsidians with ages from 21 23 ma gollu dagi dome complex near ciftlik central anatolia has given ages between 1 33 0 98 ma acigol caldera central anatolia shows three age groups 1 eruptions of precaldera bogazkoy obsidians with ages 0 18 0 15 ma 2 formation of the large intracaldera dome kocadag taskesiktepe at about 0 08 ma uncorrected apparent age of 0 075 ma and 3 acigol peripheral obsidian domes with plateau ages of 0 020 and 0 019 ma and an additional uncorrected age of 0 018 ma form a distinct age group this fission track parameters discriminate between the various obsidian sources of prehistoric obsidian artifacts

vegetation dynamics and climate during the deglaciation in the south adriatic basin from a marine record the pollen record of a marine core in the south adriatic basin that is radiometrically dated and correlated to the global climate variation by the oxygen isotope curve documents the vegetation changes which occurred around that basin since 17 ka thousands year bp during the end of the last glacial maximum at 16 7 15 ka the altitudinal range is occupied at low and high elevations by a desert and a semi desert dominated by the shrubby sage brush artemisia and at middle elevation by a grass steppe with stands of pine trees where soil conditions are favourable during the deglaciation between 15 and 10 ka a steppe forest with a succession of deciduous trees appears at middle elevation within the grass steppe but its development is interrupted by a set back a re expansion of the semi desert which is coeval with the younger dryas of higher european latitude the holocene is identified by the spread of the mixed deciduous and mediterranean forests which culminates between 8 6 and 6 ka during the end of the boreal and the atlantic chronozones while the most recent sapropel is formed in the deep marine basins of the eastern mediterranean including the south adriatic one between the cold and arid glacial maximum and the warmest and wettest climate optimum during the atlantic chronozone this vegetation dynamics is constrained by the availability of moisture at low elevation by temperature at high elevation and by a combination of both at middle elevation

local holocene environmental indicators in upper mesopotamia pedogenic carbonate record vs archaeobotanical data and archaeoclimatological models abstract it has been suggested that pedogenic carbonate coatings on stones in archaeological sites can be used to reconstruct late quaternary environmental changes in the area of the fertile crescent this research compares a pedogenic carbonate record from southeastern turkey with three other local or regional sources of palaeoenvironmental information in order to evaluate the correlation of this new proxy with other independent data from the area 1 ancient plant macroremains from archaeological sites as ecological indicators 2 stable carbon isotope composition of ancient plant macroremains available in the literature and from our own investigations in six mid holocene archaeological sites and 3 modelled holocene precipitation and temperature changes in the northern fertile crescent comparison involved selected palynological and isotopic data from lacustrine sediments as well as speleothem isotopic records in near eastern locations available in the literature although the data show a certain amount of variation of proxy records on the regional scale for the northern fertile crescent upper mesopotamia they suggest three pronounced features of the holocene environmental history 1 a trend toward warmer temperatures may have affected the area during the early holocene between ca 10 000 6000 cal bp 2 increased moisture availability and relatively high temperatures in the mid holocene ca between 5000 and 4000 cal bp and 3 a significant decrease in moisture availability around 4000 cal bp further research is needed to enhance the chronological resolution of both pedogenic carbonate and plant macrofossil records this study stresses the complexity of the holocene palaeogeography of the near east and underlines the need for careful analysis of local sources of palaeonvironmental information in the region

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

late holocene erosion in nw anatolia from sediments of lake manyas lake ulubat and the southern shelf of the marmara sea turkey abstract this paper deals with modern and ancient sedimentation in fresh water lakes and the marine shelf of the southern marmara region nw anatolia turkey most of the information has been obtained from monitoring of suspended load discharged into two lakes manyas and ulubat in the last 45 years and from 8 to 11 m thick lacustrine sediments in addition to radiocarbon dated shelf sediments this allows a holistic approach to the drainage basin denudation over time the results show that the sedimentation rates in the lakes were low 0 22 cm year 1 from 4000 to 2000 years bp and then they increased 0 29 cm year 1 up to sub recent times and reached 0 44 cm year 1 in the last century it is suggested that deforestation created high rates of sedimentation in the basins and or strong denudation of the region during the late holocene this study also shows that for shallow freshwater lakes the calculation of sedimentation rates must include fine particles lost by the outlets and coarse grained bed load deposited on their shores in addition a high rate of sedimentation has been created by short but repetitive intense depositions during the last century particularly during the last 45 years the rate of sedimentation or denudation has increased dramatically in nw turkey the two world wars and mismanagement of the land had important local effects by increasing deforestation and resulting in the present erosive conditions

historical landscape change in cappadocia central turkey a palaeoecological investigation of annually laminated sediments from nar lake coupled multiproxy indicators pollen stable isotopes and charcoal reconstructed from annually laminated lake sediments from nar ga la in cappadocia central turkey complemented by documentary and archaeological evidence provide a detailed record of environmental changes and their causes from late antiquity ad 300 to the present day stable isotope data indicate marked shifts in the variability in summer drought intensity and winter spring rainfall but these did not coincide in time with changes in vegetation and land use shown by pollen data rather human impacts appear to have been the main driver of landscape ecological changes in cappadocia over the last two millennia pollen and charcoal data indicate four principal land use phases i an early byzantine agrarian landscape characterized by cereals and tree crops and marking the later part of the so called beya ehir occupation phase ii a period of landscape abandonment and the establishment of secondary woodland from ad 670 to 950 coinc

tephrostratigraphy chronology and climatic events of the mediterranean basin during the holocene an overview the identification and characterisation of high frequency climatic changes during the holocene requires natural archives with precise and accurate chronological control which is usually difficult to achieve using only 14c chronologies the presence of time spaced tephra beds in quaternary mediterranean successions represents an additional independent tool for dating and correlating different sedimentary archives these tephra layers are potentially useful for resolving long standing issues in paleoclimatology and can help towards correlating terrestrial and marine paleoclimate archives known major tephras of regional extent derive from central and southern italy the hellenic arc and from anatolia a striking feature of major holocene tephra deposition events in the mediterranean is that they are clustered rather than randomly distributed in time several tephra layers occurred at the time of the s1 sapropel formation between c 8 4 and 9 0 ka bp mercato gabellotto fiumebianco e1 cappadocia and ot

diatom based transfer functions for inferring past hydrochemical characteristics of african lakes abstract a new dataset of 282 modern diatom samples and associated environmental information has been created by merging existing regional datasets from north and east africa and niger the relationships between diatom species distributions and hydrochemistry are examined using canonical correspondence analysis cca and partial cca variables reflecting water conductivity ph and cation and anion composition account for significant and independent components of the total variation in the diatom data predictive models transfer functions are developed using the method of weighted averaging for conductivity r 2 0 87 ph r 2 0 77 and ratios between alkali and alkaline earth metals r 2 0 81 and carbonate bicarbonate and sulphate chloride ions r 2 0 82 prediction errors are estimated using the computer intensive method of jackknifing these transfer functions enlarge the potential domain for reconstruction of past hydrochemistry from fossil diatoms preserved in lake sediments

the holocene climatic optimum and pollen records of sapropel 1 in the eastern mediterranean 9000 6000 bp abstract the most recent sapropel in the deep eastern mediterranean sea has been deposited between 9 and 6 ka bp climate conditions as revealed by the pollen records of this sapropel in marine cores were most favorable for temperate deciduous trees which is in agreement with the inferences from records of peripheral land pollen sites the abundance of deciduous oak pollen is much higher than that of artemisia sage brush indicating that annual precipitation in the mid elevation borderlands was at least 550 mm without summer drought but more probably in the range 800 1300 mm the pollen of pistacia which formed a savanna at low elevations is also at its highest abundance and signals the absence of frost in winter while being capable of withstanding summer drought the early holocene therefore appears as the post glacial climatic optimum with the highest moisture and mildest winters in southwest asia this is also the time of the neolithic population explosion with incipient domestication of cereals possibly following natural selection of the tough rachis mutation in wheat and barley by the extreme aridity of the preceding younger dryas

geomorphic responses to long term land use changes in eastern macedonia greece distinct phases of stream aggradation soil erosion and landscape stability in the basin of drama eastern macedonia greece over the past 7000 years can be tied directly to long term land use changes during the middle and late holocene 1 4 m of alluvial fill accumulated in the centre of the basin and along the angithis valley low levels of alluvial aggradation were recorded during the late neolithic and the early bronze age 7400 4000 cal bp in the centre of the basin along the lower course of the river xeropotamos the rate of aggradation has doubled since the late bronze age 0 5 0 6 mm year 1 compared to the holocene as a whole 0 25 mm year 1 moderate rates of alluvial fill were experienced during the late bronze age 3600 3000 cal bp but the most significant destabilisation of the soils occurred later than in many regions of greece two historical phases of alluvial aggradation and soil erosion are identified in the antique and the early byzantine era 3rd century bc 7th century ad and more significantly in the ottoman period beginning of the 15th to the 20th century ad in the latter period the rate of accumulation was three to five times greater than in the late holocene almost three millennia intervened between the arrival of the first farmers and the onset of erosion this is mainly explained by the settlement pattern during the neolithic and the early bronze age it seems that the early farmers preferred to cultivate the more stable soils on the gentle slopes at the centre of the basin during the late bronze age the land use pattern changed the soils then under cultivation on the foothills were less stable and the steeper slopes were more susceptible to erosion this limited the potential for forest restoration after the first noticeable land clearance and probably explains the extent of alluvial aggradation since the antique era the intensity of land use has increased the two phases of accelerated alluviation in historical times are clearly linked to land use changes particularly with the upstream progression of cropping and grazing onto more sensitive lands in foothills and mountainous areas though this was also influenced by climatic fluctuations the major period of aggradation in the ottoman period is clearly associated with both climatic and anthropogenic factors it seems that the early historic deforestation and agricultural activities rendered river systems more sensitive to relatively modest changes in climate

mechanics of seismic instabilities induced by the recovery of hydrocarbons we review earthquake distributions associated with hydrocarbon fields in the context of pore pressure diffusion models poroelastic stress transfer and isostasy theory these three mechanisms trigger or induce seismic instabilities at both local scale d 5 km and at regional scale d 20 km the modeled changes in stress are small 1 mpa whatever the tectonic setting each mechanism corresponds to different production processes 1 local hydraulic fracturing due to fluid injection induces seismic slip on cracks ml 3 within the injected reservoir through decreasing the effective stress 2 pure fluid withdrawal causes pore pressure to decrease within the reservoir it triggers adjustments of the geological structure to perturbations related to the reservoir response to depletion poroelastic mechanisms transfer this stress change from the reservoir to the surrounding levels whereml 5 seismic instabilities occur either above or below the reservoir 3 massive hydrocarbon recovery induces crustal readjustments due to the removal of load from the upper crust it can induce larger earthquakes ml 6 at greater distance from the hydrocarbon fields than the two other mechanisms

holocene environmental change in southwest turkey a palaeoecological record of lake and catchment related changes percentage concentration and accumulation pollen data together with diatom and non siliceous microfossil data are presented for the site of go lhisar go l u 37i8 n 29i36 e elevation 930 m a small intramontane lake in burdur province southwest turkey microfossil assemblages from the longest sediment core gha 813 cm record changes in local and regional vegetation and lake productivity over the last 9500 years pollen spectra indicate that vegetation progressed from an open landscape with an increase in arboreal pollen occurring 8500 bp to mixed forest comprising oak pine and juniper until around 3000 bp cal 1240 bc when a human occupation phase becomes discernible from the pollen spectra this occurs shortly after the deposition of a volcanic tephra layer which originated from the minoan eruption of santorini thera and radiocarbon dated to 3330 70 yr bp cal 1600 bc this human occupation phase is comparable to the beys ehir occupation phase recorded at other sites in southwest turkey and involved forest clearance and the cultivation of fruit trees such as olea juglans castanea and itis together with arable cereal growing and pastoralism the presence of pollen types associated with the beys ehir occupation phase in deposits above the santorini tephra layer confirms a late bronze age early anatolian dark age date for its commencement since 3000 bp notable changes in aquatic ecology associated with tephra deposition and subsequent nutrient and sediment flux from the lake catchment are recorded the beys ehir occupation phase at go lhisar go l u came to an end around 1300 bp cla ad 700 when pine appears to have become the dominant forest tree 1999 elsevier science ltd all rights reserved

chronology and stratigraphy of late quaternary sediments in the konya basin turkey results from the kopal project abstract the late quaternary environmental history of the konya plain in south central turkey is used to examine sediment facies changes in a shallow non outlet basin which has experienced major climatically driven changes in lake extent two principal types of sedimentary archive are used to reconstruct a palaeoenvironmental record namely alluvial sequences on the carsamba alluvial fan and sediments from residual lakes the latter have been used to investigate broader climatic and vegetational histories via palaeolimnological techniques including pollen diatom and stable isotope analysis these changes are dated here by radiometric techniques including radiocarbon ams and conventional osl and u th chronological agreement is generally good between the different dating techniques although typically there is greatly reduced precision beyond ca 25 ka lake sediment cores investigated have basal ages beyond the range of 14c dating but contain hiatuses as a result of subsequent alternation between phases of lacustrine sedimentation and aeolian deflation in contrast to most deepwater non outlet lake systems the konya basin may have been occupied by a single extensive lake for as little as 10 of late quaternary time mainly around the time of the lgm this lake highstand was followed by an important arid interval in the absence of unbroken chronostratigraphic sequences palaeohydrological investigation of shallow non outlet lakes may require analysis of basin wide changes in sedimentation rather than reliance on single core records stratigraphic continuity in such sedimentary environments cannot be assumed and requires independent chronological control through radiometric dating

identification and dating of tephra layers from quaternary sedimentary sequences of inner anatolia turkey abstract results presented here are part of a research programme to investigate the environmental evolution in central anatolia during the pleistocene in this study tephra are used as chronostratigraphical markers between lacustrine sequences studied in cores or in sections surrounding eruptive centres of the central anatolian province at different locations in the konya plain and cappadocia tephra have been identified characterized and linked to eruptions of the nearby volcanoes seven different tephra have been clearly identified in lacustrine sequences of the konya plain 14 c dates on shells or organic matter as well as 230 th 234 u ages on gypsum give a chronological framework to the tephra layers in addition the study of the sediment fill of the eski acigol maar near nevsehir has allowed the recognition of several eruptions during late glacial and holocene in the vicinity of acigol the results show the first tephra to be identified in lacustrine sequences of anatolia they also show the cappadocian volcanism to be very young 35 ka this young volcanism is often of a basaltic type and does not include thick differenciated pyroclastic deposits

natural and human induced environmental changes preserved in a holocene sediment sequence from the etoliko lagoon greece new evidence from geochemical proxies abstract a key feature of greece is the large amount of historical and archaeological records the sedimentary record of the etoliko lagoon aetolia western greece offers an ideal opportunity to study human environment interaction and to disentangle natural and anthropogenic imprints in the sedimentary record by applying an interdisciplinary approach of combining geoscientific methods xrf loi grain size analysis with archaeological and historical records the 8 8 m long sedimentary sequence eto1c reveals the palaeoenvironmental history of the lagoon and its catchment since 11 670 cal bp with a thorough chronology based on 14 c age depth modelling including varve counting different evolutionary stages were put in a chronological context these stages include a lake period 11 670 8310 cal bp followed by a period of sporadic saltwater intrusion 8310 1350 cal bp as a result of continuing transgression phases of limnic predominance associated with freshwater inflow of episodically activated distributaries around 5230 cal bp still occurred by 1350 cal bp ongoing sea level rise had connected the lagoons of etoliko and messolonghi and freshwater influence had ceased with the onset of settlement activity in the late helladic 1700 1100 cal bc humans took advantage of the prevailing environmental landscape a sudden increase in coarse sedimentation correlates with the history of human occupation with its peak of prosperity from the late helladic until the end of the hellenistic period 30 cal bc

the temperature of europe during the holocene reconstructed from pollen data we present the first area average time series reconstructions of warmest month coldest month and mean annual surface air temperatures across europe during the last 12 000 years these series are based on quantitative pollen climate reconstructions from over 500 pollen sites assimilated using an innovative four dimensional gridding procedure this approach combines three dimensional spatial gridding with a fourth dimension represented by time allowing data from irregular time series to be focussed onto a regular time step we provide six regional reconstructed temperature time series as well as summary time series for the whole of europe the results suggest major spatial and seasonal differences in holocene temperature trends within a remarkably balanced regional and annual energy budget the traditional mid holocene thermal maximum is observed only over northern europe and principally during the summer this warming was balanced by a mid holocene cooling over southern europe whilst central europe occupied an intermediary position changes in annual mean temperatures for europe as a whole suggest an almost linear increase in thermal budget up to 7800 bp followed by stable conditions for the remainder of the holocene this early holocene warming and later equilibrium has been mainly modulated by increasing winter temperatures in the west which have continued to rise at a progressively decreasing rate up to the present day

causes of early holocene desertification in arid central asia paleoclimate records of effective moisture precipitation minus evaporation or p e show a dry low effective moisture period in mid latitude arid semi arid central asia during the early holocene 11 000 8 000 years ago relative to the middle and late holocene in contrast to evidence for greater than present precipitation at the same time in the south and east asian monsoonal areas to investigate the spatial differences in climate response over mid latitude central asia and monsoonal asia we conducted a series of simulations with the community climate system model version 3 coupled climate model for the early middle and late holocene the simulations test the climatic impact of all important forcings for the early holocene including changes in orbital parameters the presence of the remnant laurentide ice sheet and deglacial freshening of the north atlantic model results clearly show the early holocene patterns indicated by proxy records including both the decreased effective moisture in arid central asia which occurs in the model primarily during the winter months and the increase in summer monsoon precipitation in south and east asia the model results suggest that dry conditions in the early holocene in central asia are closely related to decreased water vapor advection due to reduced westerly wind speed and less evaporation upstream from the mediterranean black and caspian seas in boreal winter as an extra forcing to the early holocene climate system the laurentide ice sheet and meltwater fluxes have a substantial cooling effect over high latitudes especially just over and downstream of the ice sheets but contribute only to a small degree to the early holocene aridity in central asia instead most of the effective moisture signal can be explained by orbital forcing decreasing the early holocene latitudinal temperature gradient and wintertime surface temperature we find little evidence for regional subsidence related to a stronger summer asian monsoon in forcing early holocene aridity in central asia as has been previously hypothesized

reconstruction of holocene precipitation patterns in europe using pollen and lake level data abstract lake level data can be used to refine palaeoclimate reconstructions based on pollen data this approach is illustrated for the european holocene estimates of p pet precipitation minus potential evapotranspiration were first inferred from modern pollen analogues the pollen based estimates were then compared with the status of lakes within a 5 radius analogues with p pet anomalies inconsistent with the lake level changes were rejected the constrained sets of analogues were used to estimate continental scale patterns of annual mean temperature and annual precipitation at 3000 yr intervals estimated temperature anomalies differed only slightly from the unconstrained reconstructions estimated precipitation anomalies however showed improved spatial coherence and increased regional contrast and were occasionally reversed in sign the effect of the constraint was to impose a rational selection among almost equally similar modern pollen analogues with similar temperatures but widely varying moisture regimes the resulting maps showed clear spatially coherent patterns of change in precipitation as well as temperature suitable for comparison with climate model results further improvement of these maps will become possible as a more extensive coverage of lake level data is obtained

assessing whether the 2017 mw 5 4 pohang earthquake in south korea was an induced event the moment magnitude m w 5 4 pohang earthquake the most damaging event in south korea since instrumental seismic observation began in 1905 occurred beneath the pohang geothermal power plant in 2017 geological and geophysical data suggest that the pohang earthquake was induced by fluid from an enhanced geothermal system egs site which was injected directly into a near critically stressed subsurface fault zone the magnitude of the mainshock makes it the largest known induced earthquake at an egs site

palaeoclimate and the formation of sapropel s1 inferences from late quaternary lacustrine and marine sequences in the central mediterranean region abstract synchronous responses to climatic changes during the late pleistocene holocene transition are inferred from marine and lacustrine stratigraphic records in the central mediterranean region new stratigraphic data are presented from well dated sequences in the meso adriatic depression mad two crater lakes in the lazio region and in the tyrrhenian sea the sequences all span the last termination and the holocene but we focus here on the evidence in each record for the time period during which sapropel s1 formed in the mediterranean ca 9 0 to 6 8 cal kyr b p the new records provide evidence of palaeoenvironmental changes on land and sea that can be reconstructed at a high temporal resolution and which throw some light on the processes which led to the formation of s1 the collective evidence indicates that i organic rich sediments occurred in both the marine and the crater lake sites during the time of formation of the s1 sapropel ii there is evidence of increased stratification and anoxia in the sea water column during the period of s1 formation iii the s1 period in the study area is divisible into two sub phases s1a and s1b which reflect short term variations in oceanographic conditions stratification and anoxia iv changes in stratification in the marine column were contemporaneous with regional climate variations that are inferred from the terrestrial records we conclude that the key factor that initiated the formation of s1 was increased discharge of freshwater into the mediterranean following a change post 9 0 cal kyr b p to a warmer and wetter climate furthermore the period of s1 formation was interrupted by a short lived episode ca 500 years of comparatively cooler and drier conditions during the early middle holocene transition emht

european lakes as palaeohydrological and palaeoclimatic indicators abstract lakes in temperate regions have fluctuated in size on annual to millenial time scales changes in water level or depth can be reconstructed by applying geomorphic sedimentological and biostratigraphic methods to transects of sediment cores this systematic field based approach has been used at a number of sites in europe it is illustrated by reconstructions of water level changes in lakes from southern sweden these lakes have shown broadly synchronous changes during the holocene such synchronous changes in water levels at several sites in a region reflect climatic changes inferences about the mechanism of the climatic change depend on identifying both synchronous changes within a region and differences in the direction magnitude and timing of lake level changes between regions continental compilations of lake level data are therefore necessary detailed studies are not available from enough sites but the interpretation of already existing stratigraphic and biostratigraphic data in terms of lake level changes has greatly increased the number of sites available for a continental scale synthesis in europe this eclectic literature based approach is illustrated with examples from southern europe lakes in the mediterranean region were high around the glacial maximum and again somtime during the first half of the holocene in the western mediterranean the peak of late glacial aridity occurred at 15 000 16 000 bp and the lakes were already high again by 12 000 bp in the east maximum late glacial aridity occurred between 13 000 and 11 000 bp and there was a gradual return to wetter climates during the early holocene such that 9000 bp was more arid than 6000 bp most lakes in the mediterranean region were high at 6000 bp the transition to arid conditions after 5000 bp occurred abruptly in the west and more gradually in the east the lakes of southern sweden indicate drier climates in the early holocene ca 9000 bp more effective moisture between 8000 and 6000 bp increased aridity between 5500 and 3500 bp and increased effective moisture again during the last 3000 years the history of lake level changes in southern sweden and the mediterranean region can be partially explained in terms of changes in the direct effects of insolation and in the strength and position of the westerlies and of the subtropical high pressure cell during the late quaternary

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