stable oxygen isotope and pollen records from eastern scotland and a consideration of late glacial and early holocene climate change for europe the presence of marl deposits belonging to the lateglacial period in a former lake basin at lundin tower in fife scotland has allowed palaeoenvironmental investigations by means of carbonate 13c and 18o and organic matter 13c in addition to palynology the variations that emerge reveal strong similarities between the pollen and isotope records and these are interpreted as reflecting climatic shifts the classic late glacial pattern of oldest dryas bolling older dryas allerod younger dryas may be evident and other climatic oscillations are shown to have occurred not only during the allerod but also in the preboreal the problem of the time discordance between isotopic change and pollen representation is addressed through explanations involving lags in plant colonization a comparison of the 18o records from 43 sites across europe reveals two different regional patterns which raises fundamental questions over the nature of late glacial palaeoclimates

reply to comments on trace element and isotopic evidence for archean basement in the lonar crater impact breccia deccan volcanic province by ramananda chakrabarti and asish r basu

a 14 000 year sediment yield record from western germany based on annually laminated lake sediments the reconstruction of sediment yield data for the catchment of lake holzmaar 205 8 ha in the eifel mountains western germany is based on high resolution geochemical and physical analyses of an absolutely dated sediment record this technique provides flux rates of allochthonous minerogenic deposition for the last 13 840 years the pleistocene holocene transition is characterized by instable soils and vegetation caused by adjustment of the catchment to interglacial climatic conditions these instabilities are the reason for elevated mean sediment yields in the catchment of 16 t km 2 yr 1 until 9800 cal bp during most of the holocene erosive processes are insignificant and sediment yields are very low 1 5 t km 2 yr 1 since humans cleared the forests for agriculture and early industrial purposes the natural environment has been disturbed and sediment yields increased to mean values of 14 t km 2 yr 1 during the last 2750 years comparisons of reconstructions from the eifel area with similar data from southern sweden and with measured data from lakes reservoirs and monitoring sites suggest that quantitative reconstructions based on lake holzmaar sediments may be regarded as reliable despite uncertainties related to the methods of reconstruction applied

holocene vegetation and land use changes in response to climatic changes in the forelands of the southwestern alps italy the holocene sediment of lago piccolo di avigliana piedmont italy 356 m a s l was dated by 14 c and analysed for pollen to reconstruct the vegetation history of the area the early and mid holocene pollen record shows environmental responses to centennial scale climatic changes as evidenced by independent palaeoclimatic proxies when human impact was low or negligible con tinental mixed oak forests decreased at ca 9300 bc in response to the early holocene preboreal cli matic oscillation abies alba expanded in two phases probably in response to higher moisture availability at ca 6000 and ca 4000 bc while fagus expanded later possibly in response to a cli matic change at 3300 bc during and after the bronze age five distinct phases of intensified land use were detected the near synchroneity with the land use phases detected in wetter regions in northern and southern switzerland points to a common forcing factor in spite of cultural differences increasing minerogenic input to the lake since 1000 bc coincided with late bronze iron age technical innovations and probably indicate soil erosion as a consequence of deforestation in the lake catchment the highest values for cultural indicators occurred at 700 450 and at 300 50 bc coinciding with periods of high solar activity inferred from 14 c this suggests that iron age land use was enhanced by high solar activity while re occupation of partly abandoned areas after crises in earlier periods match better with the grip stable isotope record on the basis of our data and comparison with independent palaeoclimatic proxies we suggest that precipitation variation was much more important than tem perature oscillations in driving vegetation and societal changes throughout the holocene copyright 2006 john wiley sons ltd

a major widespread climatic change around 5300 cal yr bp at the time of the alpine iceman palaeoenvironmental and archaeological data from arbon bleiche lake constance switzerland give evidence of a rapid rise in lake level dated by tree ring and radiocarbon to 5320 cal yr bp this rise event was the latest in a series of three successive episodes of higher lake level between 5550 and 5300 cal yr bp coinciding with glacier advance and tree limit decline in the alps this west central european climate change may have favoured the quick burial and the preservation of the alpine iceman recently found in the tyrolean alps it has possible equivalents in many records from various regions in both hemispheres dating to 5600 5000 cal yr bp and corresponds to global cooling and contrasting patterns of hydrological changes this major mid holocene climate event marks the hypsithermal neoglaciation transition possibly resulting from a combination of different factors including orbital forcing changes in ocean circulation and variations in solar activity copyright 2004 john wiley sons ltd

lateglacial and early holocene palaeoclimatic reconstruction based on glacier fluctuations and equilibrium line altitudes at northern folgefonna hardanger western norway northern folgefonna c 23 km 2 is a nearly circular maritime ice cap located on the folgefonna peninsula in hardanger western norway by combining the position of marginal mor aines with ams radiocarbon dated glacier meltwater induced sediments in proglacial lakes draining northern folgefonna a continuous high resolution record of variations in glacier size and equili brium line altitudes elas during the lateglacial and early holocene has been obtained after the termination of the younger dryas c 11 500 cal yr bp a short lived 100 150 years climatically induced glacier readvance termed the jondal event 1 occurred within the preboreal oscillation pbo c 11 100 cal yr bp bracketed to 10 550 10 450 cal yr bp a second glacier readvance is named the jondal event 2 a third readvance occurred about 10 000 cal yr bp and corresponds with the erdalen event 1 recorded at jostedalsbreen an exponential relationship between mean solid winter precipitation and ablation season temperature at the ela of norwegian glaciers is used to reconstruct former variations in winter precipitation based on the corresponding ela and an indepen dent proxy for summer temperature compared to the present the younger dryas was much colder and drier the jondal event 1 pbo was colder and somewhat drier and the jondal event 2 was much wetter the erdalen event 1 started as rather dry and terminated as somewhat wetter varia tions in glacier magnitude elas and corresponding palaeoclimatic reconstructions at northern folge fonna suggest that low altitude cirque glaciers lowest altitude of marginal moraines 290 m in the area existed for the last time during the younger dryas these low altitude cirque glaciers of sug gested younger dryas age do not fit into the previous reconstructions of the younger dryas ice sheet in hardanger copyright 2005 john wiley sons ltd

reconstruction of late glacial summer temperatures from chironomid assemblages in lac lautrey jura france a chironomid july air temperature inference model based on chironomid assemblages in the surface sediments of 81 swiss lakes was used to reconstruct late glacial july air temperatures at lac lautrey jura eastern france the transfer function was based on weighted averaging partial least squares wa pls regression and featured a leave one out cross validated coefficient of determination r2 of 0 80 a root mean square error of prediction rmsep of 1 53 c and was applied to a chironomid record consisting of 154 samples covering the late glacial period back to the oldest dryas the model reconstructed july air temperatures of 11 12 c during the oldest dryas increasing temperatures between 14 and 16 5 c during the bolling temperatures around 16 5 17 0 c for most of the allerod temperatures of 14 15 c during the younger dryas and temperatures of ca 16 5 c during the preboreal the lac lautrey record features a two step july air temperature increase after the oldest dryas with an abrupt temperature increase of ca 3 3 5 c at the oldest dryas bolling transition followed by a more gradual warming between ca 14 200 and 13 700 bp the transfer function reconstructs a less rapid cooling at the allerod younger dryas transition than other published records possibly an artefact caused by the poor analogue situation during the earliest younger dryas and an abrupt warming at the younger dryas holocene transition during the allerod two centennial scale 1 5 2 0 c coolings are apparent in the record although chronologically not well constrained the first of these cold events may be synchronous with the beginning of the gerzensee oscillation the second is inferred just before deposition of the laachersee tephra at lac lautrey and is therefore coeval with the end of the gerzensee oscillation in contrast to the greenland oxygen isotope records the lac lautrey palaeotemperature reconstruction lacks a clearly defined greenland interstadial gi event 1d and the decreasing temperature trend during the bolling allerod interstadial copyright 2005 john wiley sons ltd

early preboreal cooling in the nordic seas region triggered by meltwater at the younger dryas preboreal transition a high resolution core from the northeastern norwegian sea reveals a two step warming of sea surface temperatures dated at respectively 10 200 10 000 and 9700 9500 14 c yr b p 11 450 11 350 and 11 150 11 000 cal yr b p warming was interrupted by a period having stable temperatures and a reduction in sea surface salinity and we suggest that this pause in warming was triggered by an increase in freshwater supply that may have hampered the north atlantic heat conveyor the freshwater influx correlates to an atmospheric cooling over both the greenland ice sheet and northwest europe and to cooling of surface temperatures in the nordic seas freshwater may have been supplied from the waning fennoscandian ice sheet

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

younger dryas and allerod summer temperatures at gerzensee switzerland inferred from fossil pollen and cladoceran assemblages linear and unimodal based inference models for mean summer temperatures partial least squares weighted averaging and weighted averaging partial least squares models were applied to a high resolution pollen and cladoceran stratigraphy from gerzensee switzerland the time window of investigation included the allerod the younger dryas and the preboreal characteristic major and minor oscillations in the oxygen isotope stratigraphy such as the gerzensee oscillation the onset and end of the younger dryas stadial and the preboreal oscillation were identified by isotope analysis of bulk sediment carbonates of the same core and were used as independent indicators for hemispheric or global scale climatic change in general the pollen inferred mean summer temperature reconstruction using all three inference models follows the oxygen isotope curve more closely than the cladoceran curve the cladoceran inferred reconstruction suggests generally warmer summers than the pollen based reconstructions which may be an effect of terrestrial vegetation not being in equilibrium with climate due to migrational lags during the late glacial and early holocene allerod summer temperatures range between 11 and 12 c based on pollen whereas the cladoceran inferred temperatures lie between 11 and 13 c pollen and cladocera inferred reconstructions both suggest a drop to 9 10 c at the beginning of the younger dryas although the allerod younger dryas transition lasted 150 160 years in the oxygen isotope stratigraphy the pollen inferred cooling took 180 190 years and the cladoceran inferred cooling lasted 250 260 years the pollen inferred summer temperature rise to 11 5 12 c at the transition from the younger dryas to the preboreal preceded the oxygen isotope signal by several decades whereas the cladoceran inferred warming lagged major discrepancies between the pollen and cladoceran inference models are observed for the preboreal where the cladoceran inference model suggests mean summer temperatures of up to 14 15 c both pollen and cladoceran inferred reconstructions suggest a cooling that may be related to the gerzensee oscillation but there is no evidence for a cooling synchronous with the preboreal oscillation as recorded in the oxygen isotope record for the gerzensee oscillation the inferred cooling was ca 1 and 0 5 c based on pollen and cladocera respectively which lies well within the inherent prediction errors of the inference models

evidence for late glacial and holocene environmental changes from subfossil assemblages in sediments of lake neuchâtel switzerland abstract ostracod and diatom assemblages mollusc remains plus pollen and sediment stratigraphy from three cores taken at sites 40 80 and 135 m deep in lake neuch tel switzerland show distinct changes since deglaciation shifts are interpreted in terms both of climatic change and major changes in the catchment input caused by the aar river entering or bypassing lake neuch tel three palaeoenvironmental phases are recognized 1 the late glacial with the inflow of the river before 10 000 yr b p 2 the early to mid holocene with temporary bypassing of the river between 10 000 and 4850 yr b p and 3 the mid to late holocene without river input after approx 4850 yr b p during periods with river input rhythmites were deposited ostracods indicate a well oxygenated hypolimnion suggesting deep ventilation enhanced by the river inflow the diatom assemblage indicates eutrophic to mesotrophic conditions and is dominated by generally well preserved periphytic species the high number of unidentifiable pollen suggests oxidation during transport in the river during periods without river input a massive calcareous silt with abundant authigenic calcite was deposited diatoms indicate a change to mesotrophic and oligotrophic conditions and decreased sedimentation rates and higher alkalinity enhanced the dissolution of diatoms terrestrial and littoral molluscs as well as periphytic diatoms indicate erosion of the shore when the lake level rose or fell with onset or offset of the river inflow before 12 600 yr b p the patchy vegetation cover led to intensive soil erosion and high sedimentation rates the lake was still frozen during the winter months after approx 12 600 yr b p the sediment changed from clastic rhythmites to thinly bedded non glacial rhythmites the vegetation cover became denser the abundance of ostracods increased and molluscs started to colonize the profundal zone of the lake the younger dryas approx 10 700 10 000 yr b p displays maximum abundance of ostracods indicating deep ventilation the transition to the holocene is characterized by a change in the ostracod assemblage and the river bypassed the lake between approximately 10 000 and 8900 yr b p when the river reentered the lake after approximately 8900 yr b p a new ostracod species appeared after two short periods of river bypassing between approximately 7200 and 6950 yr b p diatoms indicate a higher trophic level about 6000 5000 yr b p associated with higher erosion rates and increased nutrient input due to neolithic agricultural activities after approximately 4850 yr b p the river bypassed the lake again and the trophic level decreased in contrast to the early to mid holocene periods of decreased oxygen supply the mid to late holocene is characterized by deep ventilation this is attributed to the northward retreat of the polarfront and enhanced westerlies consequent to decreased insolation after 6000 yr b p the change of the river flow pattern correlates with glacier oscillations and may suggest a climatic control the final cessation of the inflow is attributed to diversion of the river consequent to isostatic uplift and late neolithic clearance activity

the preboreal climate reversal and a subsequent solar forced climate shift accurate chronologies are essential for linking palaeoclimate archives carbon 14 wiggle match dating was used to produce an accurate chronology for part of an early holocene peat sequence from the borchert the netherlands following the younger dryas preboreal transition two climatic shifts could be inferred around 11 400 cal yr bp the expansion of birch betula forest was interrupted by a dry continental phase with dominantly open grassland vegetation coeval with the pbo preboreal oscillation as observed in the grip ice core at 11 250 cal yr bp a sudden shift to a humid climate occurred this second change appears to be contemporaneous with i a sharp increase of atmospheric c 14 ii a temporary decline of atmospheric co2 and iii an increase in the grip be 10 flux the close correspondence with excursions of cosmogenic nuclides points to a decline in solar activity which may have forced the changes in climate and vegetation at around 11 250 cal yr bp copyright c 2004 john wiley sons ltd

tephrostratigraphy of paleoclimatic archives in central mediterranean during the bronze age abstract re examination of central mediterranean paleoclimate archives on tephra layers indicates that three widely dispersed tephra layers occurred during the bronze age namely agnano mt spina from campi flegrei ca 4 4 cal ka bp avellino from somma vesuvius ca 3 9 cal ka bp and fl from etna ca 3 3 cal ka bp stratigraphical correlations of selected archives using these tephra layers indicate that some records have severe chronological biases posing important limitations to the use of these archives for defining the paleoclimate conditions during the bronze age regardless of the temporal mismatches the agnano mt spina tephra layer seems to have occurred at the beginning of a centennial scale period of climatic deterioration while the avellino tephra layer taking place during a wetter period seems to mark the end of this event the dry event bounded by the two tephra layers seems to be correlated with the so called 4 2 event instead the fl tephra from etna seems to herald a new climatic deterioration at ca 3 3 3 2 cal ka bp although the general frame is still incomplete these three tephra layers appear to play a fundamental role in synchronizing archives and can lead to the definition of a detailed paleoclimatic framework of the bronze age in the central mediterranean area

a mid european decadal isotope climate record from 15 500 to 5000 years b p oxygen isotope ratios of precipitation delta18op inferred from deep lake ostracods from the ammersee southern germany provide a climate record with decadal resolution the record in detail shows many of the rapid climate shifts seen in central greenland ice cores between 15 000 and 5000 years before the present b p negative excursions in the estimated delta18op from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the north atlantic deviating millennial scale trends however indicate that climate gradients between europe and greenland changed systematically reflecting a gradual rearrangement of north atlantic circulation during deglaciation

contrasting patterns of hydrological changes in europe in response to holocene climate cooling phases the quantitative reconstruction of climatic parameters from pollen and lake level data obtained at saint jorioz lake annecy eastern france gives evidence for cooler and wetter conditions during the 8 2 ka cold event a comparison of these regional data with other hydrological records reconstructed in europe for the same period suggests as a working hypothesis that mid latitudes between ca 50 and 43 underwent wetter conditions in response to the cooling whereas northern and southern europe were marked by drier climate in the latter case leading to an interruption of the sapropel 1 formation in the mediterranean a similar hydrological tri partition of europe can be observed during other holocene cooling phases associated with north atlantic ird events data indicate that the middle zone characterised by wetter climate conditions could have had a more extended latitudinal amplitude during phases of climate cooling weaker than the 8 2 ka event the differences in expansion of the wet mid european zone depending on holocene climate cooling phases could reflect variations in the strength of the atlantic westerly jet in relation with the thermal gradient between high and low latitudes

holocene climate variability as reflected by mid european lake level fluctuations and its probable impact on prehistoric human settlements abstract a data set of 180 radiocarbon tree ring and archaeological dates obtained from sediment sequences of 26 lakes in the jura mountains the northern french pre alps and the swiss plateau was used to construct a holocene mid european lake level record the dates do not indicate a random distribution over the holocene but form clusters suggesting an alternation of lower and higher climatically driven lake level phases they provide evidence of a rather unstable holocene climate punctuated by 15 phases of higher lake level 11 250 11 050 10 300 10 000 9550 9150 8300 8050 7550 7250 6350 5900 5650 5200 4850 4800 4150 3950 3500 3100 2750 2350 1800 1700 1300 1100 750 650 cal bp and after 1394 ad a comparison of this mid european lake level record with the gisp2 polar circulation index pci record the north atlantic ice rafting debris ird events and the 14 c record suggests teleconnections in a complex cryosphere ocean atmosphere system correlations between the gisp2 pci the mid european lake level the north atlantic ird and the residual 14 c records suggest that changes in the solar activity played a major role in holocene climate oscillations over the north atlantic area

holocene environmental variability the record from lago grande di monticchio italy abstract the holocene pollen record from lago grande di monticchio reveals environmental changes throughout the holocene comparison of this record with other records of holocene environmental variability indicates that there is a temporal correlation between these changes and north atlantic events however the nature of this relationship and the underlying mechanism s is yet to be determined it is evidently complex with the apparent coincidence of sea surface temperature cooling events with both species expansions and disappearances the picture is further complicated by the interaction between human activity and natural environmental changes

rare earth and alkali elements in stalagmites as markers of mediterranean environmental changes during termination i abstract speleothems represent a key source of information on climate variations in continental environments as they enable high temporal resolution reconstructions the stalagmite salam3 presented in this study comes from the salamandre cave se france gard region its growth period determined by 230th 234u chronology and mod age extrapolation falls between 10 91 1 00 kyr bp and 13 43 0 25 kyr bp which corresponds to the transition between the last glacial period and the holocene this period is essential for the understanding of past and future climate variations in this study trace elements were measured along the growth axis of this stalagmite and results were compared with the elementary composition of bedrock and soil above the cave three periods were identified with high li rb cs th and rare earth element ree concentrations between 13 43 0 25 and 13 11 0 27 between 12 70 0 34 and 12 30 0 15 kyr and between 11 31 0 86 and 11 15 0 87 kyr our results suggest that the alkali metals alkalis studied are either associated in the detrital phase with the clay and particle fraction correlation with th or with the organic matter and colloids as complexed ligands correlation with mn to attribute the origin of ree measured within the stalagmite we compared their pattern with those of soil and bedrock and two sources were deduced i periods with an enrichment in light ree and no cerium anomaly corresponding to mobilization from soil during weathering episodes such as the bolling allerod period ii from bedrock during a longer residence time of water in the epikarst such as during the younger dryas and the holocene thus as illustrated in this study combined analysis of ree and alkalis can provide key information on soil weathering linked to climate environmental change

early holocene humidity patterns in the iberian peninsula reconstructed from lake pollen and speleothem records abstract comparison of selected well dated lacustrine speleothem and terrestrial pollen records spanning the holocene onset and the early holocene ca 11 7 8 cal kyrs bp in the iberian peninsula shows large hydrological fluctuations and landscape changes with a complex regional pattern in timing and intensity marine pollen records from alboran the mediterranean and off shore atlantic sites show a step wise increase in moisture and forest during this transition however available continental records point to two main patterns of spatial and temporal hydrological variability i atlantic influenced sites located at the northwestern areas enol sanabria lucenza prd 4 characterized by a gradual increase in humidity from the end of the younger dryas to the mid holocene similarly to most north atlantic records and ii continental and mediterranean influenced sites laguna grande villarquemado fuentillejo padul estanya banyoles salines with prolonged arid conditions of variable temporal extension after the younger dryas followed by an abrupt increase in moisture at 10 9 cal kyrs bp different local climate conditions influenced by topography or the variable sensitivity gradual versus threshold values of the proxies analyzed in each case are evaluated vegetation composition conifers versus mesothermophilous taxa and resilience would explain a subdued response of vegetation in central continental areas while in mediterranean sites insufficient summer moisture availability could not maintain high lake levels and promote mesophyte forest in contrast to atlantic influenced areas comparison with available climate models greenland ice cores north atlantic marine sequences and continental records from central and northern europe and the whole mediterranean region underlines the distinctive character of the hydrological changes occurred in inner iberia throughout the early holocene the persistent arid conditions might be explained by the intensification of the summer drought due to the high seasonality contrast at these latitudes caused by the orbital induced summer insolation maximum new records particularly from western and southernmost iberia and palaeoclimate models with higher spatial resolution would help to constrain these hypotheses

were abrupt lateglacial and early holocene climatic changes in northwest europe linked to freshwater outbursts to the north atlantic and arctic oceans during the lateglacial and early holocene abrupt millennial scale climatic variations are recorded in a wide range of high resolution proxy records from marine and terrestrial archives in nw europe our review of the evidence for these rapid climate events do not show an apparent link to possible forcing factors such as long term orbitally induced variations in solar radiation short term variations in solar activity as inferred from 14 c atmospheric carbon dioxide concentration or volcanic sulphate as recorded in the gisp2 ice core record there is however a remarkable degree of similarity with the number duration and timing of episodes of increased e ux of fresh water to the north atlantic and arctic oceans from the laurentide ice sheet and from the baltic ice lake in sw sweden these freshwater outburst events occurred when continental runoff from the laurentide ice sheet was rerouted from the mississippi river to the hudson river st lawrence river hudson strait and along the mackenzie river to the atlantic and arctic oceans and when the baltic ice lake in sw sweden drained to skagerrak periods of increased freshwater e ow to the north atlantic and arctic oceans may thus provide a mechanism to explain the abrupt and signie cant lateglacial and early holocene climate events in nw europe the idea that freshwater outbursts might drive abrupt climate events is not new but previous work may have underestimated the extent of support from proxy data and overestimated the ine uence of the laurentide ice sheet

environmental and climatic changes in the jura mountains eastern france during the lateglacial holocene transition a multi proxy record from lake lautrey this paper presents a multi proxy reconstruction of the climatic and environmental changes during the last glacial interglacial transition as recorded by a sediment sequence from lake lautrey jura eastern france this reconstruction is based on analysis of pollen chironomid organic matter oxygen isotope mineralogical magnetic susceptibility and inferred lake level data at a high temporal resolution the chronology is derived using ams radiocarbon dates the position of the laacher see tephra lst and of correlation between the lautrey and grip oxygen isotope records this data set reveals a detailed sequence of environmental changes in the jura mountains from greenland stadial 2a to the early holocene biotic and abiotic indicators allow the recognition of major abrupt changes associated with the gs 2a gi 1e gi 1a gs 1 and gs 1 preboreal transitions and other minor fluctuations related to the cold events gi 1d gi 1b and the preboreal oscillation pbo they also suggest additional cooling spells at ca 14 550 and 14 350 cal yr bp intra bolling cold periods at ca 13 500 and ca 12 700 cal yr bp just before the gs 1 onset and at ca 11 350 cal yr bp just before the pbo as well as an intriguing brief warming episode within gs 1 at ca 12 080 cal yr bp summer temperature increased by ca 5 c at the start of gi 1e and by 1 5 3 c at the holocene onset while it decreased by ca 3 4 c at the beginning of gs 1 major changes in local hydrology and in seasonality appear to be also associated with the gs 2a gi 1e gi 1a gs 1 and gs 1 preboreal transitions pollen and abiotic indicators suggest a greater sensitivity of the vegetation cover to climatic oscillations during the first part of the lateglacial interstadial than during the second part after ca 13 700 cal yr bp when a closed forest had been restored in this area by contrast the restoration of forest cover took less than 300 yr after the end of gs 1 at the beginning of gi 1e and gs 1 no lag occurs within the sampling resolution of 20 50 yr in the responses of aquatic chironomids and terrestrial pollen ecosystems while at the onset of the holocene the response of the vegetation appears slightly delayed in comparison with that of the chironomid community finally the recognition of two successive tephra layers which were deposited just before the lst at ca 12 950 cal yr bp and which originated from le puy de la nugere massif central france provides an additional tephrochronological tool for correlation between lateglacial european sequences

hydrological changes in the european midlatitudes associated with freshwater outbursts from lake agassiz during the younger dryas event and the early holocene abstract recent studies of lake level fluctuations during the last deglaciation in eastern france jura mountains and pre alps and on the swiss plateau show distinct phases of higher water level developing at the beginning and during the latter part of greenland stade 1 i e younger dryas event and punctuating the early holocene period at 11 250 11 050 10 300 10 000 9550 9150 8300 8050 and 7550 7250 cal yr b p the phases at 11 250 11 050 and 8300 8050 cal yr b p appear to be related to the cool preboreal oscillation and the 8200 yr event assumed to be associated with deglaciation events a comparison of this mid european lake level record with the outbursts from proglacial lake agassiz in north america suggests that between 13 000 and 8000 cal yr b p phases of positive water balance were the response in west central europe to climate cooling episodes which were induced by perturbation of the thermohaline circulation due to sudden freshwater releases to oceans this probably was in response to a southward migration of the atlantic westerly jet and its associated cyclonic track moreover it is hypothesized that during the early holocene varying solar activity could have been a crucial factor by amplifying or reducing the possible effects of lake agassiz outbursts on the climate

environmental humidity changes inferred from multi indicators in the jianghan plain central china during the last 12 700 years abstract time sequence of the jz 2010 profile derived from ams 14 c dating and the content of the sediment elements ti rb and sr the rb sr values as well as the granularity and the magnetic susceptibility are utilized to reconstruct the environmental humidity changes in the jianghan plain since 12 700 cal bp the comprehensive analyses of multiple alternative indicators indicate that the regional moisture turned from relatively dry to wet after the late glacial period and reached its optimum until the mid holocene however the trend was punctuated by several decreased humidity phases beginning with the severe dry event approximately 4400 4100 cal bp the environment was dry as a whole with modest humidity from approximately 3900 cal bp humidity changes in the study area are dominated by the east asian monsoon system which is under the influence of the gradual southward migration of the itcz driven by the summer solar insolation changes in the northern hemisphere due to orbital forcing as the first attempt to apply rb sr value and ti concentration in tracing moisture evolution in a region with typical subtropical humid climate this study highlights the different effects and consequences of the proxies throughout the palaeoenvironmental change process and the impacts of regional topography that sustained tectonic subsidence since the cretaceous as well as the southeast tilt that opened the plain to the summer monsoon moreover the fluctuation of magnetic susceptibility is associated with the granularity feature the reduction oxidation conditions and the impact of human factors on the natural sedimentary environments during the historic period in the jianghan plain

lateglacial and holocene water level changes of the gościaz lake central poland derived from carbon isotope studies of laminated sediment abstract radiocarbon and stable carbon isotope ratios have been measured in organic and carbonate fractions of laminated sediment of the go ciaz lake central poland parallel varve counting in four cores taken from the deep central part of the lake have led to the development of an independent varve chronology which may be compared with results of radiocarbon dating comparison of measured 14 c activities in carbonate fractions of lake marl with varve ages allow for the accurate estimation of secular changes of the 14c dilution factor of total dissolved inorganic carbon using the geochemical model developed by broecker and walton 1959 and reconstructed changes of 14 c dilution it has been possible to reconstruct mean lake level during the lateglacial and holocene the results of model calculations are compared with an independent record of lake level changes deduced from 14 c dated lithological boundaries marking low and high lake stands in numerous cores taken along lake shores as well as with lake level data available from southern sweden and france obtained patterns of lake level fluctuations show remarkable similarities with behaviour of swedish lakes and general agreement with available records from european lakes the behaviour of go ciaz lake during the last 12 ka bp reflects global climatic changes fairly well

selective organic matter preservation in burn down turbidites on the madeira abyssal plain 1 oxidized intervals of five organic rich madeira abyssal plain map turbidites deposited during the miocene pliocene and pleistocene all displayed comparable major loss of total organic carbon toc 84 3 1 accompanied by a negative isotopic 13c shift ranging from 0 3 to 2 9 major but significantly lower loss of total nitrogen ntot 61 7 1 also occurred leading to a decrease in toc relative to ntot c ntot and a 1 3 to 2 7 ntot isotopic 15n shift compound specific isotopic measurements on plant wax n alkanes indicate the terrestrial organic component in the unoxidized deposits is 13c enriched owing to significant c4 contribution selective preservation of terrestrial relative to marine organic carbon could account for the 13c behavior of toc upon oxidation but only if a 13c depleted component of the bulk terrestrial signal is selectively preserved in the process although the c ntot decrease and positive 15n shift seems inconsistent with selective terrestrial organic preservation results from analysis of a modern eolian dust sample collected in the vicinity indicate these observations are compatible regardless of the specific explanation for these isotopic observations however our findings provide evidence that paleoreconstruction of properties such as pco2 using the 13c of toc is a goal fraught with uncertainty whether or not the marine sedimentary record considered is contaminated with significant terrestrial input nonetheless despite major and selective loss of both marine and terrestrial components as a consequence of postdepositional oxidation intensive organic geochemical proxies such as the alkenone unsaturation index u37k appear resistant to change and thereby retain their paleoceanographic promise

short term climate changes during the last glacial holocene transition comparison between mediterranean records and the grip event stratigraphy this paper presents biostratigraphical and stable isotope data obtained from core cm92 43 which was recovered from the central adriatic as part of a comprehensive investigation of the palaeoenvironmental history of the basin the data span the period of the last glacial holocene lg h transition ca 18000 to 8000 grip ice core yr bp regional biozones are defined on the basis of characteristic assemblages of planktic foraminifera and these are compared with other foraminiferal biostratigraphical schemes from the southern adriatic and the tyrrhenian sea variations in relative abundance of selected planktic foraminifera and in selected pollen types are shown alongside variations in 18o and 13c obtained from globigerina bulloides and relative abundance of globigerinoides ex gr ruber the data are compared with the grip ice core record and the event stratigraphy scheme based on this record and it is concluded that the climate forcing mechanisms that controlled climate variations in the north atlantic region during the lg h transition also extended their influence into the mediterranean region over the same period copyright 1999 john wiley sons ltd

late glacial climatic oscillations as recorded in swiss lake sediments regional pollen assemblage zones for the late glacial period of the swiss plateau are introduced and defined they include four major zones artemisia juniperus hippophae betula pinus paz with several subzones pollen and oxygen isotope analyses on lacustrine sediments from several lakes in the area reveal four distinct phases of climatic oscillation in the time period of 13 000 9500 yr bp the first oscillation termed the aegelsee fluctuation occurs shortly before 12 000 yr bp and varve counts suggest its duration was ca 100 yr it is characterised by a short decrease in the oxygen isotopes as well as a short increase in nap associated with a depression in birch pollen values the second oscillation which occurs in the 18o record shortly before the deposition of the laacher see tephra ca 11 000 yr bp is termed the gerzensee fluctuation it occurs during a pine dominated phase and its vegetational effects cannot be determined palynologically the most prominent regressive phase is the younger dryas biozone ca 10 700 10 000 yr bp characterised by an increase in heliophilous nap and low 18o values the younger dryas biozone can often be subdivided palynologically into two parts a first part rich in grasses and juniper and a second part with higher filipendula and birch values during the preboreal biozone another distinct oscillation is evidenced only in the oxygen isotope ratios comparison of the swiss oxygen isotope profiles with the greenland dye 3 record suggests that not only the three major shifts in the 18o curves but also the minor ones are closely comparable suggesting some common climatic control

land ice teleconnections of cold climatic periods during the last glacial interglacial transition independent calendar year chronologies are a basic requirement for the establishment of high resolution land ice teleconnections the annually laminated meerfelder maar record provides both an independent chronology established by varve counting and high resolution lithological proxy data for the period of the last glacial interglacial transition these data reveal a series of four periods of climatic deterioration coinciding with negative isotopic deviations in the grip record signal thus demonstrating the synchronicity of environment changes in western germany and temperature shifts in greenland the terrestrial data supports a further sub division of the event stratigraphy based on the grip core by introducing the cold event gi 1c2 between 13 500 and 13 400 calendar years bp multiproxy analyses reveal that the environmental response at meerfelder maar was not linear throughout the lateglacial but was modified by local processes a change in the response of the lake environment to climate deterioration was observed during sub stage gi 1b gerzensee oscillation the only event with gradual rather than abrupt transitions the two fold character of the younger dryas as seen in the grip record is more pronounced in the meerfelder maar record this lithological signal occurred with a delay of 60 years to the grip signal and has been linked to a shift in the catchment it is proposed that the trigger for this shift was a trend towards a more humid second half of the younger dryas

records of the 8200calbp cold event reflected in the composition of subfossil cladocera in the sediments of three lakes in poland abstract the 8200 cal bp cold event was documented by analyzing cladoceran subfossil remains in sediments of three polish lakes to date this cold event has primarily been identified in areas located at higher latitudes of the northern hemisphere it has mainly been confirmed by results of oxygen and carbon stable isotope analyses this survey represents an attempt to find traces of the 8200 cal bp cold event in lake sediments based on changes in the species composition and frequency of cladoceran individuals both archival accurately dated sediments lake ostrowite lake go ci z and recently cored samples lake charzykowskie were used the analysis of subfossil cladocerans was performed at a high resolution this allowed derivation of detailed conclusions regarding early holocene changes within lakes and therefore conclusions on short term climate changes in lakes ostrowite charzykowskie and go ci z changes in the zooplankton cladocera composition occurred at the same time as the cold event certain species disappeared completely and the percentage share of the majority of zooplankters decreased significantly certain species camptocercus lilljeborgi alonopsis elongata that are typical of lakes in northern areas appeared during the cold event although not in large numbers

major δ14c excursions during the late glacial and early holocene changes in ocean ventilation or solar forcing of climate change the atmospheric 14c record during the late glacial and the early holocene shows sharp increases simultaneous with cold climatic phases these increases in the atmospheric 14c content are usually explained as the effect of reduced oceanic co2 ventilation after episodic outbursts of large meltwater reservoirs into the north atlantic in this hypothesis the stagnation of the thermohaline circulation is the cause of both climate change as well as an increase in atmospheric 14c as an alternative hypothesis we propose that changes in 14c production give an indication for the cause of the recorded climate shifts changes in solar activity cause fluctuations in the solar wind which modulate the cosmic ray intensity and related 14c production two possible mechanisms amplifying the changes in solar activity may result in climate change in the case of a temporary decline in solar activity 1 reduced solar uv intensity may cause a decline of stratospheric ozone production and cooling as a result of less absorption of sunlight this might influence atmospheric circulation patterns extension of polar cells and equatorward relocation of mid latitude storm tracks with effects on oceanic circulation and 2 increased cosmic ray intensity may stimulate cloud formation and precipitation while 14c production increases

diatom inferred lateglacial and holocene climatic variability in the south carpathian mountains romania climatic and environmental changes were studied using siliceous algae diatoms and chrysophycean cysts analyses in a mountain lake in the south carpathian mountains for the lateglacial and holocene lake brazi 1740 a s l is a small shallow lake in the retezat mountains according to the basal radiocarbon dating of the core the lake was formed around 15 750 cal bp and sediment accumulation has been continuous ever since high resolution diatom analyses were carried out together with loss on ignition and biogenic silica measurements total epilimnetic phosphorus tp concentrations and ph were reconstructed quantitatively ten statistically significant zones were distinguished six of which appeared in the lateglacial and early holocene suggesting the instability of diatom assemblages after deglaciation the uppermost zone covered six thousand years which suggests that diatom assemblages remained quite stable during the second half of the holocene high lake level occurred between 9500 and 9000 cal bp after 6300 cal bp the lake level gradually increased again until 5800 cal bp a further increase was detected at 3000 cal bp while after 1500 cal bp water level decreased although there is limited knowledge regarding the environmental constraints of several diatom taxa present in the sequence e g aulacoseira laevissima which makes the precise environmental interpretation of the diatom record more difficult the available data provide an important new insight into the environmental history of lake brazi and the carpathian mountains the most remarkable changes in the aquatic ecosystem were observed at 6000 cal bp in the holocene and 12 800 cal bp at the onset of the younger dryas marked changes were also detected at 10 500 10 300 9800 9500 9000 8900 8800 8300 6300 5800 and 3100 3000 cal bp

comments on trace element and isotopic evidence for archean basement in the lonar crater impact breccia deccan volcanic province by ramananda chakrabarti and asish r basu in earth and planetary science letters 247 2006 197 211

freshwater outbursts to the oceans from glacial lake agassiz and their role in climate change during the last deglaciation abstract lake agassiz was the largest lake in north america during the last deglaciation as the laurentide ice sheet lis retreated large volumes of water stored in this proglacial lake were episodically released into the oceans these waters were variably routed to the gulf of mexico arctic ocean north atlantic ocean and hudson bay during this period the three largest cooling events in the northern hemisphere closely followed 4 of the 5 largest outbursts from lake agassiz 1 the younger dryas which was preceded by a release of 9500 km 3 2 the preboreal oscillation preceded by releases of 9300 km 3 and 5900 km 3 and 3 the 8 2 ka cold event preceded by a 163 000 km 3 outburst these are respectively fluxes of 0 30 sv 0 29 sv 0 19 sv and 5 2 sv if released in 1 year because the influx of freshwater reaching the north atlantic ocean can inhibit thermohaline circulation partly depending on whether the ocean was in a glacial interglacial or transitional mode of circulation we believe that at least these large outbursts from lake agassiz may have provided the triggers for changes in ocean circulation and in turn for widespread climate change

termination of the last glaciation in the iberian peninsula inferred from the pollen sequence of quintanar de la sierra abstract a 4 5 m thick late glacial pollen sequence supported by 17 ams14c dates has been investigated at the quintanar de la sierra marshland iberian cordillera north central spain pollen zones were defined that correspond to successive phases in vegetation history during the end of the late wurm late glacial interstade and younger dryas periods a transfer function approach has been adopted to derive quantitative climate estimates from the pollen assemblage data a first expansion ofjuniperusandhippophae about 13 50014c yr b p indicates the beginning of the late glacial interstade which is characterized by ajuniperus betula pinussuccession that suggests higher temperatures and moisture than during full glacial time the younger dryas interval is recorded by a 120 cm thick sediment unit that is dominated by herbaceous pollen transfer function estimates suggest that the climate during this period was cold with low precipitation during most of the year although not in summer the holocene arboreal recolonization in the area started about 10 00014c yr b p with a renewedjuniperus betula pinussuccession related to a strong increase in annual temperature and precipitation the start of this process was synchronous with mean sea surface temperature changes as recorded from the nearby su 81 18 marine core the strong affinity with other european late glacial pollen sequences demonstrates that the pattern of climatic changes during the last glacial interglacial transition was similar in both northwestern and southwestern europe

late glacial and early holocene changes in vegetation and lake level at hauterive rouges terres lake neuchâtel switzerland palynological and sedimentological analyses of a sedimentary sequence sampled at hauterive rouges terres lake neuch tel switzerland provide documentation of changes in vegetation and lake level during the bolling younger dryas and preboreal pollen zones and have allowed a comparison with sequences covering the same period from other sites located in the western part of the swiss plateau the juniperus hippophae zone regional pollen assemblage zone rpaz chb 2 first part of the bolling ca 14 650 14 450 cal yr bp was characterised by a generally low lake level a weak rise occurred during this zone the juniperus hippophae to betula zone transition coincided with a lake level lowering interrupted by a short lived but marked phase of higher lake level recorded at the neighbouring site of hauterive champreveyres but not present at hauterive rouges terres owing to an erosion surface shortly after the beginning of the betula zone rpaz chb 3 second part of the bolling ca 14 450 14 000 cal yr bp a marked rise in lake level occurred it was composed of two successive periods of higher level coinciding with high values of betula separated by a short episode of relatively lower lake level associated with raised values in artemisia and other non arboreal pollen the last part of rpaz chb 3 saw a fall in lake level the lower lake levels during rpaz chb 2 to early rpaz chb 3 can be correlated with the abrupt warming at the beginning of the greenland interstadial gi 1e thermal maximum the successive episodes of higher lake level punctuating the gi 1e might be linked to the so called intra bolling cold oscillations identified from several palaeoclimatic records in the north atlantic area and also documented in oxygen isotope data sets from swiss plateau lakes the hauterive rouges terres lake level record provides evidence for marked climatic drying through the second part of the younger dryas event gs1 during the gs1 preboreal rpaz chb 4b 4c transition except for a rise at ca 11 450 11 400 cal yr bp and at the rpaz chb 4c 5 preboreal boreal transition following the preboreal oscillation after 11 150 cal yr bp the preboreal oscillation coincided with higher lake levels its end being followed by a rapid expansion of corylus quercus ulmus and tilia the hauterive rouges terres lake level record suggests that radiocarbon plateau at 12 600 10 000 and 9500 14c yr bp corresponded to periods of generally lower lake level this suggests that an increase in solar activity may have contributed to both climatic dryness and a decrease in atmospheric radiocarbon content copyright 2002 john wiley sons ltd

early holocene climatic oscillations recorded by lake level fluctuations in west central europe and in central italy abstract on the basis of lake level data the period of the preboreal oscillation pbo at 11 300 11 150 cal yr bp as defined by the grip oxygen isotope record appears to correspond to wetter climatic conditions in west central europe and to a marked drying in north central italy additional short lived phases of higher lake level have been identified before the pbo at ca 11 450 11 400 and 11 350 cal yr bp in west central europe and at ca 11 500 cal yr bp in italy such multiple climatic oscillations around the pbo have been observed in various records in northwestern europe on the basis of various proxies a map of changes in moisture over western europe during the pbo indicates a mid latitude zone between 58 and 43 n characterised by wetter conditions while a drier climate developed in southern and northern europe this wet middle zone shows a larger extension and suggests a more meandering weaker atlantic westerly jet during the pbo than during the 8 2 kyr event a comparison of lake level records in west central europe with 1 outbursts from north american and north european proglacial lakes and 2 variations in solar activity as reflected by 14 c and the 10 be records supports the hypothesis that the pbo was a response to successive meltwater pulses at 11 300 11 250 11 200 and 11 170 cal yr bp and to a sudden decrease in solar activity at 11 250 cal yr bp this study points to the necessity of developing integrated multi proxy approaches to construct more robust regional event stratigraphies and of better documenting palaeohydrological changes in the mediterranean area

the preboreal oscillation around the nordic seas terrestrial and lacustrine responses the occurrence of an early preboreal climatic cooling oscillation pbo in lacustrine and glacial records from northwest europe iceland and greenland is reviewed and documented the often subtle response of the proxy records to this oscillation in combination with its short duration make it difficult to detect owing to its chronostratigraphic position between the 10 000 9900 and 9600 9500 14 c plateaux c 11 300 11 150 calendar yr bp it is also difficult to 14 c date with precision we find that the vegetation response to the pbo varies between sites and regions in contrast to the pioneer vegetation in iceland and southern sweden the expanding birch pine forest in germany denmark was more susceptible to deteriorating growing conditions the combined lacustrine tree ring and glacial records imply that the pbo was characterised by cool and humid conditions throughout northwestern and central europe this is documented by vegetation changes decreased aquatic production increased soil erosion increased 2 h and 13 c content in tree rings readvances or stillstands of the ice sheet in norway and finland and ingression of brackish water into the baltic icelandic proxy records from lake sediments and glacial moraines imply cooler conditions than during the previous preboreal period but not as extreme as during the younger dryas greenland records suggest that the early preboreal was characterised by ice readvances as an effect of cool climate and increased precipitation in relation to the younger dryas it was not until the end of the pbo that climate was warm enough to melt the land based ice sheet this preboreal oscillation found on both sides of the nordic seas is interpreted as an effect of increased freshwater forcing on the thermohaline circulation in the nordic seas which is implied by a simultaneous and distinct rise in the atmospheric 14 c 12 c ratio a slow down of the thermohaline circulation may tempor arily have pushed the polar front further south 1997 by john wiley sons ltd preboreal oscillation thermohaline circulation lacustrine records glacial records chronology

the cold event 8200 years ago documented in oxygen isotope records of precipitation in europe and greenland stable oxygen isotope ratios of ostracod valves in late glacial and holocene sediments of core as 92 5 from deep lake ammersee southern germany reflect variations of mean oxygen isotope ratios in past atmospheric precipitation the record reconfirms the strong similarity of climate evolution in europe and greenland during the last deglaciation for the first time in europe we find a 200 year long negative 18o excursion which is contemporaneous with the strongest negative 18o excursion in the greenland ice around 8 2 ky before present the 8 2 ky isotopic event on both sides of the north atlantic ocean is interpreted as a cold period most probably induced by a perturbation of the north atlantic thermohaline circulation we discuss two possible triggering mechanisms 1 weak forcing as proposed by alley et al and 2 forcing by a strong and sudden freshwater pulse from the collapse of the hudson ice dome

synchronized terrestrial atmospheric deglacial records around the north atlantic on the basis of synchronization of three carbon 14 c 14 dated lacustrine sequences from sweden with tree ring and ice core records the absolute age of the younger dryas preboreal climatic shift was determined to be 11 450 to 11 390 80 years before the present a 150 year long cooling in the early preboreal associated with rising delta 14 c values is evident in all records and indicates an ocean ventilation change this cooling is similar to earlier deglacial coolings and box model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the north atlantic heat conveyor although the younger dryas may have begun as an anomalous meltwater event

late glacial and early holocene lake level fluctuations in ne poland tracked by macro fossil pollen and diatom records abstract late glacial and early holocene vegetation history and lake level fluctuations in ne poland were described based on high resolution plant macrofossils analyses and records of pollen diatoms and radiocarbon dates the development of lake kojle perty began in the allerod gi 1c cooling during the younger dryas gs 1 led to the development of communities of heliophyte herbaceous plants palaeobotanical and lithostratigraphical records demonstrate that abrupt climate changes at approximately 11 600 and 9450 cal bp resulted in distinct changes in the vegetation and water level of lake kojle perty climate warming in the younger dryas holocene transition 11 600 cal bp caused the development of the terrestrial vegetation dominated by cold deciduous forest betula and appearance of thermophylious aquatic plants typha latifolia najas marina and ceratophyllum demersum a gradual decrease in the lake level since 11 200 cal bp is evident from the appearance of plants from shallow lake environments potamogeton natans and hippuris vulgaris the low water levels since 10 700 cal bp resulting from increased temperature and evaporation caused the development of peat on limnic sediments the dry and warm climatic phase with lowest lake level in the lakes of ne poland were coeval with the expansion of temperate deciduous forests corylus and ulmus that commenced at approximately 10 500 cal bp a distinctive increase in lake levels at approximately 9450 cal bp is suggested by the development of rush plants such as cladium mariscus and aquatic plants such as najas marina chara sp and nuphar lutea in the shallow parts of lake kojle perty the increased lake levels correspond with the expansion of alnus glutinosa in north east ne poland our reconstructions of the vegetation development and lake level changes align with results from other studies in the region

evidence for a chondritic impactor evaporation condensation effects and melting of the precambrian basement beneath the target deccan basalts at lonar crater india the similar to 1 88 km diameter lonar impact crater formed similar to 570 ka ago and is an almost circular depression hosted entirely in the poladpur suite of the similar to 65 ma old basalts of the deccan traps to understand the effects of impact cratering on basaltic targets commonly found on the surfaces of inner solar system planetary bodies major and trace element concentrations as well as nd and sr isotopic compositions were determined on a suite of selected samples composed of basalts a red bole sample which is a product of basalt alteration impact breccia and impact glasses either in the form of spherules 1 mm and 43 0 the group 1 spherules are further subdivided into groups 1a and 1b with group 1a spherules showing higher ni and mostly higher cr compared to the group 1b spherules iridium and cr concentrations of the spherules are consistent with the admixture of 1 8 wt of a chondritic impactor to the basaltic target rocks the impactor contribution is most prominent in the group 1a and group 2 spherules which show higher ni co ni cr and cr co ratios compared to the target basalts in contrast the group 1b spherules show major and trace element compositions that overlap with those of the impact breccia and are characterized by high efth enrichment factor for th defined as the nb normalized concentration of th relative to that of the average basalt as well as fractionated la sm n and higher large ion lithophile element lile concentrations compared to the basalts the relatively more radiogenic sr and less radiogenic nd isotopic composition of the impact breccia and non spherical impact glasses compared to the target basalts are consistent with melting and mixing of the precambrian basement beneath the deccan basalt with up to 15 wt contribution of the basement to these samples variations in the moderately siderophile element mse concentration ratios of the impact breccia as well as all the spherules are best explained by contributions from three components a chondritic impactor the basaltic target rocks at lonar and the basement underlying the deccan basalts the large variations in concentrations of volatile elements like zn and cu and correlated variations of efcu efzn efpb efzn efk efzn and efna efzn particularly in the group 1a spherules are best explained by evaporation condensation effects during impact while most spherules irrespective of their general major and trace element composition show a loss in volatile elements e g zn and cu relative to the target basalts some spherules mainly of group 1 display enrichments in these elements that are interpreted to reflect the unique preservation of volatile rich vapour condensates resulting from geochemical fractionation in a vertical direction within the vapour cloud c 2017 elsevier ltd all rights reserved

the use of foraminifera as a record of the past neodymium isotope composition of seawater 1 we present new isotopic data for sedimentary planktonic foraminifera as well as for potential water column and sedimentary sources of neodymium nd which confirm that the isotopic composition of the foraminifera is the same as surface seawater and very different from deep water and sedimentary nd the faithfulness with which sedimentary foraminifera record the isotopic signature of surface seawater nd is difficult to explain given their variable and high nd ca ratios ratios that are often sedimentary foraminifera ratios that are often much higher than is plausible for direct incorporation within the calcite structure we present further data that demonstrate a similarly large range in nd ca ratios in plankton tow foraminifera a range that may be controlled by redox conditions in the water column cleaning experiments reveal in common with earlier work that large amounts of nd are released by cleaning with both hydrazine and diethylene triamine penta acetic acid but that the nd released at each step is of surface origin while further detailed studies are required to verify the exact location of the surface isotopic signature and the key controls on foraminiferal nd isotope systematics these new data place the use of planktonic foraminifera as recorders of surface water nd isotope ratios and thus of variations in the past supply of nd to the oceans from the continents via weathering and erosion on a reasonably sure footing

climate oscillations and tephrochronology in eastern middle sweden during the last glacial interglacial transition abstract two sequences spanning the last glacial interglacial transition in southern o stergo t land eastern middle sweden have been investigated for high resolution vegetation change andtephrochronology organic carbon and pollen analysis indicates that the younger dryas pre boreal climatic transition was characterised by at least one well de ned oscillation or possiblytwo shorter climatic oscillations the vedde ash ca 12000 grip yr bp or ca 10300 14 cyrbp has been identi ed at both sites signi cantly increasing the known distribution of thismarker horizon in addition a previously unrecorded rhyolitic tephra of icelandic origin hasbeen identi ed at ca 9000 14 c yr bp the expansion of corylus into southern o stergo tland isestimated to be ca 9400 14 c yr bp copyright 1999 john wiley sons ltd keywords preboreal oscillation lacustrine records vedde ash last glacial interglacial transition expan sion of corylus introduction the last glacial interglacial transition 15 10 k cal yr bp was a period characterised by a succession of rapid extremeclimatic oscillations throughout the north atlantic the eventstratigraphy recently proposed by bjo rck

the use of microtephra horizons to correlate late glacial lake sediment successions in scotland evidence is presented to show that two measurable concentrations of microtephra particles can be detected in deposits of late devensian late glacial age in three sites in scotland one layer is attributed to the vedde ash a marker horizon within the younger dryas chronozone the second is a new tephra reported for the first time which we name the borrobol tephra this occurs consistently near the base of the late glacial interstadial organic sediments at each site and is thought to date to around 12 5 14c ka bp geochemical determinations using an electron microprobe confirm the identification of the vedde ash suggest the borrobol tephra to have an icelandic origin and demonstrate the consistency of the geochemical signals at all three sites 1997 john wiley sons ltd

high resolution analyses of an early holocene climate event may imply decreased solar forcing as an important climate trigger early holocene lacustrine tree ring ice core and marine records reveal that the northern hemisphere underwent a short cooling event at 10 300 calendar yr b p 9100 14 c yr b p the records were compared on a common high resolution time scale and show that the event lasted less than 200 yr with a cooling peak of 50 yr and the event coincides with a distinct holocene thermohaline disturbance recognized in the north atlantic ocean in spite of wellknown freshwater forcings at the time of the event the negligible difference between the modeled d 14 c record based on the gisp2 greenland ice sheet project 2 10 be data and the measured values does not allow for detectable d 14 c changes related to global ocean ventilation we can however show that the onset of the cooling coincides with the onset of one of the largest holocene 10 be flux peaks this finding may imply that the climate system is more

14c ams wiggle matching of raised bog deposits and models of peat accumulation abstract high resolution accelerator mass spectrometer ams 14 c dates of selected plant macrofossils from the raised bog engbertsdijksvenen eastern netherlands show century scale wiggles analogous to the radiocarbon calibration curve we used three relative time scales viz based on depth mass and pollen concentration respectively to match the peat ams dates to the calibration curve this procedure is repeated for one conventionally dated core for each relative time scale realistic confidence intervals are calculated depth appears to be the best time scale for certain stratigraphical units of a core this justifies using depth for wiggle matching conventionally dated mire cores published by others even when 14 c errors are larger our evidence shows four major sources of 14 c variation for mire deposits compared to treerings 1 dating error due to sample composition this includes a reservoir effect demonstrated for many bulk peat samples 2 hiatuses causing a sudden leap of peat 14 c age 3 changing accumulation rates apparent from a break in the slope of the peat 14 c ages 4 sampling error these results shed doubt on the assumed continuities in theoretical peat accumulation models both mire stratigraphy and changing accumulation rates can be explained in qualitative hydrological terms more evidence for a previously discovered reservoir effect in bog deposits is presented though the physical biological mechanisms remain uncertain

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

chironomidae insecta diptera succession in żabieniec bog and its palaeo lake central poland through the late weichselian and holocene abstract subfossil chironomidae assemblages were studied in a sediment sequence from abieniec bog in central poland the climate history and habitat changes in the palaeo lake were reconstructed from these assemblages currently no chironomid based climate calibration set is available from poland and so past mean july air temperatures were inferred from chironomid climate calibration data sets from norway russia and switzerland during the late weichselian the three calibration functions from these data sets provided similar temperature inferences but there was some divergence in the reconstructions for the younger dryas and holocene in the late pleniglacial inferred summer air temperature was relatively low 8 12 c and the lake was oligotrophic at about 16 5 ka bp temperature rapidly rose to 15 c and assemblage diversity substantially increased during the interstadial temperature stayed at this level in the younger dryas july air temperature was only 1 2 c lower than in the interstadial as inferred from the norwegian calibration data set whereas the russian and swiss calibration functions did not indicate any temperature decrease from the beginning of the holocene taxa typical of meso eutrophic conditions dominated there was an increased abundance of phytophilous species and the assemblage composition was also influenced by changes in water level palaeotemperature reconstructions differed in their values from 8 0 to 8 7 ka bp inferences based on the swiss and russian data sets indicated a cold oscillation while reconstructions based on the norwegian data set did not show any temperature decrease after 2 5 ka bp assemblage diversity and head capsule concentrations decreased in the last millennium semi terrestrial taxa dominated except from late medieval to early modern times when shallow water species reappeared

trace element and isotopic evidence for archean basement in the lonar crater impact breccia deccan volcanic province abstract the lonar impact crater in the deccan traps of the indian peninsula provides unique opportunities to study physical and chemical processes of impact cratering on basaltic targets because terrestrial impact craters on basalts are extremely rare such studies are needed for determining provenance and other parameters of the excavated rocks and the cratering phenomenon that may have implications for similar crater formations in lunar martian and other basaltic targets in the solar system considering some of these objectives we analyzed trace elements and nd sr pb isotopes of impact breccia rocks and target basalts collected from the lonar crater chondrite normalized rare earth element ree patterns in the target basalts and breccia rocks show similar light ree enriched patterns although in detail the impact breccia are more fractionated in la sm compared to the target basalts the target basalts also show much lower concentrations of rb ba th u and pb compared to the breccia and are characterized by rb ba and pb depletions with respect to the primitive mantle normalized th u nb ta and the ree contents the breccia rocks are significantly enriched in rb ba and pb and to a lesser extent in th and u compared to the target rocks the nd sr and pb isotopic compositions of the lonar target basalts can be correlated with those of the poladpur suite one of the mid section volcano stratigraphic units of the deccan traps in contrast to the host basalts the impact breccia rocks show more radiogenic sr less radiogenic nd and higher rb sr and lower sm nd ratios indicating an additional component other than the target basalt that must have been derived from beneath the basaltic target rocks at the impact site the deccan traps in western india are underlain by archean to mid proterozoic cratonic rocks the overall geochemical signatures of the impact breccia rocks specifically the trace element concentrations negative end values radiogenic sr isotopic composition as well as the high 207pb 204pb at low 206pb 204pb indicate that a major component of the lonar impact breccia was derived from melting of archean basement rocks we argue that the archean component in the breccia cannot be from the incorporation of paleosols that are weathering products of the target basalts or from the inter trappean sediments that are most commonly cherts and limestones of mesozoic age similarly the possible role of eolian sediments in causing the archean pb isotopic signature identical to those of the deccan basement in the breccia rocks can be excluded the basement beneath the lonar region is believed to be similar to the dharwar craton of peninsular india based on their similar pb isotopic compositions with the breccia rocks we suggest the archean chitradurga group of rocks of this craton to be present in the basement beneath the deccan lavas of the lonar region the thickness of the basaltic target rocks at the crater site 400 m and the inferred crater depth 350 m 610 m based on depth to diameter ratios in simple planetary craters 0 2 0 33 are consistent with our conclusion regarding melting and incorporation of these ancient basement rocks in the impact breccia of the lonar crater using pi group scaling relations the observed crater diameter and density of the basaltic target rocks we have estimated with reasonable approximation the diameter of the lonar impactor to be either 70 m 86 m or 120 m assuming the bolide to be an iron meteorite stony iron meteorite or an ordinary chondrite respectively

early holocene glacial lake meltwater injections into the labrador sea and ungava bay 1 in this paper we analyze drainage routes and estimate fluxes of meltwater released from labrador ungava glacial lakes into the labrador sea ungava bay and hudson bay between 7 5 and 6 0 kyr bp 8 4 7 0 calendar cal years ka the analysis and estimates are based on landform based reconstructions of the laurentide ice sheet lis decay pattern and the associated glacial lake evolution geomorphological data constraining the spatial extent of glacial lakes are coupled to a digital terrain model for meltwater volume calculations the lis ice recession between 7 5 and 6 0 kyr bp led to the formation of a large number of glacial lakes which drained in approximately 30 meltwater pulses with fluxes exceeding 0 015 sv 1 sv 106 m3 s 1 into labrador sea ungava bay and hudson bay the inferred rapid ice margin retreat during late stages of deglaciation indicates that these drainage events were relatively short lived the early holocene glacial lakes of labrador ungava released meltwater resulting in a total inflow of 6000 km3 freshwater to the north atlantic the pulsed nature of meltwater release from the lakes is likely to have resulted in rapid repeated cooling of the labrador sea surface water

variability of the western mediterranean sea surface temperature during the last 25 000 years and its connection with the northern hemisphere climatic changes sea surface temperature sst profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a w e latitudinal transect encompassing the gulf of cadiz atlantic ocean the alboran sea and the southern tyrrhenian sea western mediterranean the results document the sensitivity of the mediterranean region to the short climatic changes of the north atlantic ocean particularly those involving the latitudinal position of the polar front the amplitude of the sst oscillations increases toward the tyrrhenian sea indicating an amplification effect of the atlantic signal by the climatic regime of the mediterranean region all studied cores show a shorter cooling phase 700 years for the younger dryas yd than that observed in the north atlantic region 1200 years this time diachroneity is related to an intra yd climatic change documented in the european continent minor oscillations in the southward displacement of the north atlantic polar front may also have driven this early warming in the studied area during the holocene a regional diachroneity propagating west to east is observed for the sst maxima 11 5 10 2 kyr b p in the gulf of cadiz 10 9 kyr b p in the alboran sea and 8 9 8 4 kyr b p in the thyrrenian sea a general cooling trend from these sst maxima to present day is observed during this stage which is marked by short cooling oscillations with a periodicity of 730 40 years and its harmonics

preboreal climate oscillations in europe wiggle match dating and synthesis of dutch high resolution multi proxy records abstract in order to compare environmental and inferred climatic change during the preboreal in the netherlands five terrestrial records were analysed detailed multi proxy analyses including microfossils e g pollen spores algae and fungal spores macroremains e g seeds fruits wood mosses etc and loss on ignition measurements were carried out with high temporal resolution to link the five preboreal records accurate chronologies were produced by ams 14c wiggle match dating the dutch records show that following the lateglacial holocene climate warming birch woodlands expanded between 11 530 and 11 500 cal bp during the friesland phase of the preboreal after the friesland phase two distinct climatic shifts could be inferred 1 around 11 430 11 350 cal bp the expansion of birch forests was interrupted by a dry continental phase with open grassland vegetation the rammelbeek phase this phase was coeval with the coldest part of the preboreal oscillation pbo as observed in the 18o record of the greenland ice core records and has been attributed to a large meltwater flux that resulted in a temporary decrease of the thermohaline circulation in the north atlantic 2 at the start of the late preboreal between 11 270 and 11 210 cal bp a sudden shift to a more humid climate occurred and birch forests expanded again a simultaneous increase in the cosmogenic nuclides 14c and 10be suggests that these changes in climate and vegetation were forced by a sudden decline in solar activity expansion of pine occurred during the later part of the late preboreal at the onset of the boreal between 10 770 and 10 700 cal bp dense woodlands with hazel oak elm and pine started to develop in the netherlands

towards a european tephrochronological framework for termination 1 and the early holocene the record of deposition of tephras in europe and the north atlantic during the period 18 5 8 0 14 c ka bp the last termination and early holocene is reviewed altogether 34 tephras originating from four main volcanic provinces iceland the eifel district the massif central and italy have been identi ed so far in geological sequences spanning this time interval most of the records have been based until very recently on observations of visible layers of tephras here we report on the potential for extending the areas over which some of the tephras can be traced by the search for layers of micro tephra which are not visible to the naked eye and on the use of geochemical methods to correlate them with known tephra horizons this approach has greatly extended the area in northern europe over which the vedde ash can be traced the same potential exists in southern europe which is demonstrated for the rst time by the discovery of a distinct layer of micro tephra of the neapolitan yellow tu in a site in the northern apennines in italy far to the north of the occurrences of visible records of this tephra the paper closes by considering the potential for developing a robust european tephrostratigraphy to underpin the chronology of records of the last termination and early holocene thereby promoting a better understanding of the nature timing and environmental e ects of the abrupt climatic changes that characterized this period

mid holocene emergence of a low frequency millennial oscillation in western mediterranean climate implications for past dynamics of the north atlantic atmospheric westerlies the nature and tempo of holocene climate variability is examined in the record of forest vegetation from western mediterranean marine core md95 2043 episodes of forest decline occurred at 10 1 9 2 8 3 7 4 5 4 4 5 and 3 7 2 9 cal ka bp and between 1 9 cal ka bp and the top of the record 1 3 cal ka bp wavelet analysis confirms a 900 yr periodicity prior to and during the early holocene and the dominance of a 1750 yr periodicity after 6 cal ka bp the 900 yr periodicity has counterparts in numerous north atlantic and northern hemisphere palaeoclimate records and in solar irradiance proxies 14c and 10be and may relate to a sun climate connection during the early holocene comparisons between the md95 2043 forest record and strategically located records from morocco iceland norway and israel suggest that the 1750 yr mid to late holocene oscillation reflects shifts between a prevailing strong and weak state of the zonal flow with impacts similar to the positive and negative modes of th

target rocks impact glasses and melt rocks from the lonar impact crater india petrography and geochemistry the lonar crater india is the only well preserved simple crater on earth in continental flood basalts it is excavated in the deccan trap basalts of cretaceous tertiary age a representative set of target basalts including the basalt flows excavated by the crater and a variety of impact breccias and impact glasses were analyzed for their major and trace element compositions impact glasses and breccias were found inside and outside the crater rim in a variety of morphological forms and shapes comparable geochemical patterns of immobile elements e g rees for glass melt rock and basalt indicates minimal fractionation between the target rocks and the impactites we found only little indication of post impact hydrothermal alteration in terms of volatile trace element changes no clear indication of an extraterrestrial component was found in any of our breccias and impact glasses indicating either a low level of contamination or a non chondritic or otherwise iridium poor impactor

the 8 2 kyr bp event simulated by a global atmosphere sea ice ocean model seven freshwater perturbation experiments were performed with a global atmosphere sea ice ocean model to study the mechanism behind the 8 2 kyr bp holocene cooling event these experiments differed in initial state and duration of the applied freshwater pulse while the amount of freshwater was kept constant 4 67x10 14 m 3 one of the scenarios with freshwater added to the labrador sea at a rate of 0 75 sv during 20 years resulted in weakening of the north atlantic thermohaline circulation during 320 years and surface cooling varying from 1 to 5 degreesc over adjacent continents this result is consistent with proxy data suggesting that a meltwater induced weakening of the thermohaline circulation caused the event moreover our results indicate that the time scale of the meltwater release and the initial state are important as both have a strong effect on the magnitude and duration of the produced model response

diatom responses to holocene environmental changes in a karstic lake vrana in dalmatia croatia abstract the 11 m sediment core of karstic lake vrana located at the dalmatian coast of eastern adriatic croatia was investigated through the analyses of diatoms the diatoms exhibited six marked changes in diatom zones dz with included water sediment interface as the record of environmental changes detected by marine and other terrestrial palaeoclimate records the diatoms recorded at the deepest sediments were interpreted to represent pleistocene holocene transition the dated holocene history is top 810 cm core section ca 8 1 cal kyr bp to the present the first zone record 1101 1050 cm was interpreted as alkaline oligo mesotrophic oxic lentic ecosystem of the karstic flooding plain based on the dominance of epithemia adnata enhanced bioproductivity of the shallow and unstable environment was noticed in the second diatom zone 1050 815 cm which was interpreted as the beginning of the holocene and it was divided into 4 subzones because of rapid environmental fluctuations a warmer period of temperate climate with a pluvial phase initiated development of the oligo mesosaprobic shallow lake in the early holocene the expansion of the macrophytes and higher cyanobacteria production that caused acidification and oxygen depletion at the lake bottom was determined in the mid holocene 810 713 cm 8 1 7 1 cal kyr bp mid holocene 8 1 4 7 cal kyr bp is marked by oligohalobic freshwater epithemia argus characteristic for alkaline water high cyanobacteria production was determined as a consequence of algal production that induced anoxic conditions in the lake bottom sediments from the warmer period till today the initial marine influx through the permeable karst underground was observed in the sediment record from ca 5 cal kyr bp the discovered marine influence on the lake indicating brackish water conditions related to the holocene sea level high stand the sea intrusion had different intensities through time and is still observed today in the seasonal fluctuation of lake water salinity the late holocene 2 7 cal kyr bp to the present sediment record is characterized with the strongest marine influxes and highest biodiversity of the mesosaprobic lake major changes in the water sediment interface of very shallow karstic lake were caused by anthropogenic agricultural activity in vrana diatom compositions of lake vrana indicate that they are sensitive to both paleoclimatic changes freshwater influx and sea level rise marine intrusion through permeable karst

high resolution sediment and vegetation responses to younger dryas climate change in varved lake sediments from meerfelder maar germany abstract this work focuses on a 1900 year section of varved sediments from lake meerfelder maar mfm extending from the late allerod to the preboreal varve counting provides the chronological framework and determines the length of younger dryas to 1025 1090 years a strong relation between climate change environment response and depositional processes has been found in consequence varve microfacies variations are a sensitive proxy for environment changes these are reflected for example in erosion processes within the lake s catchment minerogenic input and lake productivity diatom blooms the observed varve changes have been quantified by multiproxy analyses of physical and chemical sediment parameters with a resolution of between 8 and 40 years depending on sedimentation rate in addition high resolution palynological investigations provide the biostratigraphical subdivision based on changes in the vegetation occurring during the same time interval varve observations reveal that environment changes at the beginning and the end of the younger dryas occurred within 20 50 years furthermore sediment and vegetation changes were synchronous within the actual precision of the mfm and grip chronologies divergence of only a few decades terrestrial responses in western europe occurred quasi synchronous to temperature changes in greenland

the holocene climatic evolution of mediterranean italy a review of the continental geological data we present a synthesis of geological stratigraphic geomorphological and stable isotope data collected from continental archives to highlight the environmental and climatic differences between the first and second half of the holocene of central and southern italy the beginning of the holocene is marked by rapid environmental change in mediterranean italy between c 9500 cal bp and c 6000 5500 cal bp average temperatures were probably higher and environmental conditions were generally stable between c 9000 and 7000 cal bp meteoric precipitation was at its highest the end of the wetter period seems to occur later at c 6000 5000 cal bp since c 6000 5000 cal bp rapid climatic excursions are apparent in different palaeoclimate proxies with both variability in meteoric precipitation and temperature evident of particular relevance is the event occurring at c 4200 cal bp this event heralds a period of significant environmental change in the apennines and more generally in central italy

oxygen isotopes of lake marl at gerzensee and leysin switzerland covering the younger dryas and two minor oscillations and their correlation to the grip ice core the ratio of oxygen isotopes is a temperature proxy both in precipitation and in the calcite of lacustrine sediments the very similar oxygen isotope records from greenland ice cores and european lake sediments during the last glacial termination suggest that the drastic climatic changes occurred quasi simultaneously on an extra regional probably hemispheric scale in order to study temporal relations of the different parameters recorded in lake sediments for example biotic response times to rapid climatic changes a precise chronology is required in unlaminated lake sediments there is not yet available a method to provide a high resolution chronology especially for periods with radiocarbon plateaux alternatively an indirect time scale can be constructed by linking the lake stratigraphy with other well dated climate records new oxygen isotope records from gerzensee and leysin with an estimated sampling resolution of between 15 and 40 years match the greenlandic isotope record in many details under the assumption that the main variations in temperature and thus in oxygen isotopes occurred about simultaneously in greenland and switzerland we have assigned a time scale to the lake sediments of gerzensee and leysin by wiggle matching their stable isotope records with those of greenland ice cores which are among the best dated climatic archives we estimate a precision of 20 to 100 years during the last glacial termination

high resolution stable isotope records from southwest sweden the drainage of the baltic ice lake and younger dryas ice margin oscillations benthic foraminifera in two shallow marine sediment cores from southwest sweden were analyzed for oxygen isotopes several deglaciation events previously recognized in terrestrial and lake sediments throughout the baltic region are identified and radiocarbon dated an initial baltic ice lake bil drainage at the mount billingen threshold is inferred from a distinct 2 4 18o oscillation in one of the investigated cores the estimated radiocarbon age for this event is approximately 10 900 14c years the final drainage which ended bil history occurred in two steps during the younger part of the radiocarbon plateau at 10 000 14c years biostratigraphy suggests that the final drainage took place in the climatically warm early preboreal at approximately 11 150 14c years the deglacial trend toward lighter isotopic composition was interrupted and slightly reversed and is interpreted to represent the onset of the cold younger dryas period for a few hundred years prior to the younger dryas melting of the fennoscandian ice sheet appears to have been rapid besides the dramatic drainage events and reduced melting during the younger dryas the records display several other salinity variations these variations may reflect ice margin oscillations during the younger dryas previously identified throughout scandinavia as ice marginal deposits the isotopic records suggest approximately 10 climatically induced ice margin recession readvances of the southeastern fennoscandian ice sheet during the younger dryas

coastal slope terracing and relative sea level changes deductions based on computer simulations although a traditional geological survey of terraced coastal slopes is an essential part of studies aimed to reconstruct relative sea level changes the stratigraphic and chronological data so obtained frequently prove inadequate to completely unravel the sometimes very complex history of sea level fluctuation especially where erosion has prevailed over deposition and or deposits are difficult to date on the basis of our experience we think that much additional information can be gained through geomorphological interpretation of the profiles of those slopes in order to facilitate such interpretation a computer simulation model is developed that is able to predict the morphogenic response to a variety of possible relative sea level histories the results can be used to envisage some new interpretation keys for the analysis of real situations and hopefully as bases for the conception of general models of coastal slope evolution under the action of a variable sea level though preliminary the results so far obtained permit identification of the geomorphological consequences in terms of resulting slope profile of ordered successions of transgressions and regressions of different amplitude rate order and style moreover they provide interesting insights into the role that different styles of tectonic uplift may play in the phenomenon of multiple terracing of coastal slopes

successive oceanic and solar forcing indicated by younger dryas and early holocene climatic oscillations in the jura abstract the recent extension of 1 the residual 14 c curve back to 11 400 cal yr b p and 2 the lake level reconstruction in the jura back to ca 13 500 cal yr b p offers the opportunity of testing by proxy data the relationships between climate atmospheric 14 c the sun and the ocean recently suggested from the atmospheric 14 c record the climatic significance of the jura record is supported by correlations with climatic oscillations reconstructed in the alps from glaciers and timberline movements correspondence between the 14 c and paleoclimatic record from the jura suggests a working hypothesis two intervals within the holocene can be distinguished in the middle latitudes of western and central europe an early holocene period shows abrupt climatic oscillations linked to ocean forcing major colder climate phases developed between ca 9000 and 8800 and between ca 8000 and 7000 cal yr b c that coincide with higher 14 c values after 6000 cal yr b c a second period is characterized by smoother multicentury climatic oscillations linked to solar forcing

late glacial to holocene environmental changes and climate variability evidence from voldafjorden western norway sedimentological micropalaeontological benthic foraminifers and dinoflagellate cysts stable isotope data and ams 14c datings on cores and surface samples in addition to acoustic data have been obtained from voldafjorden western norway based on these data the late glacial and holocene sedimentological processes and variability in circulation and fjord environments are outlined glacial marine sedimentation prevailed in the voldafjorden between 11 0 kyr and 9 2 kyr bp radiocarbon years in the later part of the allerod period and for the rest of the holocene there was deposition of fine grained normal marine sediments in the fjord basin turbidite layers recorded in core material and on acoustic profiles dated to ca 2 1 6 9 7 6 ca 9 6 and ca 11 0 kyr bp interrupted the marine sedimentation the event dated to between 6 9 and 7 6 kyr bp probably corresponds to a tsunami resulting from large scale sliding on the continental margin off norway the storegga tsunami during the later part of the allerod period voldafjorden had a strongly stratified water column with cold bottom water and warm surface water reaching interglacial temperatures during the summer seasons during the younger dryas cold event there was a return to arctic sea surface summer temperatures possibly with year round sea ice cover the entire benthic fauna being composed of arctic species the first strong holocene warming observed simultaneously in bottom and sea surface temperature proxies occurred at ca 10 1 kyr bp bottom water proxies indicate two cold periods possibly with 2 c lowering of temperatures at ca 10 0 pbo 1 and at 9 8 kyr bp pbo 2 these events may both result from catastrophic outbursts of baltic glacial lake water the remainder of the holocene experienced variability in basin water temperature indicated by oxygen isotope measurements with an amplitude of ca 2 c with cooler periods at ca 8 4 9 0 5 6 5 2 4 6 4 2 3 5 2 2 1 2 and 0 4 0 8 kyr bp changes in the fjord hydrology through the past 11 3 kyr show a close correspondence both in amplitude and timing of events recorded in cores from the norwegian sea region and the north atlantic these data suggest a close relationship between fjord environments and variability in large scale oceanic circulation copyright 2001 john wiley sons ltd

quantitative reconstruction of younger dryas to mid holocene paleoclimates at le locle swiss jura using pollen and lake level data abstract pollen and lake level data from le locle in the swiss jura were used to quantitatively reconstruct climatic parameters for the younger dryas event and the first half of the holocene period the younger dryas cold event at le locle was characterized by i a general trend toward a slight increase in summer temperature and a decrease in annual precipitation and ii a marked drying phase at ca 11 900 cal yr b p that occurred between two wetter ones further phases of major deficit in moisture occured at ca 11 500 cal yr b p younger dryas holocene transition 10 800 cal yr b p 8700 cal yr b p and 6500 cal yr b p climatic parameters reconstructed here suggest that phases of higher lake level developing at ca 12 500 12 000 11 750 11 600 11 200 10 900 synchronous with the preboreal oscillation 10 400 8900 8400 8300 possibly related to the 8200 yr event and 7800 7000 cal yr b p coincided with an increase in annual precipitation a decrease in summer temperature and a shorter growing season conversely periods of low lake level corresponded to a decrease in annual precipitation an increase in summer temperature and a longer growing season this general pattern could have resulted from alternate southward northward displacements of the atlantic westerly jet

environmental changes related to the 8 2 ka event and other climate fluctuations during the middle holocene evidence from two dystrophic lakes in ne poland multi proxy palaeoecological data pollen diatom cladocera about the environment during the middle holocene from suchar ii and suchar wielki dystrophic lakes in ne poland are presented fluctuations in the pollen concentration indicative of changes in pollen productivity and shifts in woodland composition document the considerable instability of the climate in ne poland between 9200 and 5750 cal yr bp the recognised colder events were dated to ca 9050 8950 8700 7800 7600 7250 7100 6600 and 6050 5900 cal yr bp all these coolings are expressed as decreases in the pollen concentration of thermophilous taxa such as corylus avellana ulmus quercus tilia cordata t and fraxinus exelsior the most pronounced was the second of these cold climatic anomalies which lasted about nine centuries and can be equated with the 8 2 ka event significant cooling at that time is confirmed by the appearance of cold water species of cladocerans and diatoms

why this revolution explaining the major technical shift in southwestern europe during the 7th millennium cal bc during the course of the 7th millennium cal bc a major change occurred in stone working techniques and tool types among the lithic industries of mesolithic hunter gatherers in north africa and western europe these mutations not only affected the function and shape of certain tools but also modified volume management and the techniques used for blade removal this article proposes a new exploration of this shift which is the most important during the mesolithic in europe based on the interrogation of a database of 570 sites using very strict ordering criteria the examination of the first occurrences of these industries region by region reveals a diffusionist process that seems to begin in north africa tunisia at the end of the 8th or the very beginning of the 7th millennium cal bc before spreading progressively towards the atlantic ocean the data are not yet reliable enough to understand the process beyond the north of the loire river northern france it then underwent a regional stylistic diversification everywhere this technical mutation has not been recorded for bone tools or personal ornaments it was not accompanied by a transformation in social organization such as for cemeteries during the early mesolithic an analysis of the available data also calls into question all the economic changes sometimes evoked for these periods climatic change does not have a direct impact on this phenomenon apart from portugal which is on the geographic fringe of this shift the 6200 cal bc climatic crisis clearly occurred after this diffusion and had no direct effect on its development on the other hand the geographic modifications induced by the holocene warming clearly affected the extension of this phenomenon to western europe with the marine transgression

multiple early holocene climate oscillations at silver lake new jersey and their possible linkage with outburst floods abstract episodic discharges from the laurentide ice sheet are considered to be one of the major causes of climate oscillations during the glacial to interglacial transition these outburst floods disrupted thermohaline circulation and might have caused cooling events in the north atlantic region and beyond including the younger dryas preboreal oscillation and 8 2 ka events however few terrestrial sedimentary records show regional climate changes directly linked to outburst floods during the early holocene here we present lithologic and isotopic data from silver lake in northern new jersey to document temperature and moisture changes during the early holocene and to discuss possible linkage with outburst flooding events the lithologic record shows multiple intervals with coupled decreases in carbonate and increases in organic matter during the early holocene suggesting lower lake levels and drier climate conditions simultaneous with these changes were decreases in carbonate 18 o values likely reflecting a decrease in air temperature during these dry periods the apparent correlation of these sedimentary events at silver lake with documented outburst floods from the melting ice sheet suggests a possible causal connection implying that the climate in the mid atlantic region was extremely sensitive to perturbations of ocean circulation