lateglacial holocene environmental changes in the mediterranean alps inferred from lacustrine sediments this study investigates sediment cores from the mediterranean alpine lakes located in upvalley cirques upper than 1700 metres a s l using sedimentological palynological and geomorphological studies in order to document environmental changes following the last phase of glacier retreat these results are considered in the framework of the deglaciation characterized from 16 sediment cores from high altitude lakes and mires including 104 14c ages and geomorphological studies of the mediterranean alps considering each sediment core proxy as an independent observation i e comparisons between 14c ages and palynostratigraphy between 14c ages and lithostratigraphy between palynostratigraphy and lithostratigraphy these data are aimed at contributing to a better understanding of the timing of postglacial environmental changes the 14c ages combined with pollen biostratigraphy indicate that the deglaciation of cirque catchments is dated between 14 500 and 13 000 cal bp i e during the lateglacial interstadial greenland interstadial 1e the sixteen lacustrine and mire sediment records are systematically characterized by three units from bottom to top organic poor blue clay beige to light brown silty clay and organic rich dark brown gyttja lithotype during the younger dryas lakes located below 2300 m a s l were ice free and their pollen record indicates steppe conditions the sedimentary facies also informs on the timing of glacial dominated processes the onset of organic rich gyttja is dated at 11 000 cal bp suggesting the last influence of cirque glaciers in these lakes at the beginning of the holocene the timing of the onset of this organic rich unit differs in sites 2000 years probably due to an altitudinal and exposure gradient of the glacial cirques the presence of gyttja from 11 000 cal bp to present indicates biogenic infilling lake for all the holocene even though the literature have indicated rock glacier advances occurred during the holocene subboreal and lia in the south of the alps no significant sedimentological patterns related to glacier fluctuations are recorded in lake vens the glacier fluctuations in the mediterranean alps are concomitant with those dated in the non mediterranean alps thus suggesting a main common climate forcing however the increase in terrigenous sediment inputs since 1800 cal bp is mainly due to human activities

last 1000 years of environmental history in southern bucovina romania a high resolution multi proxy lacustrine archive geo ecological and landscape change studies at a local scale are scarce in central eastern europe and particularly in romania however this focus is directly relevant to ecosystems and humans as both are dependent on local environmental changes we perform a high resolution multi proxy analysis of physical and geochemical sediment properties coupled to plant macrofossil pollen and charcoal analysis at iezerul sadovei lake and present the first palaeoenvironmental reconstruction from bucovina mountains the north eastern romania the sedimentary record spanning the last 950 years is laminated throughout and reveals high intensity catchment responses to changes in hydrological conditions and human impact results show major landscape disturbances 950 years ago and during the last 200 years the enhanced catchment instability from the onset of sedimentation to 1400 ce was characterised by landsliding and subsequent erosion and related mainly to natural factors however the most recent since c 1800 ce environmental changes i e deforestation enhanced channel and slope erosion and lake in filling are a consequence of direct human interventions changes in the composition and extent of forest cover were also driven by the combination of natural disturbances climate variability and anthropogenic activities from 1400 ce and more clearly over the last 200 years early successional and disturbed habitat taxa appeared to respond primarily to anthropogenic drivers including forest management the higher proportion of abies alba 30 and fagus sylvatica 20 in the local forest and their dramatic decline was recorded earlier i e 1150 ce and 1400 ce respectively than reported in other parts of the romanian carpathians using this palaeoenvironmental evidence as an analogue projected climate changes i e increased seasonal heavy precipitation and more frequent extreme events superimposed on increasing human pressure are likely to lead to the destabilisation of the catchment through erosion and possible reactivation of landslides

constraining the time span between the early holocene hasseldalen and askja s tephras through varve counting in the lake czechowskie sediment record poland we report the first findings of coexisting early holocene hasseldalen and askja s cryptotephras in a varved sediment record in lake czechowskie poland a time span of 152 11 8 varve years between the two tephras has been revealed by differential dating through varve counting this is in agreement within the uncertainties with calculations from radiocarbon based age models from the non varved hasseldala port record in southern sweden but shorter than assumed from the non varved lake record on the faroe islands we discuss possible reasons for the observed differences in duration between the two tephras and provide a revised absolute age for the askja s tephra of 11 228 226 cal a bp based on anchoring our floating varve chronology to the absolute timescale by using the hasseldalen tephra as dated in the hasseldala port sediments 11 380 216 cal a bp this age agrees with radiocarbon age models with larger uncertainty ranges but is slightly older than radiocarbon based age models with narrow uncertainty bands and is even 200 300 years older than the age reported from the faroe islands record in addition to these chronological issues we discuss the possible response of the czechowskie sediment record to the preboreal climate oscillation

tsunami history of an oregon coastal lake reveals a 4600 yr record of great earthquakes on the cascadia subduction zone bradley lake on the southern oregon coastal plain records local tsunamis and seismic shaking on the cascadia subduction zone over the last 7000 yr thirteen marine incursions delivered landward thinning sheets of sand to the lake from nearshore beach and dune environments to the west following each incursion a slug of marine water near the bottom of the freshwater lake instigated a few year to several decade period of a brackish 4 salinity lake four additional disturbances without marine incursions destabilized sideslopes and bottom sediment producing a suspension deposit that blanketed the lake bottom considering the magnitude and duration of the disturbances necessary to produce bradley lake s marine incursions a local tsunami generated by a great earthquake on the cascadia subduction zone is the only accountable mechanism extreme ocean levels must have been at least 5 8 m above sea level and the cumulative duration of each marine incursion must have been at least 10 min disturbances without marine incursions require seismic shaking as well over the 4600 yr period when bradley lake was an optimum tsunami recorder tsunamis from cascadia plate boundary earthquakes came in clusters between 4600 and 2800 cal yr b p tsunamis occurred at the average frequency of 3 4 every 1000 yr then starting 2800 cal yr b p there was a 930 1260 yr interval with no tsunamis that gap was followed by a 1000 yr period with 4 tsunamis in the last millennium a 670 750 yr gap preceded the a d 1700 earthquake and tsunami the a d 1700 earthquake may be the fi rst of a new cluster of plate boundary earthquakes and accompanying tsunamis local tsunamis entered bradley lake an average of every 390 yr whereas the portion of the cascadia plate boundary that underlies bradley lake ruptured in a great earthquake less frequently about once every 500 yr therefore the entire length of the subduction zone does not rupture in every earthquake and bradley lake has recorded earthquakes caused by rupture along the entire length of the cascadia plate boundary as well as earthquakes caused by rupture of shorter segments of the boundary the tsunami record from bradley lake indicates that at times most recently 1700 yr b p overlapping or adjoining segments of the cascadia plate boundary ruptured within decades of each other

devensian lateglacial environmental changes in britain a multi proxy environmental record from llanilid south wales uk abstract a multi proxy environmental record for the devensian weichselian lateglacial and early holocene periods which includes pollen plant macrofossil coleopteran geochemical and stable isotope data is described from a site at llanilid south wales uk the geochronology of the sequence is derived from two age depth models which show a broad measure of agreement over much of the profile this data set provides the basis for a detailed reconstruction of changing environmental conditions in western britain during the transition from the last cold stage to the present holocene interglacial ca 15 000 10 000 cal yr bp two marked cooling episodes are recorded during the course of the lateglacial interstadial greenland interstadial 1 with mean july temperatures falling by more than 5 c from a maximum of around 20 c during the early interstadial and by a further 4 5 c around 13 100 cal yr bp the initial drop in temperature led to a reduction in juniperus scrub while the second and more abrupt temperature decline resulted in a significant contraction in areas of betula woodland a relatively slight and short lived warming during the later interstadial enabled tree birch to expand once again mean july temperatures of 10 11 c characterised the loch lomond younger dryas stadial greenland stadial 1 between ca 12 600 and 11 400 cal yr bp during which time a scrub tundra with betula salix and a range of open habitat taxa became established locally the onset of the holocene interglacial at ca 11 400 cal yr bp is marked by an abrupt temperature rise of the order of 9 c and by the rapid expansion of betula woodland the llanilid palaeoclimate record is similar to that from the gransmoor site in northeast england and also to the climatic sequence inferred from the grip ice core particularly during the later part of the lateglacial interstadial ca 14 000 12 600 cal yr bp during the loch lomond younger dryas stadial and in the early holocene the llanilid chronology is less secure during the early part of the lateglacial interstadial pre 14 000 cal yr bp but it is possible that warming may have begun earlier in this part of western britain than in greenland

early holocene deglaciation chronology in vastergotland and narke southern sweden biostratigraphy clay varve 14c and calendar year chronology this thesis outlines an event stratigraphy for the last glacial holocene transition in eastern middle sweden events are short lived occurrences that have left traces in the geological record and w

rg as a depth discriminant for earthquakes and explosions a case study in new england fundamental mode rayleigh waves with periods between about 0 4 and 2 5 sec rg are often observed on seismograms of explosions and very shallow focus earthquakes the rg phase is particularly prominent on seismograms of quarry blasts in this study rg waves generated by small earthquakes and explosions in new england are investigated to evaluate the extent to which rg waves can be used to estimate depths of events in the upper crust the data were recorded by the new england seismic network nesn operated by weston observatory the strongest rg signals recorded by the nesn are generally in the period range of 0 5 to 1 5 sec in that period range rg displacement is essentially confined to the upper 5 km of the crust with most of the rg wave energy in the upper 2 or 3 km sources deeper than about 4 km would not be expected to generate strong rg signals at these periods and so if rg can be clearly identified on a seismogram the source is most likely very shallow observed rg waves can therefore be used to discriminate very shallow focus events from deeper events provided that rg can be identified and distinguished from other phases a method for identifying rg waves at distances up to about 170 km is presented in this paper rg is identified and distinguished from other phases by measuring amplitudes at particular periods and arrival times using a narrow bandpass filter analysis rg p and rg lg ratios are estimated by forming the ratios of amplitudes in the appropriate group velocity frequency windows on vertical component seismograms the phase referred to as lg is actually a complicated wave train recorded on short period seismograms that travels with group velocities appropriate for s and lg waves an rg lg ratio appears to be a better measure of the presence of rg on a seismogram than an rg p ratio observed rg lg ratios are used to estimate depths of two earthquakes recorded by the nesn

a paleoecological analysis of a southern permafrost peatland charlevoix quebec the southernmost site where permafrost has been located in the quebec labrador peninsula is in a peatland on the subalpine summit of lac des cygnes mountain 47 41 n 70 36 w because of the thickness of its peat deposit this site contains rich ecological information about the history of the peatland and its surrounding subalpine environment we conducted a detailed macrofossil analysis to reconstruct the 6000 year history of the peatland in general the development of the lac des cygnes mountain peatland has followed the classic succession of rich fen poor fen bog found in other peatlands in subarctic boreal and temperate environments an abrupt decline in all tree macrofossils ca 4000 bp suggests that a major deforestation event occurred on the summit of lac des cygnes mountain the exact cause of this deforestation event is unknown but fire is a possible factor the lack of absolute chronological resolution near the top of the macrofossil record precludes proper dating of permafrost inceptio

radiocarbon dating of bulk peat samples from raised bogs non existence of a previously reported reservoir effect in 1995 an unexpected reservoir effect was reported in sequences of bulk c 14 dates of raised bog peat in most peat studies bulk c 14 dates are used for obtaining chronologies therefore it is important to confirm and quantify such a c 14 reservoir effect five bulk peat samples from the raised bog engbertsdijksveen were conventionally c 14 dated the same core had previously been precisely dated by c 14 ams dates of carefully selected above ground plant remains the existence of a reservoir effect in bulk peat c 14 samples could not be confirmed other explanations for the reported reservoir effect are discussed c 2004 elsevier ltd all rights reserved

vegetation patterns under climate changes in the eemian and early weichselian in central europe inferred from a palynological sequence from ustkow central poland abstract this paper presents a fresh examination of a pollen profile from ustkow central poland which after preliminary results was thought to span a period between the early eemian mis 5e and the upper pleni weichselian mis 3 the newly obtained results confirmed the age assessment of the bottom series but revealed a much older age for the uppermost part of the profile as far back as the rederstall stadial mis 5b palynological research showed slightly different patterns of vegetation in comparison to other sites located in central europe among them were an early ulmus maximum coinciding with the betula optimum in the early eemian a relatively late optimum of taxus baccata during the decline of the middle eemian and a distinct division of the older part of the late eemian into phases of abies picea and picea pinus forest domination the herning stadial mis 5d falls into a typical bipartition reflected by heathland domination during its older part and the prevalence of juniperus thickets and artemisia poaceae steppe during its younger part which makes this succession similar to those from northern germany the pollen spectra reflecting the brorup interstadial mis 5c distinctly revealed an intra brorup cold oscillation rarely detected in profiles from central europe and a period of larix dominated forests during the latest part of the interstadial extraordinarily high percentages exceeding 15 of the total pollen sum local pollen taxa together with the lithological composition of deposits revealed that there was a water body in the area during the periods of the late saalian early eemian transition middle eemian the decline of the tilia phase the herning stadial mis 5d the early brorup interstadial mis 5c and the rederstall stadial mis 5b between these time intervals a poor and or rich fen and or bog functioned

test of ams 14c dating of pollen concentrates using tephrochronology previous attempts to radiocarbon date sediments 10 kyr from the high rainfall region of westland new zealand a critical location for investigation of interhemispheric patterns of climate change have been problematic this study building on recent work by vandergoes and prior 2003 shows that ams 14c dating of pollen concentrates has potential to provide more reliable ages than other sediment constituents including plant macrofossils the method was applied to sediments from three sites containing the 22 6k 14c yr kawakawa tephra which provided an independent test of the 14c ages although some minor laboratory contamination was detected in tests on background standards the modelled relationship between sample mass and measured 14c content permitted an appropriate correction to be determined improved pollen concentrations derived by density separation between 1 4 and 1 2 specific gravity and sieving in the range 10 50 m provided either older ages than other fractions of the same sample or where in situ contamination was not evident equivalent ages differences in degree of in situ contamination between depositional environments indicated that in westland lake sites may be less susceptible to contamination by younger carbon than peat sites where this process may be facilitated by root penetration into underlying sediments copyright 2006 john wiley sons ltd

an arctic perspective on dating mid late pleistocene environmental history to better understand pleistocene climatic changes in the arctic integrated palaeoenvironmental and palaeoclimatic signals from a variety of marine and terrestrial geological records as well as geochronologic age control are required not least for correlation to extra arctic records in this paper we discuss from an arctic perspective methods and correlation tools that are commonly used to date arctic pleistocene marine and terrestrial events we review the state of the art of arctic geochronology with focus on factors that affect the possibility and quality of dating and support this overview by examples of application of modern dating methods to arctic terrestrial and marine sequences event stratigraphy and numerical ages are important tools used in the arctic to correlate fragmented terrestrial records and to establish regional stratigraphic schemes age control is commonly provided by radiocarbon luminescence or cosmogenic exposure ages arctic ocean deep sea sediment successions can be correlated over large distances based on geochemical and physical property proxies for sediment composition patterns in palaeomagnetic records and increasingly biostratigraphic data many of these proxies reveal cyclical patterns that provide a basis for astronomical tuning recent advances in dating technology calibration and age modelling allow for measuring smaller quantities of material and to more precisely date previously undatable material i e foraminifera for c 14 and single grain luminescence however for much of the pleistocene there are still limits to the resolution of most dating methods consequently improving the accuracy and precision analytical and geological uncertainty of dating methods through technological advances and better understanding of processes are important tasks for the future another challenge is to better integrate marine and terrestrial records which could be aided by targeting continental shelf and lake records exploring proxies that occur in both settings and by creating joint research networks that promote collaboration between marine and terrestrial geologists and modellers

reconstructions of late holocene paleofloods and glacier length changes in the upper engadine switzerland ca 1450 bc ad 420 article i nfo article history the relationship between summer autumn floods in central europe and climate warming is poorly con strained by available instrumental historical proxy and model data to investigate this relationship a complete record of paleofloods regional glacier length changes and associated climate phases and regional glacier advances and retreats and associated climate transitions are derived from the varved sediments of lake silva plana ca 1450bc ad420 upperengadine switzerland incombination theserecordsprovideinsightintothe behavior of floods i e frequency under a wide range of climate conditions eighty five paleofloods are identified from turbidites in the sediments of lake silvaplana regional glacier length changes and associated cool and or wet and warm and or dry climate phases are inferred from centennial anomalies in the square root of low pass lp filtered mass accumulation rates marlp

ams radiocarbon analyses from lake baikal siberia challanges of dating sediments from a large oligotrophic lake abstract a suite of 146 new accelerator mass spectrometer ams radiocarbon ages provides the first reliable chronology for late quaternary sediments in lake baikal in this large highly oligotrophic lake biogenic and authigenic carbonate are absent and plant macrofossils are extremely rare total organic carbon is therefore the primary material available for dating several problems are associated with the toc ages one is the mixture of carbon sources in toc not all of which are syndepositional in age this problem manifests itself in apparent ages for the sediment surface that are greater than zero however because most of the organic carbon in lake baikal sediments is algal autochthonous in origin this effect is limited to about 1000 500 years which can be corrected at least for young deposits the other major problem with dating lake baikal sediments is the very low carbon contents of glacial age deposits which makes them extremely susceptible to contamination with modern carbon this problem can be minimized by careful sampling and handling procedures the ages show almost an order of magnitude difference in sediment accumulation rates among different sedimentary environments in lake baikal from about 0 04 mm year on isolated banks such as academician ridge to nearly 0 3 mm year in the turbidite depositional areas beneath the deep basin floors such as the central basin the new ams ages clearly indicate that the dramatic increase in diatom productivity in the lake as evidenced by increases in biogenic silica and organic carbon began about 13 ka in contrast to previous estimates of 7 ka for the age of this transition holocene net sedimentation rates may be less than equal to or greater than those in the late pleistocene depending on the site this variability reflects the balance between variable terrigenous sedimentation and increased biogenic sedimentation during interglaciations the ages reported here and the temporal and spatial variation in sedimentation rates that they imply provide opportunities for paleoenvironmental reconstructions at different time scales and resolutions

an mis 3 age organic deposit from balglass burn central scotland palaeoenvironmental significance and implications for the timing of the onset of the lgm ice sheet in the vicinity of the british isles this paper reports the analysis of a glaciotectonised organic deposit located between a lower weathered till and an upper unweathered till at balglass burn north of the campsie fells in central scotland uk close to the centre of ice accumulation in scotland sedimentology pollen macroscopic plant remains and coleoptera indicate accumulation in a small pond as part of an open tundra landscape with low floral diversity mcr palaeotemperature reconstructions for the coleoptera give a mean temperature for the warmest and the coldest months of 8 to 10 c and 26 to 10 c respectively indicating the presence of at least discontinuous permafrost six ams dates on carex fruit and coleoptera fragments give ages between 34 480 and 28 050 14c yr bp ca 39 8 to ca 32 8 cal yr bp fairbanks et al 2005 the upper till and the glaciotectonism are attributed to glaciation during the lgm glaciotectonic deformation means that the ages do not indicate sequential development and it is not possible to relate this palaeo evidence to the fine resolution palaeoclimatic signature for mis 3 however the fact that this part of central scotland was ice free at this time means that some recent proposals suggesting that the british ice sheet began to accumulate around the middle of mis 3 are unlikely to be correct copyright 2006 john wiley sons ltd

reconstructing the late holocene history of a subalpine environment charlevoix quebec using fossil insects in southern quebec charlevoix canada reconstructions of the subalpine insect assemblages were made in environments that were transformed by fire during the late holocene since 4500 bp the ecological requirements of beetle species likely to be found as fossils were studied by collecting living beetles in pitfall traps in forest suibalpine and alpine environments the late holocene changes of insect assemblages were reconstructed by recovering fossil insects from 13 peat sections modem beetle assemblages are valuable indicators of tree cover well developed podzol soils under peat as well as numerous spruce charcoal remains overlaying the podzol in all sampling sites suggest that a dense spruce cover was present before the beginning of the accumulation of peat and was eliminated by fire 4570 800 bp ground beetle and bark beetle assemblages at the base of the peat sections contained a mixture of forest and open environment species indicating that the postfire environment was a subalpine one w

osl ages in central norway support a mis 2 interstadial 25 20 ka and a dynamic scandinavian ice sheet recent work has suggested that the scandinavian ice sheet was much more dynamic than previously believed and its western marine based margin can provide an analogue to the rapid paced fluctuations

chronology and palaeoenvironmental reconstruction in the sub tidal zone a case study from hinkley point evidence from the severn estuary demonstrates that this region was exploited by mesolithic hunter gatherer fishers bell 2007 the potential for future archaeological discoveries bell 2007 webster 2007 273 bell and warren 2013 39 and the well preserved palaeoenvironmental evidence in the fine grained and organic sediments of the somerset avon and gwent levels hosfield et al 2007a 40 makes the area of importance for archaeological study small quantities of worked flint have been recovered from the foreshore around stolford porlock and minehead bay mullin et al 2009 canti et al 1995 implying human activity in the present intertidal zone which is further enhanced by the suggestion of possible deliberate burning of reed swamps jones et al 2005 similar to that postulated in the severn estuary brown 2005 timpany 2005 bell 2007 while considerable research has been carried out within terrestrial and intertidal contexts remarkably little archaeological work has been undertaken below the mean low water mark webster 2007 273 the bristol channel and severn estuary has seen considerable change in sea level since the last glacial maximum long et al 2002 philips and crips 2010 extending our knowledge beyond the intertidal zone is therefore of key importance for understanding the late palaeolithic and mesolithic palaeogeography of the region hosfield et al 2007b developments in the recovery of offshore holocene peat and sediment sequences now permit the production of multi proxy palaeoenvironmental datasets and landscape reconstructions from submerged sample sites this paper uses evidence from three cores recovered from submarine peat deposits at hinkley point bristol channel uk to explore the issues and challenges associated with producing radiocarbon chronologies from deeply submerged peat sequences within a marine environment we emphasise the importance of analysis of multiple sequences to construct robust chronologies for local hydrological change and landscape reconstruction edwards 2006 the need for local evidence is critical if we are to move beyond generalised and potentially misleading models of human environment interaction scaife 2011 because as this case study demonstrates complex processes and landscape variability might have been features of even highly localised palaeoenvironments

chironomids as a tool for inferring holocene climate an assessment based on six sites in southern scandinavia abstract chironomid subfossil assemblages from six low alpine and sub alpine holocene stratigraphies are presented and compared they are from five lakes in mid southern and western norway and one in central sweden when comparing the chironomid inferred july air temperatures there are many time segments with a poor among lake fit in inferred temperatures possible environmental variables influencing the fossil chironomid assemblages are discussed using a modern norwegian calibration data set to indicate taxon environment relationships these analyses indicate that local changes in ph water chemistry and productivity at times may have overridden the regional temperature signal in addition other causes of poor among site temperature fit are discussed in particular those related to chronological uncertainties holocene temperature inferences from single cores based on chironomids may not always be able to provide a reliable regional temperature signal but can act as a guide from which hypotheses about past environmental conditions can be tested with the aid of chironomid inferred temperatures from several sites and from other environmental proxies we have obtained a regional picture of holocene summer temperature change by developing a consensus reconstruction based on the overall temperature signal from all six sites this consensus is developed by fitting a smoother through all 330 site specific temperature deviations from the holocene mean the consensus temperature deviations vary from 0 8 c at 8800 cal years bp to 0 8 c at 6500 cal years bp

the holocene shore displacement of gastrikland eastern sweden a contribution to the knowledge of scandinavian glacio isostatic uplift the holocene shore displacement of gastrikland eastern sweden a contribution to the knowledge of scandinavian glacio isostatic uplift

problematic 14c ams dates of pollen concentrates from lake gosciaz poland pollen concentrates and macrofossils of mid holocene age from the annually laminated sediments of lake gosciaz poland are dated by 14c ams dating the sediment by matching to the radiocarbon calibration curve is possible for the macrofossils the 14c ages of the pollen concentrates however do not support the varve chronology probably due to an as yet not fully explained reservoir effect

the lateglacial and holocene environmental history of the ioannina basin north west greece this study centres on palaeoenvironmental analysis of the upper part of a long core from the partially drained tectonic ioannina basin north west greece the data span the lateglacial and holocene and comprise pollen mollusc magnetic susceptibility loss on ignition and particle size analyses these augment previously published ostracod and stable isotope data from the same sediment sequence the age model for the sequence is based on 19 ams dates five of which were obtained using a novel procedure for the separation of microcharcoal from sediment the pollen data suggest that although temperate woodland expanded at the beginning of the lateglacial only limited woodland contraction occurred during the younger dryas chronozone despite strong evidence for a sharp drop in sea surface temperature in the neighbouring adriatic at this time in contrast large scale vegetational and sedimentological changes occur in concert during the holocene some of which may be ascribed to human impact comparison with other records from the ioannina basin suggests that previous more littoral pollen sequences did not constitute a wholly representative record of lateglacial and holocene vegetational change

long mis 5e 3 environmental history of a paleolake in central poland recorded in the succession from kublowo abstract one of the longest above 7 m thick uninterrupted eemian vistulian weichselian pollen successions in poland is known from kublowo central poland the huge importance of this succession is manifested in the possibility of study the evolution of the lake environment under the influence of changing from interglacial to glacial climatic conditions the reconstruction of the environmental changes at kublowo and its surroundings show the short climate fluctuations and a detailed picture of the natural conditions prevailing in central poland central europe during the period from approximately 126 000 to 55 000 years bp based on the results of multi proxy analysis four lacustrine stages linked with a higher water level and three boggy stages low water level of evolution of the kublowo paleolake were observed the pollen diagram from kublowo reveals a succession of eighteen local pollen assemblage zones k1 k18 l paz the k1 to k7 lpaz zones record the interglacial succession correlated with the eemian the next pollen zones k8 to k18 are linked with the vistulian the pollen sequence shows between the eemian interglacial mis 5e and the last glaciation second stadial of the plenivistulian mis 4 3 four cold intervals that are interpreted as stadial phases herning rederstall schalkholtz and ebersdorf separated by three temperate intervals interstadials brorup odderade and oerel in the studied sediments 25 species of subfossil cladocera were identified and ten zones of fauna development were distinguished the unique feature of this profile is the good preservation of above 100 000 year old cladocera remains and a high diversity of species which are primarily littoral the middle and late eemian were periods convenient to cladocera development due to high temperatures high water levels high trophy and occurrence macrophytes a deterioration of fauna living conditions started in the late eemian and next took place in the vistulian cold events the results of isotopic and geochemical analyses of organic matter from kublowo have enabled the reconstruction of varying environmental conditions and the origin of organic matter the organic carbon content toc changes from 1 to 40 and is closely related to climatic conditions during the eemian the amount of toc systematically increased the lowest values are recorded in the coldest periods during the herning rederstall and schalkholz stadials the c n atomic ratio fluctuates from 13 to 34 and the highest values occur in the brorup interstadial the values of 13 c change from 27 9 to 12 9 and 15 n values oscillate between 1 6 and 5 3

constraining the age of lateglacial and early holocene pollen zones and tephra horizons in southern sweden with bayesian probability methods the sediment sequence from hasseldala port in southeastern sweden provides a unique lateglacial early holocene record that contains five different tephra layers three of these have been geochemically identified as the borrobol tephra the hasseldalen tephra and the 10 ka askja tephra twenty eight high resolution 14 c measurements have been obtained and three different age models based on bayesian statistics are employed to provide age estimates for the five different tephra layers the chrono and pollen stratigraphic framework supports the strati graphic position of the borrobol tephra as found in sweden at the very end of the older dryas pollen zone and provides the first age estimates for the askja and hasseldalen tephras our results however highlight the limitations that arise in attempting to establish a robust chronologically independent lacustrine sequence that can be correlated in great detail to ice core or marine records radiocarbon samples are prone to error and sedimentation rates in lake basins may vary considerably due to a number of factors any type of valid and realistic age model therefore has to take these limitations into account and needs to include this information in its prior assumptions as a result the age ranges for the specific horizons at hasseldala port are large and calendar year estimates differ according to the assumptions of the age model not only do these results provide a cautionary note for over dependence on one age model for the derivation of age estimates for specific horizons but they also demonstrate that precise correlations to other palaeoarchives to detect leads or lags is problematic given the uncertainties associated with establishing age depth models for sedimentary sequences spanning the lateglacial period however this exercise employing bayesian probability methods represents the best possible approach and provides the most statistically significant age estimates for the pollen zone boundaries and tephra horizons copyright 2006 john wiley sons ltd

early holocene monsoonal fluctuations in the garhwal higher himalaya as inferred from multi proxy data from the malari paleolake abstract a 4 9 m thick lake sequence formed due to the landslide damming of a stream in the semiarid garhwal himalaya was studied to understand past monsoonal variations in the region the optically stimulated luminescence osl chronology indicates that the lake existed between 12 and 7 ka ago chronologically constrained trends of sand percent organic phosphorus op apatite inorganic phosphorus aip and parameters of environmental magnetism were measured in the paleolake profile measured proxies indicate that the indian summer monsoon ameliorated in the early holocene after 12 ka cooling and it appears that all the proxies from the lake have captured this globally recognized early holocene warming four phases of wet conditions intensified monsoon are recognized at 11 5 ka 11 10 5 ka 10 9 ka and 8 7 ka with maximum uncertainties of 1000 years the wet phases are characterized by high magnetic susceptibility increased op and reduced aip in an attempt to understand the primary forcing of the sharp fluctuations in monsoonal activity in the region we show that changes in magnetic susceptibility match variations of residual atmospheric 14c suggesting a role for solar variability as an explanation of climatic variability

characteristics of rain induced landslides in the indian himalaya a case study of the mandakini catchment during the 2013 flood abstract landslides triggered by monsoon rainfall are a recurring hazard that lead to loss of life and cause enormous property and infrastructure damage in the indian himalaya this study is focused on understanding the role of extreme rainfall and physical factors in causing landslides in the indian himalaya particularly in the mandakini catchment where an enormous landslide and flood disaster occurred in june 2013 following a two day extreme rainfall event results indicate that sub daily extreme rainfall depths causing landslides vary with elevation across the catchment antecedent rainfall six days prior to the extreme rainfall event was found to have substantial depths that could have primed the area for landslides except for aspect of slopes the causative factors including land use land cover lithology elevation slope river network distance to roads and total extreme rainfall as a triggering factor were found to be statistically significant in causing landslides in the catchment the final product of the study is a new landslide susceptibility map that better delineates the landslide prone regions in the disaster prone mandakini catchment after the june 2013 extreme rainfall event the map was prepared using logistic regression that shows medium and high susceptibility zones at upper sections of the catchment as well as along the mandakini river and its tributaries where major sacred shrines tourist spots and human establishments are located

variation in 14c age of macrofossils and different fractions of minute peat samples dated by ams accurate 14c dating of peat samples is crucial if peat stratigraphies are to be used as historical archives to analyse the variation in 14c age within small peat samples the 14c age of different mire plant remains and peat fractions n 39 from 2 cm thick peat slices was determined using accelerator mass spectrometry the 14c ages of mosses were assumed to be the most accurate to verify this we also tested the possibility that uncertainties could be introduced by mosses at the mire surface reassimilating co2 produced during the decomposition of old peat the average 14c content of living mosses 110 5 110 9 absolute modern pm did not differ between threesphagnum species representing hummock carpet and lawn growing species their 14c contents were also identical within experimental limits to the current 14c content of the atmosphere depending on sampled depth and peat type the differences in calibrated 14c age between different fragments or fractions within specific 2 cm thick peat samples

fluvial incision and channel downcutting as a response to late glacial and early holocene climate change the lower reach of the river meuse maas the netherlands detailed fieldwork and new extensive 14c dating of residual channel infillings provide data for the reconstruction of the late glacial channel downcutting and incision history of the venlo boxmeer lower reach of the river meuse maas in the southern netherlands within a period of 500 1300 yr after late glacial climatic amelioration the meuse responded to increased discharges and decreased sediment supply by adjusting the width depth ratio of its channels two main phases of channel downcutting are followed by two main phases of floodplain lowering and narrowing indicating net floodplain degradation by the fluvial system as a non linear response to late glacial and early holocene climate change some 1300 yr after initial late glacial warming channels downcut rapidly during the early bolling 13 3 12 5 kyr bp and adopted a high sinuosity meandering style channel downcutting paused around 11 9 kyr bp possibly in response to rising groundwater levels and or the older dryas cooling event between 11 9 and 11 3 kyr bp a new floodplain was formed then lateral erosion took place and initiated a first phase of 2 6 m floodplain lowering during the late allerod gradual climate deterioration during the allerod progressively broke up soils and vegetation cover from 11 3 to 10 9 kyr bp the meuse gradually adjusted to an increased ratio of sediment supply over transport capacity through higher width depth ratios main channels became shallower and adopted a low sinuosity pattern finally culminating in a braided river system during the younger dryas the final holocene warming resulted within 500 yr in renewed rapid channel downcutting by a single low sinuosity channel during the early preboreal followed by a second phase of 1 8 2 8 m floodplain lowering copyright 1999 john wiley sons ltd

changes in solar activity and holocene climatic shifts derived from 14c wiggle match dated peat deposits closely spaced sequences of accelerator mass spectrometer ams 14 c dates of peat deposits display century scale wiggles which can be e tted to the radiocarbon calibration curve by wiggle matching such sequences high precision calendar age chronologiescan be generated which show that changes in mire surface wetness during the bronze age iron age transition c 850 cal bc and the little ice age wolf sporer maunder and dalton minima occurred during periods of suddenly increasing atmospheric concentration of 14 c replicate evidence from peat based proxy climate indicators in northwest europe suggest these changes in climate may have been driven by temporary declines of solar activity carbon accumulation rates of two raised peat bogs in the uk and denmark record low values during the little ice age which ree ects reduced primary productivity of the peat forming vegetation during these periods of climatic deterioration

luminescence dating indicates radiocarbon age underestimation in late pleistocene fluvial deposits from eastern england robust geochronological control is crucial for interpreting and correlating the environmental record from fragmentary terrestrial sequences from the last glacial period traditional terrestrial stratigraphies are typically reliant on radiocarbon dating although estimates of antiquity for samples older than 40 ka may be unreliable optically stimulated luminescence osl dating of sediments is an alternative for dating the whole of the last glacial period and also provides the opportunity to independently test radiocarbon based chronologies this paper presents a set of nine directly comparable paired osl and accelerator mass spectrometry ams radiocarbon ages from multiple sites within devensian fluvial sediments in lowland britain and shows that it is possible to obtain robust osl age estimates throughout this time period the two techniques agree well for ages younger than ca 29 14c ka bp ca 35 cal ka bp but disagree beyond ca 35 14c ka bp ca 40 cal ka bp this is thought to be due to radiocarbon ages on older organic material having been contaminated by low levels of modern carbon it is therefore suggested that all conventionally pre treated radiocarbon ages greater than 35 14c ka bp should be treated with extreme caution copyright 2009 john wiley sons ltd

fluvial sediments correlations and palaeoenvironmental reconstruction the development of robust radiocarbon chronologies abstract multiple sequences of radiocarbon dates extracted from organic materials are increasingly being used to provide robust chronologies for landscape development particularly the timing and correlation of significant climatic and process events whilst the validity of using such frameworks in sedimentary environments such as lake basins and raised bogs has been the focus of much attention such debates have not extended to fluvial systems using examples from three lowland vertically accreting river valleys in east anglia uk this paper assesses the robustness of their associated radiocarbon chronologies by assessing the contrasting age estimates that are obtained by dating different parts of the same organic sample humic humin and plant macrofossils at a variety of stratigraphic levels overall the humin and humic acid fraction results were statistically consistent whilst the plant macrofossil remains were found to be of a slightly younger age in these examples it is argued that the younger ages appear to be the result of phragmites common reed roots pushing plant macrossils through the sedimentary sequence or opening up voids for material to fall through although studies in lacustrine and mire environments suggest alternative explanations may also be possible whichever explanation is preferred this study demonstrates clearly that the complexity of valley floor stratigraphy and processes is such that using single radiocarbon dates whether ams or bulk samples to reconstruct chronologies of geomorphic system response may need to be refined and subjected to the same level of assessment that has been applied in other sedimentary systems

response of the indian summer monsoon circulation and rainfall to seasonal snow depth anomaly over eurasia several observational and modeling studies indicate that the indian summer monsoon rainfall ismr is inversely related to the eurasian snow extent and depth the other two important surface boundary conditions which influence the ismr are the pacific sea surface temperature sst to a large extent and the indian ocean sst to some extent in the present study observed soviet snow depth data and indian rainfall data for the period 1951 1994 have been statistically analyzed and results show that 57 of heavy snow events and 24 of light snow events over west eurasia are followed by deficient and excess ismr respectively out of all the extreme monsoon years care has been taken to identify those when eurasian snow was the most dominant surface forcing to influence ismr during the years of high low eurasian snow amounts in spring winter followed by deficient excess ismr atmospheric fields such as temperature wind geopotential height velocity potential and stream function based on ncep ncar reanalyses have been examined in detail to study the influence of eurasian snow on the midlatitude circulation regime and hence on the monsoon circulation results show that because of the west eurasian snow anomalies the midlatitude circulations in winter through spring show significant changes in the upper and lower level wind geopotential height velocity potential and stream function fields such changes in the large scale circulation pattern may be interpreted as precursors to weak strong monsoon circulation and deficient excess ismr the upper level velocity potential difference fields between the high and low snow years indicate that with the advent of spring the winter anomalous convergence over the indian region gradually becomes weaker and gives way to anomalous divergence that persists through the summer monsoon season also the upper level anomalous divergence centre shifts from over the northern hemisphere and equator to the southern hemisphere over the indian ocean and australia

building and testing age models for radiocarbon dates in lateglacial and early holocene sediments the growing importance of understanding past abrupt climate variability at a regional and global scale has led to the realisation that independent chronologies of past environmental change need to be compared between various archives this has in turn led to attempts at significant improvements in the required precision at which records can be dated radiocarbon dating is still the most prominent method for dating organic material from terrestrial and marine archives and as such many of the recent developments in improving precision have been aimed at this technique these include 1 selection of the most suitable datable fractions within a record 2 the development of better calibration curves and 3 more precise age modelling techniques while much attention has been focussed on the first two items testing the possibilities of the relatively new age modelling approaches has not received much attention here we test the potential for methods designed to significantly improve precision in radiocarbon based age models wiggle match dating and various forms of bayesian analyses we demonstrate that while all of the methods can perform very well in some scenarios caution must be taken when applying them it appears that an integrated approach is required in real life dating situations where more than one model is applied with strict error calculation and with the integration of radiocarbon data with sedimentological analyses of site formation processes

reconstruction of a lateglacial younger dryas mountain ice field in sutherland northwestern scotland and its palaeoclimatic implications quaternary geomorphological and geological mapping of a large area 1800 km2 in the northwestern scottish highlands has led to the reconstruction of a coherent mountain ice field approximately 45 km long and 30 km wide at its maximum extent this west sutherland ice field covered an area of 350 km2 and had a mean equilibrium line altitude of 334 m assuming that the outlet glaciers all reached their maxima simultaneously numerical dating strongly suggests a younger dryas 12 9 11 7 ka age of the mapped limits of this mountain ice field this study also shows that the area of northwestern scotland covered by younger dryas glaciers was five times larger than previously thought palaeo temperature estimates obtained from chironomid and beetle assemblages elsewhere have been used to reconstruct palaeo precipitation during the younger dryas for west sutherland using a previously published global empirical dataset annual precipitation of 2344 248 mm a 1 at sea level is inferred from our new palaeo glacier reconstruction suggesting slightly wetter conditions compared to the present day these figures are in good agreement with those reconstructed for other parts of the scottish highlands and islands and this may indicate a marked w e palaeo precipitation gradient during the younger dryas this paper goes on to discuss the wider validity of palaeo climatic reconstructions from inferred palaeo glacier geometries and presents a number of possible scottish lateglacial climate scenarios which warrant further testing copyright 2010 john wiley sons ltd

vegetation history and environmental development since ca 6000 cal yr bp in and around ispani 2 kolkheti lowlands georgia abstract the kolkheti lowlands of western georgia have a unique vegetation and a rich cultural history palynological and macrofossil analysis accompanied by ams 14c dates of the deposits of the ispani 2 mire near kobuleti allow the reconstruction of regional vegetation environmental history and local peatland development within the context of black sea level and cultural changes comparison of two adjacent peatland cores confirms spatial differences in wetland development prior to 5400 cal yr bp the ispani basin was a floodplain of an active river system where overbank deposits with fluvially transported castanea pollen were deposited subsequently a lake or lagoon developed in which reeds expanded these were succeeded by herb rich open alder carrs after 1900 cal yr bp carpinus and fagus expanded on the dry grounds where formerly quercus was more abundant also castanea declined local reedbeds that burned regularly succeeded the alder carr after 1000 cal yr bp a percolation bog developed resulting in the formation of 4 m of loose porous and largely undecomposed sphagnum austinii peat with molinia roots the upper 50 cm of the analysed section show extensive human impact on the landscape during the 20th century

mid to late holocene land use change and lake development at dallund s0 denmark study aims natural and cultural setting chronology and soil erosion history dallund s0 a lake on the island of funen denmark is positioned in a landscape that has been heavily impacted by human activities and land use change over thousands of years in 1998 a project was initiated to utilize a variety of palaeoecological analyses to investigate lake response to changing land use through the period of agricultural impact on the danish landscape i e the last 6000 years this paper describes the overall aims of the study the natural and cultural setting sediment core collection sampling and physical properties the chronology and erosion history the long term changes in the terrestrial and aquatic ecosystem are assessed in the following papers in this research set using i pollen ii diatoms macrofossils and pediastrum and iii zooplankton these papers are followed by a synthesis paper focusing on the linkage between land use change and lake development

non glacial paleoenvironments and the extent of weichselian ice sheets on severnaya zemlya russian high arctic abstract the extent of the barents kara sea ice sheet northern europe and russia during the last glacial maximum lgm in marine isotope stage mis 2 is controversial especially along the southern and northeastern russian high arctic margins we conducted a multi disciplinary study of various organic and mineral fractions obtaining chronologies with 14 c and luminescence dating methods on a 10 5 m long core from changeable lake 4 km from the vavilov ice cap on severnaya zemlya the numeric ages indicate that the last glaciation at this site occurred during or prior to mis 5d 4 early middle weichselian deglaciation was followed by a marine transgression which affected the changeable lake basin after the regression the basin dried up in late middle weichselian time ca 25 40 ka reworked marine sediments were deposited in a saline water body during the late weichselian mis 2 the basin was not affected by glaciation and lacustrine sediments were formed which reflect cold and arid climate conditions during the termination of the pleistocene and into the holocene warmer and wetter climate conditions than before led to a higher sediment input thus our chronology demonstrates that the northeastern margin of the lgm barents kara sea ice sheet did not reach the changeable lake basin this result supports a modest model of the lgm ice sheet in northern europe determined from numeric ice sheet modelling and geological investigations

pollen and plant macrofossils at lac de fully 2135 m a s l holocene forest dynamics on a highland plateau in the valais switzerland we use pollen stomata and plant macrofossil records to infer holocene timberline fluctuations and changes in forest composition at lac superieur de fully 2135 m a s l a small lake located near the modern regional timberline on a highland plateau in the central alps our records suggest that during the early holocene vegetation was rather open on the plateau eg heaths of dryas octopetala juniperus nana the only tree that was able to build major stands was betula other timberline trees eg pinus cembra and larix expanded in the catchment of the lake after 8200 cal bp when abies alba expanded at lower elevation the late appearance of these timberline trees contrasts with previous plant macrofossil records in the region which show that the tim berline had reached elevations up to at least 2350 m already at 11 000 cal bp we suggest that local climatic conditions may have delayed the expansion of closed stands of coniferous trees in the catchment of lac de fully until c 8200 cal bp when climate shifted to more humid and less continental conditions after c 4600 cal bp vegetation around the lake primarily responded to human impact which caused a local lowering of the timber line by at least 150 m

holocene palaeomagnetic secular variation recorded in multiple lake sediment cores from eastern finland summary holocene palaeomagnetic secular variation psv in inclination and declination recorded in the sediment remanent magnetization of two small lakes lake lehmilampi 63 37 n 29 06 e and lake kortejarvi 63 37 n 28 56 e in eastern finland is presented as an outcome of systematic coring eight cores 300 753 cm in length were investigated all samples lehmilampi n 1320 kortejarvi n 943 were subjected to palaeo and mineral magnetic analyses the directions of the characteristic remanent magnetization chrm were obtained from progressive alternating field demagnetization of the natural remanent magnetization nrm followed by principle component analysis the younger sections of the sediment columns in the studied lakes are annually laminated providing detailed chronologies for dating psv features back to 5100 cal bp the underlying older sections of the cores were dated by palaeomagnetic pattern matching in respect to varve dated lake nautajarvi psv data ojala saarinen 2002 thus yielding a composite age model covering nearly the whole holocene epoch average sedimentation rates ranging from 0 68 to 0 74 mm yr 1 enabled recording of changes in the geomagnetic field at decadal resolution the carriers of remanence are dominantly magnetite of stable single domain to pseudo single domain grain size accompanied by magnetic minerals of harder coercivity the sediments from both lakes exhibit strong and stable single component magnetizations nearly throughout the whole cores the sediment magnetization lock in delay is estimated to range between 80 and 100 yr psv data were transformed into time series and subsequently stacked to comprise north karelian stack and fisher statistics were used to calculate mean directions together with the 95 per cent confidence level 95 a comparison of declination and inclination features of the north karelian stack with previously published data expresses remarkable similarity therefore confirming the similar source behind the changes in the nrm directional records the high quality of the psv data extracted from lehmilampi and kortejarvi in terms of dating as well as amplitude reconstruction have a high potential to improve existing and future geomagnetic field models

lithology radiocarbon chronology and sedimentological interpretation of the lacustrine record from laguna potrok aike southern patagonia the 106 m long composite profile from site 2 of icdp expedition 5022 pasado at laguna potrok aike documents a distinct change in sedimentation patterns from pelagic sediments at the top to dominating mass movement deposits at its base the main lithological units correspond to the holocene to the lateglacial and to the last glacial period and can be interpreted as the result of distinct environmental variations overflow conditions might have been achieved during the last glacial period while signs of desiccation are absent in the studied sediment record altogether 58 radiocarbon dates were used to establish a consistent age depth model by applying the mixed effect regression procedure which results in a basal age of 51 2 cal ka bp radiocarbon dates show a considerable increase in scatter with depth which is related to the high amount of reworking validation of the obtained chronology was achieved with geomagnetic relative paleointensity data and tephra correlation

the holocene floods and their affinity to climatic variability in the western himalaya india abstract the present study in the middle satluj valley explores the sedimentary records of past floods with an objective to understand the climatic processes responsible for their genesis based on lithostratigraphy sedimentology and grain size variability 25 flood events are identified the geochemical data indicate that the flood sediments were mostly generated and transported from the higher himalayan crystalline and the trans himalaya our study suggests that the floods were generated by landslide lake outburst floods llofs during extreme precipitation events however the existing database does not allow us to negate the contribution from glacial lake outburst floods glofs field stratigraphy supported by optical chronology indicates four major flood phases that are dated to 13 4 10 4 8 3 3 6 2 2 1 4 and

carbon 14 wiggle match dating of peat deposits advantages and limitations carbon 14 wiggle match dating wmd of peat deposits uses the non linear relationship between c 14 age and calendar age to match the shape of a series of closely spaced peat c 14 dates with the c 14 calibration curve the method of wmd is discussed and its advantages and limitations are compared with calibration of individual dates a numerical approach to wmd is introduced that makes it possible to assess the precision of wmd chronologies during several intervals of the holocene the c 14 calibration curve shows less pronounced fluctuations we assess whether wiggle matching is also a feasible strategy for these parts of the c 14 calibration curve high precision chronologies such as obtainable with wmd are needed for studies of rapid climate changes and their possible causes during the holocene copyright c 2004 john wiley sons ltd

sea level rise and anthropogenic activities recorded in the late pleistocene holocene sedimentary infill of the guadiana estuary sw iberia abstract this study reviews data on sea level rise during the last 13000 yr cal bp 13 kyr as recorded in the estuarine sediments of the guadiana river se portugal sw spain we combined new data from a 63 m long borehole drilled through the entire postglacial sedimentary sequence with information on five previously studied cores by integrating sedimentological geochemical and palaeontological proxies we were able to make a palaeoenvironmental reconstruction of the guadiana terminal palaeovalley during the last 13 kyr and propose a curve of sea level rise for the sw iberian atlantic margin our foraminifera based palaeoecological reconstruction anchored to a 14 c age model reveals rapid sea level rise from 13 kyr interrupted during the younger dryas and resuming ca 11 5 kyr the pace of marine transgression slackened ca 7 5 kyr and since then has progressed upwards at a rate of 1 2 mm yr 1 holocene anthropocene sediments from two boreholes were also analysed to assess the timing levels and sources of trace metals produced by acid mine drainage from the iberian pyrite belt study of metal aluminium ratios through the profiles allowed background metal concentrations to be estimated from lithostratigraphic units older than ca 5 kyr i e unaffected by anthropogenic activities human activities are especially evident from 4 5 kyr the beginning of the copper age with anthropogenic sources of metal fluxes prevailing over natural sources especially pb co ni and mn and to a lesser extent zn cu and ni mining activities became particularly intensive between the late bronze age and the roman period 3 1 5 kyr when the highest metal enrichment factors were recorded ef pb 2 ef cd 10 ef cr 2 ef cu 3 ef zn 1 4 this study reveals the utility of postglacial sedimentary records for reconstructing historical changes in regional water sediment quality and separating natural and anthropogenic sources of geochemical contaminants

palaeohydrological evolution and implications for palaeoclimate since the late glacial at laguna de fuente de piedra southern spain abstract here we present a terrestrial multi proxy record of late quaternary environmental changes in the southern iberian peninsula covering approximately 30 ka this sedimentary record originates from a saline playa lake laguna de fuente de piedra hosted within a complex geological setting dominated by triassic claystones and evaporites jurassic carbonates and miocene deposits leading to a complex hydrogeological setting dissolution of evaporites in the catchment and intense evaporation are responsible for saline waters fluctuating in the basin thus salinity as palaeohydrological proxy requires a decoupling of internal and external hydrogeochemical processes the greatest accumulation of evaporites in the lfp late pleistocene holocene record coincides with a more humid or at least less evaporative period based on multi proxy data we describe five lacustrine lithofacies 2 5 and fluvial deposits 1 from sediment cores the proposed conceptual lake margin model contains three main lake water stages repeated within the sedimentary succession and building up the characteristic lithofacies lake water stages refer to a flooding stage influx outflux high water stage influx outflux and low water stage influx

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

assessing operative natural and anthropogenic forcing factors from long term climate time series of uttarakhand india in the backdrop of recurring extreme rainfall events over northwest himalaya abstract the entire indo himalayan region from northwest kashmir to northeast assam is facing prevalence of floods and landslides in recent years causing massive loss of property human and animal lives infrastructure and eventually threatening tourist activities substantially extremely intense rainfall event of 2013 c e between 15 and 17 june kicked off mammoth flash floods in the kedarnath area of uttarakhand state resulting in huge socioeconomic losses to the state and country uttarakhand is an important hilly region attracting thousands of tourists every year owing to numerous shrines and forested mountainous tourist spots though recent studies indicate a plausible weakening of indian summer monsoon rainfall overall recurrent anomalous high rainfall events over northwest himalaya e g 2010 2013 and 2016 point out the need for a thorough reassessment of long term time series data of regional rainfall and ambient temperatures in order to trace signatures of a shifting pattern in regional meteorology if any accordingly here we investigate 100 year long monthly rainfall and air temperature time series data for a selected grid 28 5 n 31 25 n 78 75 e 81 25 e covering most parts of uttarakhand state we also examined temporal variance in interrelationships among regional meteorological data temperature and precipitation and key global climate variability indices using advance statistical methods major findings are i significant increase in pre monsoon air temperature over uttarakhand after 1997 ii increasing upward trend in june july rainfall and its relationship with regional may temperatures iii monsoonal rainfall june july august and september jjas showing covariance with interannual variability in eurasian snow cover esc extent during the month of march and iv enhancing tendency of anomalous high rainfall events during negative phases of arctic oscillation obtained results indicate that under warming scenario jj rainfall over as may further increase with occasional extreme rainfall spells when ao index march is negative

the lateglacial and early holocene vegetation and environment in the dovre mountains central norway as signalled in two lateglacial nunatak lakes abstract by using heavy coring equipment in two high altitudinal lakes 1253 and 1316 m a s l at dovre central norway 1 1 5 m of unsorted coarsely minerogenic sediments were retrieved below the holocene organic sediments the minerogenic sequence contained well preserved pollen and chironomid remains revealing new and detailed palaeoenvironmental knowledge of the mountains in central norway during the last 5 6000 years of the lateglacial lg period however the lg chronology is based on biostratigraphical correlations and not on 14c dates due to low organic content in the minerogenic sediments the emerging lg nunataks probably indicating a thin and multi domed scandinavian ice sheet was rapidly inhabited by immigrating species which could explain the present centric distributions of certain arctic alpine plants the lg vegetation development included a pre interstadial dominated by mineral soil pioneers an interstadial dominated by shrubs and dwarf shrubs and the younger dryas cold period with recurring dominance of pioneers pollen and stomata of pinus and picea indicate their local lg presence at dovre lg climate oscillations are indicated by pollen stratigraphy and for the later part of lg also by chironomids these oscillations could correspond to heinrich event 1 gi 1d gi 1b and the younger dryas cold events the lg interstadial reached july mean temperatures of more than 7 8 c similar to the present chironomids colonized the lake already during the onset of the interstadial albeit at very low richness and abundances starting from yd there are sufficient chironomid head capsules to perform a temperature reconstruction the holocene warming of about 2 c initiated a vegetation closure from snow beds and dwarf shrub tundra to shrubs and forests birch forests established about 10 ka cal bp slightly earlier than pine forests alnus expanded ca 9 2 ka cal bp and a thinning of the local forests occurred from ca 7 ka cal bp two short lasting climate deteriorations found in the pollen record and the chironomid record may represent the preboreal oscillation and the 8 2 event the holocene thermal maximum is indicated around ca 7 8 7 3 ka cal bp showing a chironomid inferred july mean of at least 11 c this is ca 3 c warmer than today

quaternary of himalaya abstract tectonically active himalayan mountains evolves via feedbacks from deep earth and surface processes the complex interaction of various processes results into the landscape which is dynamic both at longer and shorter time scales the extreme hydrological events that possibly ride over a long term climate cycle bring the changes in the landscape that impact human societies more closely these events in the himalaya frequently cause huge damage to economy and human lives the geologist community under the umbrella of himalaya karakorum tibet hkt workshop in its 30 th edition convened a special session and deliberated on the subject this special issue quaternary of himalaya is an outcome of papers presented and discussion held during this session it consists of 18 papers in three sub themes i extreme events in himalaya ii paleoglaciation in himalaya and iii expressions of climate and neotectonics in himalaya

oxygen isotope wiggle matching as a tool for synchronising ice core and terrestrial records over termination 1 abstract in nw europe the large number of terrestrial records that are now available from termination 1 15 10 kcal yr bp form the basis for a highly detailed picture of lateglacial environmental change nevertheless the greenland oxygen isotope records grip gisp2 are still regarded as the best high resolution climate proxy for the north atlantic region in order to evaluate spatial contrasts and leads and lags in the climate system integration of ice core marine and terrestrial records is becoming increasingly important intimate objectives however comparisons between different environments require a common time scale for the proxy climate records stable isotope analyses performed on lateglacial lacustrine calcareous deposits in the netherlands provide a terrestrial oxygen isotope record comparable to that from the greenland ice core these atmospherically controlled lacustrine oxygen isotope signals not only constitute an independent palaeoclimatic proxy but provide the basis for synchronising records from these environments as well more over this synchronisation reveals some remarkable aspects concerning the timing of the oxygen isotope and palynological events as recorded in the netherlands above all oxygen isotope wiggle matching offers a means of correlating terrestrial and ice core records

stable isotope evidence of dual arabian sea and bay of bengal vapour sources in monsoonal precipitation over north india abstract high resolution time series data of hydrogen d and oxygen 18o isotope values of precipitation have been generated for the first time at kolkata eastern india where the summer monsoon clouds from bay of bengal bob commence their journey over india use of a rayleigh cum two component mixing model and comparison of kolkata data with the international atomic energy agency iaea global network of isotopes in precipitation gnip data base of new delhi suggest that the precipitation at new delhi cannot be explained by simple continental effect of a bob vapour source alone traveling and raining successively along kolkata new delhi route it is necessary to invoke an admixture of 20 vapour originating from the arabian sea with the vapour coming from bob and finally causing summer monsoon rains at new delhi the findings have major implications to the regional water vapour budget over india

high resolution climatic monsoonal variability reconstructed from a continuous 2700 year sediment record from northwest himalaya ladakh a chronologically well constrained sedimentary archive from upshi ladakh was studied using a multi proxy approach namely palynology environmental magnetism total organic carbon toc total nit

a review of the history of the baltic sea 13 0 8 0 ka bp abstract the dynamic history of the baltic sea during the millennia following the last deglaciation has been one of the main topics for many generations of quaternary geologists around the baltic sea based on the present state of knowledge and certain hypotheses a model for the development during the baltic ice lake yoldia sea and ancylus lake stages are presented the oresund strait was the threshold of the initial stage of the baltic ice lake and was eroded down to bedrock as a result of the isostatic uplift the emerging threshold forced the baltic ice lake to rise above sea level at ca 12 0 ka bp this gradual up damming ended at ca 11 2 ka bp when the large glacial lake was lowered 5 10m by possible subglacial drainage at mt billingen a glacial readvance during the younger dryas ended a ca 400 year long land bridge between sweden and the continent by blocking the former drainage route once again the baltic ice lake had to rise above sea level to be drained over the oresund strait at ca 10 5 ka bp a gradual ice recession began and 200 years later when the receding ice sheet could not withhold the up dammed water masses the final drainage of the baltic ice lake occurred which rapidly lowered the water level within the baltic basin with ca 25 m and ended the baltic ice lake stage the next stage the yoldia sea was characterized by a complex pattern of relative sea level changes with large differences within the baltic basin a very restricted baltic sea in the south and thus an extensive landbridge at ca 9 9 ka bp a short 100 200 years saline ingression is seen in the baltic sediment records from stockholm in the north to the southernmost parts of the yoldia sea the gradually shallower strait in south central sweden the narke strait ended the saline influence 300 400 years later the two remaining outlets west of lake vanern gota alv and otteid steinselva had become too shallow to swallow the outflowing yoldia sea waters at this stage the baltic lake vanern level could thus not fall in pace with the relative sea level fall outside the outlet areas this was the isolation of lake vanern and the baltic from the sea and the beginning of the ancylus lake since the water depth of the larger gota alv outlet had to be more or less maintained the ancylus lake level had to rise in pace with the uplift of the outlet region this caused a significant and rapid transgression 10 30 m in ca 300 years in the southern baltic which flooded large areas with recently immigrated pine forests since the oresund strait during the yoldia sea stage had been uplifted more than southerly areas the ancylus transgression ended with a new drainage pathway at ca 9 2 ka bp through the darss sill area in the southern baltic and northwards through the store belt strait this so called dana river had cut off the former large land bridge the quaternary deposits of this new threshold were eroded and a fairly rapid regression set in at ca 9 0 ka bp the dana river had eroded down to the sea level which isolated lake vanern from the ancylus lake and created a land bridge between southern sweden and northwards ca 800 years later when the sea level rose above the oresund threshold marine water could enter the baltic and at ca 8 0 ka bp brackish water characterized the southern baltic this marks the end of the ancylus lake

age depth relationship and accumulation rates in four sediment sequences from the retezat mts south carpathians romania abstract this study summarizes the results of radiocarbon dating and age depth modelling in four mountain lakes brazi gales bucura and lia in the retezat mountains altogether 69 ams 14 c measurements were performed on these deposits mostly on terrestrial plant macrofossils in several cases plant macrofossils aquatic animal remains cladoceran eggs and bulk sediment were measured from the same depth allowing for the comparison of various sediment components in terms of their dating potential age depth models were developed using both bayesian modelling with the bacon and smooth spline curve fitting with the clam software in this study bayesian models are applied to identify outlier 14 c dates while smooth spline models are used to model sediment accumulation age depth relations as these are more likely to follow natural deposition time changes of lake sediments changes in sediment deposition times dt in relation to catchment size and climate are also studied dt varied considerably in the late glacial lg part of the records the sediment sequence characterised by high deposition rates during the late glacial dt maximum around 100 110 years cm 1 was defined by small catchment size lake brazi 6 ha surface area 0 5 ha in contrast much slower lg sediment deposition in the southern slope lake characterised by large catchment area lake lia 171 ha 20 years cm 1 principally reflecting strong erosion in these catchment areas at times when vegetation cover was scarce holocene was characterised again by variable dt values but only lake gales showed extreme values 62 110 years between 10 900 and 6050 cal yr bp followed by much slower sediment deposition in the last 6000 years av 29 years cm 1 generally sediment deposition times were largely dependent on the stability and vegetation cover of the slope in the case of high altitude deep lakes while lower altitude shallow lakes showed slower sediment deposition time in the early and mid holocene when summer insolation was higher than today this reflects that in these shallow lakes in lake organic production probably increased with summer insolation which was a significant driver in the rate of deposition

timing and east west correlation of south swedish ice marginal lines during the late weichselian abstract the retreat of the late weichselian ice sheet over the southern part of sweden is marked along the southwest coast by distinct marginal moraine ridges their timing can directly and indirectly be assessed based on a number of radiocarbon dates and pollen stratigraphic investigations on lake sediment sequences adjacent to the ice marginal lines along the southeastern side of the peninsula the ice recession has been reconstructed based on a combination of clay varve chronology pollen and radiocarbon stratigraphy a morphological correlation of ice marginal lines between the west and east coast is problematic since the distinct west coast moraines cannot be followed through the central part of the peninsula towards the east coast this paper is an attempt to reconstruct an age equivalent west east extension of the ice recession lines on the basis of existing data sets for our correlation we use calibrated radiocarbon ages for ice marginal deposits on the west coast and compare these with a partly radiocarbon dated clay varve chronology on the east coast we conclude that the two oldest moraines on the west coast formed at 18 000 16 000 and 15 400 14 500 cal yr bp respectively during the following rapid deglaciation which may have coincided with the beginning of the bolling pollen zone large parts of southernmost sweden became ice free except for higher elevated areas where stagnant ice remained for another 400 500 yr a best guess is that the formation of the next younger ice marginal lines may have occurred at 14 400 14 200 14 200 and 13 400 cal yr bp and during the younger dryas cold event

an event stratigraphy for the last termination in the north atlantic region based on the greenland ice core record a proposal by the intimate group it is suggested that the grip greenland ice core should constitute the stratotype for the last termination based on the oxygen isotope signal in that core a new event stratigraphy spanning the time interval from ca 22 0 to 11 5 k grip yr bp ca 19 0 10 0 k 14 c yr bp is proposed for the north atlantic region this covers the period from the last glacial maximum through termination 1 of the deep ocean record to the pleistocene holocene boundary and encompasses the last glacial late glacial of the traditional northwest european stratigraphy the isotopic record for this period is divided into two stadial episodes greenland stadials 1 gs 1 and 2 gs 2 and two interstadial events greenland interstadials 1 gi 1 and 2 gi 2 in addition gi 1 and gs 2 are further subdivided into shorter episodes the event stratigraphy is equally applicable to ice core marine and terrestrial records and is considered to be a more appropriate classificatory scheme than the terrestrially based radiocarbon dated chronostratigraphy that has been used hitherto 1998 john wiley sons ltd

lacustrine radiocarbon reservoir ages in co ngoin and zige tangco central tibetan plateau abstract a series of 14 c ages were made in two lake sediment cores from co ngoin and zige tangco central tibetan plateau china using bulk organic carbon plant remains chitin of cladocera and carbonates the old 14 c ages of the surface sediments in both cores suggests that there is a significant reservoir effect in these lakes the magnitude of the reservoir age of different material is variable authigenic carbonate has the largest reservoir age while plant remains and chitin show smaller deviations due to a lack of terrestrial macrofossils at most depths a regression approach was used to obtain the approximate 14 c reservoir correction for bulk organic matter which is 3260 14 c bp and 2010 14 c bp for co ngoin and zige tangco respectively

pitfalls in the ams radiocarbon dating of terrestrial macrofossils the ams 14 c technique has the advantage that small samples of late quaternary age can be dated with high accuracy and that errors due to reservoir effects can be avoided if specifically determined terrestrial micro and macrofossils are measured however to obtain such high accuracy measurements it is important how small samples are handled prior to treatment in the radiocarbon laboratories here we present a set of 51 ams 14 c measurements of which 31 dates gave expected ages and 20 dates resulted in anomalously young ages despite the fact that all samples consisted of clearly identified late weichselian terrestrial plant macrofossils to evaluate possible sources of error we compared these samples in respect to preparation methods sample storage and sample weight our results show that the long term storage of wet macrofossil samples appears to have a significant effect on the radiocarbon age obtained even when the samples are kept cool fungi or micro organisms may easily be incorporated into a sample during preparation and identification and can easily contribute to the contamination of a sample if stored cool and wet for several months 1998 john wiley sons ltd

late holocene glacier growth in svalbard documented by subglacial relict vegetation and living soil microbes much renewed research interest in arctic regions stems from the increasing concentration of atmospheric greenhouse gases and the alleged climatic sensitivity of high latitude areas glacier and permafrost changes are among a number of proxies used for monitoring past and present arctic climate change here we present observations on frozen in situ soil and vegetation found below cold based glacier longyearbreen 78813 n 2 km upstream from the present glacier terminus dating of the relict vegetation indicates that the glacier has increased in length from about 3 km to its present size of about 5 km during the last c 1100 years the meteorological setting of non surging longyearbreen suggests this example of late holocene glacier growth represents a widespread phenomenon in svalbard and in adjoining arctic regions in addition we use the subglacial permafrozen soil system to evaluate microbial survival capacity over considerable time periods and we present evidence for microbes having survived more than 1100 years in a subglacial permafrozen state

pollen and macrofossils attributable to fagopyrum in western eurasia prior to the late medieval an intercontinental mystery abstract the widespread perception that buckwheat fagopyrum esculentum and f tataricum did not occur in western eurasia prior to the late medieval is challenged by numerous pollen finds we traced some 240 localities from the area with pollen or macrofossils attributed to fagopyrum in often much earlier time slices this paper evaluates various explanations for these finds within the context of palaecological methods vegetation history and cultural development the clear morphological characteristics make large scale misidentification of the pollen unlikely although some records are suspect contamination is improbable for the vast majority of the pollen diagrams also long distance transport of pollen of fagopyrum snowdenii or oxygonum from africa seems unlikely as the pollen rain of that continent hardly contains that pollen the option that fagopyrum was present in western eurasia already much earlier than the late medieval must therefore be seriously considered cultivated species may have reached the area by trade between the mediterranean and eastern chinese realms which was regular since 2000 bce as the low pollen values argue against large scale cultivation the taxon may merely have occurred as a weed or its pollen was transported with other products and subsequently re emitted the pervasive notion that buckwheat was cultivated on large scale by the scythians in the ukrainian realm since 800 bce is highly ambiguous and probably wrong there are some indications that wild fagopyrum or a related taxon may have occurred widespread in eurasia during the pleistocene glaciations and the early middle holocene i e predating 2000 bce

effects of handling storage and chemical treatments on δ13c values of terrestrial fossil organic matter with the need to interpret small isotopic variations 13c analyses of sedimentary organic matter are more and more widespread in the field of paleo climatology recent developments require an evaluation of the reliability and reproducibility of the whole data acquisition chain literature abounds in protocols for sediment pretreatment prior to physical measurements these procedures differ at every step from sampling handling and storage conditions to leaching procedure without cross evaluation in this study we focus on two sediment samples a modern temperate soil and a 70 ka typical loess we review different protocols that characterize each step of the sediment pretreatment handling and storage conditions are tested e g finger skin contact mild to high temperature oven dry and freeze drying likewise different decarbonation protocols are compared wet decarbonation under cold 0 6 n hcl 2 n hcl and boiling 1 n hcl and acid fuming with 36 hcl this study identifies up to 1 5 isotopic shifts linked to experimental bias this large bias might be at the origin of erroneous paleoclimatic interpretation on the basis of these results we propose specific treatments adapted to the sample type

lake heimtjonna at dovre mid norway reveals remarkable late glacial and holocene sedimentary environments and the early establishment of spruce picea abies alder alnus cf incana and alpine plants with present centric distributions abstract two and a half meters of sediments from lake heimtjonna in the scandes mountains reveal changes in the vegetation climate and sediment environment since deglaciation the lake was deglaciated in the late glacial lg perhaps as early as 16 18 ka cal bp after deglaciation the sediment environment at the heimtjonna coring point was extraordinary and challenging to interpret the genesis of the 1 7 m basal unsorted sediments including large stones is discussed concluding that the layer was rafted by lake ice after the lg deglaciation the younger dryas yd established a semi perennial lake ice that stopped the deposition of the ice rafted stone rich sediments in the early holocene the unstratified and well sorted clayey silt shows fluvial origin in late holocene strong flood activity including the major flood disaster stor ofsen in ad 1789 caused a sediment hiatus at the coring point from ca 9 5 ka cal bp to ca 250 a cal bp the lg interstadial warming initiated the succession from pioneer plants on mineral soils towards local dwarf shrub heath july temperatures reached at least 7 8 oc in the lg and early holocene papaver radicatum artemisia norvegica and campanula cf uniflora today occurring at dovre and with centric scandinavian distributions locally established all have previously been connected to weichselian survival on nunatak refugia continuous pollen curves of spruce picea abies support the much debated lg and early holocene presence of spruce in the scandes mountains for the first time it is shown that both grey alder alnus incana and armeria occurred in the scandes in the lg and early holocene due to dating errors lg ages is exclusively based on stratigraphical correlations and considerations the lg chronology must be thoroughly tested by future studies providing reliable ams 14c dates of terrestrial fossils

limits to resolving catastrophic events in the quaternary fluvial record a case study from the nene valley northamptonshire uk flood events within rivers are responsible for much erosion and deposition thus deposits laid down during floods could potentially comprise the bulk of the quaternary fluvial record however it is difficult to detect individual flood events as effectively illustrated by the middle devensian weichselian to holocene fluvial sequence from the nene valley northamptonshire described in this paper this is due to limits in the resolution of sedimentological palaeontological and geochronological techniques geochronological techniques have the highest resolution but error bars of c 50 years radiocarbon and up to 2 ka optically stimulated luminescence in the late glacial do not allow detection of floods lasting only a few weeks or less geochronology is however essential for linking periods of fluvial deposition to climatic phases at the marine isotope substage scale thus multiple age determinations show remnant middle devensian deposits within a facies association mainly of younger dryas age showing similar fluvial response to climate during both time periods palaeontological assemblages suggest that climate was also similar although with some subtle differences determining average fluvial activity in response to broad climate phases improves understanding of how rivers behave over long time periods even though determination of the role of flood events in the quaternary fluvial record remains elusive

late weichselian environmental history in southeastern sweden during the deglaciation of the scandinavian ice sheet abstract late weichselian litho bio and chronostratigraphy 14 c and varves in southeastern sweden provide a detailed picture of the deglaciation pattern and dynamics shore displacement late glacial sedimentation and history of the landscape vegetation and climate two plausible glacial models were tested against lithologic chronologic and climatic data permafrost at and outside the ice margin and topographic conditions beneath the ice apparently caused inward spread of frozen glacier bed conditions this led to a buildup of a large zone of debris rich basal ice a climatic amelioration about 12 700 yr b p changed the temperature profile in the ice sheet deposition of basal melt out till began at the previously frozen glacier bed and a rapid recession of the clean ice set in thin exposed debris rich basal ice which was separated from the active ice margin about 150 yr later in this zone of stagnant ice there followed a 200 300 yr period marked by subglacial and supraglacial melt out and resedimentation forming a large hummocky transverse moraine the mild climate favored rapid plant immigration and a park tundra was established the gradual closing of the landscape was interrupted by a 100 to 150 yr period of tundra vegetation and a cool dry climate with local vegetational differences caused by differences in soil moisture about 12 000 yr b p a second climatic amelioration set in and during the next 1000 yr a birch and pine woodland gradually developed soils stabilized and empetrum heaths became abundant as the climate gradually deteriorated at the end of this period by 11 000 yr b p the area had become a tundra again with scattered birch stands dominated by herbs such as artemisia chenopodiaceae grasses and sedges some 500 yr later a birch pine woodland again succeeded and within about 500 yr the vegetation changed to a rather closed woodland as the climate ameliorated further however the time lag between climatic and vegetation change was considerable