holocene glacial activity and climatic variations in the swiss alps reconstructing a continuous record from proglacial lake sediments cores recovered from proglacial lake silvaplana swiss alps were investigated to examine the influence of holocene glaciers on lacustrine sedimentation during times of glacial activity in the catchment the sedimentation in the lake is dominated by the input of silt and clay sized material delivered by glacial meltwaters the deposition of fine grained material and the formation of varves reflect the existence of glaciers in the catchment and can therefore be used for the reconstruction of glacial history sedimentation rates are up to nine times higher in the varved than in the non varved sediments indicating significantly higher erosion rates under glaciated catchment conditions glacial varves were deposited in lake silvaplana during glacial retreat in the latest pleistocene and early holocene until 9400bp non varved deposits having a higher organic content and coarser grain sizes accumulated at lower rates when glacial activity was absent or negligible within the catchment between 9400 and 3300 bp

schmidt hammer exposure age dating shd performed on periglacial and related landforms in opplendskedalen geirangerfjellet norway implications for mid and late holocene climate variability schmidt hammer exposure age dating shd was applied to a variety of boulder dominated periglacial landforms in an attempt to establish a local mid late holocene chronology for the geirangerfjelle

the chronology of holocene alluvial sediments from the wetterau germany provided by optical and 14c dating holocene floodplain chronologies are often hard to establish the principal limitation being the scarc ity of organic remains in the present study optical dating of flood loam was carried out in

glacier variations in breheimen southern norway relative age dating of holocene moraine complexes at six high altitude glaciers lichenometric evidence and schmidt hammer r values are used to date holocene moraine sequences in front of six high altitude 1500 m glaciers in breheimen central southern norway at three glacier forelands with southerly aspects hogsetbreen vestre hoybre and ostre hoybre relatively small 4 m high discrete boulder moraine ridges are shown to date from the little ice age the remaining three glaciers ostre tundradalskyrkjabre nordre tundradalskyrkjabre and hestdalshogdibreen with northerly or easterly aspects and large multiridged rampart like moraine complexes 15 30m thought to be ice cored and of the push deformation type lie above the local altitudinal limit of permafrost negatively skewed r value distributions from these moraine complexes provide critical evidence for pre little ice age glacier expansion as they indicate the survival of long weathered boulders on moraine surfaces where late lying snow may reduce or prevent lichen growth formation of the moraine complexes ap

glacier variations in breheimen southern norway dating little ice age moraine sequences at seven low altitude glaciers moraine sequences in front of seven relatively low altitude glaciers in the breheimen region of central southern norway are described and dated using a multi proxy approach to moraine stratigraphy lichenometric dating based on the rhizocarpon subgenus is used to construct a composite moraine chronology which indicates eight phases of synchronous moraine formation ad 1793 1799 1807 1813 1845 1852 1859 1862 1879 1885 1897 1898 1906 1908 and 1931 1933 although the existence of a few cases of older moraines possibly dating from earlier in the eighteenth or late in the seventeenth centuries cannot be ruled out by lichenometry schmidt hammer r values from boulders on outermost moraine ridges suggest an absence of holocene moraines older than the little ice age twenty three radiocarbon dates from buried soils and peat associated with outermost moraines at three glaciers tverreggibreen storegrovbreen and greinbreen also indicate that the little ice age glacier maximum was the neoglacial maximum at most if not all glaciers several maximum age estimates for the little ice age glacier maximum range between the fifteenth and seventeenth centuries with the youngest from a buried soil being ad 1693 a pre little ice age maximum cannot be ruled out at greinbreen however where the age of buried peat suggests the outermost moraine dates from ad 981 1399 at variance with the lichenometric evidence glaciofluvial stratigraphy at tverreggibreen provides evidence for minor glacier advances about ad 655 963 and ad 1277 1396 respectively copyright 2003 john wiley sons ltd

composition and origin of natural gases accumulated in the polish and ukrainian parts of the carpathian region gaseous hydrocarbons noble gases carbon dioxide and nitrogen abstract ten natural gas samples associated and non associated with oil in the polish and ukrainian flysch carpathians and mesozoic basement of the carpathian foredeep were analysed for molecular and stable isotope compositions as follows 12 13c in ch4 c2h6 c3h8 and co2 1 2h in ch4 14 15n in n2 and 3 4he 20 21 22ne 36 38 40ar 84kr and 132xe in noble gases the gaseous hydrocarbons both in the silesian unit of the outer flysch carpathians and mesozoic basement are generally genetically related to thermogenic processes and occasionally to microbial carbon dioxide reduction these gases were mainly generated from mixed type ii iii kerogen during middle stage of the low temperature thermogenic processes gaseous hydrocarbons from starunia in the boryslav pokuttya unit were generated from type ii kerogen during middle stage of the low temperature thermogenic processes he is generally of crustal origin with more than 99 2 of radiogenic 4he but appreciable amount of 3he is probably derived from the upper mantle the 3he might have been derived from the pieniny klippen belt deep seated fault system or neogene and pleistocene andesitic and basaltic volcanism occurred in the eastern carpathian area nucleogenic 21ne and 22ne were analysed in all the samples the nucleogenic 21ne shows good correlation with radiogenic 4he with the production ratio of 4he 21ne 1 3 107 in the crust these isotopic values indicate a common source for these gases where both the nuclear reactions of decay and n are occurring concentrations of radiogenic 4he and 40ar and excess 21ne in the samples from the mesozoic basement are generally higher and more scattered compared with those in the silesian unit the larger concentrations of radiogenic and nucleogenic isotopes in the natural gases from the mesozoic basement is probably related to older geological formations than younger formations of the silesian unit carbon dioxide was generally generated during the thermal transformation of organic matter and occasionally during microbial processes nitrogen was mainly generated during thermal transformation of organic matter and also originated from atmosphere a least part of carbon dioxide and nitrogen may have been produced in crust

release of mantle helium from forearc region of the southwest japan arc abstract shikoku japan is an island located on the forearc region of the western sector of the southwest sw japan arc that was formed by subduction of the philippine sea plate beneath the eurasian plate noble gas isotope analyses were carried out for 30 bubbling gas samples and spring water samples collected in shikoku in addition chemical and carbon isotope analyses were conducted for six gas samples observed 3 he 4 he ratios were 0 17 r r a to 3 56 r r a showing that several samples contain mantle helium components although some samples contain helium of crustal origin geographical distributions of 3 he 4 he ratios show that high 3 he 4 he ratios originate mainly from two areas one along the median tectonic line mtl a major active fault in japan the other coinciding with a region in which non volcanic long period tremors occur about 30 km deep obara k 2002 nonvolcanic deep tremor associated with subduction in southwest japan science 296 1679 1681 this fact indicates that fluids liberated from the slab in the forearc region cause deep tremors and fracturing within the crust thereby easing the transfer of fluids to the surface that are mixed with mantle helium to the surface an active fault system can also provide an efficient path for mantle helium transfer

climate control of decadal scale increases in apparent ages of eogenetic karst spring water abstract water quantity and quality in karst aquifers may depend on decadal scale variations in recharge or withdrawal which we hypothesize could be assessed through time series measurements of apparent ages of spring water we tested this hypothesis with analyses of various age tracers 3h 3he sf6 cfc 11 cfc 12 cfc 113 and selected solute concentrations dissolved oxygen do no3 mg and so4 from 6 springs in a single spring complex ichetucknee springs in northern florida over a 16 yr period these springs fall into two groups that reflect shallow short group 1 and deep long group 2 flow paths some tracer concentrations are altered with cfc 12 and cfc 113 concentrations yielding the most robust apparent ages these tracers show a 10 20 yr monotonic increase in apparent age from 1997 to 2013 including the flood recession that followed tropical storm debby in mid 2012 this increase in age indicates most water discharged during the study period recharged the aquifer within a few years of 1973 for group 2 springs and 1980 for group 1 springs inverse correlations between apparent age and do and no3 concentrations reflect reduced redox state in older water positive correlations between apparent age and mg and so4 concentrations reflect increased water rock reactions concentrated recharge in the decade around 1975 resulted from nearly 2 m of rain in excess of the monthly average that fell between 1960 and 2014 followed by a nearly 4 m deficit to 2014 this excess rain coincided with two major el nino events during the maximum cool phase in the atlantic multidecadal oscillation although regional water withdrawal increased nearly 5 fold between 1980 and 2005 withdrawals represent only 2 5 of ichetucknee river flow and are less important than decadal long variations in precipitation these results suggest that groundwater management should consider climate cycles as predictive tools for future water resources

discovery of early holocene wood and peat on the forefield of the pasterze glacier eastern alps austria during recent years a number of fragments of pinus cembra and larix decidua as well as peat were found in front of the tongue of the pasterze glacier in the eastern alps these were washed out by the stream from under the present ice the wood originates from trees which reached ages of upto 400 years or more radiocarbon dating shows them to come from the early holocene they indicate that between cal bc 8100 and cal bc 6900 the pasterze glacier was smaller than at present the pasterze glacier advanced around cal bc 6900 a lump of peat shows that around cal bc 6300 at the latest the pasterze glacier was again smaller than today the radiocarbon age of the fulvic acid fraction of thepeat suggests that growth could have continued until cal bc 5430 5080 further wood samples dated to around cal bc 4800 and cal bc 3800 show that at these times the pasterze glacier was smaller than at present the pasterze glacier had a relatively limited extent over long periods inthe early holocene thus mostly favou

holocene glacier activity at the southwestern part of hardangerjokulen central southern norway evidence from lacustrine sediments lacustrine sediments from lake isdalsvatn downstream from the southwestern margin of the plateau glacier hardangerjokulen central southern norway show that the lake received glacial meltwater until 7890 95 bp a thin bluish grey minerogenic silt layer probably reflects a short glacial re advance between 7005 90 and 6835 150bp after the latter date inflow of glacial meltwater ceased indicating that small or more probably no glaciers existed on the southwestern hard angerjokulen plateau a drop in organic content and a slight increase in detrital content inferred from magnetic susceptibility at 120cm depth in the core may indicate some glacier activity in the catchment from about 3400 bp textural changes at 50cm depth indicate increased neoglacial activity in the upper catchment area from 2265 80 bp differences in glacier chronologies between the southern and northern sectors of hardangerjokulen may be explained partly by different glacier responses to the precipitation and wind distribu

scandinavian glacial and climatic fluctuations during the holocene abstract historical documents and lichenometric studies give a detailed picture of the little ice age in scandinavia there was a large advance in norway which has been dated at a few places to 1750 small readvances during the retreat occurred around a d 1780 1810 1840 1850 1850 1870 1890 1910 and 1930 in sweden most of these advances have been recognized and in addition extensive advances are dated by lichenometry to around a d 1600 1650 and 1700 1720 soils buried beneath moraines often yield radiocarbon dates that are much too old methods dependent on these must therefore be used with care evidence for pre little ice age advances are often considered equivocal the most reliable information is probably provided by studies of lacustrine sediments combining information from all sources the most significant pre little ice age glacier advances most likely occurred in 7 5 5 1 4 5 3 2 2 8 2 2 1 9 and 1 5 1 1 radiocarbon ka bp advances that were less extensive or for which there is less evidence occurred around 6300 5600 2500 940 600 560 and 380 bp

widespread distribution of ascending fluids transporting mantle helium in the fore arc region and their upwelling processes noble gas and major element composition of deep groundwater in the kii peninsula southwest japan abstract chemical and isotopic studies including analyses of noble gases were comprehensively conducted on the groundwater of the entire kii peninsula which is located in the fore arc region of southwest japan groundwater of na cl hco3 na hco3 cl and na cl types was shown to be distributed across the whole area groundwater in the inland central part of the peninsula shows relatively low salinity whereas groundwater from the area along the ene trending median tectonic line mtl on the north side of the peninsula shows high salinity up to 18 800 mg l of cl and the presence of unusual heavy oxygen isotopes this trend is similar to that documented in saline waters from the arima region the so called arima type thermal water high 3he 4he ratios relative to the atmospheric value up to 6 7 ra were recorded throughout the kii peninsula covering a wider area than documented previously the saline groundwater is also strongly depleted in 20ne and heavy noble gases from the wide distribution of high 3he 4he values and the associated 20ne and cl concentrations we infer that aqueous fluids derived from dehydration of the subducting slab are present at depth beneath almost the entire kii peninsula these aqueous fluids may ascend along the major north dipping boundary faults the isotopic composition of groundwater from the southern part of the peninsula suggests that the contribution from these dehydration derived fluids is relatively small in this region however volatile components e g noble gases and co2 in the groundwater of this area may originate from the dehydration derived fluids upwelling of arima type thermal water of the na cl hco3 type is expected to undergo a phase separation of volatile species due to decompression as the fluid ascends the variety of water types documented may be due to this water gas separation and the subsequent incorporation of gaseous species into shallow meteoric groundwater the observed high 3he 4he ratios in the absence of a mantle wedge below the southern part of the kii peninsula may reflect the oblique ascent of these fluids along north dipping boundary faults

a continuous holocene glacial record inferred from proglacial lake sediments in banff national park alberta canada abstract sediment cores from three proglacial lakes in northern banff national park alberta preserve a record of holocene glacial activity upvalley which is more continuous and better dated than available surficial records dating of the cores is based on tephrochronology and 16 ams14c ages of terrestrial macrofossils all cores contain a threefold sequence of lacustrine sediments overlying a late pleistocene diamicton basal lacustrine sediments 10 10014c yr old contain little organic matter sediment composition indicates a large glacigenic contribution a sharp increase in organic content marks the beginning of the altithermal interval at all three lakes this transition occurred abruptly at about 10 10014c yr b p at crowfoot lake and possibly more gradually at the other lakes altithermal sediments contain relatively little glacigenic material and during most of the altithermal glaciers may have been absent above crowfoot and bow lakes glaciers draining into hector lake appear to have persisted through the altithermal a subsequent decrease in organic content in each lake reflecting increased clastic sedimentation marks the end of the altithermal and the onset of neoglacial ice advances the transition took place between about 5800 and 400014c yr b p and may be time transgressive beginning earlier in hector lake than in crowfoot lake changing neoglacial clastic sedimentation rates through the neoglacial interval indicate two main periods of increased glacier extent between ca 3000 and 1800 varve yr ago ca 2900 190014c yr b p and during the last several hundred years during the intervening period glaciers were less extensive but much more extensive than during the recessions of the altithermal interval

dating ultra deep mine waters with noble gases and 36cl witwatersrand basin south africa abstract concentrations and isotopic ratios of dissolved noble gases 36cl d and 18o in water samples from the ultra deep gold mines 0 718 to 3 3 km below the surface in the witwatersrand basin south africa were investigated to quantify the dynamics of these ultra deep crustal fluids the mining activity has a significant impact on the concentrations of dissolved gases as the associated pressure release causes the degassing of the fissure water the observed under saturation of the atmospheric noble gases in the fissure water samples 70 98 normalized to asw at 20 c and 1013 mbar is reproduced by a model that considers diffusive degassing and solubility equilibration with a gas phase at sampling temperature corrections for degassing result in 4he concentrations as high as 1 55 10 1cm3stp4he g 1 40ar 36ar ranging between 806 and 10331 and 134xe 132xe and 136xe 132xe ratios above 0 46 and 0 44 respectively corrected 134 136 xe 132xe and 134 136 xe 4he ratios are consistent with their production ratios whereas the nucleogenic 4he 40ar and 134 136 xe 40ar ratios generally indicate that these gases are produced in an environment with an average u th k content 2 3 times above that of crustal average in two scenarios one considering only accumulation of in situ produced noble gases the other additionally crustal flux components the model ages for 14 individual water samples range from 13 to 168 ma and from 1 to 23 ma respectively the low 36cl ratios of 4 37 10 15 and comparatively high 36cl concentrations of 8 350 10 15 atoms 36cl l 1 reflect subsurface production in secular equilibrium indicating an age in excess of 1 5 ma or 5 times the half life of 36cl in combination the results suggest residence times of the fluids in fissures in this region up to 3 3 km depth are of the order of 1 100 ma we cannot exclude the possibility of mixing and that small quantities of younger water have been mixed with the very old bulk

the effect of thermal transfer on the zeroing of the luminescence of quartz from recent glaciofluvial sediments abstract the natural optically stimulated luminescence osl response of quartz grains extracted from a range of recent glaciofluvial and other glaciogenic sediments from western greenland is presented all samples were deposited within the last 10 years many only days or hours before collection consequently we would expect to measure zero or very small d e values had optical resetting of the osl signal been complete in the case of most samples d e values in the range 0 5 10 gy are observed while higher values are observed for a handful of samples however the regenerated osl growth curves constructed after daylight exposure of at least several hours also show large apparent d e values negative x axis intercepts corresponding samples from four different locations in the indian himalaya display similar osl characteristics the measurement of several regenerated osl growth curves omitting the preheat procedure which normally precedes osl measurement confirms that a significant degree of thermal transfer is occurring during the preheating it is this thermal transfer of charge during the preheat which is responsible for a significant contribution to the large apparent d e values observed for the regenerated osl growth in this paper we describe combined osl and tl measurements which have been used to monitor the charge transfer in detail for one sample an attempt is made to describe the charge transfer behaviour and we discuss methods appropriate to eliminating the unwanted effects of this phenomenon during osl dating preliminary results from the application of these techniques are presented and the implications of these observations for the osl dating of glaciogenic sediments are discussed

the mineral magnetic properties of an annually laminated holocene lake sediment sequence in northern sweden detailed mineral magnetic measurements were conducted on a 9000 year varved lake sediment sequence in northern sweden lake sarsjon the results demonstrate that the paramagnetic susceptibility reflects the concentration of detrital minerogenic material in the lake sediments which is controlled to a large extent by the intensity of the spring snow melt in contrast the concentration of ferrimagnetic magnetite reflected by initial magnetic susceptibility and magnetic hysteresis parameters is positively correlated to the concentration of organic carbon which is most likely of an autochthonous origin this magnetite has magnetic properties that are characteristic of stable single domain magnetite grains produced by magnetotactic bacteria the paramagnetic susceptibility record clearly points to a climatic excursion in the early holocene between 6100 174 bc and 5700 167 bc which can be correlated to an d18o excursion a cold event in the greenland ice cores and lake sediments in southern germany an

lake sediment studies of holocene glacial activity in the karsa valley northern sweden contrasts in interpretation a multidisciplinary study of lake sediments deposited in lake basins in the karsa valley northern sweden suggests the complete disappearance of the karsa glacier during the early and mid holocene glacier reformation indicated by the deposition of sediment with a fine particle size distribution and low organic content in the three lakes took place at c 3000 14 c years bp this interpretation contrasts with a study based on the weight loss on ignition of the same sediments which suggests several glacier advances throughout the entire holocene the contrasting interpretation is due to different methodological approaches single core site studies should be avoided in the future and only features that are consistently reproducible and can be dated in spatially distributed cores should be interpreted in terms of variations in glacial activity environmental conditions and ultimately climate

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

the greenland 8200 cal yr bp event detected in loss on ignition profiles in norwegian lacustrine sediment sequences high resolution loss on ignition analyses of lacustrine sediment cores from both proglacial and non glacial lakes in southern norway have revealed a specific pattern characterised by a significant two peaked reduction of the loss on ignition values in the basal half of the cores in non glacier fed lakes the loss on ignition variations are interpreted to reflect mainly lake productivity and hence variability in surface summer air temperature sediments deposited in proglacial lakes however reflect mainly the glacier activity in the lake catchment bulk ams radiocarbon dates from the core sequences and the loss on ignition curve pattern suggest that this event correlates with the 8200 cal yr bp event recorded in the grip and gisp2 greenland ice cores termed the finse event in southern norway copyright 2001 john wiley sons ltd

holocene millennial scale summer temperature variability inferred from sediment parameters in a non glacial mountain lake danntjorn jotunheimen central southern norway holocene changes in summer temperature in the jotunheimen area have been inferred from variations in several sediment parameters from a composite combined from two overlapping sediment cores lake core record mean time resolution of 15 years from lake danntjorn a small mountain lake located close to the modern pine tree limit in jotunheimen central southern norway loss on ignition analysis at contiguous 0 5 cm intervals throughout the cores revealed that the variations in residue after ignition of the sediments at 5501c in the upper 260 cm 8500 calendar years were not associated with variations in magnetic susceptibility in the basal deglacial and early holocene sequence of the lake sediments however the two sediment parameters fluctuated mainly in phase in addition the biogenic silica bsi concentration is relatively high thus in the early part of the holocene the variations in the residue were probably primarily driven by input of minerogenic detrital material inwash and or windblown and biological productivity including bsi from diatoms in the lake itself and in the lake surroundings from approximately 8500 calendar years bp variations in the residue probably primarily reflect variations in low minerogenic low magnetic susceptibility with little variations and diatom bsi productivity as demonstrated with analysis of bsi concentration between 260 and 233 cm 8500 7760 calendar years bp the highest residue values probably mainly reflecting high diatom productivity occurred at 7800 7200 7000 6700 6200 5400 5050 4300 2500 1800 1550 900 700 and o100 calendar years bp the most significant o8000 calendar years bp residue minima mainly low diatom productivity were recorded at 7100 6800 6600 6000 5700 5000 4400 4200 3800 3600 3200 3000 2750 2300 1900 1700 1070 740 600 380 and 80 calendar years bp bp ad 2000 the lake record from jotunheimen is discussed in the context of holocene terrestrial and marine records from the north atlantic region and possible natural climate forcing factors r 2004 elsevier ltd all rights reserved

comparison of oxygen isotope records from the gisp2 and grip greenland ice cores recent results1 2 from the greenland ice core project grip summit ice core suggest that the climate in greenland has been remarkably stable during the holocene but was extremely unstable for the time period represented by the rest of the core spanning the last two glaciations and the intervening eemian inter glacial here we present the complete oxygen isotope record for the greenland ice sheet project 2 gisp2 core drilled 28 km west of the grip core we observe large rapid climate fluctuations throughout the last glacial period which closely match those reported for the grip core however in the bottom 10 of the cores spanning the eemian interglacial and the previous glacia tion there are significant differences between the two records it is possible that ice flow may have altered the chronological sequences of the stratigraphy for the bottom part of one or both of the cores considerable further work will be necessary to evaluate the likelihood of this and the extent to which it will still be possible to extract meaningful climate information from the lowest sections of the cores

geographical distribution of 3he 4he ratios in japan implications for arc tectonics and incipient magmatism the 3he 4he and 4he 20ne ratios of 115 natural gas samples including various types of gases from volcanoes hot springs mineral springs water wells petroleum fields and natural gas fields were measured using a mass spectrometer the observed 3he 4he and 4he 20ne ratios range from 7 47 10 8 to 9 65 10 6 and from 0 26 to 1100 respectively the 3he 4he ratios reflect well the geotectonic structure of the japanese islands in northeastern ne japan there is a clear geographical difference in the 3he 4he ratios between the frontal arc forearc and volcanic arc back arc regions lower ratios were found in the trench side region and higher ratios in the back arc side this result suggests that the mantle derived helium in the volcanic arc region is associated with the diapiric uprise of a magma lower 3he 4he ratios in the frontal arc region may be due to radiogenic he produced by radioactive decay of u and th in the crustal and sedimentary rocks in southwestern sw japan there is no clear geographical contrast in the 3he 4he ratios some samples in the frontal arc region show quite high 3he 4he ratios the tendency of the 3he 4he ratios agrees with the distribution of terrestrial heat flow data and reflects geotectonic structures different from ne japan the high 3he 4he ratios observed in the frontal arc region in sw japan may be indicative of renewed or incipient magmatism due to a descending young and warm slab

the water content of lake sediments and its relationship to other physical parameters an alpine case study the water content of lake sediment cores provides informative data for environmental reconstruction in addition to its usefulness for between core correlation significant nonlinear relationships between water content organic matter and dry density measurements suggest that high resolution records of organic matter and bulk density in alpine lake sediments can be estimated indirectly using water content as a surrogate for bulk density and organic matter data can be collected at much higher temporal scales than possible with current density samplers these results lend further credence to empirical relationships between bulk density water content and organic matter presented elsewhere

dissolved gases in groundwater and groundwater dating methods how useful for hydrogeological modeling foreword to the special issue one of the major challenges in hydrogeology is the basic spatial lack of continuous data as this is restricted to available boreholes basic information is provided by the measurements of physical parameters e g porosity and permeability at the well scale information related to a larger part of the aquifer are provided for example by continuous measurement of piezometric levels or spring flow temporal information is extremely powerful in order to characterize aquifer functioning globally groundwater dating has thus been developed in order to provide time constraints in aquifer studies

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

testing for fullerenes in geologic materials oklo carbonaceous substances karelian shungites sudbury black tuff comment and reply reply buseck et al s 1992 1 discovery of fullerenes in fractures in a shungite sample enclosed in diabase from russian karelia has been followed by several substantiating reports see buseck 2002 2 p 785 as well as by conflicting reports e g ebbesen et al 1995 3 mossman et al

age limit and age underestimation using different osl signals from lacustrine quartz and polymineral fine grains as part of a systematic palaeohydrological reconstruction of lake level fluctuations during the last glacial maximum a transect of cores from ancient lake xinias in centra greece has already been studied with respect to pollen sediment and mineral magnetic analyses the chronology was based on c 14 ams dating of terrestrial plant macrofossil remains from peat and clayey peat palaeogeog palaeoclimatol palaeoecol 158 2000 65 this site thus provides an opportunity for the comparison of fine grain optically stimulated luminescence osl ages of water lain sediments with an independent chronology we present here infrared ir post ir blue and blue osl characteristics of the fine grain sediments from lake xinias and a preliminary comparison with independent ages the equivalent doses based on the ir results are about 40 of those based on post ir blue stimulation which in turn are 10 15 below those based on quartz osl we discuss the ages derived from the 3 signals in terms of the independent chronology and draw conclusions about initial bleaching of the quartz and feldspar components and the reliability of the post ir blue signal as a chronometer c 2003 elsevier science ltd all rights reserved less

the 8k event cause and consequences of a major holocene abrupt climate change abstract a prominent abrupt climate event about 8200 years ago brought generally cold and dry conditions to broad northern hemisphere regions especially in wintertime in response to a very large outburst flood that freshened the north atlantic changes were much larger than typical climate variability before and after the event with anomalies up to many degrees contributing to major displacement of vegetative patterns this 8k event provides a clear case of cause and effect in the paleoclimatic realm and so offers an excellent opportunity for model testing the response to north atlantic freshening has the same general anomaly pattern as observed for older events associated with abrupt climate changes following north atlantic freshening and so greatly strengthens the case that those older events also reflect north atlantic changes the north atlantic involvement in the 8k event helps in estimating limits on climate anomalies that might result in the future if warming caused ice melt and hydrologic cycle intensification at high latitudes lead to major changes in north atlantic circulation few model experiments have directly addressed the 8k event and most studies of proxy records across this event lack the time resolution to fully characterize the anomalies so much work remains to be done

osl dating of coarse grain fluvial quartz using single aliquot protocols on sediments from ne peloponnese greece abstract optical ages of quartz extracts in holocene sediments from the north eastern peloponnese greece are reported the single aliquot regenerative dose protocol proposed by murray and wintle 2000 radiation measurements 32 57 73 was used to estimate the equivalent dose in these samples a large inter aliquot scatter in d e values was observed for all samples this is ascribed to heterogeneous bleaching of the samples at deposition to estimate a d e for age calculation a technique is suggested based on the analysis of the d e scatter obtained from nine different quartz samples which were artificially bleached and irradiated this procedure is especially useful when the sample quantity is limited the optical age estimates increase with sampling depth an average aggradation rate of 1 5 mm yr is derived using the osl ages this value is consistent with the known uplift rate of 1 2 mm yr

latest pleistocene and holocene alpine glacier fluctuations in scandinavia abstract during the early holocene abrupt decadal to centennial scale climate variations caused significant glacier variations in norway increased freshwater inflow to the north atlantic and arctic oceans has been suggested as one of the most likely mechanisms to explain the abrupt and significant lateglacial and early holocene climatic events in nw europe the largest early holocene glacier readvances occurred 11 200 10 500 10 100 9700 9200 and 8400 8000 cal yr bp the studied norwegian glaciers apparently melted away at least once during the early mid holocene the period with the most contracted glaciers in scandinavia was between 6600 and 6000 cal yr bp subsequent to 6000 cal yr bp the glaciers started to advance and the most extensive glaciers existed at about 5600 4400 3300 2300 1600 cal yr bp and during the little ice age times with overall less glacier activity were apparently around 5000 4000 3000 2000 and 1200 cal yr bp it has been proposed that several glacier advances occurred in scandinavia including northern sweden at 8500 7900 7400 7200 6300 6100 5900 5800 5600 5300 5100 4800 4600 4200 3400 3200 3000 2800 2700 2000 1900 1600 1200 1000 and 700 200 cal yr bp glaciers in northern sweden probably reached their greatest little ice age extent between the 17th and the beginning of the 18th centuries evidence for early holocene glacier advances in northern scandinavia however has been questioned by more recent multi disciplinary studies the early to mid holocene glacier episodes in northern sweden may therefore be questioned most norwegian glaciers attained their maximum little ice age extent during the mid 18th century cumulative glacier length variations in southern norway based on marginal moraines dated by lichenometry and historic evidence show an overall retreat from the mid 18th century until the 1930s 40s subsequently most norwegian glaciers retreated significantly maritime outlet glaciers with short frontal time lags 15 20 years continued their retreat to the 1970s and 1980s however maritime glaciers started to advance as a response to higher winter accumulation during the first part of the 1990s after 2000 several of the observed glaciers have retreated remarkably fast annual frontal retreat 100 m mainly due to high summer temperatures the general glacier retreat during the early holocene and the neoglacial advances after 6000 cal yr bp are in line with orbital forcing due to the decrease of northern hemisphere summer solar insolation and the increase in winter insolation in addition regional weather modes such as the north atlantic oscillation nao and the arctic oscillation ao play a significant role with respect to decadal and multi decadal climate variability

surface and deep ocean interactions during the cold climate event 8200 years ago evidence from a north atlantic deep sea sediment core reveals that the largest climatic perturbation in our present interglacial the 8200 year event is marked by two distinct cooling events in the subpolar north atlantic at 8490 and 8290 years ago an associated reduction in deep flow speed provides evidence of a significant change to a major downwelling limb of the atlantic meridional overturning circulation the existence of a distinct surface freshening signal during these events strongly suggests that the sequenced surface and deep ocean changes were forced by pulsed meltwater outbursts from a multistep final drainage of the proglacial lakes associated with the decaying laurentide ice sheet margin

cosmogenic 10be and 26al ages of holocene moraines in southern norway i testing the method and confirmation of the date of the erdalen event c 10 ka at its type site abstract cosmogenic nuclide dating 10be and 26al is applied to boulders on two moraine ridges at the type site of the early holocene erdalen event southern norway dated previously using radiocarbon quartz rich rock samples yielded 10be age estimates between 9 8 1 2 and 10 1 1 1 ka external uncertainties 1 with an average of 9 95 ka these age estimates are statistically indistinguishable from the independent radiocarbon age estimate 26al age estimates which ranged from 9 4 1 1 to 11 2 1 3 ka and averaged 10 1 ka provided useful corroboration of the 10be results although current levels of precision and accuracy are insufficient to distinguish between the ages of younger inner and older outer moraines the results demonstrate the potential of the method at suitable sites where radiocarbon dating is not possible several environmental factors including effective glacial erosion stability of moraine slopes snow cover of sufficiently shallow depth and short duration and the absence

holocene glacier fluctuations waskey lake northeastern ahklun mountains southwestern alaska lake sediments from waskey lake ahklun mountains southwestern alaska were studied to decipher the history of upvalley glacier e uctuations during the holocene several indicators of glacier activity were measured including magnetic susceptibility organic matter content grain size distribution bulk sediment mineralogy and diatom assemblages seven radiocarbon ages on macrofossils along with cross checks by tephrochronology provide the chronology of the cores the results from core wl 1 indicate that glaciers lingered near waskey lake until 9100 cal yr bp perhaps under conditions of high winter accumulation peak organic matter content occurs at 7400 cal yr bp when precipitation might have shifted to summer the onset of neoglaciation occurred 3100 cal yr bp and glaciers reached their maximum extent 700 cal yr bp this chronology is consistent with the lichenometrically dated moraines from the glacier foree elds although the ages are tentative the youngest and most widespread group of moraines was deposited sometime between 650 and 200 cal yr bp during the little ice age since then glaciers in the waskey lake area have shrunk by 50 and equilibrium line altitudes ela have risen by 35 6 22 m this rise in ela is much less than the 100 to 200 m rise observed elsewhere in alaska and indicates considerable spatial variability in late holocene climatic change

correlation of late quaternary moraines impact of climate variability glacier response and chronological resolution abstract the last decade has seen a global surge in the number and resolution of well dated geomorphological reconstructions of mountain glacier fluctuations and former ice sheet extents this has been facilitated by the widespread deployment of large samples of terrestrial cosmogenic nuclide dating tcnd allowing more sophisticated probability analyses for reducing the statistical uncertainty of moraine ages and testing of correlations at local regional and hemispheric scales geochronological advances in the field laboratory and on model calibration have taken place in parallel with modelling of palaeoclimate based on glacier reconstructions and of glacier sensitivity to temperature and precipitation forcing in spite of these advances basic conceptual issues remain this review questions whether the technical leap forward in dating has encouraged us to over reach our interpretive limits particularly in terms of the concept and practice of correlation we propose that to enable reliable correlation glacier chronologies should first be examined for their climatic integrity spatial coherence and chronological robustness even with excellent dating interpretive complexity remains due to complex climate signals and glacier response characteristics and to erosion censoring of the landform record all are issues which must be addressed to avoid either spurious lumping correlation or splitting differentiation of glacier chronologies and thus misinterpretation of the climatic significance of reconstructed glacier advances we suggest that the reliability of correlation is no better than the weakest link in the chain of reasoning which connects climatic fluctuations with dated landforms and sediments improved dating means that poor chronological resolution is less likely to be the limiting factor for correlation but shifts the focus onto other less quantifiable sources of uncertainty these conceptual statements are exemplified with reference to holocene glacial chronologies of contrasting mid latitude environments in southern norway iceland and new zealand

cosmogenic 10be and 26al ages of holocene moraines in southern norway ii evidence for individualistic responses of high altitude glaciers to millennial scale climatic fluctuations abstract 10be and 26al exposure ages are reported for boulder moraine ridges in front of two high altitude cirque glaciers austanbotnbreen jotunheimen and ostre tundradalskyrkjabre breheimen in southern norway ages and 1 external uncertainties for austanbotnbreen moraines range from 7 4 0 75 ka to 8 7 0 9 ka when no adjustment for snow shielding is made with the maximum conceivable snow cover effect 2 m thick a density of 0 2 g cm3 6 months duration at the exposed site the resulting adjusted 7 7 0 8 to 10 9 1 3 ka as well as unadjusted ages suggest moraine formation possibly during both the 8 2 ka event finse event in southern norway and the erdalen event c 10 0 ka in contrast ages obtained for the outer ridges of the large moraine complex in front of ostre tundradalskyrkjabre range from 1 1 0 3 ka to 1 9 0 4 ka assuming no snow shielding assuming extreme snow lie conditions 4 m thick 0 2 g cm3 density 6 months duration at this more sheltered site the adjusted ages

a first chironomid based summer temperature reconstruction 13 5 ka bp around 49 n in inland europe compared with local lake development temperature reconstructions for the end of the pleistocene and the first half of the holocene based on biotic proxies are rare for inland europe around 49 n we analysed a 7 m long sequence of lake deposits in the vihorlat mts in eastern slovakia 820 m a s l chironomid head capsules were used to reconstruct mean july temperature tjuly other proxies diatoms green algae pollen geochemistry were used to reconstruct local environmental changes that might have affected the climate reconstruction such as epilimnetic total phosphorus concentrations tp lake level changes and development of surrounding vegetation during the younger dryas yd temperature fluctuated between 7 and 11 c with distinct decadal to centennial scale variations that agree with other palaeoclimate records in europe such as 18o content in stalagmites or greenland ice cores the results indicate that the site was somewhat colder than expected from the general south to north yd temperature gradient within europe possibly because of north facing exposition the warmer phases of the yd were characterised by low water level or even complete desiccation of the lake 12 200 12 400 cal yr bp at the late glacial holocene transition tjuly steeply increased from from 11 to 15 5 c 11 700 11 400 cal yr bp the highest tjuly for entire sequence this rapid climate change was reflected by all proxies as a compositional change and increasing species diversity the open woodlands of pinus betula larix and picea were replaced by broad leaved temperate forests dominated by betula later by ulmus and finally by corylus ca 9700 cal yr bp at the same time input of eroded coarse grained material into the lake decreased and organic matter loi and biogenic silica increased the early holocene climate was rather stable till 8700 cal yr bp with temporary decrease in tjuly around 11 200 cal yr bp the lake was productive with a well developed littoral as indicated by both diatoms and chironomids a distinct decline of tjuly to 10 c between 8700 and 8000 cal yr bp was associated with decreasing chironomid diversity and increasing climate moistening indicated by pollen tychoplanktonic and phosphorus demanding diatoms increased which might be explained by hydrological and land cover changes later a gradual warming started after 7000 cal yr bp and representation of macrophytes periphytic diatoms and littoral chironomids increased our results suggest that the holocene thermal maximum was taking place unusually early in the holocene at our study site but its timing might be affected by topography and mesoclimate we further demonstrated that temperature changes had coincided with variations in local hydrology

late holocene climatic variability south of the alps as recorded by lake level fluctuations at lake ledro trentino italy a lake level record for the late holocene at lake ledro trentino northeastern italy is presented it is based on the sediment and pollen analysis of a 1 75 m high stratigraphic section observed on the southern shore site ledro i and a 3 2 m long sediment core taken from a littoral mire on the southeastern shore site ledro ii the chronology is derived from 15 radiocarbon dates and pollen stratigraphy the late holocene composite record established from these two sediment sequences gives evidence of centennial scale fluctuations with highstands at c 3400 2600 1700 1200 and 400 cal bp in agreement with various palaeohydro logical records established in central and northern italy as well as north of the alps in addition high lake level conditions at c 2000 cal bp may be the equivalent of stronger river discharge observed at the same time in central italy s rivers in agreement with the lake level record of accesa tuscany the ledro record also suggests a relatively complex palaeohydrological pattern for the period around 4000 cal bp on a millennial scale sediment hiatuses observed in the lower part of the ledro i sediment sequence indicate that except for a high stand occurring just after 7500 cal bp lower lake levels generally prevailed rather before c 4000 cal bp than afterwards finally the lake level data obtained at lake ledro indicate that the relative continuity of settlements in humid areas of northern italy during the bronze age in contrast to their general abandonment north of the alps between c 3450 and 3150 cal bp does not reflect different regional patterns of climatic and palaeohy drological conditions in contrast the rise in lake level dated to c 3400 cal bp at ledro appears to coincide with a worldwide climate reversal observed in both the hemispheres while palaeoenvironmental and archaeological data collected at lake ledro may suggest as a working hypothesis a relative emancipation of proto historic societies from climatic conditions

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

evidence for holocene climate variability from the sediments of a scottish remote mountain lake high resolution sampling of sediment cores covering approximately the last 4000 yr from lochan uaine a small corrie loch in the scottish cairngorm mountains show quasi periodic cycles in organic matter measured as percentage loss on ignition analysis of these cycles show correspondences between loss on ignition d 13 c values and chironomid head capsule abundance we interpret the changes as reflecting changes in lake productivity and hypothesise that they are driven by climate variability however it is not yet clear whether the periods of relatively high organic matter production and preservation are associated with colder or with warmer conditions nevertheless the results indicate the value of using sediments from remote undisturbed mountain lakes as recorders of holocene climate variability copyright 2001 john wiley sons ltd

a regional 8200 cal yr bp cooling event in northwest europe induced by final stages of the laurentide ice sheet deglaciation the most notable change in 18o in greenland ice cores during the holocene occurs at 8200 cal yr bp here we present a new high resolution marine record from the northern north sea along with tree ring data from germany which contain evidence of a pronounced temperature drop 2 c contemporaneous with that of the greenland ice core records the synchronous timing of the cooling event in the greenland ice cores marine record and tree ring data from northwest europe reflects a regional influence on the north atlantic ocean atmospheric system suggesting a prominent role of the north atlantic thermohaline circulation the operation of the north atlantic ocean circulation is sensitive to variation in the freshwater budget implying that any change in freshwater flux is capable of altering the north atlantic circulation system we hypothesise minor but long term freshwater fluxes in the final stages of the deglaciation of the laurentide ice sheet as a forcing mechanism 1998 john wiley sons ltd

structure of the 8200 year cold event revealed by a speleothem trace element record abrupt first order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western ireland during the 8200 year event the major cooling episode 8200 years before the present are interpreted as responses to a drier climate lasting about 37 years both shifts are centered on 8330 80 years before the present coinciding with a large oxygen isotope anomaly and a change in the calcite petrography in this very high resolution monthly record antipathetic second order oscillations in phosphorus and strontium reveal decreased growth rates and increased rainfall seasonality growth rate variations within the event reveal a two pronged structure consistent with recent model simulations

a new approach to calculating holocene winter precipitation by combining glacier equilibrium line altitudes and pine tree limits a case stud from hardangerjokulen central southern norway at hardangerjokulen central southern norway detailed knowledge of the number age and magnitude of holocene glacier fluctuations is used to reconstruct variations in equilibrium line altitude ela for the last 10 000 years present and past elas are based on an accumulation area ratio aar of 0 7 and are adjusted for land uplift a synchronous relationship between advanced glacier positions and the highest pine tree limits pinus sylvestris l is demonstrated for the early to mid holocene in southern scandinavia which indicates that warm summers were compensated for by high winter precipitation based on pine tree limit fluctuations as a measure of mean ablation season temperature holocene variations in winter precipitation at hardangerjokulen have been calculated by substitution in the close exponential relationship between mean ablation season temperature and winter precipitation at the ela of norwegian glaciers setting the winter precipitation during the period ad 1961 1990 at 100 mean values

dating very old pore waters in impermeable rocks by noble gas isotopes the sup 4 he sup 40 ar and sup 136 xe content dissolved in the pore water of sedimentary rock samples was measured on samples from borehole cores near the repository for nuclear waste in morsleben germany due to the very low permeabilities of the rock formations conventional groundwater sampling was almost impossible hence the authors developed a new sampling method for noble gases in the pore water of freshly drilled rock cores this method provides vertical noble gas profiles in high depth resolution even in impermeable rocks by application of the new technique quantitative age information of groundwater and pore water have been derived the authors find palaeowaters from the last glaciation depleted in delta d and delta sup 18 o with a sup 4 he age of about 55 kyr the high saline pore solutions below are at least 6 mio years old this has been concluded from the profiles of radiogenic sup 4 he and sup 40 ar close to diffusion in steady state and from xenon isotopes produced by spontaneous fission of sup 238 u in the rocks a sup 4 he flux of 2 center dot 10 sup minus 7 cc stp cm sup 2 yr is derived from the profile which is due to local sup 4 he production within the investigatedmore sediments less

7200 years of rhone river flooding activity in lake le bourget france a high resolution sediment record of nw alps hydrology magnetic susceptibility ms was measured with high resolution 5 mm on a 9 m long 14c dated core from lake le bourget savoie france spanning the last 7200 years the strong correlation r 0 85 of the ms with the silicate borne suite of elements si al fe mg k and anti correlation with the carbonate content r 0 87 allows it to be used as a proxy for the fluctuations of the abundance of riverborne clastic fraction versus authigenic carbonates in sediment as the rhone is the only river bringing a significant amount of silicate minerals to the coring site the ms downstream is interpreted as a proxy of the rhone suspended load discharge in lake le bourget this is confirmed over the last 3000 years by the good match with the evolution of hydrological activity of the rhone as it is known through geomorphological studies of well dated archaeological sites over the last 7200 years the record is consistent with the regional record of lake water level fluctuations while the intensity of the ms

the alps with little ice evidence for eight holocene phases of reduced glacier extent in the central swiss alps glacially deformed pieces of wood organic lake sediments and clasts of reworked peat have been collected in front of alpine glaciers since ad 1990 the palaeoglaciological interpretation of these organic materials is related to earlier phases of glacier recession surpassing that of today s shrunken glaciers and to tree growth and peat accumulation in the valleys now occupied by the glaciers glacial transport of the material is indicated by wood anatomy incorporated silt sand and gravel particles missing bark and deformed treerings a total of 65 samples have been radiocarbon dated so far and clusters of dates provide evidence of eight phases of glacier recession 9910 9550 9010 7980 7250 6500 6170 5950 5290 3870 3640 3360 2740 2620 and 1530 1170 calibrated years bp allowing for the timelag between climatic fluctuations glacier response and vegetation colonization these recession phases may lag behind climatic changes by 100 200 years

late holocene glacier fluctuations in bevringsdalen jostedalsbreen region western norway ca 3200 1400 bp lithostratigraphy and radiocarbon dates from a 1 3 m deep gully section in bevringsdalen sw of jostedalsbreen in western norway with alternating minerogenic glacial and peat non glacial layers demonstrate that glaciers upvalley from the site were present during the following intervals 2595 85 bp 840 700 cal bc to 2360 80 bp 525 385 cal bc between 2250 65 bp 395 225 cal bc and 2150 80 bp 360 105 cal bc between 1740 75 bp cal ad 205 385 and 1730 75 bp cal ad 210 395 and subsequent to 1430 45 bp cal ad 595 645 detailed altitudinal fluctuations of the glaciation threshold equilibrium line relative to the present have been reconstructed for the time interval between 1430 45 bp cal ad 595 645 and 3180 90 bp 1540 1395 cal bc

centennial scale climate cooling with a sudden cold event around 8 200 years ago the extent of climate variability during the current interglacial period the holocene is still debated temperature records derived from central greenland ice cores show one significant temperature anomaly between 8 200 and 8 100 years ago which is often attributed to a meltwater outflow into the north atlantic ocean and a slowdown of north atlantic deep water formation this anomaly provides an opportunity to study such processes with relevance to present day freshening of the north atlantic anomalies in climate proxy records from locations around the globe are often correlated with this sharp event in greenland but the anomalies in many of these records span 400 to 600 years start from about 8 600 years ago and form part of a repeating pattern within the holocene more sudden climate changes around 8 200 years ago appear superimposed on this longer term cooling the compounded nature of the signals implies that far field climate anomalies around 8 200 years ago cannot be used in a straightforward manner to assess the impact of a slowdown of north atlantic deep water formation and the geographical extent of the rapid cooling event 8 200 years ago remains to be determined

probability of moraine survival in a succession of glacial advances emplacement of glacial moraines normally results in obliteration of any older moraines deposited by less extensive glacial advances a process we call obliterative overlap a probability analysis of the likely impact of obliterative overlap on the completeness of the glacial record assumes that moraines were deposited at various distances from their glacial source areas randomly over time assuming randomness and obliterative overlap after 10 glacial episodes the most likely number of surviving moraines is only three the record of the pleistocene is in agreement with the probability analysis the 10 glaciations during the past 0 9 m y inferred from the deep sea record resulted in moraine sequences in which only two or three different aged moraine belts can generally be distinguished

reconstruction of former glacier equilibrium line altitudes based on proglacial sites an evaluation of approaches and selection of sites abstract various approaches are used to record variations in glacier activity and equilibrium line altitudes elas based on proglacial sites lacustrine and terrestrial these approaches are based on a conceptual model of glacier meltwater induced sedimentation in which the minerogenic nonorganic component of the sediments is related to the occurrence of a glacier in the catchment the principal coupling to former glacier activity and elas is common for these approaches however different methods and techniques may complement each other and both possibilities and limitations are demonstrated site selection for reconstructing variations in glacier activity elas is evaluated and critical factors are discussed rerouting of glacier meltwater streams across local watersheds in combination with proglacial sites gives a distinct on off signal for former glacier activity elas together with representative lateral moraines of known age local watersheds are important for calibrating reconstructed glacier activity elas based on a chain of proglacial lakes based on the modern analogue principle various proxies can record whenever glaciers existed in a catchment in a chain of proglacial lakes with different sensitivity to record variations in glacier activity elas these proxies can be calibrated against independent records for one site approaches however variations in glacier activity elas depend on the interpretation and sensitivity of the proxies used

holocene glacier history of bjornbreen and climatic reconstruction in central jotunheimen norway based on proximal glaciofluvial stream bank mires abstract holocene variations of bjornbreen smorstabbtinden massif west central jotunheimen are reconstructed from the lithostratigraphy of two alpine stream bank mires flooded episodically by meltwater the approach uses multiple sedimentological indicators weight loss on ignition mean grain size grain size fractions bulk density moisture content and magnetic susceptibility an a priori model of overbank deposition of suspended glaciofluvial sediments a detailed chronology based on 56 radiocarbon dates and a little ice age sedimentological analogue rapid late preboreal deglaciation was indicated by immigration of betula pubescens by 9700 cal bp an interval of at least 3000 years in the early holocene when glaciers were absent was interrupted by two abrupt episodes of glacier expansion around the time of the finse event the first at ca 8270 7900 cal bp bjornbreen i event and the second at ca 7770 7540 cal bp bjornbreen ii event neoglaciation began shortly before ca 5730 cal bp with gradual build up to the maximum of the bjornbreen iii event at ca 4420 cal bp later maxima occurred at ca 2750 cal bp bjornbreen iv event and at 1300 1260 1060 and 790 cal bp all within the bjornbreen v event glaciers were smaller than today and possibly melted away on several occasions in the late holocene ca 3950 1410 and 750 cal bp minor maxima also occurred at ca 660 and 540 cal bp within the late mediaeval warm period and the early little ice age respectively the little ice age maximum was dated to 213 25 bp ca 205 cal bp the relative magnitudes of the main glacier maxima were determined erdalen event little ice age event bjornbreen vi bjornbreen i finse event bjornbreen ii bjornbreen v bjornbreen iv bjornbreen iii these episodic events of varying magnitude and abruptness were used in conjunction with an independent summer temperature proxy to reconstruct variations in equilibrium line altitude ela and a holocene record of winter precipitation since the preboreal ela varied within a range of about 390 m and winter precipitation ranged between 40 and 160 of modern values winter precipitation variations appear to have been the main cause of these century to millennial scale holocene glacier variations

effects of terrigenic he components on tritium helium dating a case study of shallow groundwater in the saijo basin abstract dating using a combination of 3h and 3he is believed to be the most practical method for estimating the short residence time of shallow groundwater however this method must estimate tritiogenic 3he alone and tends to overestimate the residence time of groundwater if terrigenic 3he from the mantle cannot be excluded from the total dissolved 3he we demonstrate the exclusion of terrigenic 3he in the saijo basin where mantle he is easily released along the major active fault median tectonic line the 3he 4he ratios suggest that the west bank of the kamo river which lies within the basin has experienced greater emanations of mantle he than the east bank we estimate the residence times to be 1 1 96 years by the proposed exclusion method

stable isotope variations in stalagmites from northwestern sweden document climate and environmental changes during the early holocene this paper presents two early holocene 9 6 5 9 ka bp high resolution stable isotope records of stalagmites from two caves in northwestern sweden korallgrottan and labyrintgrottan close similarities between the swedish records and a previously presented norwegian stalagmite oxygen isotope record emphasize the potential of scandinavian stalagmites to provide high resolution regional palaeoclimatic information the stable oxygen isotope records are interpreted to reflect the temperature evolution during the early holocene with a gradual warming from c 9 6 ka bp interrupted by cooler conditions at 8 5 8 0 ka bp the results indicate that the cooler conditions were driven by two to three abrupt cold events rather than one 8 2 event only except for these cold events the stalagmite oxygen isotope records show that temperatures in northwestern sweden were warmer than today between 9 6 and 5 9 ka bp and that during this period the interval between 7 8 and 5 9 ka bp seems to have been the warmest the hig

glacier fluctuations during the past 2000 years abstract a global compilation of glacier advances and retreats for the past two millennia grouped by 17 regions excluding antarctica highlights the nature of glacier fluctuations during the late holocene the dataset includes 275 time series of glacier fluctuations based on historical tree ring lake sediment radiocarbon and terrestrial cosmogenic nuclide data the most detailed and reliable series for individual glaciers and regional compilations are compared with summer temperature and when available winter precipitation reconstructions the most important parameters for glacier mass balance in many cases major glacier advances correlate with multi decadal periods of decreased summer temperature in a few cases such as in arctic alaska and western canada some glacier advances occurred during relatively warm wet times the timing and scale of glacier fluctuations over the past two millennia varies greatly from region to region however the number of glacier advances shows a clear pattern for the high mid and low latitudes and hence points to common forcing factors acting at the global scale globally during the first millennium ce glaciers were smaller than between the advances in 13th to early 20th centuries ce the precise extent of glacier retreat in the first millennium is not well defined however the most conservative estimates indicate that during the 1st and 2nd centuries in some regions glaciers were smaller than at the end of 20th early 21st centuries other periods of glacier retreat are identified regionally during the 5th and 8th centuries in the european alps in the 3rd 6th and 9th centuries in norway during the 10th 13th centuries in southern alaska and in the 18th century in spitsbergen however no single period of common global glacier retreat of centennial duration except for the past century has yet been identified in contrast the view that the little ice age was a period of global glacier expansion beginning in the 13th century or earlier and reaching a maximum in 17th 19th centuries is supported by our data the pattern of glacier variations in the past two millennia corresponds with cooling in reconstructed temperature records at the continental and hemispheric scales the number of glacier advances also broadly matches periods showing high volcanic activity and low solar irradiance over the past two millennia although the resolution of most glacier chronologies is not enough for robust statistical correlations glacier retreat in the past 100 150 years corresponds to the anthropogenic global temperature increase many questions concerning the relative strength of forcing factors that drove glacier variations in the past 2 ka still remain

holocene fluctuations of a polythermal glacier in high alpine eastern jotunheimen central southern norway abstract bukkehammarbreen is a polythermal cirque glacier lying in the permafrost zone of eastern jotunheimen central southern norway in the proglacial lake bukkehammartjorna sediment analyses of loss on ignition loi magnetic susceptibility and analyses of grain size distribution have been used to reconstruct holocene variations in glacier activity and other catchment processes the glacier has low sediment production hence a low signal to noise ratio of minerogenic sediment flux is found grain size analyses are used to enhance the glacigenic signal and to detect glacier variations and other changes in sediment input the sedimentological record from bukkehammartjorn is compared with three other lake records from the same region in order to separate the glacial signal from variations in organic production and episodes of enhanced non glacial minerogenic sedimentation subsequent to the deglaciation after the younger dryas a preboreal glacial advance culminated before 10 100 cal bp this was followed by a prolonged period with no glaciers in the catchment until 7500 cal bp after which there is evidence of limited glacier activity lasting until 6800 cal bp between 6700 and 6000 cal bp the catchment was deglaciated after 6000 cal bp bukkehammarbreen reformed increasing in size towards 3800 cal bp with evidence for reduced glacier activity around 5200 cal bp a glacier with approximately similar size as at present has existed after 3800 cal bp the investigation has demonstrated the usefulness of multi site and multi parameter lacustrine investigations in reconstructing glacier fluctuations and for testing and validating the results the investigations have shown that grain size variations in sediment cores located at increasing distance from the meltwater inlet of a lake may provide an indicator of paraglacial activity in the catchment during the holocene the results also suggest that the lower altitudinal limit of permafrost in eastern jotunheimen remained below about 1800 m during the holocene

the lacustrine sedimentary sequence in sygneskardvatnet western norway a continuous high resolution record of the jostedalsbreen ice cap during the holocene abstract two lacustrine sediment cores from sygneskardvatnet sunndalen confirm that at least the northern part of the jostedalsbreen ice cap melted away during the atlantic chronozone between 6475 and 5300 14 c yr bp 7340 and 6150 cal bp possibly interrupted for short intervals of glacier activity around 6000 and 5800 14 c yr bp 6900 and 6700 cal bp prior to this periods of glacier expansion culminated at ca 8500 8400 8200 7750 7600 and 7400 cal bp the 8400 8200 cal bp advances are correlated with the widespread 8200 event finse event recorded in greenland ice cores lacustrine and proglacial sites and marine sediments during the early part of the holocene periods of glacier contraction culminated at ca 8450 8300 7900 7500 and 6250 cal bp of which the last represents climatic optimum conditions lowest supply of minerogenic sediments and or highest organic production the sedimentary record also shows that the ice cap has existed continuously since 5300 14 c yr bp 6150 cal bp neoglaciation involved three main phases 1 6150 4500 cal bp 2 4500 2700 cal bp 3 2700 cal bp to the present and a series of low amplitude glacier advances which occurred at 6000 5800 5700 5600 5500 5200 5100 4900 4800 4700 4550 4450 4300 4200 4150 4050 4000 3900 3800 3550 3300 2550 2450 2350 2250 2150 2000 1800 1700 1600 1400 1300 1150 1050 and the 1000 cal bp including the little ice age loss on ignition analyses indicate however that episodes of less glacier activity occurred during the mid and late holocene at around 5900 5800 5550 5450 5300 5050 4850 4750 4500 4400 4100 3950 3700 3450 3100 2650 2500 2400 2300 2200 1850 1700 1550 1350 1250 1050 1000 cal bp and during the twentieth century altogether the lacustrine record from sygneskardvatnet indicates that the holocene has been interrupted by 41 periods of increased glacier activity mean return period of ca 150 years and by 36 events of glacier contraction mean return period of 210 years spectral analysis of the loi data show peaks at periods of about 50 85 110 250 285 500 and 2000 calendar years the mean time resolution in core sygneskardvatnet 2 is ca 20 yr cm 1 while the mean sedimentation rate is 0 5 mm yr 1

holocene glacier variations in central jotunheimen southern norway based on distal glaciolacustrine sediment cores abstract sediment cores from two glacier fed lakes are used to reconstruct a continuous record of glacier variations since about 10 000 cal bp in the smorstabbtinden massif of central jotunheimen southern norway particular attention is paid to the century to millennial scale pre little ice age glacial signal based on an estimated temporal resolution of 55 and 25 yr cm 1 for bovertunsvatnet and dalsvatnet respectively visible lithostratigraphic variations organic content loss on ignition calcium carbonate content magnetic susceptibility and grain size fractions especially the fine silt are used as proxy indicators of glacier presence and extent in the lake catchments following deglaciation the early holocene was characterized by generally small glaciers until a major advance the finse event peaking at approximately 8200 cal bp from 7900 to at least 5300 cal bp glaciers appear to have been absent from central jotunheimen there is evidence of glacier expansion between about 2400 and 1600 cal bp the bovertun i event and between about 1400 and 800 cal bp the bovertun ii event before reduced glacier extent during the mediaeval warm period finally the most extensive neoglacial maximum occurred during the little ice age after 500 cal bp in addition to providing a record of the broad pattern of climatically forced holocene glacier variations periodicities at 110 140 200 285 and about 500 yr have been identified uncertainties remain concerning the precise timing of events glacierization and deglacierization detection thresholds a possible mid to late holocene 5300 2500 cal bp neoglacial build up of small glaciers and shorter term decadal to century scale variations in glacier size for which more proximal sites are required

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

glacier contraction during the middle holocene in the western italian alps evidence and implications radiocarbon dates of peat from the top and base of a bog exposed by recent retreat of rutor glacier show that the glacier front terminated upvalley from the bog from 8400 until at least 6000 b p the evidence is consistent with botanical data that point to a high tree line during the interval and to reconstructed mean july temperatures at least 4 c warmer than present temperatures if the mass balance history of the glacier is typical of other glaciers in this region it is likely that average equilibrium line altitudes during the interval of contraction remained above those of the present and well above those of subsequent neoglacial ice advances

timing equilibrium line altitudes and climatic implications of two early holocene glacier readvances during the erdalen event at jostedalsbreen western norway following the younger dryas the e rst evidence of glacial activity in southern norway in response to climatic change occurred during the early holocene when terminal moraines from the erdalen event formed beyond the position of later little ice age moraines in front of present outlet glaciers on both sides of the jostedalsbreen ice cap sets of pre little ice age marginal moraines have been morphostratigraphicallycorre lated with the erdalen event the lithostratigraphyin a peat bog at hellemyrane in jostedalen western norway provides e rm evidence for a two phase erdalen event associated with two glacier readvances of nigardsbreen at the preboreal boreal transition radiocarbon dates from the peat bog give age estimates for the two phases the e rst erdalen event readvance took place between 10 100 and 10 050 cal bp while the second occurred close to 9700 cal bp the lowering of the equilibrium linealtitude ela during these readvances is estimated using the little ice age ratio lr approach to be about 230 m and 215 m respectively the e rst readvance is attributed to an increase in winter precipitation while the second readvance may have been primarily caused by a marked drop in summer temperature which reactivated already existing ice masses

north pacific and north atlantic sea surface temperature variability during the holocene holocene climate variability is investigated in the north pacific and north atlantic realms using alkenone derived sea surface temperature sst records as well as a millennial scale simulation with a coupled atmosphere ocean general circulation model aogcm the alkenone sst data indicate a temperature increase over almost the entire north pacific from 7 cal kyr bp to the present a dipole pattern with a continuous cooling in the northeastern atlantic and a warming in the eastern mediterranean sea and the northern red sea is detected in the north atlantic realm similarly sst variations are opposite in sign between the northeastern pacific and the northeastern atlantic a 2300 year long aogcm climate simulation reveals a similar sst seesaw between the northeastern pacific and the northeastern atlantic on centennial time scales our analysis of the alkenone sst data and the model results suggests fundamental inter oceanic teleconnections during the holocene

use of lacustrine sedimentary sequences as indicators of holocene glacial history banff national park alberta canada abstract bottom sediments from three lakes in the canadian rocky mountains were examined with the aim of evaluating the usefulness of downvalley sediment studies in reconstruction of holocene glacial histories analyses of organic carbon and carbonate contents of core sediments provide information on changing sedimentation rate and changing relative importance of glacial and non glacial sediment sources sedimentary histories of the three lakes are similar suggesting that they record regional glacial climatic forcing rather than localized events and thus that they may be useful in reconstructing holocene glacial history lacustrine sediments indicate a period of high sedimentation rates and relatively large glacial sediment contribution prior to 7500 7000 yr b p with much reduced rates and decreased glacial sediment contribution between about 6000 and 4000 yr b p possibly interrupted by a brief period of increased glacial sediment output shortly after 5000 yr b p sometime after 4000 yr b p sedimentation rates and glacial sediment output began to rise again reaching approximately present levels by 2750 2650 yr b p and have not since returned to low mid holocene levels in detail over the last 3000 yr there is some indication of a slight decrease in sedimentation rate for more than 1000 yr after about 2200 yr b p sedimentation rates and glacial sediment input into all three lakes rose between about 900 and 750 yr b p and have remained very high since if the lake sediments are interpreted as a proxy record of upvalley glacial activity they allow the development of a glacial chronology which is at once generally consistent with and more complete and easily datable than the surficial glacial record

reconstruction of holocene glacier history from distal sources glaciofluvial stream bank mires and a glaciolacustrine sediment core near sota saeter breheimen southern norway this study attempts to reconstruct the holocene glacier history of breheimen southern norway from four stream bank mire sites and a downstream lake sediment core near sota saeter based on lithostr

holocene palaeoclimate reconstructions at vanndalsvatnet western norway with particular reference to the 8200 cal yr bp event analyses of organic content magnetic susceptibility grain size and pollen in sediments from the proglacial lake vanndalsvatnet in western norway provide a high resolution terrestrial record and pollen based quantitative estimates of mean july and january temperatures and annual precipitation across the 8200 cal yr bp event glaciers in the catchment melted away at approximately 8600 cal yr bp immediately following deglaciation a series of thin minerogenic layers indicate several abrupt short lived glacial episodes peaking at 8550 8450 8350 8250 8200 7900 7300 and 7150 cal yr bp a single mid holocene glacial episode occurred at 49004800 cal yr bp between 2000 and 1400 cal yr bp six short lived glacial episodes occurred 2000 1900 1800 1700 1600 and 1500 cal yr bp the part of sporteggbreen that drains to vanndalsvatnet has existed continuously since 1400 cal yr bp just prior to a first loss on ignition minimum reflecting a glacial episode centred at 8200 cal yr bp pollen inferred july temperatures were relatively high january temperatures were low and annual precipitation was relatively low during the period 82007900 cal yr bp july temperatures showed a falling trend both january temperature and annual precipitation however were relatively high after 7900 cal yr bp july temperatures increased but both january temperatures and annual precipitation were lower than in the preceding period the pollen analytical and sedimentary data suggest that the glacial advance during the finse event seems not to have been a response to cooler summers but to milder winters and increasing precipitation similar to a positive north atlantic oscillation weather mode

little ice age glacier variations in jotunheimen southern norwvay a study in regionally controlled lichenometric dating of recessional moraines with implications for climate and lichen growth rates a new approach to regional lichenometric dating is developed and applied to little ice age moraine ridge sequences on 16 glacier forelands in jotunheimen southern norway lichenometric dating curves based on the rhizocarpon subgenus are constructed independently for west central and east jotunheimen although there are differences between the subregions a composite regional moraine chronology for jotunheimen identifies 12 episodes of moraine formation in ad 1743 1750 the regional little ice age glacier maximum 1762 1771 1782 1790 1796 1802 1811 1818 1833 1838 1845 1854 1860 1868 1871 1879 1886 1898 1915 1922 and 1927 1934 spatial and temporal patterns in glacier behaviour between the subregions and between jotunheimen and the neighbouring jostedalsbreen are explained in terms of the interaction of annual to decadal variations in summer temperature and winter precipitation glacier advances and moraine formation events driven primarily by winter precipitation variations exhibit subregio

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

development of an osl chronology for late pleistocene channel belts in the lower mississippi valley usa abstract the broad alluvial valley of the lower mississippi river contains large channel belts for which age control has been limited by the lack of organic material for radiocarbon dating and deposit ages greater than the limit of radiocarbon in order to produce a detailed chronology of fluvial evolution samples for optical dating were collected from late pleistocene channel belt deposits quartz sand was analyzed using the coarse grained single aliquot regenerative dose sar technique samples showed little evidence of partial bleaching and optical ages are for the most part consistent with the available radiocarbon and relative age constraints optical ages range from 85 to 11 ka and along with geomorphic and stratigraphic relationships indicate that the mississippi river was meandering during the end of the last interglacial 85 83 ka and switched to a braided regime by 64 50 ka during initial marine oxygen isotope stage ois 4 3 glaciation of the upper mississippi drainage basin the mississippi river switched back to a meandering regime after formation of the youngest braid belt at 11 ka the 69 optical ages presented here provide the first detailed chronology of lower mississippi valley braid belt and pleistocene meander belt formation and provide an example of the utility of optical dating in fluvial settings where material for radiocarbon dating is scarce

utilizing physical sediment variability in glacier fed lakes for continuous glacier reconstructions during the holocene northern folgefonna western norway the maritime plateau glacier of northern folgefonna in western norway has a short subdecadal response time to climatic shifts and is therefore well suited for reconstructing high resolution glac

holocene glacier fluctuations of flatebreen and winter precipitation changes in the jostedalsbreen region western norvay based on glaciolacustrine sediment records the history of holocene glacier variations of flatebreen an independent glacier close to the sw part of the jostedalsbreen ice cap has been reconstructed from lacustrine sediments in the proglacial lake jarbuvatnet the sedimentary succession shows evidence of three maini episodes of holocene glacier expansion the first is recorded in the basal part of the core up to 370 cm according to the age depth relationship in the sediment core based on 12 ams radiocarbon dates this glacier expansion episode terminated about 10200 cal yr bp the second major glacier phase lasted from 8400 to 8100 cal yr bp while the third was initiated around 4000 cal yr bp and has continued up to the present at 43 cm in the core the medium silt content increases significantly accompanied by a minor increase in the sand content this textural change is interpreted as the first time that the tenninus of flatebreen extended inlto an upstream lake at 1083 m a s l the age model suggests that this event took place around

holocene glacier variations of blaisen hardangerjokulen central southern norway abstract a 1 m deep gully section 460 m beyond the maximum little ice age marginal moraines of blaisen hardangerjokulen central southern norway revealed alternations of minerogenic and organic sediments the geographical geological settings of the dated section provides a unique on off signal of holocene glacier fluctuations of blaisen lithostratigraphy sediment characteristics and radiocarbon dates from the study section indicate one period of glacier re advance between the late preboreal deglaciation of the inland ice sheet and 8660 100 yr b p a grey sand layer 56 57 cm below the surface is interpreted to be of fluvial colluvial origin and is radiocarbon dated to about 7700 yr b p at 48 cm below the surface a bluish grey sand silt layer is radiocarbon dated to 7590 12 yr b p 6560 6240 b c and interpreted to be glaciofluvial origin a minor glacier oscillation postdates 1130 70 yr b p 810 990 a d the medieval little ice age glacier advance of blaisen beyond its modern extent occurred after 1040 60 yr b p 960 1030 a d calculations of the modern and little ice age equilibrium line altitudes elas on hardangerjokulen suggest an ela depression of ca 130 m during the little ice age maximum