glacial stage ice core records from the subtropical dunde ice cap china the first ice core record of both the holocene and wisconsin wiirm late glacial stage lgs from the subtropics has been extracted from three ice cores to bedrock from the dunde ice cap on the north central qinghai tibetan plateau ice thicknesses at the ice cap summit average 138 m the bedrock surface is relatively flat surface and basal temperatures are 7 3 and 4 7 c respectively and the ice cap exhibits radial flow away from the summit dome these records reveal a major change in the climate of the plateau 10 000 years ago and suggest that lgs conditions were colder wetter and dustier than holocene conditions this is inferred from the more negative 6180 ratios increased dust content decreased soluble aerosol concentrations and reduced ice crystal sizes which characterize the lgs part of the cores total b radioactivity from shallow ice cores indicates that over the last 24 years the average accumulation rate has been 400 mm a 1 at the summit the ice cores have been dated using a combination of annual layers in the insoluble dust and 6180 in the upper sections of core visible dust layers which are annual and ice flow modeling the oxygen isotope record which serves as a temperature proxy indicates that the last 60 years have been the warmest in the entire record

temporal variations of accumulation and temperature during the past two centuries from belukha ice core siberian altai 1 the temporal variation of accumulation and temperature in the siberian altai were investigated using a 86 m long ice core from belukha glacier 49 48 26 n 86 34 43 e 4062 m a s l covering the time period 1816 to 2001 as temperature sensitive parameters the melt percent profiles and the stable oxygen isotopes 18o were evaluated representing summer season and march to november temperatures respectively the accumulation record showed no long term trend and only minor deviations of limited duration from the accumulation average of 0 5 m water equivalent y weq y were observed in contrast the two temperature proxies indicate a strong warming trend in the order of 1 6 0 4 c and 1 7 1 1 c over the last century inferred from melt percentages and the 18o record respectively and 2 5 1 7 c since the mid 19th century inferred from the 18o record this reflects an amplified regional climate response following the little ice age lia as compared to the northern hemisphere average most probably caused by the strong continentality of the siberian altai region the sudden onset of large melt features since 1988 indicates that the upper reaches of belukha glacier are experiencing a change from the recrystallization to the cold infiltration zone that now allows for multiannual percolation of meltwater implying that the conservation of accumulation and geochemical properties including those providing temperature proxies is currently endangered

newly discovered eastern dispersal of the youngest toba tuff volcanic glasses with minor mafic mineral fragments such as biotite and hornblende found in deep sea sediments of the south china sea basin scsb have been clearly identified as eruptive products of the youngest toba tuff ytt northern sumatra indonesia the tephra layer occurs between marine oxygen isotopic event 5 1 79 3 ka and event 4 22 64 1 ka with an interpolated age of 74 0 ka which is in good consistence with previous radiometric dating 73 75 ka and ice core dating 71 5 ka of the ytt the tephra consists predominantly of bubble wall shards with minor elongated vesicles of pumice fragments geochemical characteristics of the tephra such as high total alkali content high 87 sr 86 sr ratio and uniformity of their compositions all suggest that the recovered tephra is of the youngest toba tuff this finding supports an extended dispersal of coarse 63 mm glass shards over 1500 km northeast of the toba caldera a direction opposite to what previously conceived while providing a better documentation of the distribution extent of the toba ash this report points to the need to reestimating the eruptive volume of the ytt and re evaluating its environmental impact q 2000 elsevier science b v all rights reserved

experimental studies of the fluidization of layered sediments and the formation of fluid escape structures experiments demonstrate that fluid escape structures can be produced as a result of unstable fluidization behaviour where a lower base layer of granular material is inhibited from fluidizing by the presence of an overlying non fluidizing top layer before the base layer can fluidize the weight of the overlying material must be balanced and this is accomplished by base layer material pressing against the bottom surface of the confining top layer forming a static layer this static layer allows the top layer to lift away from the base layer which is then free to fluidize a water filled crack forms below the static layer and as this grows instability causes the static layer and top layer to bend and conical voids to form below the antiformal sections rupture occurs at the apex of the water void allowing the underlying water and fluidizing material to burst out through the top layer the fluidized base layer material then flows through the rupture until all of this material except that in the static layer is deposited above the previously overlying layer and a stable fluidization system results the top layer material is bent upwards around the rupture and the resulting pillar type escape structure is preserved if flow then ceases the vigour of the burst out is greatest when the base layer material has a grain size 15 of the top layer material if the base layer grain size is less than 8 of the top layer then base layer material will pass through the top layer pore spaces without forming an escape structure if cohesive material is present escape structures form when a layer of fine grained cohesive material overlies a layer of cohesionless material at low flow rates small pipes with scattered angular bends pierce the top layer and base layer material passes through them the base layer material is ejected on to the top layer and builds up around the mouth of each pipe to form constructional structures sand volcanoes this is in contrast to the cohesionless experiments where the weight of material being deposited on the top layer caused an ejecta filled depression to form around the rupture if flow then ceases both the pipes and the sand volcanoes are preserved at high flow rates where the base layer fluidizes the top cohesive layer becomes fragmented small fragments circulate within the fluidizing base layer and are preserved as floating clasts large fragments sink to the bottom of the fluidizing base layer erosion of the bottom surface of these larger fragments causes this surface to become convex downward the experimentally derived structures are similar to pillar type structures observed in the field and the processes described can be used to investigate the development of these structures fluidization experiments also demonstrate the genesis of dish structures and the cohesive behaviour can be applied to the deformation of these structures after initial formation

glacial regime of the highest tien shan mountain pobeda khan tengry massif major processes controlling the existence of a large sub continental glacier system were identified on the basis of glaciological meteorological and isotopic analyses using expeditionary and long term data observations were made on the southern inylchek glacier located in the pobeda khan tengry massif the largest sub continental glacier system on the northern periphery of central asia more than 1200 glaciers with a total area of about 4320 km comprise the massif melt is for the most part caused by radiation and is most intensive during periods of anticyclonic weather with fohn development the proportion of solar radiation input in relation to heat balance is more than 90 evaporation and condensation are negligible during most times and comprise 7 of heat expenditure accumulation was associated with cold cyclonic weather four ice formation zones were identified the upper boundary of liquid runoffis at 5200 m and the recrystallization zone is above 5900 m the calculated net glacier mass is negative 318 kg m 2 a 1 and indicates the degradation of modern pobeda khan tengry glaciers

chemical composition of snow and ice from chhota shigri glacier central himalaya abstract a systematic study of the chemical composition of snow firn from a shallow core surface ice and of meltwater samples collected from the chhota shigri glacier central himalaya is reported here the average concentrations of na and cl in snow are 402 and 753 g l 1 respectively whereas those in old surface ice are relatively low 185 g l 1 and 375 g l 1 respectively the average cl na weight ratio in these samples is 1 9 quite similar to that in the sea salts suggesting that both cl and na are predominantly of marine origin the concentrations of other major ions such as k mg ca no3 and so4 in snow and ice samples are generally less than 1 mg l 1 the major ion concentrations when normalized to na indicate that the abundances of k and ca are dominated by terrestrial sources whereas mg appears to have both marine and terrestrial sources based on the seasonal variations of na and cl concentrations observed in the ice core samples an approximate accumulation rate at the core site has been estimated to be 1 6 m year 1 640 kg m 2 year 1

abrupt and moderate climate changes in the mid latitudes of asia during the holocene a multiple parameter dating technique was used to establish a depth age scale for a 171 3 m 145 87 m w e surface to bedrock ice core bl2003 recovered from the cold recrystallization accumulation zone of the western belukha plateau 4115 m a s l in the siberian altai mountains the ice core record presented visible layering of annual accumulation and of delta o 18 delta d stable isotopes and a clear tritium reference horizon a steady state glacier flow model for layer thinning was calibrated and applied to establish a depth age scale four radiocarbon c 14 measurements of particulate organic carbon contained in ice core samples revealed dates for the bottom part of bl2003 from 9075 1221 cal a bc at 145 2 0 1 m w e 0 665 m w e from the bedrock to 790 93 ad at 121 1 m w e depth sulfate peaks coincident with volcanic eruptions the tunguska meteorite event and the 1842 dust storm were used to verify dating analysis of the bl2003 ice core reveals that the modern altai glaciers were formed during the younger dryas yd similar to 10 950 to similar to 7500 cal a bc and that they survived the holocene climate optimum hco similar to 6500 to similar to 3600 cal a bc and the medieval warm period mwp similar to 640 to similar to 1100 ad a decrease in air temperature at the beginning and an abrupt increase at the end of the yd were identified intensification of winds and dust loading related to asian desert expansion also characterized the yd during the yd major ion concentrations increased significantly up to 50 times for na background up to 45 times for ca2 and mg2 and up to 20 times for so42 relative to the recent warm period from 1993 to 2003 a warm period lasted for about three centuries following the yd signaling onset of the hco a significant and prolonged decrease in air temperature from similar to 2000 to similar to 600 cal a bc was associated with a severe centennial drought scd a sharp increase in air temperatures after the scd was coincident with the mwp after the mwp a cooling was followed gradually with further onset of the little ice age during the modern warm period 1973 2003 an increase in air temperature is noted which nearly reaches the average of hco and mwp air temperature values

deposition of anthropogenic aerosols in a southeastern tibetan glacier 1 measurements of elemental carbon ec water insoluble organic carbon wioc and inorganic ions from a very high resolution snow firn core retrieved from a glacier on the southeastern tibetan plateau reveal increasing concentrations associated with deposition of anthropogenic aerosols during the period 1998 2005 ec wioc and so42 concentrations in the core were 4 7 56 0 and 4 2 ng g 1 in 1998 but increased to 16 8 144 4 and 162 1 ng g 1 in 2005 respectively comparison of ec to so42 and k concentrations indicates a relatively greater impact of fossil fuel burning on ec deposition compared to biomass burning significant contribution of secondary oc production is apparent from the low ec wioc ratios ec concentrations show large seasonal variability with nonmonsoon precipitation containing more than double the concentrations found in monsoon snowfall since snow cover on the tibetan plateau extends to its maximum aerial extent during the nonmonsoon season the high ec concentrations in snowfall during this time can cause advanced snowmelt and enhanced radiative forcing

the last 40 ka tephrostratigraphic record of lake ohrid albania and macedonia a very distal archive for ash dispersal from italian volcanoes abstract a 1075 cm long core lz1120 was recovered in the south eastern part of the lake ohrid republics of macedonia and albania and sampled for identification of tephra layers magnetic susceptibility investigations show rather high magnetic values throughout the core with peaks unrelated to the occurrence of tephra layers but instead to the relative abundance of detrital magnetic minerals in the sediment naked eye inspection of the core allowed us to identify of two tephra layers at 896 897 cm and 1070 1075 cm laboratory inspection of the grain size fraction 125 m allowed for the identification of a third cryptotephra at 310 315 cm major element analyses on glass shards of the tephra layers at 896 897 cm and 1070 1075 cm show a trachytic composition and indicate a correlation with the regionally dispersed y 3 and y 5 tephra layers dated at ca 30 and 39 cal ka bp the cryptotephra at 310 315 cm has a mugearitic benmoreitic composition and was correlated with the fl eruption of mt etna dated at 3370 70 cal yr bp these ages are in agreement with five 14 c ams measurements carried out on plant remains and macrofossils from the lake sediments at different depths along the core the recognition of distal tephra from italian volcanoes allows us to link the lake ohrid succession to other archives located in the mediterranean area and in eastern europe the benmoreitic mugearitic tephra layer at 310 315 cm is the first recognition in the balkan area of a distal ash deposit from a mid intensity explosive eruption of mt etna as far as 600 km from the source

tropical glaciers potential for ice core paleoclimatic reconstructions the objective of this work is to evaluate the potential of tropical glaciers and ice caps for the reconstruction of past climatic conditions by the analysis of firn and ice cores samples were collected in pits and from cores retrieved on three snow fields in the south american andes quelccaya ice cap and huascaran in peru and chimborazo in ecuador these are compared with results from west africa and indonesia measurements include the microparticle concentration oxygen isotopic abundance ratios and total beta radioactivity which in polar regions often exhibit seasonal depositional cycles annual variations in these three parameters are fairly well defined on quelccaya and huascaran and are apparently absent on chimborazo the quelccaya ice cap contains the best preserved annual signal for all three parameters and although in some instances the annual cycle is difficult to distinguish the measurement of more than one stratigraphic parameter aids in the interpretation of the firn core records the relatively flat bottom topography under quelccaya suggests a simple ice flow regime and depth age calculations indicate that an ice core to bedrock should contain a record of 600 to 1300 years this inference was confirmed by drilling to bedrock in 1983 this investigation of tropical glaciers indicates that the quelccaya ice cap on the eastern edge of the peruvian andes has excellent potential to contain a lengthy and interpretable record of climatic conditions within the tropics of south america

soluble ionic and oxygen isotopic compositions of a shallow firn profile baishui glacier no 1 southeastern tibetan plateau in the summer of 2004 a firn profile 18 3m long extending down to glacier ice was recovered in the accumulation area of the largest glacier baishui no 1 on yulong mountain the southernmost glacier covered area in mainland eurasia multivariate empirical orthogonal function eof and statistical correlation analyses of major ion data from the profile demonstrate that three distinct types of ionic material contribute to the chemical characteristics of firn in this monsoonal region material of marine origin which is transported by the indian southwest monsoon crustal materials which come from local sources and anthropogenic pollutants which are produced by industrial and agricultural activities in south asia although the influence of post depositional processes on the seasonal isotopic and soluble ionic compositions is significant dust layers in the firn profile are clearly visible due to the effects of meltwater percolation the dust layers generally coincide with latesummer snow surfaces we therefore use the dust layers combined with the seasonal variations of electrical conductivity ec ca and mg to establish a depth age scale for the firn profile the reconstructed net accumulation has a significant negative correlation with the temperature at lijiang whereas the correlation between the net accumulation and the precipitation amount at lijiang is weak although the do time series of the firn profile was modified significantly by meltwater percolation the correlation between annual mean do values and the indian southwest monsoon index wsi1 is significant this result suggests that do records from monsoon influenced temperate glaciers can provide a valuable record of past variations of the indian southwest monsoon

enigmatic deep water depositional mechanisms upper part of the oquirrh group utah abstract textures body fossil assemblages trace fossil assemblages and lack of sedimentary structures formed by tractive currents indicate that upper pennsylvanian and wolfcampian sandstones and limestones of the oquirrh group in northwestern utah were deposited in deep water however the abundant thick bedded to massive sandstones are not classical turbidites the depositional mechanisms of five deep water lithofacies have been inferred 1 massive and thickly bedded sands were transported by turbidity currents and deposited by grain flows 2 rippled sands were deposited from turbidity currents 3 bioclast packstones similar to walker s 1978 pebbly sandstones formed from sediments emplaced by turbidity currents and grain flows 4 non channelized conglomerates were deposited by dense turbid flows gram flows and debris flows and 5 thinly bedded siltstones are of hemipelagic origin the lateral continuity of individual beds is generally not known but it is well documented that 100 m thick sets of beds are continuous over several kilometers of distance and that units dominated by a single lithofacies can be mapped from 10 to over 10 kilometers nevertheless the lateral depositional geometry of the upper part of the oquirrh group remains enigmatic indications of an integrated submarine fan distribution system are vague at best

major element geochemistry of glass shards and minerals of the youngest toba tephra in the southwestern south china sea an ash layer newly discovered in core md01 2393 from the southwestern south china sea has been studied in order to characterize its major element features the layer 4 0 cm thick light grayish and silt size occurs right at the marine isotope stage 4 5 transition ca 74 kyr ago the morphology and geochemistry of glass shards combined with oxygen isotope and carbonate stratigraphy confirm the youngest toba eruption in northern sumatra as the origin of the ash layer major element data on mineral crystals i e biotite plagioclase and hornblende from the ash layer suggest that biotite is phenocrystic while hornblende and some plagioclase are xenocrystic implying that these xenocrysts were incorporated into the youngest toba magma before the eruption q 2005 elsevier ltd all rights reserved

climatological significance of δ18 o in precipitation and ice cores a case study at the head of the urumqi river tien shan china stable oxygen isotope ratios 18 o of precipitation and ice core samples collected from the headwaters of the urumqi river tien shan china were used to test the relationship between 18 o and contemporaneous surface air temperature t a a strong temporal relationship is found between 18 o in precipitation and t a particularly for the monthly averages which remove synoptic scale influences such as changes in condensation level condensation temperature and moisture sources yao and others 1996 linear fits as high as 0 95 c for precipitation events and 1 23 c for monthly averages are found although the 18 o amplitude in ice cores drilled at the nearby urumqi glacier no 1 2 km from the precipitation sampling site decreased dramatically compared to the precipitation samples the ice core records of annually averaged 18 o are still positively correlated with contemporaneous air temperature especially summer air temperature at the nearby daxigou meteorological station nevertheless the relationship between the ice core 18 o records and contemporaneous air temperature is less significant than that for the precipitation samples due to depositional and post depositional modification processes which are highlighted by the successive snow pit 18 o profiles from the urumqi glacier no 1 our results might extend the application of high altitude and subtropical ice core 18 o t a records for palcoclimate reconstruction

revised age and distribution of ca 87ka aso 4 tephra based on new evidence from the northwest pacific ocean the major element compositions of glass shards of aso 4 tephra can be distinguished from those of other widespread tephras in and around the japanese islands by analysing 325 tephras in 27 sediment cores collected from the northwest pacific ocean and the sea of okhotsk aso 4 tephra was identified at 14 locations on the basis of the glass major element composition and refractive indices of glass shards and phenocrysts similarity coefficients between aso 4 type and its correlatives ranged between 0 92 and 0 99 whereas comparisons between aso 4 tephra and 92 other widespread quaternary tephras were all 0 85 cao feo plots clearly show the bimodal composition of glass shards in aso 4 tephra aso 4 tephra reached the northern part of the shatsky rise 2910 km from its source caldera its thickness and grain size suggest that the axis of fall out zone is oriented to the northeast of the aso caldera a detailed 18o isotopic stratigraphy embracing the last 144 ka has been determined for core md01 2421 collected off central japan aso 4 tephra is present in this core and occurs in zone mis 5b more precisely at 86 8 87 3 ka using this datum the sedimentation rate in the northwest pacific basin to the north of the 37 5 n latitude is greater than that to the south of 35 n latitude this new information on the distribution and age of aso 4 tephra improves our understanding on the magnitude of this eruption and provides a precise chronostratigraphic marker in the late quaternary pelagic sediment of the northwest pacific ocean

turbidite facies fluid escape structures and mechanisms of emplacement of the oligo miocene aljibe flysch gibraltar arc betics southern spain abstract the aljibe flysch the largest tectono sedimentary unit in the gibraltar arc provides a record of oligo miocene sedimentation in the betic orogen southern spain the aljibe flysch can be subdivided into two sub units the beneiza flysch late oligocene and the aljibe arenites early miocene which have very different depositional histories and mechanisms of emplacement the beneiza flysch is characterised by laterally continuous and thin bedded lithic arenites siltstones and mudstones which contain complete and partial bouma sequences these are interpreted to have been deposited in a sheet turbidite system which may have formed part of the north african flysch trough by contrast the aljibe arenites comprise of thick bedded super mature quartz arenites which are dominated by fluid escape structures these sandstones are similar to facies group b1 b2 disorganised sands of pickering et al 1989 which are interpreted to be the product of deposition from high density turbidity currents fluid escape structures have been classified according to the scheme of lowe 1975 and their vertical arrangement indicates that a large volume of sediment was deposited extremely rapidly during frequent remobilisation events consideration of the origin of the fluid escape structures and their vertical arrangement has identified problems in their interpretation and identified key areas for future research the boundary between the beneiza flysch and aljibe arenites is interpreted to be a significant stratigraphic boundary across which there is a major change in sediment source and mechanism of sediment emplacement several models can be put forward for the generation of this stratigraphic break and these serve to set the agenda for future research into the emplacement of other similar flysch sequences and the origin of the gibraltar arc flysch

late quaternary uplift rate inferred from marine terraces muroto peninsula southwest japan forearc deformation in an oblique subduction zone abstract tectonic uplift rates across the muroto peninsula in the southwest japan forearc the overriding plate in the southwest japan oblique subduction zone were estimated by mapping the elevations of the inner edges of marine terrace surfaces the uplift rates inferred from marine terraces m1 and m2 which were correlated by tephrochronology with marine isotope stages mis 5e and 5c respectively include some vertical offset by local faults but generally decrease northwestward from 1 2 1 6 m ky 1 on cape muroto to 0 3 0 7 m ky 1 in the kochi plain the vertical deformation of the muroto peninsula since mis 5e and 5c was interpreted as a combination of regional uplift and folding related to the arc normal offshore muroto misaki fault a regional uplift rate of 0 46 m ky 1 was estimated from terraces on the muroto peninsula and the residual deformation of these terraces was attributed to fault related folding a mass balance calculation yielded a shortening rate of 0 71 0 77 m ky 1 for the muroto peninsula with the muroto misaki fault accounting for 0 60 0 71 m ky 1 but these rates may be overestimated by as much as 10 given variations of several meters in the elevation difference between the buried shoreline angles and terrace inner edges in the study area a thrust fault model with flat 5 10 dip and ramp 60 dip components is proposed to explain the shortening rate and uplift rate of the muroto misaki fault since mis 5e bedrock deformation also indicates that the northern extension of this fault corresponds to the older muroto flexure

stable isotopic composition of precipitation over the northern slope of the central himalaya stable water isotope data 6d and 18 o from three groups of samples fresh snow and snow pit samples collected on qomolangma mount everest and xixabangma during field seasons 1997 1998 and 2001 and precipitation samples collected at tingri station during summer 2000 are presented and used to survey the isotopic composition of precipitation over the northern slope of the central himalaya multi year snow pit samples on qomolangma have a local meteoric water line slope 8 close to the global value deuterium excess d d 8 18 o values at tingri are much lower than those in fresh snow from qomolangma probably due to differences in moisture source and air mass trajectories as well as local weather conditions there is no obvious seasonal trend for d values in the qomolangma region a negative relationship exists between 18 o and d values in both fresh snow on qomolangma and precipitation at tingri fresh snow samples collected from different altitudes on xixabangma allow us to investigate the altitude effect on 18 o values in snow of four storm events only one has an obvious altitude effect on 18 o variation and a very low gradient of 0 1 per 100 m elevation

high precision analysis of hydrous rhyolitic glass inclusions in quartz phenocrysts using the electron microprobe and inaa a high precision electron microprobe emp technique has been developed that is capable of analyzing major minor and trace element abundances si ti ai fe mn mg ca na k cl in hydrous rhyolitic glasses the technique was developed to characterize the chemical compositions of rhyolitic glass inclusions in phenocrysts that occur in layers of paleozoic altered volcanic ash the compositions of these inclusions serve as excellent chemical fingerprints of the altered volcanic ash layers for use in stratigraphic correlation the precision and reproducibility of the analyses is sufficientnot only to distinguish one altered volcanic ash layer from another on the basis of inclusion compositions but also to discern differencesin the compositions of different inclusions from the same layer a high precision instrumental neutron activation analytical inaa technique was also developed that is capable of measuring an additional suite oftrace elements e g sc co rb cs sr ba la ce sm eu tb yb lu zr hf ta in rhyolitic glass inclusions in quartz phenocrysts with excellent accuracy and precision after correcting for the presence of the host quartz the abundances of elements measured by the emp technique and the corrected abundances determined using the inaa technique are identical within analytical uncertainty thus demonstrating the internal consistency of the results

a review of central asian glaciochemical data the glaciers of central asia provide suitable locations from which to recover continuous high resolution glaciochemical records on a continental scale although the glaciochemical investigations undertaken to date in central asia are few in number and limited in terms of spatial coverage and length of record some preliminary observations can be made concerning regional and seasonal trends in snow chemistry in this region the sodium chloride ratio for most snow samples collected in central asia approaches the ratio found in sea water 0 86 in leq kg i reflecting a marine source for these constituents sodium and chloride concentrations are on average 3 10 times higher in the himalayas than in the karakoram demonstrating the greater influence of monsoonal sources of moisture in the himalayas very high sodium concentrations from khel khod glacier probably reflect a local crustal source from surrounding ice free areas low nitrate concentrations were found in snow collected from the southern margin of the himalayas and high concentrations in snow deposited on the north margin of the himalayas this strong regional trend in the spatial distribution of nitrate suggests the influx of continental aerosols rich in nitrate originating from the arid regions of central asia high calcium concentrations measured in snow from mount everest and the north west corner of china are also indicative of dust derived from the arid regions of central asia very high sulfate concentrations found in snow from the tien shan and the bogda shan most likely reflect local anthropogenic sources the altitude effect on isotopic composition is not apparent from snow samples collected in central asia understanding the processes which control the chemical content of snow the local to regiona l scale complexities

characteristics of atmospheric dust deposition in snow on glacier no 4 mt bogeda china wind blown mineral dust derived from the crustal surface is an important atmospheric component affecting the earth s radiation budget deposition of dust particles was measured in snow on the glacier no 4 mt bogeda in the eastern tian shan china the mean number concentration of dust particles with 0 57 d 26 m in the snowpack is 279 103 ml 1 with a mean mass concentration of 1 480 g kg 1 dust number size distribution showed the dominant particles with d 2 m while volume size distribution showed single modal structures having volume median diameters from 3 to 25 m results were compared with the data from other sites in the tian shan and various northern hemisphere sites a backward trajectory model was also employed to examine the transport process of dust particles in this region most of the air mass originated from the southern and northwestern regions e g the taklimakan and gurbantunggut deserts in springtime during the asian dust period which may bring plentiful aerosol dust particles from the sandy deserts transport of dust from western chinese deserts to adjacent mountains is in agreement with a growing body of evidence on the importance of dust inputs to alpine regions

late quaternary cryptotephra detection and correlation in loess in northeastern japan using cummingtonite geochemistry abstract we detected late pleistocene cummingtonite bearing cryptotephras in loess deposits in ne japan and correlated them with known tephras elsewhere by using major element compositions of the cummingtonite this is the first time cryptotephras have been identified by analysis of a crystal phase rather than glass shards in central ne japan four cummingtonite bearing tephras the ichihasama pumice the dokusawa tephra the naruko nisaka tephra and the adachi medeshima tephra are present in late pleistocene loess deposits because the cummingtonite chemistry of each tephra is different and characteristic it is potentially a powerful tool for detecting and identifying cryptotephras an unidentified cummingtonite bearing cryptotephra previously reported to be present in the late pleistocene loess deposits at kesennuma pacific coast did not correlate with any of the known cummingtonite bearing tephras in central ne japan but instead with the numazawa kanayama tephra erupted from the numazawa caldera southern ne japan although kesennuma is well beyond the previously reported area of the distribution of the numazawa kanayama tephra three new cummingtonite bearing cryptotephras in the mid and late pleistocene loess deposits estimated to be less than 82 ka 100 200 ka and ca 250 ka on the isawa upland were also detected

an overview of distal tephrochronology in northern europe during the last 1000 years several tephra layers from the last millennium have been identified in distal peat and lake sediment sequences in northern europe forming a framework of volcanic events of great value for palaeoenvironmental investigations most of the tephras within this framework have an origin in iceland but distal layers from jan mayen have also been identified the predominant transport pathway in an easterly southeasterly direction has led to the deposition of these tephras in a number of terrestrial deposits in northern europe ash from silicic eruptions 63 sio2 dominate at these sites even though many of the documentary records in distal areas report tephra fall from several basaltic eruptions here we provide an overview of the distribution shard concentration and geochemistry of these tephras to highlight the most important isochrones for addressing key dating issues in particular three horizons hekla 1 ad 1104 oraefajokull ad 1362 and askja ad 1875 are found at a number of different locations in northern europe and as such are valuable tie points for improving and validating chronological models and for synchronisation of records spanning the last 1000 years in addition we present new data identifying tephra from the grimsvotn volcanic system within the lomonosovfonna ice cap on svalbard demonstrating that some tephras have been transported 2000 km to as far north as 798 n along a northeasterly trajectory this discovery highlights the potential for utilising tephrochronology as a correlation tool for palaeoarchives located in more northerly areas and the complex nature of fall out from different eruptions copyright 2009 john wiley sons ltd

isotope studies of inner snow layers in a temperate region post depositional change of isotope concentration was investigated in a temperate snow pack daily snow pit studies were carried out at moshiri hokkaido for about a week in april 1998 during this time the snow layers were at the melting point isotope analysis was conducted on snow particles and the liquid water in between the particles every 5 cm in depth and on the precipitation and the runoff water from the bottom of the snow pack collected during the observation period it was found that the oxygen isotope concentration in the liquid part was smaller by about 2 than the solid part of the wet snow the difference between the isotope concentrations of the liquid and the solid was low in the surface snow layer but increased at the bottom the results suggested that isotope fractionation took place between the liquid and the solid when liquid water formed by melting at the snow surface layer flowed groundwards copyright 2002 john wiley sons ltd

rhyolitic glass in ordovician k bentonites a new stratigraphic tool fresh volcanic glasses in the form of melt inclusions within quartz phenocrysts are commonly present in paleozoic k bentonites from new york state iowa kentucky pennsylvania newfoundland and quebec because these glasses are compositionally distinct from one layerto another their geochemistry can be used to define chronostratigraphic horizons in new york state the k bentonites occur within flat lying calcareous black shales of the middle ordovician utica formation this glass has survived 1 because it has been sealed within a host crystal that is stable under most diagenetic conditions and 2 because of the modest burial depths the ordovician strata in this region to demonstrate the potential of these volcanic glasses for stratigraphic correlations isochronous surfaces have been established among three localities separated by 35 km the immaculate preservation of these ordovician glasses bodes well for the general application of this approach to younger and perhaps even older strata where geologic conditions have favored the survival of glass inclusions

soft sediment deformation structures induced by rapid sedimentation in early cretaceous turbidites lingshan island eastern china turbidites of the early cretaceous lingshandao formation on lingshan island eastern china show numerous soft sediment deformation structures the turbidites accumulated in a rift basin plain on the distal part of a low energy fan together with autochthonous fine grained sediments that settled from suspension occasionally sets of both types of sediments slumped down the basin slope the turbidites were studied in two sections paleocurrent directions measured from sole marks at the base of the sandy turbidites indicate a slope from se to nw this is consistent with the dip direction of the axial planes of the major slump folds among the numerous types of soft sediment deformation structures that are present two types are of special interest because of their specific genesis viz rip up clasts and dome structures it appears that rapid sedimentation must be considered as the main trigger behind these deformations the rapid accumulation of particularly the sandy turbidites resulted in overloading

analysis of titanomagnetite within weathered middle pleistocene kmt tephra and its application for fluvial terrace chronology kanto plain central japan abstract the widespread kaisho kamitakara tephra kmt derived from the source vent located in the hida mountains is a favorable marker tephra for the chronological study of the middle pleistocene in the kanto plain central japan as the kmt in aeolian sediments is strongly weathered the chemical composition of titanomagnetite resistant to weathering was determined for its identification the age of the kmt was estimated at 0 62 ma mis 16 0 by nakazato 2006 horizon and age of kaisho kamitakara tephra from the inubo group in the northeastern part of chiba prefecture central japan programme and abstracts japan association for quaternary research 36 106 107 in japanese revising a previous estimate of 0 58 0 69 ma by suzuki 2000 kaisho kamitakara tephra erupted from the hida mountains in early half of middle pleistocene and its significance for geomorphic chronology of central japan geographical review of japan 73 1 25 in japanese the stratigraphic position of the kmt in the azuyama and sayama terrace surfaces in southwest kanto and the kitsuregawa upper terrace surface in north kanto indicates that these terraces are correlative it is assumed that the dissected fluvial terrace surfaces were formed a few tens of thousands of years prior to the deposition of the kmt alluvial fan deposits constituting these terrace surfaces were formed during the period from mis 17 3 to 16 2 during a transition from interglacial to glacial geomorphic conditions during this period of the middle pleistocene were stable allowing the formation of broad fans

late quaternary distal tephra fall deposits in lacustrine sediments kenai peninsula alaska tephra fall deposits from cook inlet volcanoes were detected in sediment cores from tustumena and paradox lakes kenai peninsula alaska using magnetic susceptibility and petrography the ages of tephra layers were estimated using 21 14 c ages on macrofossils tephras layers are typically fine gray ash 1 5 mm thick and composed of varying proportions of glass shards pumice and glass coated phenocrysts of the two lakes paradox lake contained a higher frequency of tephra 0 8 tephra 100 yr 109 over the 13 200 yr record the unusually large number of tephra in this lake relative to others previously studied in the area is attributed to the lake s physiography sedimentology and limnology the frequency of ash fall was not constant through the holocene in paradox lake tephra layers are absent between ca 800 2200 3800 4800 and 9000 10 300 cal yr bp despite continuously layered lacustrine sediment in contrast between 5000 and 9000 cal yr bp an average of 1 7 tephra layers are present per 100 yr the peak period of tephra fall 7000 9000 cal yr bp 2 6 tephra 100 yr in paradox lake is consistent with the increase in volcanism between 7000 and 9000 yr ago recorded in the greenland ice cores 2007 university of washingston all rights reserved

interpretation of the chemical and physical time series retrieved from sentik glacier ladakh himalaya india analyse a partir de mesures de la radioactivite d analyses chimiques chlorures sodium fer silicates phosphates ammonium d 18 o et ph et de donnees physiques des variations cycliques temporelles des glaciers application aux paleoclimats

el nino southern oscillation events recorded in the stratigraphy of the tropical quelccaya ice cap peru snow accumulation measured during 1982 1983 on the quelccaya ice cap peru was 70 percent of the average from 1975 through 1983 inspection of 19 years 1964 through 1983 of accumulation measured near the summit of quelccaya reveals a substantial decrease 30 percent in association with the last five el nino southern oscillation enso occurrences in the equatorial pacific the enso phenomenon is now recognized as a global event arising from large scale interactions between the ocean and the atmosphere understanding this extreme event with the goal of prediction requires a record of past occurrences the quelccaya ice cap which contains 1500 years of annually accumulated ice layers may provide a long and detailed record of the most extreme enso events

the effect of refreezing on the isotopic composition of melting snowpack the isotopic composition of solid and liquid portions of natural melting snowpack is investigated in detail by the separating of liquid water from snow grains at different depths of the snowpack the slope of the d 18o line for the liquid phase is found to be lower than for the solid phase this is proved to be due to the isotopic fractionation occurring in the melt freeze mass exchange within the snowpack melting of the snowpack has no clear impact on the d 18o line for the solid phase but the slope of the d 18o line for the liquid shows an overall slight decrease in the melting period when the snowpack is refrozen the refreezing process would inevitably cause the slope of the solid phase to decrease because of the discrepancy between the slopes of the two phases thus the slope of the solid would become lower and lower as the diurnal melt freeze episodes cycle throughout the melting season this effect is then demonstrated by looking into the isotopic composition changes of glacier firn the extent of the effect depends on the snowpack properties and environmental conditions the slope changes also result in a decreasing trend in deuterium excess copyright 2007 john wiley sons ltd

use of ice cores from glaciers with melting for reconstructing mean summer temperature variations this study examines a new method for reconstructing mean summer temperature variations by using an ice core from a wet snow zone on a summer accumulation type glacier in july 2001 a 25 1 m deep ice core was recovered from the accumulation area of sofiyskiy glacier 49847 0 n 87843 0 e 3435 m a s l located in the southern chuyskiy range of the russian altai mountains and a 4 5 m deep pit was excavated about 50 m northwest of the drill site the observation site has a positive balance even during summer when melting occurs the summer balance for each year from 1990 to 2000 was estimated from pinaceae and artemisia pollen peaks in these samples pinaceae pollen marks spring whereas artemisia pollen marks autumn moreover meltwater intrusion did not reach the previous year s accumulation thus the ice between these pollen peaks in the same year was used to estimate a summer balance the reconstructed summer balance variations were negatively correlated with mean summer temperature variations r 0 72 p 0 05 this study shows that for summer accumulation type glaciers such as sofiyskiy glacier the most important climate factor controlling the glacier s surface mass balance is mean summer temperature therefore the summer layer thickness in an ice core can be used as a proxy for reconstructing mean summer temperature variations

accumulation and flow rates of ice on chhota shigri glacier central himalaya using radio active and stable isotopes systematic isotopic studies based on natural and artificial radio isotopes 32 si 137 cs stable isotopes 18 o and total activity measurements have been carried out on chhota shigri glacier himachal pradesh central himalaya to study the dynamics of the ice meltwater composition and to identify the deposition of the chernobyl fall out in the himalayan region using 32 si concentrations the snout ice has been dated at 250 years based on which the past average surface ice flow rate has been estimated as 28 m year 1 based on 18 o variations in a shallow ice core the accumulation rate of the ice has been estimated at 520kgm 2 year 1 32 si measurements of snout ice and englacial meltwaters indicate that at least 55 of the snow meltwater mixed with 45 of the old ice melt water that emerged from englacial streams in the month of august 1987 deposition of the artificial radionuclide 137 cs and the very high total activity observed in snow samples on chhota shigri glacier give the first evidence of chernobyl fall out deposition in the indian himalaya

the isotopic composition of meteoric water along altitudinal transects in the tian shan of central asia abstract the tian shan in central asia are a unique mountain range in that they are in the world s most continental location seasonal precipitation in the northern tian shan is segregated into distinct elevation bands where high elevations receive precipitation primarily during summer and low elevations to the north receive precipitation primarily during the late winter and spring in this study we sampled stream water along multiple altitudinal transects to determine the effect unique seasonal patterns of precipitation have on the isotopic composition of surface water our results suggest that the northern tian shan exhibits an isotopic lapse rate for waters sampled in late spring but not for those sampled in late summer when stream water budgets are dominated by high elevation precipitation and snow melt deuterium excess results suggest that subcloud evaporation significantly affects the isotopic composition of precipitation at low elevations in spring and that sublimation of snow has a minor impact on 18o values of summer melt water because high and low elevation 18o values are similar conventional paleoaltimetry based on rayleigh distillation of an air mass is not applicable to the kyrgyz tian shan stream water proxies from the rock record are likely to reflect changes in the seasonal distribution of precipitation which occur on the same spatial scale as altitudinal changes these results highlight the need to understand modern controls on local stable isotopes of meteoric water in reconstructions of past climate or topography using geologic proxy materials

teleconnections with tropical precipitation surges abstract precipitation surges in the equatorial pacific dry zone as delineated in a study by doberitz reveal statistically significant teleconnections with midlatitude tropospheric flow patterns during all seasons these connections are strongest however during winter and agree with linear numerical model results there is evidence that deep troughs in the central north pacific antecede precipitation surges in the equatorial dry zone during that season suggesting the possibility of triggering of such surges by middle latitude planetary wave perturbations nonlinear numerical model results also indicate that the midlatitude planetary wave response is strongest when north pacific cold sea surface temperature anomalies and equatorial east pacific warm anomalies are present simultaneously the planetary wave pattern associated with equatorial pacific precipitation surges appears to be in phase with orographically generated wave patterns whereas an anomalous low latitude heat source over the extreme eq

on the isotopic composition in δd and δ18o of water and ice during freezing experiments on progressive unidirectional freezing are coi1 ducted to determine rhe evol ution in 00 and 51 bo of successive water samples and ice layers ta ken during the course of freezing r es ults indicate t hal lhi s evoluti on takes pl ace in a bd bibo diagram a long a strai ght line wi th a characteri sti c slope this slope different from that due to the precip itation effec t gives a finger print of the occurrence of a freezing or of a melt ing refreez ing process in the stud ied reservoir residual water was sampled at the beginning of the experiment after 40 80 85 90 and 95 of the material had frozen when the freezing process was complete the ice core was recovered and sectioned the samples covered the freezing ranges from 0 to 10 10 to 20 20 to 50 50 to 60 60 to 70 70 to 80

the role of tephras in developing a high precision chronostratigraphy for palaeoenvironmental reconstruction and archaeology in southern kyushu japan since 30 000 cal bp an integration abstract tephras are important for the chronostratigraphy of palaeoenvironmental and archaeological records in southern kyushu because numerous tephra beds enable these records to be connected and dated precisely using tephrochronology a regional tephra based framework or lattice for the past 30 000 calendar cal years is proposed in the style of recent intimate projects elsewhere we review stratigraphic compositional age and distributional data for a range of tephras and comment on the relationship of several marker tephras to distinct palaeoenvironmental and cultural events in the southern kyushu region since 30 000 cal bp more than 90 visible tephra beds are recorded deriving from kakuto aira ata and kikai volcanic centres which incorporate large calderas and the tokara volcanic islands the tephra record is underpinned by two widespread tephras aira tn tephra at ca 30 000 cal bp and kikai akahoya tephra k ah ca 7300 cal bp in addition to at and k ah locally distributed marker tephra beds are related to the chronostratigraphy of terrestrial and marine palaeoenvironments including sea level and coastal environments vegetation and culture some tephras notably at k ah and sakurajima satsuma tephra sz s ca 12 800 cal bp have been recognized in marine and laminated lake sediments and hence dated with high precision thereby facilitating correlation of those records to global high resolution ice marine and terrestrial stratotypes sz s is a useful isochron for the last deglaciation in southern kyushu our integrated regional chronostratigraphic model for southern kyushu founded by tephras and with further potential via systematic identification of cryptotephras will enable change in regional palaeoenvironments and culture to be evaluated in national and global contexts

tracing volcanic events in the ngrip ice core and synchronising north atlantic marine records during the last glacial period five basaltic tephra horizons have been identified in the ngrip ice core during the last glacial period geochemical analyses indicate that these tephras are of icelandic origin with one horizon identified as the faroe marine ash zone iii fmaz iii an important marker horizon in several marine records within the faroe islands margin the fmaz iii is a few millimetres thick and is constrained to 38 122 723 yr b2k before year ad 2000 according to the greenland ice core chronology gicc05 this event falls directly at the thermal peak of greenland interstadial 8 gi 8 and a marine ice correlation based on the position of this tephra suggests a close coupling of the marine and atmospheric systems at this time the remaining tephras originate from the eastern volcanic zone with the katla volcanic system pinpointed as the dominant source these are thought to represent previously unknown volcanic events which add considerably to our knowledge of icelandic volcanism during this period independent ages are assigned to these events and together with major element characterisation form the backbone of the tephrochronology framework presented here despite the identification of these tephras this study also demonstrates that the sulphate record may not always act as a suitable proxy for the identification of tephra horizons in ice core records

cryptotephra detection using high resolution trace element analysis of holocene marine sediments southwest japan abstract detection techniques for invisible tephra known as cryptotephra have been exploited to construct precise and high resolution correlations for a broad range of sedimentary sequences we demonstrate that continuous trace element profiles are an effective means for detecting probable positions of distal cryptotephra in holocene hemipelagic sediments instrumental neutron activation analyses were performed on specimens of bulk sediments from five piston and gravity cores water depths 300 1500 m taken from the southern japan east sea the down core variations in the ta sc ratio identify the positions of one to three alkaline cryptotephra in four of these cores the cr sc profiles show the position of one rhyolitic cryptotephra in three of the cores the existence of tephra derived components glass crystals was confirmed by microscopic observation sem epma analysis and refractive index measurement on grains extracted from these layers based on microscopic observation and the stratigraphic correlations between cores we identified eruption ages of the cryptotephras at 6 3 7 5 and 9 3 14 c kyr bp and two source volcanoes around 800 and 400 km from the study area the tephra layers visible to the naked eye contained volcanic grains coarser than 200 m and the alkaline and rhyolitic tephra component comprised 20 and 33 of the sediment on weight basis respectively in contrast the range of particle sizes of the cryptotephras detected in this study is finer than 125 m and almost all of the glass shards were finer than 40 m the alkaline and rhyolitic cryptotephras made up only 2 17 and 22 24 respectively of the sediment on weigh basis the high sensitivity of this method stems from the significant difference in trace element contents between the tephras and enclosing hemipelagic sediments in the core alkaline u oki tephra was enriched in ta by one order of magnitude over that of the sediment and depleted in sc by one order the rhyolitic tephra k ah was depleted by about one order in cr relative to that of enclosing the sediment the differences in chemical composition between within plate alkaline tephras and hemipelagic sediments are usually so large that trace element geochemical method is likely to be useful for alkaline cryptotephra detection in other areas with similar tectonic characteristics

the little ice age as recorded in the stratigraphy of the tropical quelccaya ice cap the analyses of two ice cores from a southern tropical ice cap provide a record of climatic conditions over 1000 years for a region where other proxy records are nearly absent annual variations in visible dust layers oxygen isotopes microparticle concentrations conductivity and identification of the historical a d 1600 huaynaputina ash permit accurate dating and time scale verification the fact that the little ice age about a d 1500 to 1900 stands out as a significant climatic event in the oxygen isotope and electrical conductivity records confirms the worldwide character of this event

isotopic measurements of precipitation on central asian glaciers southeastern tibet northern himalayas central tien shan the glacial regions of central asia considered in our study are influenced by tropical monsoons and western extratropical cyclones isotopic 18o and d data were obtained over 3 years in three climatic regions gongga massif of southeastern tibet windward slope of summer monsoon xixibangma massif on the northern slope of the himalayas leeward of summer monsoon and the massifs of pobeda khan tengry in the central tien shan exposed to western airstreams the survey reported here provides information from atmospheric precipitation snow pits and a 23 m ice core the significant differences of oxygen isotopic ratios from 25 1 per mil to 9 5 per mil indicate that the indian and pacific oceans as well as the atlantic ocean are sources of moisture on the northern slope of the himalayas and southeastern tibet sharply changing isotopic ratios in precipitation corresponded to changing wind direction and were associated with different sources of air masses on the northern slope of the himalayas and southeastern tibet steady isotopic ratios in atmospheric precipitation and the absence of changing 18o composition in a 23 m ice core suggest only one source of moisture in central tien shan the relatively heavier oxygen isotopic ratios in atmospheric precipitation and ice core indicate the moisture from which the precipitation was derived originated over the caspian or mediterranean seas within the eurasian continent air masses developed over the atlantic ocean advance farther than those from the pacific and indian oceans

oxygen isotopic and soluble ionic composition of a shallow firn core inilchek glacier central tien shan oxygen isotopic and soluble ionic measurements made on snow pit 2 m depth and firn core 12 4 m depth samples recovered from the accumulation zone 5100 m of inilchek glacier 43 n 79 e provide information on recent 1992 98 climatic and environmental conditions in the central tien shan region of central asia the combined 14 4 m snow pit firn core profile lies within the firn zone and contains only one observed melt feature 10 m temperature 12 c although some post depositional attenuation of the sub seasonal 18 o record is possible annual cycles are apparent throughout the isotope profile we therefore use the preserved 18 o record to establish a depth age scale for the core mean 18 o values for the entire core and for summer periods are consistent with 18 temperature observations and suggest the 18 o record provides a means to reconstruct past changes in summer surface temperature at the site major ion na k mg 2 ca 2 nh 4 cl no 3 so 4 2 data from the core demonstrate the dominant influence of dust deposition on the soluble chemistry at the site and indicate significant interannual variability in atmospheric dust loading during the 1990s anthropogenic impacts on nh 4 concentrations are observed at the site and suggest a summer increase in atmospheric nh 4 that may be related to regional agricultural nitrogen rich fertilizer use activities

a holocene pollen record from the northwestern himalayan lake tso moriri implications for palaeoclimatic and archaeological research this paper presents a new fossil pollen record from tso moriri 32 54 n 78 19 e 4512 m a s l and seeks to reconstruct changes in mean annual precipitation map during the last 12 000 years this high alpine lake occupies an area of 140 km2 in a glacial tectonic valley in the northwestern himalaya the region has a cold climate with a map 300 mm and open vegetation the hydrology is controlled by the indian summer monsoon ism but winter westerly associated precipitation also affects the regional water balance results indicate that precipitation levels varied significantly during the holocene after a rapid increase in map a phase of maximum humidity was reached between ca 11 and 9 6 cal ka bp followed by a gradual decline in map this trend parallels the reduction in the northern hemisphere summer insolation comparison of different palaeoclimate proxy records reveal evidence for a stronger holocene decrease in precipitation in the northern versus the southern parts of the ism domain the long term trend of ism weakening is overlaid with several short periods of greater dryness which are broadly synchronous with the north atlantic cold spells suggesting reduced amounts of westerly associated winter precipitation compared to the mid and late holocene it appears that westerlies had a greater influence on the western parts of the ism domain during the early holocene during this period the westerly associated summer precipitation belt was positioned at mediterranean latitudes and amplified the ism derived precipitation the tso moriri pollen record and moisture reconstructions also suggest that changes in climatic conditions affected the ancient harappan civilisation which flourished in the greater indus valley from approximately 5 2 to 3 cal ka bp the prolonged holocene trend towards aridity punctuated by an interval of increased dryness between ca 4 5 and 4 3 cal ka bp may have pushed the mature harappan urban settlements between ca 4 5 and 3 9 cal ka bp to develop more efficient agricultural practices to deal with the increasingly acute water shortages the amplified aridity associated with north atlantic cooling between ca 4 and 3 6 and around 3 2 cal ka bp further hindered local agriculture possibly causing the deurbanisation that occurred from ca 3 9 cal ka bp and eventual collapse of the harappan civilisation between ca 3 5 and 3 cal ka bp

the large scale circulation and heat sources over the tibetan plateau and surrounding areas during the early summer of 1979 part i precipitation and kinematic analyses abstract the time evolution of the large scale precipitation low level 850 mb wind moisture and vertical motion fields over the tibetan plateau and surrounding areas during a 40 day period from late may to early july 1979 is studied based on the objectively analyzed fgge level ii b data set during this period the general circulation over east asia undergoes a distinct change characterizing the onset of the summer monsoon circulation the tibetan plateau exerts profound orographic and thermal influences upon the low level wind field the inflow towards the eastern part of the plateau with a marked diurnal change in its intensity is the most prominent feature of the low level wind field the areas of organized precipitation are well related to synoptic systems seen in the 850 mb flow the quasi stationary burma india trough the disturbances forming on the trough the mei yu baiu front and the transverse trough extending eastward from the plateau there is a sharp contrast between the western an

stratigraphy of the pleistocene and holocene sediments associated with correlation of some tephra beds in the matsuyama plain ehime prefecture southwest japan

the stable isotope evolution in shiyi glacier system during the ablation period in the north of tibetan plateau china in order to firstly explore the stable isotope evolution of shiyi glacier system in the central qilian mountains a total of 167 samples have been collected from newly deposited snow surface snow snowpits meltwater and glacier fed river water from july 2012 to november 2013 the results indicated that only the newly deposited snow in 23 november 2013 showed a significant altitude effect whereas surface snow had a reverse altitude effect owing to evaporation and sublimation in summer 2012 and 2013 the d

the flysch trough thrust imbricate betic cordillera a key element of the gibraltar arc orogenic wedge 1 within the betic rif orogenic system the flysch trough units are formed mainly by siliciclastic rocks upper jurassic to lower miocene in age in the gibraltar arc area they are presently deformed as an accretionary prism sandwiched between the fold and thrust belt derived from the south iberian paleomargin sedimentary series and the metamorphic rocks of the alboran domain on top in the northern branch of the gibraltar arc the main tectonic unit of the flysch complex is the aljibe unit which shows a well organized structure of thrust imbricates post lower burdigalian in age in this unit various domains separated by major accommodation zones are characterized by their structural style and vergence this change in structural style can be explained as a consequence of the variations of rock type along the basal decollement finally these thrust systems were affected by extensional low to medium angle faults and large scale very open folds successively the organization of the aljibe unit fits a push from behind mechanism for its emplacement in which the relatively rigid back stop would be represented by the alboran domain with the data presented in this paper it is definitely shown that the aljibe unit is not chaotic as claimed in previous papers and that the tectonic transport direction around the gibraltar arc swings from a northwestward to a westward direction along its northern branch in the vicinity of the straits

characterization and correlation of cryptotephras using major element analyses of melt inclusions preserved in quartz in last interglacial marine sediments southeastern shikoku japan although sediments underlying marine terraces in se shikoku southwest japan contain no visible tephra layers late pleistocene cryptotephras were detected in a paleosol within the sediments the cryptotephras contained little or no glass but they were characterized through major element analyses of glass preserved as melt inclusions in quartz grains extracted from the paleosol the analyses enabled correlation of the cryptotephras with known eruptives from volcanoes on kyushu namely the kikai tozurahara tephra mis 5 2 5 3 the aira tn tephra 28 6 cal ka and the kikai akahoya tephra 7 5 cal ka these correlations enabled dating of the marine terrace surface known as the murotomisaki 1 surface in se shikoku as being older than mis 5 2 5 3 probably mis 5 5 in age in the absence of glass or mafic minerals because of weathering the analysis of melt inclusions in resistant quartz grains demonstrably provides a powerful method for characterizing cryptotephras to facilitate their correlation and thus their application as a linking and dating tool

from precipitation to runoff stable isotopic fractionation effect of glacier melting on a catchment scale stable isotope variability and fractionation associated with transformation of precipitation accumulation to firn to glacial river water is critical in a variety of climatic hydrological and paleoenvironmental studies this paper documents the modification of stable isotopes in water from precipitation to glacier runoff in an alpine catchment located in the central tibetan plateau isotopic changes are observed by sampling firnpack profiles glacier surface snow ice meltwater on the glacier surface and catchment river water at different times during a melt season results show the isotopic fractionation effects associated with glacier melt processes the slope of the d 18o regression line and the deuterium excess values decreased from the initial precipitation to the melt impacted firnpack slope from 9 3 to 8 5 and average d excess from 13 4 to 7 4 the slope of the d 18o line further decreased to 7 6 for the glacier runoff water the glacier surface snow ice from different locations which produces the main runoff had the same d 18o line slope but lower deuterium excess by 3 9 compared to values observed in the firnpack profile during the melt season the d 18o regression line for the river water exhibited a lower slope compared to the surface snow ice samples although they were closely located on the d 18o plot isotope values for the river and glacier surface meltwater showed little scatter around the d 18o regression line although the samples were from different glaciers and were collected on different days results indicate a high consistency of isotopic fractionation in the d 18o relationships as well as a general consistency and temporal covariation of meltwater isotope values at the catchment scale copyright 2013 john wiley sons ltd

detection and correlation of widespread cryptotephras in middle pleistocene loess in ne japan using cummingtonite geochemistry we used cummingtonite chemistry to detect strongly weathered widespread cryptotephras within middle pleistocene loess and fluvial terrace deposits and to correlate them with previously reported tephras in central and ne japan we correlated a cummingtonite bearing cryptotephra widely distributed in ne japan below the ichihasama pumice 108 146 ka and above the iwadeyama pumice iwp 160 240 ka with the iizuna kamitaru c tephra iz ktc which erupted from iizuna volcano central japan iz ktc is thus a widespread middle pleistocene tephra covering both central and ne japan moreover we detected the adachi medeshima tephra ac md which had been previously inferred to be a late pleistocene tephra 80 100 ka below the iz ktc and iwp tephras 125 150 ka and above the hagimori white ash tephra 210 250 ka therefore ac md must be a middle pleistocene tephra with an eruptive age older than 125 150 ka and younger than 210 250 ka we also detected a cummingtonite bearing tephra older than 210 250 ka and younger than 250 300 ka in the isawa area of ne japan and correlated it with a previously reported tephra in central japan thus like iz ktc this tephra is a widespread middle pleistocene tephra

aseismic controls on in situ soft sediment deformation processes and products in submarine slope deposits of the karoo basin south africa intervals of soft sediment deformation features including vertical fluid escape and load structures are common and well exposed in permian lower slope deposits of the tanqua depocentre karoo basin the structures mainly comprise elongated flames and load structures associated with ruptured sandstones and structureless siltstones observed over a range of scales the presence of an upper structureless siltstone layer linked to the flames interpreted as a product of the debouching of fine grained material transported through the flame onto the palaeo seabed together with the drag and upward folding of lower sandstone layers is evidence that the flames were formed in situ by upward movement of sediment rich fluids flames are oriented parallel to the deep water palaeoslope in lateral splay deposits between two major slope channel complexes statistical correlation and regression analyses of 180 flame structures from seven stratigraphic intervals suggest a common mechanism for the deformation and indicate the importance of fluidization as a deformation mechanism importantly deformation occurred in an instantaneous and synchronous manner liquefaction and fluidization were triggered by incremental movement of sediment over steeper local gradients that were generated by deposition of a lateral splay on an inherited local north west facing slope seismic activity is not invoked as a trigger mechanism because of the restricted spatial occurrence of these features and the lack of indications of earthquakes during the time of deposition of the deep water succession the driving mechanisms that resulted in the final configuration of the soft sediment deformation structures involved a combination of vertical shear stress caused by fluidization development of an inverse density gradient and a downslope component of force associated with the local slope ground penetrating radar profiles confirm the overall north east orientation of the flame structures and provide a basis for recognition of potential larger scale examples of flames in seismic reflection data sets

eocene paleoseismic record of the green river formation fossil basin wyoming u s a implications of synsedimentary deformation structures in lacustrine carbonate mudstones abstract laterally extensive intervals containing sedimentary deformation features are identified in outcrops of lacustrine deposits of the eocene 52 51 ma green river formation in fossil basin southwestern wyoming fossil basin is the smallest of the paleo lakes in the green river system and is located in the sevier fold and thrust belt which was tectonically active during deposition deformation structures include convolute lamination load structures hybrid brittle ductile features sedimentary dikes microfaults fluid escape features such as cusps and pipes oil shale breccias and mass transport deposits in most cases these structures are hosted by finely laminated variably organic rich carbonate mudstones that accumulated in a low energy profundal lacustrine environment deformed intervals range from a few centimeters to 5 m in thickness and are bound above and below by undeformed strata of the same facies which demonstrates the early post depositional timing of deformation the distribution of these features indicates a primary control exerted by sediment rheology resulting from variation in grain size clay and organic content and degree of lithification which in turn were governed by the depositional environment and early diagenesis based on their morphological attributes lateral extent and recurrence at different stratigraphic levels along with their sedimentary environment and the tectonic setting of the basin the deformation structures are interpreted to be seismites i e the result of stresses induced by syndepositional earthquakes and other potential trigger agents are rejected moreover stratigraphic relationships indicate that these small scale deformation features as well as the mass transport deposits formed on a virtually flat lake floor ruling out instability caused by the gravitational regime syndepositional deformation in fossil basin points to tectonic activity along the nearby absaroka and or hogsback thrusts and related fault systems seismites point to possible tectonic forcing as a mechanism for changes in bathymetry and sedimentation in the green river formation and consequently demonstrate their potential for elucidating the tectonic history of other lacustrine and marine basins

the geodynamic evolution of the internal zone of the betic cordilleras south east spain a model based on structural analysis and geothermobarometry the internal zone of the betic cordilleras consists of several superimposed major thrust sheets with different p t t evolutions on the basis of an integrated field microscopic and laboratory study the tectono metamorphic history of the mulhacen complex and almanzora unit has been reconstructed in detail the mulhacen complex has been af ected by at least five phases of penetrative deformation which have been labelled dx d dx d and dx d and d are related to continent continent collision which is indicated by high pressure low temperature wilt and subsequent intermediate pit metamorphic conditions d is related to crustal thinning and heterogeneous extension during this event the almanzora unit was juxtaposed against the mulhacen complex this phase was succeeded by the establishment of low pressure high temperature lpiht conditions and at least two phases of folding and overthrusting the almanzora unit shows a comparable tectono metamorphic evolution pt d however the pit conditions prior to d indicate a higher crustal position with respect to the mulhacen complex during the collisional event key w alpine orogeny betic cordilleras spain continent continent collision crustal thickening crustal thinning deformation structures geothermobarometry p t t path

toba ash layers in the south china sea evidence of contrasting wind directions during eruption ca 74 ka two cores from the southern south china sea contain discrete ash layers that mainly consist of rhyolithic glass shards on the basis of the specmap time scale the ash layers were dated to ca 74 ka the age of the youngest toba eruption in northern sumatra this link is supported by the chemical composition of the glass which is distinct from volcanic glass supplied from the philippines and the northern south china sea but is almost identical with the chemistry of the toba ash the youngest toba ash layers in the south china sea expand the previously known ash fall zone over more than 1800 km to the east the dispersal of ashes from sumatra in both western and eastern directions indicates two contrasting wind directions and suggests that 1 the toba eruption probably happened during the southeast asian summer monsoon season and 2 the volume of erupted magma was larger than previously interpreted

ichnological evidence for the environmental setting of the fossil lagerstatten in the devonian hunsruck slate germany analysis of the ichnology and sedimentology of the lower devonian hunsruck slate germany reveals that the distribution and preservation of the famous pyritized fauna were controlled by the deposition of fine grained turbidites that formed a firm substrate the nature of this substrate is evidenced by the preservation of laminae and the finest details of arthropod trackways the trace fossils are dominated by two ecological groups those made by epifaunal organisms and those involving burrow systems connected to the sediment water interface trace makers that moved through the sediment are poorly represented the diversity of in situ body fossils and epifaunal traces confirms that conditions within the water column remained well oxygenated even though the sediment rapidly became inhospitable the hunsruck slate konservat lagerstatten are remarkable in preserving soft tissues where unusual geochemical conditions prevailed in the environment where the animals lived rather than following transport to a different setting

equilibrium oxygen and hydrogen isotope fractionation between ice and water we have performed high precision measurements of the isotope fractionation factors between ice and water ice was grown from a stirred water mass on a cooling plate the freezing velocity was varied keeping the stirring rate of the water constant so that the equilibrium fractionation factors could be determined by extrap olating to zero freezing velocity the resulting values are a d h 1 0212 0 0004 non equilibrium freezing of lake and sea ice is briefly discussed as well as the significance of our results for the deuterium excess in polar precipitation

holocene late pleistocene climatic ice core records from qinghai tibetan plateau three ice cores to bedrock from the dunde ice cap on the north central qinghai tibetan plateau of china provide a detailed record of holocene and wisconsin wurm late glacial stage lgs climate changes in the subtropics the records reveal that lgs conditions were apparently colder wetter and dustier than holocene conditions the lgs part of the cores is characterized by more negative 18 o ratios increased dust content decreased soluble aerosol concentrations and reduced ice crystal sizes than the holocene part these changes occurred rapidly 10 000 years ago in addition the last 60 years were apparently one of the warmest periods in the entire record equalling levels of the holocene maximum between 6000 and 8000 years ago

repeated thermal resetting of phengites in the mulhacen complex betic zone southeastern spain shown by40ar 39ar step heating and single grain laser probe dating abstract this study reports the results of the first 40 ar 39 ar combined induction furnace and laser probe dating of phengites from the mulhacen hp lt metamorphic complex in the betic cordilleras southern spain laser step heating and spot fusion analyses on different halves of a split single grain were made with a continuous laser probe spot fusion analysis resulted in ages of about 30 31 ma in the core and ages as low as 25 26 ma in the rim laser step heating on the other half of the grain gave a spectrum with apparent ages increasing from about 25 ma to 29 5 ma the age spectrum and the decreasing ages towards the rim of the grain may imply that resetting essentially occurred by volume diffusion of radiogenic 40 ar due to late stage reheating resulting from extensional tectonics ages around 30 ma in the core of the grain are interpreted as minimum estimates of the cooling age of the main tectono metamorphic phase d 2 induction furnace step heating on phengite separates from mica schists and one gneiss resulted in two types of age spectra type i spectra show monotonously rising apparent ages from 14 5 1 9 ma to 20 7 0 2 ma and in a second sample from 16 9 0 7 to 29 7 0 2 ma type ii spectra are characterized by plateaus of 14 4 0 1 ma the gneiss sample 17 3 0 1 ma and 17 6 0 1 ma type ii spectra show low temperature apparent ages significantly below the plateau age implying resetting subsequent to initial cooling modelling of the age spectra demonstrated that the plateau ages are possibly the result of strong resetting 75 85 of argon loss of an older isotope system total fusion of a number of phengite single grains from marbles taken close to type ii mica schists yielded ages of 15 4 1 2 ma and 17 0 0 7 ma the observed repeated resetting is coeval with major volcanic activity in basins adjacent to the metamorphic ranges pointing to a resetting by advective fluid transport related to volcanism

chemical composition of fresh snow on mount everest one hundred freshly fallen snow samples were collected from the north side of mount everest between 5600 and 7100 m elevation in april and may of 1986 compared to snow from the rocky mountains of wyoming the everest samples have lower sulfate and nitrate concentrations reflecting a lesser anthropogenic input and much higher calcium concentrations and ph the calcium concentrations and high ph presumably reflect a large but variable input of calcium carbonate dust either from arid areas to the west and north or from more local glacial deposits

construction of volcanic records from marine sediment cores a review and case study montserrat west indies detailed knowledge of the past history of an active volcano is crucial for the prediction of the timing frequency and style of future eruptions and for the identification of potentially at risk areas subaerial volcanic stratigraphies are often incomplete due to a lack of exposure or burial and erosion from subsequent eruptions however many volcanic eruptions produce widely dispersed explosive products that are frequently deposited as tephra layers in the sea cores of marine sediment therefore have the potential to provide more complete volcanic stratigraphies at least for explosive eruptions nevertheless problems such as bioturbation and dispersal by currents affect the preservation and subsequent detection of marine tephra deposits consequently cryptotephras in which tephra grains are not sufficiently concentrated to form layers that are visible to the naked eye may be the only record of many explosive eruptions additionally thin reworked deposits of volcanic clasts transported by floods and landslides or during pyroclastic density currents may be incorrectly interpreted as tephra fallout layers leading to the construction of inaccurate records of volcanism this work uses samples from the volcanic island of montserrat as a case study to test different techniques for generating volcanic eruption records from marine sediment cores with a particular relevance to cores sampled in relatively proximal settings i e tens of kilometres from the volcanic source where volcaniclastic material may form a pervasive component of the sedimentary sequence visible volcaniclastic deposits identified by sedimentological logging were used to test the effectiveness of potential alternative volcaniclastic deposit detection techniques including point counting of grain types component analysis glass or mineral chemistry colour spectrophotometry grain size measurements xrf core scanning magnetic susceptibility and x radiography this study demonstrates that a set of time efficient non destructive and high spatial resolution analyses e g xrf core scanning and magnetic susceptibility can be used effectively to detect potential cryptotephra horizons in marine sediment cores once these horizons have been sampled microscope image analysis of volcaniclastic grains can be used successfully to discriminate between tephra fallout deposits and other volcaniclastic deposits by using specific criteria related to clast morphology and sorting standard practice should be employed when analysing marine sediment cores to accurately identify both visible tephra and cryptotephra deposits and to distinguish fallout deposits from other volcaniclastic deposits

a continuous 5300 yr holocene cryptotephrostratigraphic record from northern new zealand and implications for tephrochronology and volcanic hazard assessment a continuous 5280 calendar cal yr long cryptotephrostratigraphic record of a peat core from northern new zealand demonstrates that cryptotephra studies can enhance conventional tephra records by extending the known distribution of ash fall and enabling re assessment of volcanic hazards a systematic sampling strategy was used to locate peaks in glass shard concentrations and to determine loci of individual geochemical populations and a palynological method involving spiking samples with lycopodium spores was adapted to facilitate accurate counting of glass shard concentrations using glass shard major element compositions and a core chronology based on eight ams 14c ages and two visible macroscopic tephra layers taupo tephra unit y 1688 1748 cal bp and tuhua tephra 6800 7230 cal bp 2cr age ranges four cryptotephras were correlated with known eruptions whakaipo unit v 2743 2782 cal bp stent unit q 4240 4510 cal bp and unit k 4970 5290 cal bp erupted from taupo volcanic ce

a 150 000 year climatic record from antarctic ice during much of the quaternary the earth s climate has undergone drastic changes most notably successive glacial and interglacial episodes the past 150 kyr includes such a climatic cycle the last interglacial the last glacial and the present holocene interglacial a new climatic time series for this period has been obtained using 18 o data from an antarctic ice core

e w opening of the algerian basin western mediterranean we present geophysical and geological evidence of fast 2 cm yr 1 in the east and 5 cm yr 1 in the west e w spreading between 16 and 8 ma in the region behind the gibraltar arc in the algerian basin

correlating tephras and cryptotephras using glass compositional analyses and numerical and statistical methods review and evaluation abstract we define tephras and cryptotephras and their components mainly ash sized particles of glass crystals in distal deposits and summarize the basis of tephrochronology as a chronostratigraphic correlational and dating tool for palaeoenvironmental geological and archaeological research we then document and appraise recent advances in analytical methods used to determine the major minor and trace elements of individual glass shards from tephra or cryptotephra deposits to aid their correlation and application protocols developed recently for the electron probe microanalysis of major elements in individual glass shards help to improve data quality and standardize reporting procedures a narrow electron beam diameter 3 5 m can now be used to analyze smaller glass shards than previously attainable reliable analyses of microshards defined here as glass shards in part 2 of the review we describe critically assess and recommend ways in which tephras or cryptotephras can be correlated in conjunction with other information using numerical or statistical analyses of compositional data statistical methods provide a less subjective means of dealing with analytical data pertaining to tephra components usually glass or crystals phenocrysts than heuristic alternatives they enable a better understanding of relationships among the data from multiple viewpoints to be developed and help quantify the degree of uncertainty in establishing correlations in common with other scientific hypothesis testing it is easier to infer using such analysis that two or more tephras are different rather than the same adding stratigraphic chronological spatial or palaeoenvironmental data i e multiple criteria is usually necessary and allows for more robust correlations to be made a two stage approach is useful the first focussed on differences in the mean composition of samples or their range which can be visualised graphically via scatterplot matrices or bivariate plots coupled with the use of statistical tools such as distance measures similarity coefficients hierarchical cluster analysis informed by distance measures or similarity or cophenetic coefficients and principal components analysis pca some statistical methods cluster analysis discriminant analysis are referred to as machine learning in the computing literature the second stage examines sample variance and the degree of compositional similarity so that sample equivalence or otherwise can be established on a statistical basis this stage may involve discriminant function analysis dfa support vector machines svms canonical variates analysis cva and anova or manova or its two sample special case the hotelling two sample t2 test randomization tests can be used where distributional assumptions such as multivariate normality underlying parametric tests are doubtful compositional data may be transformed and scaled before being subjected to multivariate statistical procedures including calculation of distance matrices hierarchical cluster analysis and pca such transformations may make the assumption of multivariate normality more appropriate a sequential procedure using mahalanobis distance and the hotelling two sample t2 test is illustrated using glass major element data from trachytic to phonolitic kenyan tephras all these methods require a broad range of high quality compositional data which can be used to compare unknowns with reference training sets that are sufficiently complete to account for all possible correlatives including tephras with heterogeneous glasses that contain multiple compositional groups currently incomplete databases are tending to limit correlation efficacy the development of an open online global database to facilitate progress towards integrated high quality tephrostratigraphic frameworks for different regions is encouraged

using cryptotephras to extend regional tephrochronologies an example from southeast alaska and implications for hazard assessment abstract cryptotephrochronology the use of hidden diminutive volcanic ash layers to date sediments has rarely been applied outside western europe but has the potential to improve the tephrochronology of other regions of the world here we present the first comprehensive cryptotephra study in alaska cores were extracted from five peatland sites with cryptotephras located by ashing and microscopy and their glass geochemistry examined using electron probe microanalysis glass geochemical data from nine tephras were compared between sites and with data from previous alaskan tephra studies one tephra present in all the cores is believed to represent a previously unidentified eruption of mt churchill and is named here as the lena tephra a mid holocene tephra in one site is very similar to aniakchak tephra and most likely represents a previously unidentified aniakchak eruption ca 5300 5030 cal yr bp other tephras are from the late holocene white river eruption a mid holocene mt churchill eruption and possibly eruptions of redoubt and augustine volcanoes these results show the potential of cryptotephras to expand the geographic limits of tephrochronology and demonstrate that mt churchill has been more active in the holocene than previously appreciated this finding may necessitate reassessment of volcanic hazards in the region

origin and deformation of the neogene recent maghrebian foredeep at the gela nappe se sicily se sicily contains one of the few exposures of orogenic foreland to the maghrebian apennine orogenic system in the central mediterranean here the african foreland is represented by the hyblean plateau adjacent to the frontal thrust structures of the maghrebian chain these structures include the disrupted foredeeps to earlier parts of the thrust system one of these the gela nappe is a major structure composed of late oligocene to early pliocene sediments emplaced onto pliocene pleistocene rocks of the buried foreland this paper presents a correlation of late miocene stratigraphic units between the foreland and the foredeep basin abrupt lithological and thickness variations of these units suggest that the foredeep basin was limited towards the foreland by normal faults in the hinterland these foredeep sediments lap back onto previously emplaced thrust sheets including the far travelled units of numidian flysch the precursor oligocene serravallian foredeep may also have been controlled by normal faulting compressional tectonics are reflected in folding and thrusting which post dates deposition of lower pliocene chalks trubi formation although minor folding and erosion preceded this unit larger thrusts repeat the basin stratigraphy and carry it out onto the adjacent foreland a minimum of 8 km shortening since messinian times can be demonstrated although a more realistic figure is c 25 km at a time averaged rate off 0 5cm a 1 the stratigraphic relationships on the foredeep sedimentary sequences may provide analogues for offshore areas of the thrust belt

isotopic study on dokriani bamak glacier central himalaya implications for climatic changes and ice dynamics measurements of natural and artificial radioisotopes 32 si 210 pb and 137 cs and oxygen isotopes 18 o have been carried out on surface snow and ice shallow snow pits and an ice core collected from dokriani bamak glacier central himalaya to study the dynamics of glacier ice and short term climatic changes based on the 32 si and 210 pb activities in the meltwaters the age of the snout ice is 400 years and the flow rate of ice along the glacier length is 14 m a 1 the specific activity of 137 cs corresponding to 1963 fallout in the surface ice at the equilibrium line yields a flow rate of 32 m a a factor of two higher than that derived for the snout ice the depth variation of 137 cs concentration in a shallow ice core yields a mean accumulation rate of 0 43 m a 1 for the glacier ice over the past decade the 18 o of snout ice 13 4 is significantly depleted compared to the average value of 9 2 in the shallow ice core indicating that cooler climatic conditions prevailed around ad 1600 based on the oxygen isotopic ratios in the shallow pits an altitude effect of 0 9 per 100 m in 18 o variation is documented for this glacier

towards rapid assay of cryptotephra in peat cores review and evaluation of various methods abstract peat bogs are highly effective archives for the preservation and detection of cryptotephra but the conventional methods used to detect these hidden diminutive layers are destructive and can be time consuming we briefly review methods that have been used for cryptotephra detection and evaluate the potential of a range of alternative reconnaissance methods both non destructive and destructive to provide for more rapid examination of continuous cryptotephra content in peat cores the techniques evaluated magnetic susceptibility ms spectrophotometry and x ray fluorescence are used to pick out compositional contrasts between tephra deposits and peat measurements of organic content are also evaluated as a potential guide to tephra content based on an inverse relationship although we find limitations to each method particularly where deployed at the distal most end of tephra dispersal there is potential for all methods to be used in the detection of cryptotephra where time or material is limited these methods can also provide additional sedimentological and stratigraphic information for studies of peat cores however where a reliable cryptotephra profile is required we conclude that there is no quick or easy substitute for the conventional extraction microscopy method