dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

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

variations in the age of arctic sea ice and summer sea ice extent 1 three of the past six summers have exhibited record low sea ice extent on the arctic ocean these minima may have been dynamically induced by changes in the surface winds based on results of a simple model that keeps track of the age of ice as it moves about on the arctic ocean we show that the areal coverage of thick multi year ice decreased precipitously during 1989 1990 when the arctic oscillation was in an extreme high index state and has remained low since that time under these conditions younger thinner ice anomalies recirculate back to the alaskan coast more quickly decreasing the time that new ice has to ridge and thicken before returning for another melt season during the 2002 and 2003 summers this anomalously younger thinner ice was advected into alaskan coastal waters where extensive melting was observed even though temperatures were locally colder than normal the age of sea ice explains more than half of the variance in summer sea ice extent

boulders of mis 5 age deposited by a tsunami on the coast of otago new zealand abstract a series of elevated imbricated boulders were investigated on the otago coastline southeast new zealand through field surveying and optical luminescence dating by using established hydrodynamic relationships of sediment transport the energy required to move the clasts was calculated and compared to the historic record of marine inundations of that coast the boulders are platy in shape and are over 2 m long in some cases and are sourced from a locally outcropping conglomerate unit which appears to be the only lithology on this section of coast that erodes to produce clasts of this size it is estimated that the boulders were deposited by a tsunami between 2 and 3 m high during the latter part of marine isotope stage 5 they therefore represent the first pre holocene tsunami deposit and one composed of large boulders described on the new zealand coastline

thinning and volume loss of the arctic ocean sea ice cover 2003 2008 1 we present our best estimate of the thickness and volume of the arctic ocean ice cover from 10 ice cloud and land elevation satellite icesat campaigns that span a 5 year period between 2003 and 2008 derived ice drafts are consistently within 0 5 m of those from a submarine cruise in mid november of 2005 and 4 years of ice draft profiles from moorings in the chukchi and beaufort seas along with a more than 42 decrease in multiyear my ice coverage since 2005 there was a remarkable thinning of 0 6 m in my ice thickness over 4 years in contrast the average thickness of the seasonal ice in midwinter 2 m which covered more than two thirds of the arctic ocean in 2007 exhibited a negligible trend average winter sea ice volume over the period weighted by a loss of 3000 km3 between 2007 and 2008 was 14 000 km3 the total my ice volume in the winter has experienced a net loss of 6300 km3 40 in the 4 years since 2005 while the first year ice cover gained volume owing to increased overall area coverage the overall decline in volume and thickness are explained almost entirely by changes in the my ice cover combined with a large decline in my ice coverage over this short record there is a reversal in the volumetric and areal contributions of the two ice types to the total volume and area of the arctic ocean ice cover seasonal ice having surpassed that of my ice in winter area coverage and volume became the dominant ice type it seems that the near zero replenishment of the my ice cover after the summers of 2005 and 2007 an imbalance in the cycle of replenishment and ice export has played a significant role in the loss of arctic sea ice volume over the icesat record

distribution of clay minerals in surface sediments from the eastern barents and south western kara seas surface samples from the eastern barents and south western kara seas have been analysed for clay mineralogy transport paths the role of regional sources and local bedrock outcrops and the influence of hydrodynamic and glacigenous processes for clay distribution on the shelves are discussed in relation to central arctic ocean deep sea and sea ice sediments franz josef land and novaya zemlya show significantly different clay mineral associations although smectite concentrations are fairly high franz josef land can be excluded as a source for central arctic sea ice sediments which are relatively rich in smectite in the kara sea smectite concentrations in coastal sediments surpass even the franz josef land concentrations the large cyclonic gyre in the eastern barents sea between novaya zemlya and franz josef land which serves as a mixing zone between arctic and north atlantic water is apparently reflected within the smectite distribution pattern with the exception of franz josef land the area of investigation is typically low in kaolinite in particular coastal areas and areas north of novaya zemlya influenced by the inflow of arctic waters show the lowest kaolinite concentrations a high kaolinite occurrence within the nansen basin is most probably related to franz josef land and emphasizes the importance of long range downslope transport of sediments across the continental slope the surface water circulation pattern in close interaction with local outcrops onshore novaya zemlya and locally restricted occurrences within the eastern barents sea significantly alter the illite dispersal pattern illite concentrations are lowest around franz josef land chlorite is generally low in the area of investigation submarine outcrops and important chlorite occurrences onshore novaya zemlya bias its distribution pattern

timing of late quaternary glaciations in the himalayas of northern pakistan optically stimulated luminescence dating of late quaternary glaciogenic sediments was undertaken in critical areas of the himalayas of northern pakistan in order to examine the timing of glaciation the dates demonstrate that several glaciations occurred during the last glacial cycle in swat the grabral 2 stade and the kalam i stade were dated at ca 77 ka and ca 38 ka respectively the error on the former date is large and it is conceivable that the moraines may have formed during the early part of oxygen isotope stage 3 rather than during oxygen isotope stage 4 the kalam i stade however clearly represents a glaciation during oxygen isotope stage 3 the oldest moraines and those at the lowest altitude in the indus valley at shatial have an age of ca 60 ka these also relate to a major glacial advance during oxygen isotope stage 3 a younger series of moraines the jalipur tillite and glaciofluvial sands at liachar in the indus valley and moraines at rampur tarshing have ages of ca 27 ka ca 21 23 ka and ca 15 ka respectively these dates show that glaciers also occupied parts of the indus valley during oxygen isotope stage 2 these dates and the morphostratigraphy show that glaciation in the pakistani himalaya was more extensive during the early part of the last glacial cycle and that the local last glacial maximum in pakistan was asynchronous with the maximum extent of northern hemisphere ice sheets copyright 2000 john wiley sons ltd

arctic palaeo river discharge and environmental change evidence from the holocene kara sea sedimentary record abstract in this paper we summarize data on terrigenous sediment supply in the kara sea and its accumulation and spatial and temporal variability during holocene times sedimentological organic geochemical and micropaleontological proxies determined in surface sediments allow to characterize the modern riverine terrigenous sediment input ams 14c dated sediment cores from the ob and yenisei estuaries and the adjacent inner kara sea were investigated to determine the terrigenous sediment fluxes and their relationship to paleoenvironmental changes the variability of sediment fluxes during holocene times is related to the post glacial sea level rise and changes in river discharge and coastal erosion input whereas during the late middle holocene most of the terrigenous sediments were deposited in the estuaries and the areas directly off the estuaries huge amounts of sediments accumulated on the kara sea shelf farther north during the early holocene before about 9 cal kyr bp the maximum accumulation at that time is related to the lowered sea level increased coastal erosion and increased river discharge based on sediment thickness charts echograph profiles and sediment core data we estimate an average holocene 0 11 cal kyr bp annual accumulation of 194 106 t yr 1 of total sediment for the whole kara sea based on late holocene modern sediment accumulation in the estuaries probably 12 106 t yr 1 of riverine suspended matter i e about 30 of the input may escape the marginal filter on a geological time scale and is transported onto the open kara sea shelf the high resolution magnetic susceptibility record of a yenisei core suggests a short term variability in siberian climate and river discharge on a frequency of 300 700 yr this variability may reflect natural cyclic climate variations to be seen in context with the interannual and interdecadal environmental changes recorded in the high northern latitudes over the last decades such as the nao ao pattern a major decrease in ms values starting near 2 5 cal kyr bp being more pronounced during the last about 2 cal kyr bp correlates with a cooling trend over greenland as indicated in the gisp 2 ice core extended sea ice cover in the north atlantic and advances of glaciers in western norway our still preliminary interpretation of the ms variability has to be proven by further ms records from additional cores as well as other high resolution multi proxy arctic climate records

dating methods and geomorphic evidence of palaeoenvironmental changes at the eastern margin of the south peruvian coastal desert 14 30 s before and during the little ice age abstract the atacama desert is known to be one of the driest places on earth however in the study area between ica and nasca south peru 75 76 w 14 15 s palaeoclimate proxies show several semi arid phases during the holocene a more humid period during the early holocene favoured an open grass land which allowed the accumulation of desert loess eitel b hecht s machtle b schukraft g kadereit a wagner g kromer b unkel i reindel m 2005 geoarchaeological evidence from desert loess in the nazca palpa region southern peru palaeoenvironmental changes and their impact on pre columbian cultures archaeometry 47 137 158 the paracas and nasca cultures existing in that region between the 9th century bc and 7th century ad had propitious conditions to evolve and to settle close to the rivers fed by the monsoonal precipitation in the cordillera occidental culminating aridity after 600 ad might have caused the collapse of the nasca civilization the onset of semi arid climate towards the end of the late intermediate period 14th century ad allowed a reoccupation of the area here we present 14c and osl data from sediments of river terraces a debris flow and loess snails scutalus sp indicating appreciable geomorphic activity between 1390 and 1714 cal ad this phase is isochronous to the little ice age period on the northern hemisphere and to an increase in the ice accumulation on the quelccaya glacier in the peruvian altiplano thompson l g mosley thompson e bolzan j f koci b r 1985 a 1500 year record of tropical precipitation in ice cores from the quelccaya ice cap peru science 229 971 973

optical dating using infrared diodes young samples abstract ages are reported for unburnt sediment samples from 9 archaeological sites in england spanning 1000 5000 years samples from two modern contexts have also been measured

field observations of slush ice generated during freeze up in arctic coastal waters abstract in some years large volumes of slush ice charged with sediment are generated from frazil crystals in the shallow beaufort sea during strong storms at the time of freeze up such events terminate the navigation season and because of accompanying hostile conditions little is known about the processes acting the water saturated slush ice which may reach a thickness of 4 m exists for only a few days before freezing from the surface downward arrests further wave motion or pancake ice forms movements of small vessels and divers in the slush ice occurs only in phase with passing waves producing compression and rarefaction and internal pressure pulses where in contact with the seafloor the agitated slush ice moves cobble size material generates large sediment ripples and may possibly produce a flat rampart observed on the arctic shoreface in some years processes charging the slush ice with as much as 1000 m 3 km 2 of sediment remain uncertain but our field observations rule out previously proposed filtration from turbid waters as a likely mechanism sedimentary particles apparently are only trapped in the interstices of the slush ice rather than being held by adhesion since wave related internal pressure oscillations result in downward particle movement and cleansing of the slush ice this loss of sediment explains the typical downward increase in sediment concentration in that part of the fast ice canopy composed largely of frazil ice the congealing slush ice in coastal water does not become fast ice until grounded ridges are formed in the stamukhi zone one to two months after freeze up begins during this period of new ice mobility long range sediment transport occurs the sediment load held by the fast ice canopy in the area between the colville and sagavanirktok river deltas in the winter of 1978 1979 was 16 times larger than the yearly river input to the same area this sediment most likely was rafted from canada more than 400 km to the east during a brief time period in the previous fall ocean turbulence is greatly reduced while the congealing slush ice drifts about therefore new ice then forming in intervening open water areas is clean these events explain the patchy appearance of the fast ice after the summer snowmelt more work on the important phenomena reported here is needed to close a major gap in the knowledge of the arctic marine environment

flow of winter transformed pacific water into the western arctic abstract the dynamics of the flow of dense water through barrow canyon is investigated using data from a hydrographic survey in summer 2002 the focus is on the winter transformed bering water the highest volumetric mode of winter water in the chukchi sea which drains northward through the canyon in spring and summer the transport of this water mass during the time of the survey was 0 2 0 3 sv as the layer flowed from the head of the canyon to the mouth it sank decelerated and stretched strong cyclonic relative vorticity was generated on the seaward side of the jet which compensated for the stretching this adjustment was incomplete however in that it did not extend across the entire current possibly because of internal mixing due to shear instabilities the resulting vorticity structure of the flow at the canyon mouth was conducive for baroclinic instability and eddy formation multiple eddies of winter transformed bering water were observed along the chukchi beaufort shelfbreak those to the west of barrow canyon were in the process of being spawned by the eastward flowing shelfbreak current emanating from herald canyon while the single eddy observed to the east originated from the barrow canyon outflow it is argued that such an eddy formation is a major source of the ubiquitous cold core anti cyclones observed historically throughout the canada basin implications for the ventilation of the upper halocline of the western arctic are discussed

a key source area and constraints on entrainment for basin scale sediment transport by arctic sea ice combining field measurements remote sensing and numerical modelling a key site for ice entrainment and basinwide dispersal of sediments by sea ice has been identified near the new siberian islands the total ice bound sediment export of 18 5 x 10 6 t for an entrainment event documented in 1994 95 is of the same order of magnitude as annual sediment supply to the deep sea sector of the eurasian arctic and the greenland sea satellite imagery and ancillary data indicate that ice advection from this source may play an important role in sedimentation downstream in the transpolar drift

late quaternary aeolian sedimentation in central and south eastern tibet abstract the geomorphology and the cover sediments in the central and south eastern part of the tibetan plateau provide information about climatic change luminescence dating of aeolian and colluvial silts on top of different moraine sequences provides the first indications for the timing of these sediments during the late quaternary and holocene although there is a widespread cover of aeolian mantles in tibet only a few papers have focussed on them up to now samples from silt layers on top of pleistocene moraines or solifluction debris from central and southern tibet at elevations above 4000 m asl provide early holocene ages in most sections the aeolian silt on top of the bomi moraine in southeastern tibet situated at an elevation of about 3000 m asl provides an age of 25 ka according to geomorphological investigations the bomi moraine dates from the last ice age which can be confirmed by the luminescence data moreover one sample from a silt layer in between gravel layers xainxa is also pleistocene in age according to its sedimentary and geomorphological situation in the tibetan plateau pleistocene loess mainly occurs below 4000 m asl the holocene material a more sandy silt lying above 4000 m asl however aeolian material capping the moraines provides only minimum ages for the terminal moraines the time interval between glacier retreat and the accumulation of aeolian sediments may be several thousand years the most important fact is the trapping of dust in general lakes and a denser vegetation cover are or were the main traps for the typical loess found in the mountain areas of the tibetan plateau

slip rate on the wellington fault new zealand during the late quaternary evidence for variable slip during the holocene we investigate fault offset fluvial terraces at two sites along the hutt river near wellington new zealand to determine horizontal slip rates for the southern part of the wellington fault for the last 100 ka using photogrammetric analysis of historic aerial photos we measured the original displacements of terrace risers at emerald hill which have been modified by urban development fourteen sediment samples from this site and from another location dry creek were analyzed using optically stimulated luminescence osl methods yielding ages of between 10 ka and 100 ka from our displacement age relations we estimate an average slip rate of graphic 1 2 during the last 100 ka however slip on the wellington fault has not been steady throughout this time during the holocene there was a phase of heightened ground rupture activity between 10 and 8 ka when an incremental dextral displacement of 32 m accrued this was followed by a period of relative quiescence between 8 and 4 5 ka with 5 m of displacement during this time another period of heightened activity followed resulting in a further 20 m of slip during the last 4 5 ka our inference of variable slip during the holocene accords with independent evidence from paleoseismological studies at other sites along the wellington fault slip on the wellington fault and its variability through time may be influenced by activity on neighboring faults online material part i optically stimulated luminescence osl dating technical report and results part 2 stratigraphic logs 1 embed inline graphic 1 gif

the stratigraphy timing and climatic implications of glaciolacustrine deposits in the middle rakaia valley south island new zealand abstract stratigraphic interpretations and infrared stimulated luminescence irsl ages document the glacial history of the middle rakaia gorge section of the rakaia valley canterbury new zealand during the last two glacial cycles sheets of glaciolacustrine sediments several tens of metres in thickness can be traced at least 10 km upstream of the rakaia gorge the stratigraphic package is capped by outwash gravels associated with the last glacial maximum lgm advances the dominant inferred sedimentary environments in the sequence are 1 pro glacial and paraglacial lake beds 2 sub aqueous ice contact fans 3 sub aqueous mass flow deposits 4 supraglacial dump material and 5 outwash gravels syndepositional deformation associated with glacitectonic deformation is common the stratigraphy records glacier margin oscillations including six significant advances these occurred in early mis 6 mid mis 6 mis 5b c100 90 ka mis 5a 4 c 80 ka mid mis 3 c 48 ka and late mis 3 c 40ka all the post mis 6 advances can be corroborated from other sites in new zealand and the timings appear to coincide with both southern hemisphere insolation minima and maxima suggesting variable combinations of climatic forcing in new zealand glaciation

sediment transport by sea ice in the chukchi and beaufort seas increasing importance due to changing ice conditions abstract sediment laden sea ice is widespread over the shallow wide siberian arctic shelves with off shelf export from the laptev and east siberian seas contributing substantially to the arctic ocean s sediment budget by contrast the north american shelves owing to their narrow width and greater water depths have not been deemed as important for basin wide sediment transport by sea ice observations over the chukchi and beaufort shelves in 2001 02 revealed the widespread occurrence of sediment laden ice over an area of more than 100 000 km2 between 68 and 74 n and 155 and 170 w ice stratigraphic studies indicate that sediment inclusions were associated with entrainment of frazil ice into deformed multiple layers of rafted nilas indicative of a flaw lead environment adjacent to the landfast ice of the chukchi and beaufort seas this is corroborated by buoy trajectories and satellite imagery indicating entrainment in a coastal polynya in the eastern chukchi sea in february of 2002 as well as formation of sediment laden ice along the beaufort sea coast as far eastward as the mackenzie shelf moored upward looking sonar on the mackenzie shelf provides further insight into the ice growth and deformation regime governing sediment entrainment analysis of radarsat synthetic aperture sar imagery in conjunction with bathymetric data help constrain the water depth of sediment resuspension and subsequent ice entrainment 20 m for the chukchi sea sediment loads averaged at 128 t km 2 with sediment occurring in layers of roughly 0 5 m thickness mostly in the lower ice layers the total amount of sediment transported by sea ice mostly out of the narrow zone between the landfast ice edge and waters too deep for resuspension and entrainment is at minimum 4 106 t in the sampling area and is estimated at 5 8 106 t over the entire chukchi and beaufort shelves in 2001 02 representing a significant term in the sediment budget of the western arctic ocean recent changes in the chukchi and beaufort sea ice regimes reduced summer minimum ice extent ice thinning reduction in multi year ice extent altered drift paths and mid winter landfast ice break out events have likely resulted in an increase of sediment laden ice in the area apart from contributing substantially to along and across shelf particulate flow an increase in the amount of dirty ice significantly impacts sub ice algal production and may enhance the dispersal of pollutants

a contribution to the dating of the northern boundary of the weichselian loess belt in northern germany by luminescence dating and pedological analysis abstract sedimentological examination of the sediments in the area along the northern margin of the loess belt in northern germany show a typical stratigraphic sequence of at least five phases of aeolian sedimentation as a contribution to the chronostratigraphic classification of the sedimentary sequence in this zone 15 samples from a section close to denstorf near braunschweig in lower saxony northern germany were dated using thermoluminescence tl as well as optically stimulated luminescence osl the age estimates obtained by dating the potassium rich feldspars and quartz rich extracts lead to the assumption that the northernmost last glacial loess accumulation occurred during the late glacial period this confirms earlier suggestions that the northernmost loess deposits in northern germany represent the return of strong aeolian processes under the cold and dry conditions of the late glacial

two circulation regimes of the wind driven arctic ocean the major goal of this paper is to demonstrate the existence in the arctic ocean of two regimes of wind forced circulation we simulated the vertically averaged currents sea level heights and ice drift in the arctic ocean from 1946 to 1993 using a two dimensional wind forced barotropic model that includes frictional coupling between the ocean and ice the model has a spatial resolution of 55 5 km and is driven by winds river runoff and an imposed but realistic sea level slope between the pacific and the atlantic oceans there is a good agreement between velocities from observed buoy motions and velocities of modeled ice drift even though the model lacks ocean baroclinicity and ice thermodynamics the results indicate that wind driven motion in the central arctic alternates between anticyclonic and cyclonic circulation with each regime persisting for 5 7 years based upon our analysis of the modeled sea level and ice motion anticyclonic wind driven motion in the central arctic appeared during 1946 1952 1958 1963 1972 1979 and 1984 1988 and cyclonic motion appeared during 1953 1957 1964 1971 1980 1983 and 1989 1993 shifts from one regime to another are forced by changes in the location and intensity of the icelandic low and the siberian high the two regimes may help explain the significant basin scale changes in the arctic s temperature and salinity structure observed recently the great salinity anomaly and the variability of ice conditions in the arctic ocean

luminescence chronology of late pleistocene glacial deposits in north westland new zealand abstract the chronology of the late pleistocene glacial history of north westland south island of new zealand is refined by luminescence dating of sediments it is demonstrated by two case studies that ages determined by different luminescence techniques agree well with the results of radiocarbon dating luminescence ages determined for sediments from two key sites of the loopline formation confirm the previous correlation of this unit with marine isotope stage mis 4 this indicates that late pleistocene glaciers reached their last maximum extent in north westland during the early part of the otira last glaciation furthermore initial dating evidence on coarse alluvial deposits in the lowlands indicates their formation during mis 5b and mis 5d it is probable that these coarse gravel deposits are outwash related to glacial advances if so both advances were probably much less extensive than the glaciations during mis 4 and mis 2

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

high resolution chronologies for loess comparing ams 14c and optical dating results the nuxloch loess section in south west germany is famous in central europe for its thick deposits from the last glacial maximum it has therefore been intensively studied during the past few years and offers an excellent opportunity to compare the performance of different dating techniques covering the period 15 45 ka here we present results fromoptical and ams 14 c dating the silt sized polymineral fraction of the clastic sediments and a multiple aliquot approach was used for ir osl dating 14 c dating was carried out on organic macro remnants and humin fractions extracted fromthe sedim ents with the exception of samples taken from the uppermost 1 5 m of the section ir osl and calibrated 14 c ams ages are consistent over the entire period the inconsistencies in the upper meters are thought to be due to disturbances during soil formation in the holocene the good agreement obtained on the remaining sequence demonstrates the high accuracy of both methods when studying loess sections for the ir osl ages no significant age underestimations are obvious the results clearly document that accurate chronologies can be developed for such continental sedimentary sequences this gives access to archives that can now be studied with a high temporal resolution and allows the establishment of new paleoclimatic proxies for the study of terrestrial responses to past climatic changes r 2003 elsevier science ltd all rights reserved

luminescence dating of sediments from the luthern valley central switzerland and implications for the chronology of the last glacial cycle abstract the advancing glaciers of the last glacial maximum either eroded or deeply buried older sediments in the swiss alpine foreland however part of the swiss plateau was not covered by ice and is therefore an excellent area for investigating climate and environmental change during the upper pleistocene repeated fluvial sequences can be studied in several pits along the luthern valley the chronological framework is based on lithostratigraphy pollen analysis u th dating and recently heavy mineral analysis and luminescence dating the oldest unit the untere zeller schotter braided river deposit represents cold climate conditions and presumably a glaciation prior to the eemian interglaciation the last interglacial period and the very beginning of the last glacial cycle is represented by the mittlere zeller schotter sediments of a meandering fluvial system younger braided river sediments the obere zeller schotter seem to correlate with the cold climate of oxygen isotope stage ois 4 weathering of the top of the obere zeller schotter is likely to represent the ois 3 the advancing reuss glacier caused erosion of the recent luthern valley cutting into older sediments with local loess accumulation during the last glacial maximum as indicated by cover sediments on top of the fluvial sequence

infrared stimulated luminescence dating of holocene colluvial sediments using the 410 nm emission abstract infrared stimulated luminescence irsl ages are reported for loessic colluvial sediments from wiesenbach south germany the samples were collected by boring and the polymineral fine grain fraction t4 1 i m was used for irsl investigations irsl spectra were measured prior to dating they show two major emissions at approx 560 and 410 nm the advantages of the subtraction dating technique aitken and xie 1992 using the 410 run emission are demonstrated the ages obtained are used for the reconstruction of the landscape development at the studied site subsequent to an erosion phase the deposition of a colluvium started prior to the roman period and increased to a maximum accumulation rate during the middle ages

sediments in arctic sea ice implications for entrainment transport and release despite the arctic sea ice cover s recognized sensitivity to environmental change the role of sediment inclusions in lowering ice albedo and affecting ice ablation is poorly understood sea ice sediment inclusions were studied in the central arctic ocean during the arctic 91 expedition and in the laptev sea east siberian arctic region expedition 1992 results from these investigations are here combined with previous studies performed in major areas of ice ablation and the southern central arctic ocean this study documents the regional distribution and composition of particle laden ice investigates and evaluates processes by which sediment is incorporated into the ice cover and identifies transport paths and probable depositional centers for the released sediment in april 1992 sea ice in the laptev sea was relatively clean the sediment occasionally observed was distributed diffusely over the entire ice column forming turbid ice observations indicate that frazil and anchor ice formation occurring in a large coastal polynya provide a main mechanism for sediment entrainment in the central arctic ocean sediments are concentrated in layers within or at the surface of ice floes due to melting and refreezing processes the surface sediment accumulation in central arctic multi year sea ice exceeds by far the amounts observed in first year ice from the laptev sea in april 1992 sea ice sediments are generally fine grained although coarse sediments and stones up to 5 cm in diameter are observed component analysis indicates that quartz and clay minerals are the main terrigenous sediment particles the biogenous components namely shells of pelecypods and benthic foraminiferal tests point to a shallow benthic marine source area apparently sediment inclusions were resuspended from shelf areas before and incorporated into the sea ice by suspension freezing clay mineralogy of ice rafted sediments provides information on potential source areas a smectite maximum in sea ice sediment samples repeatedly occurred between 81 n and 83 n along the arctic 91 transect indicating a rather stable and narrow smectite rich ice drift stream of the transpolar drift the smectite concentrations are comparable to those found in both laptev sea shelf sediments and anchor ice sediments pointing to this sea as a potential source area for sea ice sediments in the central arctic ocean sea ice clay mineralogy is significantly different from deep sea clay mineral distribution patterns the contribution of sea ice sediments to the deep sea is apparently diluted by sedimentary material provided by other transport mechanisms

anchor ice seabed freezing and sediment dynamics in shallow arctic seas diving investigations confirm previous circumstantial evidence of seafloor freezing and anchor ice accretion during freeze up storms in the alaskan beaufort sea these related bottom types were found to be continuous from shore to 2 m depth and spotty to 4 5 m depth spotty anchor ice occurred as pillow shaped crystal aggregates on buried slabs of frozen sand surrounded by unfrozen sand considerations of required conditions for ice bonding and anchor ice growth allows regional extrapolation and suggests the possibility of anchor ice growth out to 20 m depth the estimated maximum depth of supercooling during fall storms anchor ice and seabed freezing apparently do not develop during a calm freeze up because of the abrupt growth of anchor ice during a freezing storm and its release soon after formation of a surface ice cover this ice type has not been documented before the concretelike nature of frozen bottom where present should prohibit sediment transport by any conceivable wave or current regime during the freezing storm but elsewhere particularly where the bonded crust is broken by grounded ice anchor ice lifts coarse material off the bottom and incorporates it into the ice canopy thereby leading to significant ice rafting of shallow shelf sediment and likely sediment loss to the deep sea

a shift in heavy and clay mineral provenance indicates a middle miocene onset of a perennial sea ice cover in the arctic ocean during the arctic coring expedition acex a 428 m thick sequence of upper cretaceous to quaternary sediments was penetrated the mineralogical composition of the upper 300 m of this sequence is presented here for the first time heavy and clay mineral associations indicate a major and consistent shift in provenance from the barents kara western laptev sea region characterized by presence of common clinopyroxene to the eastern laptev east siberian seas in the upper part of the section characterized by common hornblende amphibole sea ice originating from the latter source region must have survived at least one summer melt cycle in order to reach the acex drill site if considering modern sea ice trajectories and velocities this shift in mineral assemblages probably represents the onset of a perennial sea ice cover in the arctic ocean which occurred at about 13 ma thus suggesting a coeval freeze in the arctic and antarctic regions

modern dirty sea ice characteristics and sources the role of anchor ice extensive dirty ice patches with up to 7 kg m 2 sediment concentrations in layers of up to 10 cm thickness were encountered in 2005 and 2007 in numerous areas across the central arctic the fe grai

mysterious iron nickel zinc arctic spherules an investigation into the sources of ice rafted detritus in the central arctic ocean using microprobe analyses of detrital fe oxide minerals discovered unique magnetic spherules in 20 of 144 potential source sample sites from the shelves and coastal areas around this ocean the spherules occur only in samples from the queen elizabeth islands canada these grains are characterized by a 45 60 m diameter pitting throughout and are occasionally found as multiple joint spherules they have the optical properties of magnetite and most remarkably contain both zno and nio in subequal amounts of up to 25 the ni suggests either an anthropogenic or meteoritic source these spherules were probably ice rafted into the central arctic ocean where they are found in sediments of holocene age and back to at least 780 ka eliminating an anthropogenic source because zn is too volatile to survive entry of a meteor through the earth s atmosphere these spherules were probably formed during impact of an fe ni meteor i

luminescence dating of poorly bleached sediments from scotland abstract two types of poorly bleached sediment are differentiated and the applicability of various luminescence dating methods is assessed the methods are applied to three fluvioglacial sediments from scotland it is shown that it is possible to detect sediments that contain a mixture of well bleached and unbleached grains using the single aliquot additive dose method or the analysis of the scatter in aultiple aliquot additive dose growth curve

the last interglacial to glacial transition togiak bay southwestern alaska an 18 m high coastal bluff at togiak bay northwestern bristol bay southwestern alaska exposes marine lacustrine fluvial glacial volcanic and organic deposits that record the 50 000year long transition from the peak of the last interglaciation to the early wisconsin glaciation the base of the section is dominated by stratified sand and silt extending up to 4 3 m above sea level marine diatoms are present and pollen assemblages are characterized by relatively high percentages of picea alnus and betula and low percentages of poaceae and cyperaceae the marine sediment was probably deposited during the peak of marine oxygen isotope stage ois 5e an infrared stimulated luminescence irsl age of 151 000 13 000 yr from near the base of the exposure is permissive of this correlation the marine sand and silt are overlain by 0 8 m of peaty silt with diatoms that record a transition from marine to lacustrine conditions during this interval poaceae and cyperaceae dominate the pollen assemblages and picea and shrubs are nearly absent suggesting that herb tundra occupied the landscape this interval probably encompasses ois 5d on the basis of the herb tundra and an irsl age of 119 000 10 000 yr from 60 cm below the marine lacustrine transition the organic mud is overlain by 3 1 m of stratified sand and organic silt that apparently record shallowing of the lake reappearance of spruce and shrubs dois 5c and subsequent deepening of the lake dois 5b followed by aggradation of a floodplain dois 5a which was dry at the time basaltic lava buried the site thermoluminescence analyses on lava baked sediment indicate that the eruption occurred 70 000 10 000 yr ago sometime thereafter but prior to 53 600 14 c yr b p an outlet of the ahklun mountains ice cap advanced over the site and deposited 7 m of bouldery ice contact drift the sedimentary sequence contains at least four tephra beds major and trace element chemistry provide a basis for correlating two of the tephras with tephra beds at nearby sites the tephras luminescence ages and correlations with marine isotope stages provide the geochronological control to place the togiak bay section into a global context the site serves as an important new reference section for late pleistocene paleoenvironmental change in eastern beringia

sea ice transport of riverine particles from the laptev sea to fram strait based on clay mineral studies the aim of this study was to identify pathways and processes of modern sediment transport from the siberian hinterland to the laptev sea and further to the arctic ocean clay mineral analyses were performed on riverine suspended particulate material spm surface sediments of the laptev sea shelf and sea ice sediments sis material collected during seven expeditions was included in this study clay mineral assemblages are used to decipher the distribution of riverine sediments on the shallow laptev sea shelf the entrainment of fine particles into newly forming ice and the transport of sis from the laptev sea towards the ablation areas a cluster analysis of our data set shows that the clay mineral assemblages of laptev sea shelf sediments and sis are controlled mainly by the input of riverine spm supplied by the khatanga lena and yana rivers whereas the western shelf clay mineral province is characterized by enhanced smectite concentrations supplied by the khatanga river the eastern laptev sea is dominated by illite discharged through the lena and yana rivers the sis smectite concentration serves as an indicator for sediment source areas on the circum arctic shelves subsequently the transpolar drift can be distinguished into a siberian branch fed from the eastern kara sea and the western laptev sea and a polar branch originating from the eastern laptev sea

timing of late quaternary glaciations south of mount everest in the khumbu himal nepal moraines south of mount everest in the khumbu himal were dated using optically stimulated luminescence clustering of ages and morphostratigraphy allowed three advances to be dated 1 the periche glacial stage ca 18 25 ka 2 the chhukung glacial stage ca 10 ka and 3 the lobuche stage ca 1 2 ka the periche stage is coincident with oxygen isotope stage 2 the chhukung stage represents a late glacial or early holocene glacial advance and the lobuche stage is a late holocene glacial advance that predates the little ice age

langmuir circulation driving sediment entrainment into newly formed ice tank experiment results with application to nature lake hattie united states kara sea siberia 1 langmuir circulation lc was generated under freezing conditions in saltwater tank experiments through surface wind stress and cross waves interacting with subsurface return flow fine grained sediments distributed in the tank prior to frazil crystal formation were aligned in parallel streaks in lc bottom convergence zones downwelling at lc surface convergence zones aligned floating frazil in wind parallel rows and individual crystals rotated on helical paths down to the tank bottom and up again to the surface the crystals interacted with suspended particles in the water column and with sediment on the tank bottom preferentially collecting fine grained particles and enhancing their entrainment into new ice evidence includes higher sediment concentrations in ice and ice interstitial water ice pore water as compared to the tank water both tank ice and ice interstitial water contain more silt sized particles than tank water suspension load and tank bottom sediment sand is reduced in the ice and clay is about the same concentration in all samples this points to preferential entrainment of fine particles in newly formed ice supported by lc driven circulation comparable results of lc supported ice particle entrainment were found in lake hattie comparison of ice sediment from tank experiments run with kara sea material to ice particles from the natural kara setting showed both types of ice sediment have very similar grain size distributions and mineralogical compositions results from experiments and nature help to better understand the potentially lc driven entrainment of sediment into ice formed in shallow freezing waters

arctic perennial ice cover over the last 14 million years knowledge of the long term history of the perennial ice is an important issue that has eluded study because the cenozoic core material needed has been unavailable until the recent arctic coring expedition acex detrital fe oxide mineral grains analyzed by microprobe from the last 14 ma 164 m of the acex composite core on the lomonosov ridge were matched to circum arctic sources with the same mineral and 12 element composition these precise source determinations and estimates of drift rates were used to determine that these sand grains could not be rafted to the acex core site in less than a year thus the perennial ice cover has existed since 14 ma except for the unlikely rapid return to seasonal ice between the average sampling interval of about 0 17 ma both north america and russia contributed significant fe grains to the acex core during the last 14 ma

timing of formation of forebergs in the northeastern gobi altai mongolia implications for estimating mountain uplift rates and earthquake recurrence intervals bedrock and quaternary alluvial fans in the forelands of the northern gobi altai have been faulted and warped by foreland propagating thrust faults to form elongate hills known as forebergs forebergs near bogd town north of arsta bogd and at ih hetsuu north of baga bogd were mapped and their formation constrained using luminescence dating of lacustrine and fanglomerates sediments to give localized uplift rates of c 0 05 m ka 1 and between c 1 6 and 4 1 m ka 1 respectively comparisons between vertical surface rupture during the 1957 gobi altai earthquake with the age and amount of uplift of lacustrine sediments provide a tentative estimate of between 1288 382 to 497 120 years for the average recurrence interval of great earthquakes in the baga bogd region these localized uplifts rates support the view that the gobi altai mountains probably took between 50 and 25 million years to form and were therefore coeval with the uplift of the himalayas and the tibetan plateau

relic permafrost structures in the gobi of mongolia age and significance relict permafrost structures ice wedge casts and cryoturbation structures are present in the gobi of southern mongolia luminescence dates of sediments are presented to constrain the age of formation of permafrost structures these data show that there was a phase of permafrost development during the latter part of the last glacial after about 22 to 15 ka that resulted in cryoturbated sediments and ice wedge casts furthermore permafrost degradation occurred during late pleistocene times 13 10 ka and was absent during the early holocene these permafrost structures mark the southernmost evidence of permafrost in northern asia during late quaternary times and indicate that the mean annual air temperature was below approximately 6 c during their formation 1998 john wiley sons ltd

thermoluminescence dating tests of pleistocene sediments from uplifted marine shorelines along the southwest coastline of the calabrian peninsula southern italy abstract this paper presents tl age estimates of pleistocene raised marine terraces from southern calabria southern italy it focuses on the dating of last interglacial shallow marine sand deposits including several tyrrhenian key reference deposits whose stratigraphic assignment is based on biostratigraphic evidence presence of a strombus bubonius fauna and geochronometric data amino acid data calibrated with u th dates on coral the tl age estimates are obtained on alkali feldspar coarse grains using their blue tl emission they are in good agreement with the ir osl age estimates obtained on the same feldspar samples our feldspar tl method is tested on two tyrrhenian key reference sites ravagnese and bovetto in the reggio di calabria area their measured tl age estimates 97 11 ka and 100 10 ka are lower than their estimated geological age i e oxygen isotope substage 5e the correction for long term fading suggested by mejdahl 1988 is tested on these two samples using a lifetime of 446 ka as estimated from both calabrian and miocene sand collected within the same area this correction would yield preliminary tl ages 116 13 ka and 116 12 ka that are in better agreement with the expected geological age the application of our tl method to paleoshorelines lying below the tyrrhenian reference shoreline of ravagnese bovetto yields stratigraphically consistent tl age estimates the tl method is also applied to two supposedly pre last interglacial paleoshorelines which are geomorphologically older than the tyrrhenian reference shorelines they remain however chronologically undifferentiated both by the tl and the amino acid methods finally the preliminary feldspar tl results obtained on the miocene and the calabrian sand deposits 1 ma suggest that our feldspar tl method is limited in the sw calabrian area to about 200 ka

age and source of colluvial sediments at vaihingen enz germany abstract colluvial sediments accumulated on the lower slopes of a ridge as a result of past and present soil erosion were dated by optical 14 c and archaeological methods this allowed us to reconstruct the depositional history of the colluvium and also to identify temporary sedimentary sinks in its transportational pathway a cascade model of colluvium formation is developed colluvial sediments resulting from early soil erosion in the neolithic to iron age periods were mainly deposited on the upper slopes significant deposition on the lower slope occurred for the first time during the iron age and roman period since then deposition rates have increased because of more intensive land use

dust and loessic alluvial deposits in northwestern namibia damaraland kaokoveld sedimentology and palaeoclimatic evidence based on luminescence data abstract in northwestern namibia silty deposits are widespread the silts consist of two major components locally produced weathering detritus and allochthonous dust blown in from the western kalahari to the eastern margin of the namib desert sedimentological analysis and luminescence age estimations allow identification of distinct sedimentological and geomorphological processes associated with two different climatic periods between about 30 and 8 ka loessic alluvial deposits several metres in thickness accumulated in valleys and basins the deposition was generated by weak slope wash and or endoreic drainage of the ephemeral rivers the dust input and the accumulation of silt in the valleys indicate semi arid climatic conditions with weak summer rains and long dry seasons since about 9 8 ka silt terraces caused by fluvial incision and erosion have been formed these indicate more humid conditions than had occurred before the change from a dry to a moister semi arid climate at about 9 8 ka is confirmed by proxy data from drill cores off the namibian coast and by dune studies in the south western kalahari

new temporal constraints on the rotation of the peruvian central andes obtained from paleomagnetism new paleomagnetic data from middle eocene to middle miocene volcanic and plutonic formations of the western cordillera of central peru document a counterclockwise rotation of 11 7 4 this rotation similar to previous results reported for the northern peruvian margin is post middle miocene in age it is thus coeval with the acceleration of the andean uplift and supports isacks model

late quaternary history of the coastal wahiba sands sultanate of oman continental sediments and geomorphological features of the coastal wahiba sands sultanate of oman reflect environmental variability in southeastern arabia during the late quaternary weakly cemented dune sands interdune deposits and coastal sediments were dated by luminescence methods to establish an absolute chronology of changes in sedimentary dynamics the dating results confirm previous assumptions that during times of low global sea level sand was transported by southerly winds from the exposed shelf onto the arabian peninsula two prominent phases of sand accumulation in the coastal area took place just before and after the last glacial maximum lgm a final significant period of dune consolidation is recognised during the early holocene however no major consolidation of dunes appears to have occurred during the lgm and the younger dryas in the northern part of the wahiba sands these two periods are characterised by substantial sand deposition this discrepancy is explained by the lack of conservation potential for dunes in the coastal area probably caused by a low groundwater table due to low sea level and decreased precipitation while the times of aeolian activity reflect arid to hyper arid conditions lacustrine and pedogenically altered interdune deposits indicate wetter conditions than today caused by increased monsoonal circulation during the holocene climatic optimum copyright 2005 john wiley sons ltd

infra red stimulated luminescence dating of holocene reworked silty sediments abstract infra red stimulated luminescence irsl ages are reported for holocene colluvial lacustrine and alluvial sediments and late glacial loess for colluvial sediments irsl ages concur with independent ages age overestimation occur in the case of very poorly bleached sediments such as young less than 2000 years floodloams for which a high suspended sediment load was deduced from sedimentation rates and actually observed floods age underestimates are observed for late glacial loess probably due to inadequate preheat procedures

suspension freezing of bottom sediment and biota in the northwest passage and implications for arctic ocean sedimentation ice observations and sediment collected in a summer transit through the northwest passage provide insights on suspension freezing the most important sediment entrainment mechanism for the arctic ocean no evidence was seen for entrainment by bottom adfreezing bluff slumping river flooding dragging ice keels or significant eolian transport from land to sea lack of eolian sediment loading in the northwest passage together with that already reported for northern alaska eliminates wind as an important source for fine sediment in the pack of the beaufort gyre and related parts of the transpolar drift muddy sediment with pebbles and cobbles algae with holdfasts ostracodes with appendages and well preserved mollusks and sea urchins were collected from two sites in a 50 km long stretch of turbid ice these materials indicate that suspension freezing reaching to a water depth of 25 30 m during the previous fall was responsible for entrainment this mechanism requires rapid ice formation in open shallo

optical dating studies of quaternary organic rich sediments from southwestern british columbia and northwestern washington state the suitability of optical dating using 1 4 ev infrared excitation for determining the time of deposition or compaction of organic rich sediments and peat is assessed with measurements on seven samples from six different lithostratigraphic units one is of zero age two have associated 14c ages three are known to have been deposited during an interglaciation and one is 1 ma old the samples yield satisfactory optical ages ranging from 0 to over 100 ka we conclude that the muir point formation southern vancouver island and the whidbey formation northwestern washington state were both deposited during 18o stage 5 as previously deduced from other evidence the age obtained from the 1 ma sample was significantly too low the optical dating method is simpler and more precise than thermoluminescence dating and is recommended for future work

a robust multisite holocene history of drift ice off northern iceland implications for north atlantic climate an important indicator of holocene climate change is provided by evidence for variations in the extent of drift ice a proxy for drift ice in iceland waters is provided by the presence of quartz q

contrasts in arctic shelf sea ice regimes and some implications beaufort sea versus laptev sea the winter ice regime of the 500 km from the mainland than in the beaufort sea as a result the annual freeze up does not incorporate old deep draft ice and with a lack of compression such deep draft ice is not generated in situ as on the beaufort sea shelf the laptev sea has as much as 1000 km of fetch at the end of summer when freezing storms move in and large 6 m waves can form also for the first three winter months the polynya lies inshore at a water depth of only 10 m turbulence and freezing are excellent conditions for sediment entrainment by frazil and anchor ice when compared to conditions in the short fetched beaufort sea we expect entrainment to occur yearly different from the intensely ice gouged beaufort sea shelf hydraulic bedforms probably dominate in the laptev sea corresponding with the large volume of ice produced more dense water is generated in the laptev sea possibly accompanied by downslope sediment transport thermohaline convection at the midshelf polynya together with the reduced rate of bottom disruption by ice keels may enhance benthic productivity and permit establishment of open shelf benthic communities which in the beaufort sea can thrive only in the protection of barrier islands indirect evidence for high benthic productivity is found in the presence of walrus who also require year round open water by contrast lack of a suitable environment restricts walrus from the beaufort sea although over 700 km farther to the south we could speculate on other consequences of the different ice regimes in the beaufort and laptev seas but these few examples serve to point out the dangers of exptrapolating from knowledge gained in the north american arctic to other shallow arctic shelf settings

reconstructing the origin and trajectory of drifting arctic sea ice recent studies have indicated that drifting arctic sea ice plays an important role in the redistribution of sediments and contaminants here we present a method to reconstruct the back ward trajectory of sea ice from its sampling location in the eurasian arctic to its possible site of ori gin on the shelf based on historical drift data from the international arctic buoy program this method is verified by showing that origins derived from the backward trajectories are generally con sistent with other indicators such as comparison of the predicted backward trajectories with known buoy drifts and matching the clay mineralogy of sediments sampled from the sea ice with that of the seafloor in the predicted shelf source regions the trajectories are then used to identify regions where sediment laden ice is exported to the transpolar drift stream from the new siberian islands and the central kara plateau calculation of forward trajectories shows that the kara sea is a major contributor of ice to the barents sea and the southern limb of the transpolar drift stream

middle and late holocene dune reactivation in the nebraska sand hills usa a combination of optical dating of aeolian sand and radiocarbon dating of palaeosols and interdune sediments has allowed some refinements to the chronostratigraphy of the nebraska sand hills our results directly confirm previous inferences that multiple phases of aeolian deposition including megabarchan dune reactivation occurred within the sand hills during the middle and late holocene optical dates on stratified aeolian barchan dune sediments from two localities provide ages ranging from c 6 ka to 300 years ago weakly developed palaeosols intercalated within the dune sediments and other forms of post depositional modification indicate periods of relative stability and reduced dune mobilization optical dates on the upper 12 15 m of two dune exposures indicate repeated possibly regionally correlative reactivations which occurred between c 400 500 and 200 300 years ago comparison of late holocene aeolian activity with local and regional palaeoclimatic proxy records suggests that dune reacti

test of the partial bleach methodology as applied to the infra red stimulated luminescence of an alluvial sediment from the danube abstract a sample of fine grained distal sediment deposited by the river danube in romania was selected for luminescence measurements using infra red diodes for stimulation to obtain the equivalent dose ed a partial bleach approach was applied using a restricted spectrum in an attempt to replicate bleaching conditions underwater the results and those of the thermoluminescence measurements gave an age in agreement with the archaeological evidence suggesting that this sample was well bleached at deposition a more rigorous test was devised using a simulation experiment and the results suggested that the partial bleach method may not be able to date correctly sediments that have had only part of their infra red stimulated luminescence irsl signal removed at deposition additional types of measurement are required to detect incomplete resetting of the irsl signal at deposition

particulate matter in pack ice of the beaufort gyre ice observations and sediment samples were collected in the beaufort gyre in 1988 fine sediment occurred in very small patches of turbid ice as thin spotty surface layers in mud pellets or in old snowdrifts the latter were widespread south of 74 n containing an estimated 22 tonnes of silt and clay km 2 average particle concentration in sea ice 40 mg l 1 was much higher than in sea water 0 8 mg l 1 or in new snow but the sediment load was significantly smaller and of finer texture compared to that observed in a shelfal source area after a major entrainment event

luminescence dating applications in geomorphological research abstract chronological control remains critical to the interpretation of environmental change and to establishing long term rates of geomorphological processes radiocarbon dating will continue to be the central technique for age assessment of carbon bearing sediments deposited in the last ca 40 ka but alternative absolute dating strategies are required for older or non carbon bearing sediments they include uranium series dating of precipitated sediments k ar and ar ar dating of primary volcanic materials and cosmogenic isotopic dating of surface exposure ages an additional family of methods collectively termed luminescence techniques is increasingly providing a basis for the age assessment of detrital sedimentary deposits these methods directly date the deposition of detrital mineral grains typically quartz and feldspar and have been demonstrated to provide accurate deposition chronologies for up to 800 ka although 150 ka is more typical in the past decade a subset of luminescence techniques which employ optical sample stimulation methods called optical dating has made it possible to date samples from a much wider range of depositional systems given that the methods directly date sedimentation they allow direct assessment of depositional dynamism in numerous terrestrial and subaqueous including marine sedimentary systems and have demonstrated particular potential in the elucidation of chronologies from aeolian dune and loess fluvial colluvial coastal and volcaniclastic environments this paper provides a summary of the principles of the luminescence especially optical dating methods and shows how recent developments specifically single aliquot dating procedures have dramatically enhanced the scope and potential of the method the luminescence techniques are increasingly being incorporated into a wide range of geomorphological studies which seek to establish the nature of landscape changes over the past interglacial glacial cycle and beyond

langmuir supercells a mechanism for sediment resuspension and transport in shallow seas recent measurements at a cabled sea floor node in 15 meters of water off the coast of new jersey suggest that langmuir supercells langmuir circulations that achieve vertical scales equal to the water depth under extended storms are an important mechanism for major sediment resuspension events on the extensive shallow shelves off the eastern u s coast because sediment resuspension is a prelude to transport supercell events are a necessary condition for major sediment transport such events may also contribute to shelf sea exchange and to offshore gradation of benthic community structure in shallow seas

a luminescence dating study of open air palaeolithic sites in western epirus greece we report results of a preliminary luminescence dating study of middle to late pleistocene red beds and early holocene dune deposits from prehistoric sites in northwest greece the wide range in age estimates contradicts the impression that all the red sediments of the region are as old as the pliocene or early pleistocene and that artefacts found in them are late intrusions and hence worthless in a stratigraphic context our data provide support for a recently proposed chronological framework of the palaeolithic in the region tl irsl comparisons confirm the irsl as a more appropriate means for dating water laid deposits while both methods appear to be equally useful for aeolian sediments the study cautions that the effect of various laboratory procedures used to obtain tl or irsl dates in a context of complex depositional histories precludes a simple prima facie interpretation of the ages a proper evaluation of luminescence dates requires a full account of the laboratory procedures employed and an understanding of the depositional history of the sediments

optical dating of young modern sediments using quartz results from a selection of depositional environments abstract equivalent dose ed evaluations for quartz grains extracted from a number of modern or young samples collected from a range of depositional environments are reported the signal used was optically stimulated luminescence osl with an argon ion laser tuned to 514 nm as a light source typical equivalent dose values were 0 05 0 3 gy for the given samples which is substantially less than equivalent doses expected for similar sediments by conventional thermoluminescence tl the non zero equivalent dose exhibited by the samples may be a product of relict osl from incompletely bleached traps sample pre treatment procedures or due to signal recuperation following bleaching during antiquity the potential significance of each are discussed a number of modifications to sample pre treatment and processing are also described

luminescence chronology of late pleistocene raised beaches in southern italy new data of relative sea level changes abstract littoral sediments forming terraces along the crotone peninsula coast southern italian have been investigated using sedimentological analysis and luminescence dating techniques and adopting assessments from previous work on fossil assemblages all sediment layers analysed were deposited in the nearshore environment between 20 m below and few metres above sea level during the falling sea level of a temperate warm climate interval the restoration of almost identical environmental conditions occurred in oxygen isotope substages 5e and 5a and in oxygen isotope stage 3 limits given by luminescence physics prevented accurate dating of the uppermost lying terrace former crotonian stage terrace and the presence of a substage 5c terrace is masked by the lack of suitable material for dating constraints on the positions of relative sea level from the reliable data set show that the sea level fell from 2 m during substage 5e to 29 m during substage 5a and then rose to 15 m during stage 3 observations for oxygen isotope stage 3 sea level at the crotone peninsula coast are inconsistent with those at the huon peninsula new guinea and in the western pacific the disagreement highlights the lack of knowledge concerning mediterranean thermohaline circulations and sea water exchanges between the atlantic and mediterranean seas during glacial cycles

dating of debris flow fan complexes from lantau island hong kong china the potential relationship between landslide activity and climate change five debris flow fan complexes bordering the coastal foothills of western lantau island hong kong have been the subject of a stratigraphic and dating study to explore the potential relationship between past periods of climate change and landslide activity luminescence osl ages from the fan complexes supported by a few calibrated radiocarbon 14c ages on duplicate samples suggest six main periods of accumulation 28 000 20 000 ka 14 500 10 500 ka 5800 5000 ka 4370 4230 ka 3560 3320 ka and 1350 1050 ka the younger periods 10 000 ka appear to be dominated by relatively thin 0 5 1 5 m units deposited mainly by debris flood events whereas the older periods are dominated by thicker 1 0 3 5 m units deposited by debris flow events we hypothesise that immediately prior to the last glacial maximum lgm i e 21 000 ka the climate was cool and dry upland areas were probably devoid of vegetation providing favourable conditions for sediment production in source areas these debris laden source areas are likely to have been mobilised during periodic rainstorm activity rapidly channelised over relatively short drainage courses and then deposited as thick sediment rich debris flow deposits along the coastal foothills during the early to middle holocene the climate was warmer and more humid pluvial conditions dominated forests occupied the upland source areas leading to possibly reduced sediment yields more frequent flash floods and deposition dominated by debris floods compared with recent studies on the weathering and erosion history of the pearl river delta our landslide age data are indicative of a potential link between increased landslide activity and intensification of the east asian monsoon during the early to middle holocene

correlation of fluvial terraces within the hikurangi margin new zealand implications for climate and baselevel controls abstract a correlation of fluvial terraces is presented for eight non glacial catchments of the eastern north island new zealand within the actively uplifting hikurangi margin using a combination of loess and tephra coverbed stratigraphy and radiocarbon and osl dating of fluvial deposits and loess coverbeds we demonstrate correlation of four fill terraces t1 t4 the available age constraints suggest t1 15 30 ka t2 31 50 ka t3 50 70 ka and t4 115 ka but the association and temporal link with loess deposits suggest correlation with cold periods and thus the refinement of t2 late mis 3 31 40 ka t3 mis 4 55 70 ka t4 mi substage 5b 90 ka 5d 110 ka or mis 6 140 160 ka the ability to correlate terraces between catchments plus the lack of independent evidence for tectonic triggering events indicates terraces have probably formed in response to either climate terrestrial or baselevel sea level control climate control is indicated by the temporal link of post glacial incision with re establishment of forest cover and of lgm aggradation with limited grass and shrub cover and periglacial processes aggradation due to increased sediment supply under reduced vegetation is dramatically demonstrated by formation of the taupo pumice alluvium terrace in response to inundation by volcanic deposits unwelded ignimbrite following the 1 8 ka taupo eruption and the response to post settlement

environmental changes at the eastern namib desert margin before and after the last glacial maximum new evidence from fluvial deposits in the upper hoanib river catchment northwestern namibia in the upper hoanib river catchment area northwestern namibia fine grained silty deposits are widespread accumulated as river end deposits they form excellent geomorphological archives of a highly sensitive desert margin area different sedimentary complexes are separated sedimentologically and by luminescence dating the deposits give evidence of climate oscillations at the eastern margin of the namib desert during the past 50 000 years in northwestern namibia the dry conditions of the desert margin area with less than 200 300 mm mean annual precipitation prevailed at 60 40 ka and at 34 24 ka when sediment complex i accumulated during the last glacial maximum lgm fluvial activity and sedimentation were most likely interrupted due to arid conditions between 12 ka and the mid holocene higher rainfall and runoff led to the aggradation of sediment complex ii the climate was more humid than before the lgm but drier than at present after 3 ka runoff increased and the hoanib river re eroded the older deposits forming deep channels a prominent more sandy and gravely 4 m terrace in the upper and middle course of the hoanib river dates to the little ice age lia it is likely that this terrace is genetically linked with the amspoort silt formation in the lower hoanib valley d 2005 elsevier b v all rights reserved

holocene relief and soil changes in loess covered areas of south western germany the pedosedimentary archives of bretten bauerbach kraichgau based on infrared stimulated luminescence irsl dating of loess borne sediments a chronometry of holocene landscape evolution is established for a representative study site in the early settled kraichgau area in south western germany the results show that the gently rolling relief is due essentially to soil erosion and colluvial deposition triggered by humans cultivating the loess soils since the onset of agriculture in the neolithic period levelling of relief is accompanied by alterations in soil type patterns from haplic luvisols before the impact of humans over variably truncated luvisols with bt horizons prevailing at the slope surfaces in the middle ages to calcaric regosols characterizing both sites of erosion and accumulation since then the tremendous changes show that the effects of human activities have been recorded over thousands of years indicating an early anthropocene in a geomorphological and pedological sense most landscapes are probably more modified by humans than thought at first sight as the results show this recognition requires considering that current geomorphological and soil forming processes might work at different frequencies or magnitudes e g by changes of internal system thresholds such as increased erodibility following the complete erosion of a more resistant bt horizon and or in a different direction e g accumulation instead of erosion or sediment transport due to slope angles decreased by former deposition of colluvium than they would in the absence of a human controlled pre history

age of pre late wisconsin glacial estuarine sedimentation bristol bay alaska pleistocene glacial estuarine sediment deposited in an intertidal environment of northeastern bristol bay southwestern alaska was dated using a variety of approaches including infrared stimulated and thermoluminescence irsl and tl techniques analysis of modern and14c dated holocene tide flat mud demonstrates that the bulk of sediment in this environment is reset by solar radiation thereby lending confidence to ages obtained from similar pleistocene deposits by luminescence techniques irsl seems to be especially well suited for dating with resolution on time scales of 10 000 yr the ages of tide flat mud of the nushagak formation derived from the ahklun mountains to the northwest of bristol bay and of halfmoon bay drift derived from the alaska peninsula to the southeast suggest contemporaneous glacial estuarine deposition related to independent glacial source areas about 75 000 80 000 yr ago this age is consistent with other geochronological data that indicate a pre late wisconsin and post substage 5e age including nonfinite14c ages a lack of interglacial indicators and old crow tephra 140 000 yr atop the drift normal paleomagnetic inclinations and amino acid isoleucine epimerization ratios aile ile aile ile ratios inportlandia arctica 0 052 0 003 from a marine lag horizon at south naknek beach which separates halfmoon bay drift above from older glacial estuarine drift below are only slightly higher than inmya truncata 0 041 0 007 from last interglacial pelukian deposits at nome as laboratory heating experiments show that the two genera epimerize at similar rates these data imply correlation of the marine lag at south naknek beach with pelukian deposits hence glaciers on the alaska peninsula experienced major pre late wisconsin advances both before and after the last interglaciation shells reworked into halfmoon bay drift yield aile ile ratios of 0 028 0 005 forportlandiaat second point and 0 027 0 001 forhiatella arcticaat etolin point together with assumptions about the postdepositional temperature history these ratios indicate that the shells are at least 55 000 yr and probably closer to 90 000 yr although the uncertainty in this age estimate is broad the amino acid and luminescence data converge on an age between about 75 000 and 90 000 yr late during oxygen isotope stage 5 for a major ice advance far beyond late wisconsin limits

luminescence dating of hillslope deposits a review abstract luminescence dating determines the last exposure to light of quartz and feldspar mineral grains and thus the time a sediment was laid down prerequisite is that the sediment grains were sufficiently exposed to light prior to deposition for eolian deposits this seems a fair assumption although exceptions may well exist for other depositional environments light exposure prior to burial is often restricted in duration intensity and spectral composition and may result in an age overestimation recent developments now allow dating of sediments that were exposed to only little light prior to deposition the main developments are single aliquot techniques and statistical tests that allow extraction of valid age estimates even from deposits in which bleached and unbleached grains are mixed these developments in combination with the fact that the great majority of sediments near the earth s surface are not of eolian origin have resulted in the large interest in the luminescence dating of non eolian deposits here we review possibilities and challenges of luminescence dating of colluvial deposits we summarize techniques for the detection and handling of insufficiently bleached sediments a common condition in colluvial deposits we give an overview how luminescence dating has been applied on hillslope sediments for reconstructing landscape response to climate change to analyze past fault activity and unravel human induced soil erosion we discuss sampling strategies and give guidelines as to which techniques are best suited to establish luminescence chronologies for colluvium

optical dating of annually laminated lake sediments a test case from holzmaar germany abstract we present results of an optical dating feasibility study for annually laminated varved lake sediments the fine silt sized clastic fraction of the sediments was extracted stimulated with infrared and the 410 nm emission was detected a multiple aliquot additive dose protocol in combination with a subtraction technique was used for the equivalent dose determinations results are promising only for sediments with high amounts of clastic components for sediments with a high organic component results are inaccurate perhaps due to problems in dose rate calculation we speculate that besides the low concentrations of radio nuclides and disequilibria in the u series dose rate determination procedures are inaccurate for sediments with high contents of biogenic silica sediment compaction seems to account for minor effects only

dating the lower paleolithic open air site of holon israel by luminescence and esr techniques abstract the open air acheulian site in holon israel was dated by the luminescence methods and by electron spin resonance esr situated in the coastal plain quaternary kurkar group the holon site was first excavated in the late 1960s when typical lower paleolithic lithics and middle pleistocene fauna were found in order to date the site new test pits were dug adjacent to the earlier excavations and the archaeological bed was exposed in a section comprising a series of paleosols and aeolianites alkali feldspars separated from the sediments were dated using the infrared stimulated luminescence and thermoluminescence signals and quartz was dated using the optically stimulated luminescence signal the age of the archaeological bed is constrained by two samples to 198 000 22 000 201 000 17 000 yr the age of the base of the section is 240 000 29 000 yr and the age of the top is 81 000 8000 yr two teeth from the archaeological bed recovered from the original excavation collection yielded an average esr age of 204 000 16 000 yr calculated using the linear uptake model which is in a very good agreement with the luminescence ages these dates place holon within the range of other late acheulian and acheulo yabrudian sites in this region such as tabun e younger chronology yabrud i archaeological level 18 and berekhat ram

hypsometry and volume of the arctic ocean and its constituent seas 1 this paper presents an analysis of the arctic ocean and its constituent seas for seafloor area distribution versus depth and ocean volume the bathymetry from the international bathymetric chart of the arctic ocean ibcao is used together with limits defining this ocean and its constituent seas from the international hydrographic organization iho as well as redefined limits constructed to confine the seas to the shallow shelves ibcao is a bathymetric grid model with a resolution of 2 5 2 5 km which significantly improved the portrayal of the arctic ocean seafloor through incorporation of newly released bathymetric data including echo soundings from u s and british navies scientific nuclear submarine cruises and icebreaker cruises this analysis of seafloor area and ocean volume is the first for the arctic ocean based on this new and improved portrayal of the seafloor as represented by ibcao the seafloor area and volume are calculated for different depths starting from the present sea level and progressing in increments of 10 m to a depth of 500 m and in increments of 50 m from 550 m down to the deepest depth within each of the analyzed seas hypsometric curves expressed as simple histograms of the frequencies in different depth bins and depth plotted against cumulative area for each of the analyzed seas are presented the area and volume calculations show that the entire iho defined arctic ocean makes up 4 3 of the total ocean area but only 1 4 of the volume furthermore the iho arctic ocean is the shallowest mean depth 1201 m of all the major oceans and their adjacent seas the continental shelf area from the coasts out to the shelf break make up as much as 52 9 of the total area in the arctic ocean defined in this work as consisting of the oceanic deep arctic ocean basin the broad continental shelves of the barents kara laptev east siberian chukchi and beaufort seas the white sea and the narrow continental shelf off both the canadian arctic archipelago and northern greenland this result indicates that the arctic ocean has significantly larger continental shelves compared with all the other oceans where previous studies show that the proportion of shelves from the coasts out to the foot of the continental slopes only ranges between about 9 1 and 17 7 furthermore the derived hypsometric curves show that most of the arctic ocean shelf seas besides the barents sea beaufort sea and the shelf off northern greenland have a similar shape with the largest seafloor area between 0 and 50 m the east siberian and laptev seas in particular show area distributions concentrated in this shallow depth range and together with the chukchi sea they form a large flat shallow shelf province composing as much as 22 of the entire arctic ocean area but only 1 of the volume this implies that the circulation in the arctic ocean might be very sensitive to eustatic sea level changes one of the aims with this work is to make up to date high resolution area and volume calculations for the arctic ocean at various depths available for download

sediment dynamics in the eurasian arctic ocean during the last deglaciation the clay mineral group smectite perspective abstract this study focuses on sedimentological investigations of sediment cores recovered during the international arctic 91 expeditions with the german research ice breaker rv polarstern to the european sector of the arctic ocean here we deduce the last glacial interglacial changes in transport mechanism and sedimentation from the clay mineral group smectite we choose the smectites as an example of how sediment mineralogy can be linked with particular source regions the kara and laptev seas distinct transport mechanism sea ice and surface currents and sedimentation processes smectite contents in arctic sediments discussed for two time slices including the last glacial maximum lgm and the last deglaciation termination i reveal the highest variability subsequent to the retreat of the eurasian ice sheets our results show that smectite anomalies in the eurasian basin are associated with distinct meltwater pulses and occurred around 13 5 13 0 14c ka b p compelling evidence is provided that these anomalies are deduced from sea ice entrained sediments from the eastern kara sea that entered the arctic ocean after ice sheet break up and eventually flooding of the kara sea we propose that smectite anomalies in sediments of the eastern arctic ocean can be utilized to identify deglacial events and to help decipher configurations of the eurasian ice sheets the identification of smectite maxima along the modern sea ice edge in the eurasian basin further indicates biologically enhanced sedimentation from melting sea ice allowing the reconstruction of seasonally open water in the region hence considering the poor preservation conditions of primary paleoceanographic proxies in the arctic ocean the clay mineral contents particularly the smectite group may be one alternative tool for paleoclimatic reconstruction in the eurasian basin

a holocene record of changing arctic ocean ice drift analogous to the effects of the arctic oscillation 1 the arctic oscillation ao controls the configuration of the transpolar drift tpd if thicker ice from the beaufort gyre were exported the volume of fresh water sea ice in the nordic seas would significantly increase decreasing the formation of north atlantic deep water this would cool large parts of the northern hemisphere and affect global climate therefore in order to understand how the global climate system functions it is imperative to know how the tpd changed over the last millennium or more the provenance of grains in a sediment core located near the confluence of the tpd and the beaufort gyre provides a direct proxy for changes in seaice drift owing to these circulation systems the core has more than 200 cm of holocene sediment with intervals dominated by grains from the russian shelves alternating with intervals of abundant grains from north american sources grains matched to russian shelves indicate that the tpd was shifted toward north america similar to what occurs during a more positive phase of the ao this condition alternated with intervals where few grains matched to russian sources presumably because the tpd was restricted to the russian half of the arctic far from the core site during the last 1300 years increased influx of russian grains occurred approximately every 50 150 years this fluctuation might represent the long term oscillation of the ao which modulates the same tpd shift today

tl and irsl dating of jiahu relics and sediments clue of 7th millennium bc civilization in central china thermoluminescence tl dating of pottery and infrared stimulated luminescence irsl dating of sediments from early neolithic layers at the jiahu site henan province east central china have been achieved the pottery tl ages range from 6800 450 to 8900 640 years and the sediment irsl ages from 6750 760 to 8860 870 years confirming former 14c data both tl and irsl ages agree well with each other they reinforce the very early existence of a fully developed neolithic civilization in central china starting already in the first half of the 7th millennium bc and lasting about 2100 years from these layers finds of bone flutes and chinese characters have already been reported x li g harbottle j zhang c wang the earliest writing sign use in the seventh millennium bc at jiahu henan province china antiquity 77 2003 31 44 j zhang g harbottle c wang z kong oldest playable musical instruments found at jiahu early neolithic site in china nature 401 1999 366 368 the jiahu pottery of the 7th millennium bc belongs to the earliest in china and elsewhere

characterising and dating weichselian organogenic sediments a case study from the lusatian ice marginal valley scheibe opencast mine eastern germany abstract dates determined with three absolute dating methods 14c luminescence and 230th u supported the findings of the paleobotanical investigations of the weichselian upper fluvial sequence of the scheibe opencast mine in the niederlausitz lower lusatia eastern germany they allowed to identify three units of organogenic sediments organogenic complexes oc developed as peaty and or humic silts samples from the uppermost oc i unit displayed 14c age ranges from 32 to 28 and 26 to 24 ka respectively for the latest phase an open landscape was identified although high arboreal values point to locally extended sparse forests the lithologically and paleobotanically heterogeneous oc ii unit 37 ka represents at least two periods during which organic matter accumulated in an open landscape the uppermost subunit represents an unforested interstadial of the middle pleniglacial the lowermost oc iii unit has an age of about 56 ka or higher according to the 230th u or tl dates respectively it represents a forested interstadial assigned to the early weichselian

luminescence dating in less than ideal conditions case studies from klasies river main site and duinefontein south africa abstract luminescence dating results are reported for two south african archaeological sites where changes in the dose rate through time are apparent a subtraction procedure involving analysis of both quartz and potassium feldspar extracts is applied to detect and correct for these changes at the middle stone age site of klasies river the dose rate changes inferred from geologic evidence for shell dissolution turn out not to be significant having occurred rapidly after deposition the dates here range from 50 115 ka in broad agreement with other evidence the important howiesons poort component here appears to date somewhat later about 55 60 ka than at several other sites in south africa at the acheulian site of duinefontein the dose rate changes also thought to be caused by shell dissolution are on the other hand very significant the subtraction ages here 125 300 ka agree with independent chronological assessments