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 nature and distribution of upper cenozoic ignimbrite centres in the central andes abstract a wide variety of upper cenozoic ignimbrite centres have been identified and studied on landsat imagery of the central andes some have been investigated in the field lower miocene ignimbrite centres are distributed along an arc which in north chile diverges markedly from the line of the present trench and parallels an arc of lower miocene plutons in the eastern cordillera of bolivia much of the ignimbrite erupted since the late miocene has been erupted around the faulted margins of the altiplano basin of western bolivia particularly where the western and eastern cordilleras converge typical examples of ignimbrite centres are described some centres take the form of ignimbrite shield volcanoes other ignimbrite sheets are more widely dispersed the degree of dispersal probably relates to the height of the eruption column partial or total caldera formation sometimes took place and a few of these calderas have resurgent centres late stage lava extrusions are common and some of these are located on caldera ring fractures

quaternary tephrochronology helps define conditioning factors and triggering mechanisms of rock avalanches in nw argentina abstract ten previously defined quaternary tephra layers from northwestern argentina are described here in terms of electron microprobe analyses of glass shards in addition xrf analyses of three tephras alemania buey muerto and el paso ash were performed the alemania ash and buey muerto ash occur within 1 m of each other stratigraphically in several outcrops and exhibit identical glass chemistry as well xrf analyses show that both tephras have identical composition based on stratigraphic relations and age determinations these tephras can clearly be separated as two individual layers tephra ages were defined relatively by ams 14c dates of organic material by 10be surface exposure ages of landslides in stratigraphic association with these tephra layers or directly by 40ar 39ar ages of mineral separates or fission track dating of zircons ages of these tephra layers constrain the temporal distribution of large landslides rock avalanche type in northwestern argentina temporal distribution shows that these large collapses concentrated in deeply incised valleys during climate periods characterized by enhanced precipitation and run off in addition in the tonco valley tephra characteristics also suggest earthquake triggering of coeval landsliding in this valley four landslides one with a 10be age of 7820 830 yr lie in direct contact atop un redeposited paranilla ash showing the coeval age of these landslides the age of the dated landslide deposit coincides with the age of soft sediment deformation structures in nearby lake deposits with an ams 14c age of 7430 7570 cal yr bp

catastrophic debris avalanche deposit of socompa volcano northern chile between 10 000 and 500 yr ago the socompa volcano in northern chile experienced a catastrophic collapse of a 70 deg sector of the original cone causing a debris avalanche that descended nearly 3000 m vertically and traveled more than 35 km from the volcano the deposits cover some 490 sq km and have a minimum volume of 15 cu km parts of the original cone slumped in a nearly coherent form and are now preserved as large blocks more than 400 m high the primary avalanche traveled northwestward over sloping ground before coming to rest transiently forming a prominent marginal ridge and then slid away northeastward to form a secondary flow overriding much of the primary avalanche deposit abundant prismatic jointed dacite blocks within the debris avalanche deposit and a thin fine grained pumiceous deposit beneath it suggest that the collapse was triggered by magmatic activity and may have been accompanied by a violent lateral blast collapse was followed by eruption of pumiceous pyroclastic flows and extrusion of voluminous dacite domes

thermoluminescence dating of the middle pleistocene raised beach of sangatte northern france abstract tl dating of both quartz and potassium feldspar grains from the pleistocene beach of sangatte at the southern limit of the north sea basin give self consistent ages of 200 000 45 000 205 000 14 000 and 229 000 18 000 years respectively these results allow the beach deposits to be correlated with oxygen isotope stage 7 244 000 190 000 yr martinson et al 1987 the existence of a fossil beach cliff line at 10 m above french o d demonstrates that the strait of dover was open during the penultimate interglaciation

new evidence for a grounded irish sea glaciation of the isles of scilly uk abstract new geomorphological and sedimentological data support previously published reconstructions of an irish sea glacier advance as far south as the northern shores of the isles of scilly in the celtic sea 49 58 n offshore boulder covered bars with cores of diamicton are interpreted as moraines which together with onshore moraine ridges and trimlines mark the maximal extent of the irish sea glacier at bread and cheese cove st martin s a heterogeneous sediment unit wedged between periglacial gelifluctates is interpreted as a mixture of glacitectonized and cannibalized glacilacustrine and marine deposits as well as primary subglacial tills macrofabric signatures reflect a subglacial origin but the whole unit has been subject to down slope mass movement micromorphological analysis indicates highly variable response to deformation and glacitectonism with most features relating to ductile behaviour and wet deformation the characteristics suggest deposition during a short lived advance of the irish sea glacier over pre existing marine and contemporaneous proglacial lacustrine sediments once blocks of stratified sediment and diamicton had been driven onshore they were subject to paraglacial remobilization resulting at most locations in complete disaggregation the distribution of re worked glacigenic sediments coincides with the glacial limits inferred from the geomorphological evidence

age and origin of clayey silt brickearth in west london england the loamy brickearth deposits overlying coarse cold climate kempton park lynch hill and taplow gravels of the r thames in west london are dated by thermoluminescence and mineralogical comparisons with loesses of three known ages although much of the brickearth resembles loess it often contains more sand or clay than typical loess and the mineralogical studies suggest that even the coarse silt 16 63 m fraction is rarely similar in composition to any known english loess the thermoluminescence measurements suggest that most of the brickearth on the taplow and lynch hill gravels was deposited in the late devensian whereas that on the park gravel is mainly flandrian it is suggested that the latter is mainly floodloam whereas the earlier brickearth is a mixed aeolian sediment derived from various local sources in and close to the thames valley

thermoluminescence dating of loess and palaeosols from the lantian section shaanxi province china abstract ten samples of loess and palaeosol collected from the upper part of lantian section shaanxi have been dated using the fine grain 4 11 m tl technique palaeodose values were determined by the regeneration method readhead 1982 the tl ages obtained ranged from 2 4 104 years for the upper malan loess l1 to 1 5 105 years for the upper part of loess l2 of the lishi loess fine grain tl dating does not seem to be suitable for the samples older than 150 ka the uncertainty of the tl age estimate especially for the palaeosol sample may be primarily an effect of disequilibrium of the 238u decay chain and of water content variations since deposition of sediments

the loess and coversands of northern france and southern england loess and coversands are widespread on either side of the english channel in southern england loess is generally thin and discontinuous but locally reaches thickness of about 4 m in east kent coversands occur mainly in areas well north of the channel such as parts of east anglia and the southern side of the bristol channel most of the loess and coversand deposits in southern england date from the late devensian cold stage marine oxygen isotope stage mois 2 but there are also a few localised patches of older mainly mois 6 and 12 loess which are the dissected remnants of originally more extensive covers in france loess is widespread and locally very thick up to 12 m especially in northern and northeastern france in normandy and in the somme basin some long records indicate that accumulation began at the end of the lower pleistocene at about 900 ka nevertheless the main accumulations of typical calcareous loess are related to the upper weichselian and upper saalian stages mois 2 and end of mois 3 and mois 6 indeed before about 160 170 ka loess deposition was generally restricted to special sediment traps such as fluvial and marine terraces exposed to the east or northeast these older deposits are characterised by more sandy facies derived from local fluvial sources mainly by northwest to north northwest winds coversands occur locally along the coast of the mont saint michel bay and over the northern part of the seine estuary near le havre the main differences in thickness and extent of the loess deposits between southern england and northern france are linked to their location in relation to the source areas channel and north sea to ice sheets and to the main wind directions northwest to north northwest in france and western england but northeast in eastern england copyright 2003 john wiley sons ltd

thermoluminescence dating of the orkutsay loess section in tashkent region uzbekistan central asia abstract the chronology of loess in central asia was investigated by means of thermoluminescence dating tl in the 1970s when age estimates ranging from 20 ka to over 800 ka were taken as providing an absolute chronology this has caused major misinterpretation of central asian loess stratigraphy and palaeoclimatic reconstruction we present a new tl study of a loess section at orkutsay in the tashkent region uzbekistan nine samples spreading over a large stratigraphic interval yield apparent tl ages ranging from 20 ka to 134 ka we interpret our tl results with reference to recent tl dating studies of loess from other regions we consider most of our tl age estimates obtained by the regeneration method to be underestimated a single tl date of 92 8 ka obtained by the total bleach method for loess just below the first pedocomplex pc 1 of the last interglacial is also significantly younger than expected we attribute the underestimation to sensitivity change induced by the laboratory optical bleach and instability of the tl signal we conclude that the current tl techniques as employed in this study cannot provide a reliable absolute chronology for the sequence below pc 1 and cannot provide even a relative chronology for the loess below pc2 for the orkutsay section the dating limit is around 130 ka the results of this study suggest that the previous central asian loess chronology based on early tl studies is not valid

optical dating of romanian loess a comparison between silt sized and sand sized quartz abstract the loess palaeosol sequence near mircea vod dobrogea se romania is thought to comprise at least five glacial interglacial cycles it is considered as one of the most significant records of late quaternary environmental and climatic change in the region age information for the sequence was previously obtained through time depth modeling of magnetic susceptibility data and optically stimulated luminescence dating osl of fine silt sized 4 11 m quartz this study documents the granulometric properties of the sequence and compares the osl characteristics and age of fine sand sized 63 90 m quartz to those of silt sized quartz osl signals from both sand and silt sized quartz are dominated by a thermally stable fast decaying component a suite of laboratory test confirms that the single aliquot regenerative dose sar protocol is suitable for these samples each grain size fraction yields a set of optical ages that is consistent with the stratigraphic position of the samples the ages obtained using sand sized grains however are up to 70 higher than those obtained using silt sized quartz the discrepancy in age results is not understood as according to procedural tests the osl signal from both fractions should be suitable for dating the deposits as such it cannot be established whether the uppermost weakly developed palaeosol was formed during mis3 or mis5 and if the rate of loess accumulation varied during the last glacial only by using standard sar osl techniques both sets of ages do confirm however that the first well developed palaeosol s1 is of last interglacial age

tephrochronologic constraints on temporal distribution of large landslides in northwest argentina abstract two morphologic settings in the northwestern argentine prone to giant mountain front collapse deeply incised narrow valleys and steep range fronts bordering broad piedmonts were analyzed through detailed investigations of fossil landslides and related fluvio lacustrine sediments nine different rhyodactic tephra layers were defined by geochemical fingerprinting of glass morphology of pumice stratigraphic relationships and mineralogy the age of three tephra could be determined either directly by 40ar 39ar dating or relatively by 14c dating of associated sediments paranilla ash documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc newcommand cyr renewcommand rmdefault wncyr renewcommand sfdefault wncyss renewcommand encodingdefault ot2 normalfont selectfont decl

green amphibole distribution as a stratigraphic tool in loess sequences from belgium a review abstract the use of heavy minerals as a stratigraphic tool in the study of loess sequences from nw europe originated some 70 years ago one major problem in using the available data sets is the heterogeneous stratigraphic context of the samples given the complex historic evolution of the stratigraphic framework of loess sequences this paper aims at presenting a review of the use of heavy minerals for stratigraphic studies in loess sequences from belgium focusing on the important role of green amphiboles we provide the first synthesis of the available data for belgium in a common and accurate lithostratigraphic framework i e the loess lithostratigraphic units recently reviewed by the national commission for stratigraphy a total of 121 samples studied by 4 different researchers and collected from 13 different loess sections are considered we also document the detailed mineralogical composition of these green amphiboles based on new microprobe analyses our results show that the green amphibole content of regional loess deposits presents a remarkable consistency in their stratigraphic distribution five groups are defined here covering the entire pleistocene loess sequence from mis 11 to weichselian while ga distribution used alone is not a discriminatory criterion it becomes most of the time discriminatory when combined with the palaeoenvironmental signature of the sequence deduced from pedostratigraphy

the lunar regolith chemistry mineralogy and petrology the lunar regolith a several meter thick layer of unconsolidated debris forms the interface between the moon and its space environment the regolith forms from lithic sources by the destructional processes of comminution and the constructional processes of agglutinate formation in this manner a steady state soil can develop and will remain in a type of dynamic equilibrium until the system is disturbed by burial or mixing with new soil mixing takes place mainly on a local scale vertically through meters and horizontally over several kilometers lateral transport is a relatively inefficient process and therefore most of the lunar soil components were derived locally there is no evidence for preferential transport of the finer soil fractions relative to the coarser fractions the truly exotic derived at distances of tens of kilometers component is generally in low abundance 1 therefore remotely sensed data should provide a reasonably accurate picture of bedrock geology the chemical composition of the regolith varies with grain size the 10 m fraction is chemically fractionated from the bulk soil in most cases the 10 m fraction is enriched in al2o3 cao na2o k2o light rare earth elements and th and depleted in mgo feo mno and sc these systematics are largely a result of simple comminution with feldspar and friable mesostasis from local source rocks concentrating in the finest fraction there is evidence that agglutinate glass forms preferentially by fusion of the finest soil fractions therefore agglutinate glass like the 10 m soil fraction appears to be fractionated from bulk soil compositions highland soils are distinct from mare soils both chemically and petrologically soil samples collected near mare highland contacts are mixtures of the two lithologies mineral chemical systematics of monomineralic fragments in the lunar soil provide important clues to soil provenance they can in some cases sort out the highland mare contributions and in special cases can even further pinpoint a lithic source in theory lunar regolith cores can serve as solar probes recording the sun s activity over billions of years in practice this has generally not been the case the formation and evolution of most cores is still poorly understood for most we have not established how they formed for example how many depositional and erosional events were involved what the time span involved in the accretion of the sampled soil column was and how long that soil column has remained in situ without this information it is difficult if not impossible to read the sun s record more interdisciplinary studies on cores must be carried out before they can be used as solar probes

understanding the lunar surface and space moon interactions the surface of the moon is a critical boundary that shapes our understanding of the moon as a whole all geologic mapping and remote sensing techniques utilize only the outermost portion of the moon before leaving the moon for study in our laboratories all lunar samples that have been studied existed at or very near the surface with the exception of the deeply probing geophysical techniques our understanding of the interior of the moon is derived from surficial but not superficial information coupled with boundary of the lunar crust it is the lower boundary layer of the tenuous lunar atmosphere and constitutes both a source and a sink for atmospheric gases the surface is also where the moon interacts with the space environment causing changes in the physical nature of lunar materials and provides a laboratory for the study of processes that occur on all airless bodies the data obtained remotely by the galileo clementine and lunar prospector missions as well as data derived from lunar meteorites have resulted in major changes to our understanding of global distributions of chemistry and rocks this chapter summarizes the current understanding of this critical interface the surface of the moon in its role as the lower boundary of the lunar atmosphere the upper boundary of the crust and the window through which we view through remote sensing the composition of the crust and the history of the moon in this post lunar prospector time the view of the moon has changed lending new perspectives to lunar samples and lunar processes but the new view will likely remain in flux as we continue to digest the results from these recent space missions and move forward to a new era of lunar exploration despite the freshness of our perspective this is an important moment to capture

synthesizing multi sensor multi satellite multi decadal datasets for global volcano monitoring abstract owing to practical limitations less than half of earth s 1400 subaerial volcanoes have no ground monitoring and few are monitored consistently earth observing satellite missions provide global and frequent measurements of volcanic activity that are closing these gaps in coverage we compare databases of global satellite detections of ground deformation 1992 2016 so2 emissions 1978 2016 and thermal features 2000 2016 that together include 306 volcanoes each database has limitations in terms of spatial and temporal resolution but each technique contributed 45 86 unique detections of activity that were not detected by other techniques integration of these three databases shows that satellites detected 102 volcanic activities per year before the year 2000 and 103 activities per year after the year 2000 we find that most of the 54 erupting volcanoes without satellite detections are associated with low volcano explosivity index eruptions and note that many of these eruptions 71 97 135 occurred in the earliest decades of remote sensing pre 2000 when detection thresholds were high from 1978 to 2016 we conduct a preliminary analysis of the timing between the onset of satellite detections of deformation n 154 episodes n 71 volcanoes thermal features n 16 544 episodes n 99 volcanoes and so2 emissions n 1495 episodes n 116 volcanoes to eruption start dates we analyze these data in two ways first including all satellite detected volcanic activities associated with an eruption and second by considering only the first satellite detected activity related to eruption in both scenarios we find that deformation is dominantly pre eruptive 47 and 57 whereas available databases of thermal features and so2 emissions utilizing mainly low resolution sensors are dominantly co eruptive 88 and 76 for thermal features 97 and 96 for so2 emissions

late holocene inland dune activity in the uk a case study from breckland east anglia inland dune fields found in breckland east anglia uk have previously been correlated with the widespread late devensian coversands of the region and a seventeenth century sandflood which is known to have inundated the village of santon downham a programme of optically stimulated luminescence and radiocarbon dating undertaken on the dunes at wangford warren and santon downham reveals that episodic aeolian activity has taken place during the last 7000 years five sand depositional phases on breckland dunes are identified c 6500 c 1600 1100 c 500 c 400 335 and from c 200 30 years before present between c 2120 1840 years ago and within the period 1100 300 years ago quiescent periods allowed the development of fen peat and soils local controlling factors on aeolian activity in breckland appear to be related to anthropogenic activities and livestock sheep and rabbits reducing vegetation cover and decreased precipitation and sea levels which led to lowering of water tables breckland aeolian activity when compared to the national and sub continental holocene aeolian activity record shows a high level of concordance the underlying forcing factor for late holocene dune activity in the uk and elsewhere in europe appears to be climatic instability in the north atlantic associated with both the little ice age and previous similar events which led to increased storminess climatic variability and lower temperatures

loess in europe mass accumulation rates during the last glacial period abstract upper pleistocene loess palaeosol sequences provide excellent high resolution terrestrial archives of climate forcing due to improvements in numerical age determinations especially in luminescence dating methods a more reliable time based reconstruction of the past climate and environmental change has become available for the loess record in europe chronological information was collected from 43 sites along a northwest to southeast transect in europe thirty three of these sites had sufficient age information to allow estimation of mass accumulation rates and it was possible to isolate the mass accumulation rates of primary loess during the last glacial period 28 13 ka bp at 21 of these locations these sites fall along a coarse climatic gradient from the relatively coastal climate of belgium and france to the drier more continental climate of central europe interpreting mass accumulation rates of loess in terms of this climatic gradient is not straightforward as these deposits are dominated by sources in floodplains and large river systems thus accumulation rates are influenced strongly by regional wind and precipitation patterns but mostly by the availability of glacially derived material from the alps and the periglacial terrains that characterized european fluvial systems during and immediately following glaciation

recent advances in the understanding of quaternary periglacial features of the english channel coastlands recent advances in the understanding of quaternary periglaciation of the english channel coastlands concern laboratory modelling of periglacial processes dating of periglacial sediments and the distribution of permafrost during marine oxygen isotope stage mois 2 modelling studies have successfully simulated i ice segregation in chalk in artificial permafrost ii periglacial solifluction of natural slope sediments and iii soft sediment deformation during thaw of ice rich soil the resultant structures and deposits in these experiments have similarities with naturally brecciated chalk solifluction deposits and involutions respectively along the english channel coastlands providing insights into their genesis and palaeoenvironmental significance dating of periglacial sediments is based on radiocarbon assays of organic material in head deposits luminescence measurements of loess and coversand and mammalian biostratigraphy in raised beach and associated slope deposits most age estimates fall within mois 2 although some are within mois 6 and possibly other cold stages maps reconstructing the distribution of permafrost during mois 2 vary in detail the precise distribution of permafrost remains to be established owing to problems of i imprecise dating in the context of climatic instability ii uncertain palaeoclimatic significance of particular periglacial structures and iii sparse data on the age and distribution of relict periglacial features the wider significance of periglacial processes to the evolution of the channel coastlands is speculated to involve rapid valley development by flowing water in areas of moist frost susceptible bedrock that has been brecciated by ice segregation copyright 2003 john wiley sons ltd

chemical variability and origin of agglutinitic glass seemingly pure agglutinitic glass is riddled with many submicrometer sized vesicles and clasts as shown by scanning electron microscopy of ion etched polished grain mounts electron microprobe analyses of agglutinitic glasses that have to be identified with relatively low power optical microscopes are difficult and tend to be biased by very fine grained contaminants energy dispersive x ray analysis edxa of small spots 1 m 1 m of pure agglutinitic glass carefully selected to be free of clasts or vesicles as determined by secondary electron imagery can overcome some of the analytical problems we have performed over 600 edxa of pure glass in 32 large agglutinates from five different apollo landing sites analyses adjacent to or away from clasts do not show any difference in chemical composition and suggest that secondary assimilation of clasts by the primary impact melt has not been a major process affecting the final composition the average glass composition of several agglutinates in any single soil is different from the bulk composition of the soil it is biased toward that of the finest fraction of the soil this is consistent with agglutination models advocating the fusion and or incorporation of the finest soil fraction most of the large multigenerational agglutinates contain small glassy areas or domains that are remarkably homogeneous in chemical composition they may represent the melt from single impact events and their homogeneity indicates that total melting of a microtarget in lunar soils upon micrometeoritic bombardment might be the origin of agglutinitic glass the compositions of these domains are different in different agglutinates and even within single multigenerational agglutinates and bear no systematic relationship to the composition of either the bulk soils or their finest fractions it seems likely that random small targets in lunar soils grains 100 m or less can only produce very small volumes of melt that are not representative of the soil itself the total melting of microtargets is not contradictory to models invoking incorporation or fusion of the finest fraction because such models consider average compositions of several agglutinates with respect to the parent soils they therefore refer to larger scale effects of agglutination a large soil grain if hit directly by a micrometeorite smaller than the grain itself is likely to behave more like a solid target a collection of very fine soil grains if hit by a micrometeorite larger than the collection of the grains will behave as a porous target because porous targets produce relatively more melt than solid targets the average melt composition from a large number of random micrometeoritic impacts is expected to be biased to that of the finest fraction of lunar soils

the upper pleistocene loess record at harmignies belgium high resolution terrestrial archive of climate forcing abstract the loess palaeosol sequence in a section at harmignies in belgium is one of the most important upper pleistocene sites in northwest europe an extensive luminescence dating study was carried out to get a reliable chronological framework and to understand the climate forcing in an area where continuous permafrost dominated during most of the last glaciations twenty eight samples were investigated by infrared optically stimulated luminescence irsl and thermoluminescence tl methods resulting in more than 100 luminescence age estimates the dating results on colluvial sediments are in good agreement with landscape destabilisation phases during ois 5 during the last glacial four major periods of loess accumulation were likely to have occurred in europe at the harmignies section the oldest loess was deposited between 67 000 to 60 000 yr the second one from 60 000 to 50 000 yr the third one from 50 000 to 40 000 yr and the youngest loess accumulation period started most likely after the heinrich 3 event and lasted until the heinrich 2 event 25 000 20 000 yr two main periods of permafrost occurred at approximately 60 000 and 28 000 yr bp

thermoluminescence dating of sand dunes in rajasthan india we report here a new application of thermoluminescence tl for dating sand dunes this application assumes that exposure to sunlight causes bleaching of the geological tl of a sediment to a residual value and that tl accumulation starts again when the sediment is buried under fresh deposit and is thus shielded from the sun although the tl method has been applied to loess1 2 and ocean sediments3 4 the application of this technique to sand dunes provides the first reliable dating control for dune dynamics palaeoclimatology and spread of deserts

tl analysis of loess samples from achenheim abstract we have investigated four loess samples from achenheim sample j2a and l1 were collected above and below a horizon with a supposed age of 30 ka sample o1 was collected below the last interglacial soil and t1 below the next interglacial soil for the determination of eds the additive dose and regeneration techniques were applied using different filters the additive dose technique was complicated by the observation that the dose response could not be described by a single saturation function we have applied two saturation functions and used only the values below the intercept dose for ed determination nearly all calculated ages are younger than expected given the uncertainties there is not a significant difference between results obtained by the additive dose and the regeneration methods the use of the bg12 and ug11 filters seem to give slightly lower results than the 5 58 filter we have calculated mean lives for the tl signals of samples l1 o2 and t1 assuming the youngest possible estimates 30 130 and 240 ka our measurements imply that the thermal stability of the recorded signals is somewhere in the 100 200 ka region for the 5 58 filter and around 100 ka for the other filters due to the uncertainty of the geological age estimates these values are more likely upper limits of the thermal stability

potentially active volcanoes of peru observations using landsat thematic mapper and space shuttle imagery landsat thematic mapper tm images and space shuttle color photograph have been used to make a synoptic study of the volcanoes of southern peru 14 17 s the northernmost portin of the central volcanic zone cvz 14 28 s of the andes apart from providing consistent coverage the chief merit of the tm for this study has been the spatial resolution provided by the 30 m pixel size the optimal 20 m resolution variable lighting and viewing geometry and stereo capability of the shuttle photography provided an invaluable ancilliary data set at the resolution available subtle glacial morphological features such as valley and terminal moraines can be confidently identified and these features have been used to determine the relative ages of volcanoes volcanoes have been classified as potentially active if they have i a well preserved summit crater ii pristine lava flow texture and morphology iii flank lava flows with low albedo and iv evidence of postglacial 10 000 years activity eight major volcanoes are postulated to be potentially active most are large dominantly andesitic composite cones with edifice heights of up to 2500 m some of which threaten nearby settlements one of them sabancaya was active as recently as july 1988 other little known postglacial volcanic features include huaynaputina site of a major explosive rhyolitic eruption in 1600 a d and several fields of monogenetic scoria cones and lava flows the active volcanic front is some 200 km east of the peru chile trench and the volcanoes lie on a trenchparallel trend oblique to the ew subduction this narrow volcanic zone is thought to reflect the steep dip of the nazca plate through the zone of magma generation the break in the trend of the volcanic front in the northern extremity of the volcanic zone is thought to reflect the complexity of the crustal stress field above a major segment boundary in the subducting plate the fields of mafic monogenetic centers also occur in this region in comparison with the southern part of the cvz the general paucity of older volcanic edifices north of 17 s suggests a more recent onset of volcanism north of this latitude probably resulting from the oblique subduction of the nazca ridge and the consequent northward migration of its intersection with the pere chile trench this coupled with the lack of any large silicic caldera systems and youthful dacite domes like those found further south suggest that there are real differences between the volcanic evolution of different parts of the cvz

stratigraphy and origin of new forest brickearths england the thin loamy brickearth deposits overlying the flinty terrace gravels of the new forest are divided into older and younger members the lower older brickearth includes sediments thought to be mainly loess with some aeolian sand and possible river floodloam overbank sediment these share the common feature of palaeo argillic soil horizons in their upper layers two separate phases of pre holocene temperate pedogenesis often can be distinguished in the palaeo argillic horizons the lower brickearth is the most extensive pre devensian loess in britain the upper younger brickearth consists mainly of late devensian oxygen isotope stage 2 loess but its lower layers also contain fine sand derived mainly from local tertiary strata both brickearths occur on all the terrace surfaces of the new forest and indicate that the terraces date from oxygen isotope stage 6 or earlier

test of thermoluminescence dating of loess from new zealand and alaska abstract the accuracy of thermoluminescence tl ages for loess and sediments in general greater than 100 ka is disputed we tested the accuracy of three common tl sediment dating techniques applied to 4 11 m sized polymineral grains from known age loess using 16 samples from north island and south island new zealand and 2 samples from central alaska estimated sample ages range from 20 26 to 800 ka we varied the optical bleaching spectrum the selected window of the emission spectra ultraviolet or uv blue and green wavelengths the pre readout heat treatment and the tl equivalent dose measurement technique most of the 20 26 ka samples gave tl age underestimates of 3 6 ka that may be attributed to post burial open system behavior for the older samples the partial bleach tl method gave expected ages up to 300 ka and the total bleach tl method produced expected ages above 100 ka the partial bleach regeneration tl method gave significant age underestimates for samples older than 100 ka with a maximum tl age of 250 ka for samples having expected ages up to 350 ka two 300 360 ka samples which gave total bleach age underestimates with use of uv tl and green tl gave expected ages with use of blue tl these results demonstrate that reliable tl ages for loess from new zealand and alaska up to 800 ka can be obtained if uv and green emissions and the various regeneration methods are avoided this age range is well above the former putative 80 100 ka upper age limit for tl dating of loess from other regions which was thought to be a global limit application of our successful procedures to such loess is encouraged

thermoluminescence dating applied to a thin winter varve of the late glacial south thompson silt south central british columbia the partial bleach r procedure of thermoluminescence tl dating of unheated sediments has been applied to the 2 4 m sized feldspar dominated grains from two components of a 10 11 ka bp glaciolacustrine silt a previous tl study of the 4 11 m sized feldspars from a 12 cm thick summer layer of this varved deposit did not produce the correct age here it is shown that the 2 4 m feldspar grains from a contiguous 5 mm thick clay rich winter varve give a satisfactory tl apparent age of 14 2 2 3 ka on the other hand and consistent with the previous results the 2 4 m feldspar grains from the thicker summer layer yield an incorrect high apparent age of 55 13 ka these results have implications for general tl dating of waterlaid sediments

landscape instability at the end of mis 3 in western central europe evidence from a multi proxy study on a loess palaeosol sequence from the eastern lower rhine embayment germany abstract the lower rhine embayment hosts important loess palaeosol sequences lps within the western european loess belt yielding valuable information on landscape evolution and palaeoclimatic dynamics the study focusses on the palaeoenvironmental development based on a lps from the eastern shoulder of the lower rhine embayment dusseldorf grafenberg the palaeoenvironmental development within the study area is presented and discussed based on high resolution grain size analyses selected environmental magnetic parameters and geochemical analyses complemented by luminescence age estimates differences in grain size distribution gsd as well as the u ratio clearly reflect main stratigraphical units within the lps in addition the centered log ratio transformation of gsd gsd clr which is sensitive to post depositional grain size variations traces units of intensified soil formation despite no magnetic enhancement can be observed within the grafenberg lps environmental magnetic parameters combined with selected geochemical analyses sr rb provide direct information on the modification of silicates and magnetic minerals in the course of pedogenesis and diagenesis overall the grafenberg lps contributes to the understanding of environmental conditions within the lower rhine embayment particularly for the late mis 3 and the transition to mis 2 the lps reflects major shifts in the geomorphic system which are compared to palaeoenvironmental records from different archives and different geographic regions in north western europe indicating a direct relation to north atlantic climate oscillations during the last glacial period it is shown that the hesbaye unconformity at the mis 3 2 boundary is bound to an erosional event which can be traced over wide areas within the northern european loess belt

the production curve for agglutinates in planetary regoliths models for the production of agglutinates are developed that can be applied to the lunar surface or to any planetary or asteroidal body lacking an atmosphere models are developed using rate equations for progressively more complex situations and range from model 1 which is a simple linear increase of agglutinate content with time to model 4 which includes provision for recycling of existing agglutinates and replenishment and burial of exposed soil model 4 has some aspects of a steady state because depending on the rate constants agglutinate content may be limited to an intermediate value even for long exposure times in an extreme case agglutinate content may be limited to a value near zero these models predict that agglutinates should be low in abundance in areas of thin regolith such as the lunokhod 2 site on the moon and on asteroids the models may also help explain the apparent low agglutinate abundances of lunar regolith breccias and meteorite regolith breccias

new osl dating of uk loess indications of two phases of late glacial dust accretion in se england and climate implications windblown dust deposits or loess locally known in the uk as brickearth blanket many parts of southern england outside the limits of the british and irish ice sheet the best studied loess exposures occur in kent southeast england where the deposits are believed to be late glacial in age new sedimentological evidence is presented for phases of accretion with two distinct units a calcareous brickearth exhibiting periglacial cryoturbation and a non calcareous massive brickearth optically stimulated luminescence osl dating has been applied to chemically isolated modal quartz silts to derive a chronology for sediment accretion and to better understand the palaeoclimatic significance of these deposits

pleistocene evolution of the solent river of southern england abstract the solent river no longer exists since most of its course was drowned by eustatic sea level rise during the flandrian stage holocene previously it flowed eastwards across southeast dorset and south hampshire as an extension of the river frome as such it formed the axial major stream of the hampshire basin a sequence of fluvial aggradations ranging in height from 125 m o d to below sea level provide evidence of the former courses of this substantial river and its tributaries detailed study of the deposits supported by analysis of clast lithological assemblages provide the basis for the recognition of a series of lithostratigraphical units throughout the area the facies and sedimentary structures indicate that the bulk of the deposits accumulated in a braided river environment under periglacial climates late pleistocene fossiliferous sediments of ipswichian and flandrian age provide a biostratigraphical framework the results demonstrate that the solent river was a substantial system comparable in size to the present thames and was a tributary of the channel river during periods of low sea level cold stages evolution of the river reflects its response to climatic change local geological structure and long term tectonic activity although datable deposits limit determination of the age of the solent river sequence it is undoubtedly of considerable antiquity and potentially extends back to the early pleistocene discussion of the sequence includes placing the events within their regional context

tracing the evolution of 2010 merapi volcanic deposits indonesia based on object oriented classification and analysis of multi temporal very high resolution images abstract we compare identification delineation and recording of freshly erupted deposits around active volcanoes from very high resolution optical images with that done by traditional geologic mapping object oriented classification ooc and normalized difference spectral indices of vegetation moisture and soil redness ndvi ndwi and ndrsi have been applied to sub metric geoeye 1 and pleiades images to identify and map pyroclastic and lahar deposits and trace their spatio temporal evolution over two years following the 2010 eruption of merapi volcano indonesia we could identify several categories of pyroclastic depositional areas and also map the damaged forest and destroyed cultivated terraces and settlements in the gendol and opak river basins on the south flank of the volcano more than 75 of erupted deposits were delineated semi automatically unlike the ground geological map based on photo interpretation of the 2010 geoeye image and field observations a temporal image analysis using bivariate scatter diagrams of the three spectral indices between 2010 and 2012 and a combination of ndwi and ndvi separated areas affected by surges from unscathed vegetation use of ndrsi and ndwi allowed us to differentiate overbank pyroclastic density current deposits from wet lahar deposits ndrsi values close to 0 refer to scoria rich pyroclastic deposits about 40 of the devastated upper catchment was recolonized by vegetation between 2010 and 2012 the recovery also took place in the forested valley margins affected by ash cloud surges the morphometric analysis of the initial drainage network digitized from the 2011 2012 images demonstrated 1 the resurfacing of pristine 2010 pdc deposits by runoff and 2 incision or remobilization by lahars it took two years following the eruption in the rugged upper catchment devastated by high energy surges to fully develop the hydrographic network it is however still rudimentary on gently sloping fans created by overbank pdc deposits in the middle valley thus suggesting the importance of slope gradient grain size permeability and thickness of deposits as much as 35 of the 2010 pdc deposits emplaced in the vicinity of the river channels were remobilized by lahars over the two post eruption rainy seasons and also by constant mining activities studies on the erosion of the pyroclastic deposits after 2012 need to concentrate on the upper reach of the catchment on the south flank

the loess section at borden kent se england a 5 3m profile originally described as loess with a buried interglacial soil is reinterpreted from petrographic evidence and thermoluminescence dating as a holocene colluvial accretionary soil mineralogical analyses of coarse silt 16 63 m fractions suggest that most of the silty colluvium was derived from weathered thanet beds upslope though some loess was incorporated during the final depositional phase thin sections show that clay illuviation occurred penecontem poraneously with deposition of colluvium thermoluminescence properties suggest partial optical bleaching of the grains during rapid deposition which is consistent with a holocene colluvial origin

geomorphology and structural development of the nested summit crater of lascar volcano studied with terrestrial laser scanner data and analogue modelling abstract many volcano summits host craters that are partially overlapping the formation of such nested craters has been commonly interpreted as vent migration here we present an additional mechanism that may explain the geometry of nested craters at volcanoes lascar volcano the most active volcano of the central volcanic zone in the chilean andes hosts ene wsw trending summit craters that are partially overlapping nested details on the evolution and interaction between the different craters remain unclear to create a robust dataset terrestrial laser scanner tls data were collected at the summit of lascar in 2013 the resulting topographic data set consisting of more than 15 million data points with centimetre sampling allows visualising almost the complete eastern edifice of the volcano s summit from the tls data a digital elevation model dem and a slope map were generated allowing us to create a lineament map and quantify the observed morphological and structural features to further improve our understanding of the processes responsible for the formation of the craters and geomorphology we designed sandbox analogue models results suggest that one of the craters is a parasite crater formed as a consequence of ongoing activity in the adjacent crater our data suggest that the nested craters have all been modified since the last major eruption in 1993 by near surface effects associated with cooling compaction and gravitational sliding of the crater floor infill as the active crater deepens the adjacent inactive crater extends and partially slumps towards the active one understanding the structural development of these nested craters is relevant for assessing potential future eruption sites thus making lascar a dynamic target for a detailed morphology study these findings may similarly be applied to other volcanoes where nested craters have developed

loess of the lizard peninsula cornwall sw britain abstract the geology of the lizard peninsula the uk s most southerly projection into the english channel is dominated by serpentinised peridotites gabbro and amphibolites of the palaeozoic lizard complex its cainozoic history dates to at least the palaeogene resulting in a relatively complete record of events involving the deposition of the anomalous quartzose crousa gravels intense weathering possible fault controlled uplift development of the current drainage pattern subsequent coastal modification by marine erosion prior to the deposition of presumed mid to late pleistocene raised beaches soliflucted diamicts and late pleistocene loess the lizard loess a uk lithostratigraphic formation is generally perceived as a thin deposit extensively developed inland and capping the thicker diamict head sequences on the coast this study indicates that these sequences coastal head units are themselves loessic on the serpentinised peridotite and amphibolite coasts and gabbroic headlands the location and distribution of loess on the peninsula have been influenced by its rock types and their local weathering erosion regime there appears to have an earlier phase of late pleistocene loess deposition associated with dynamic periglacial processes contemporaneous with other head deposits both on the lizard and elsewhere in south cornwall a later widely preserved phase with more quiescent conditions followed the currently accepted 15 9 ka age for the lizard loess almost certainly belongs to this later phase

the late pleistocene loess deposits and palaeosols of eastern belgium new tl age determinations fourteen samples from the pleistocene loess exposures at kesselt belgian limbourg have been dated with the thermoluminescence method using the regeneration technique and a double analysis with two types of blue transmittant filters reproducible age estimates were obtained up to about 130 140 ka for the basal part of the late weichselian brabant loess and the underlying cryorurbated nagelbeek horizon we arrived at ages of 20 22 ka which is consistent with the radiocarbon age of this horizon 22 3 ka our tl dates further constrain the formation of a lower luvisol profile the bt horizon of which has been correlated with the rocourt palaeosol to the period 50 60 ka these dates however may overstimate the true age of the sediment because they were obtained on reworked loess they indicate that this palaeosol was formed during a middle weichselian interstadial and not during the eemian as is generally accepted the boundary between the weichselian and the older loess is situated at a lower level in the kesselt profile the loess bracketing the deeper tundra gleysols yielded tl ages up to 130 140 ka and the ages further rapidly increased with depth indicating that the sediments may even be much older than saalian 1998 john wiley sons ltd

stratigraphy and palaeontology of pleistocene cold stage deposits at alton road quarry farnham surrey england summary pleistocene deposits exposed at alton road quarry farnham in 1980 have been sub divided into two formal stratigraphical units of member status the wrecclesham gravel is the lowest unit and consists primarily of fluvial sands and gravels silts which occurred as a channel fill within this member contained a macro and micro fossil flora indicative of open country conditions and included a species of moss previously unreported from the european pleistocene tentative thermoluminescence dating indicates an early devensian age for this unit although radiocarbon dating of the plant macrofossils yielded an age of a b p the overlying farnham silty loam is separated from the wrecclesham gravel by a discontinuous and variable thickness of matrix supported gravels interpreted as a slope deposit the farnham silty loam appears to be at least in part of aeolian origin mineralogical investigations suggest that it is predominantly of local derivation whilst thermoluminescence dating suggests that it is of late devensian age

small scale disequilibrium in a magmatic inclusion and its more silicic host basaltic andesite inclusions and their host dacite from the purico chascon complex in northern chile are isotopically distinct textural characteristics of the inclusions are typical of those resulting from magma mingling serial sectioning across the interface of an inclusion and its host dacite complemented by microdrill sampling and detailed microprobe work has enabled us to examine the scale of mixing and chemical isotopic and trace element disequilibrium the results of this work show that 1 the composition of the inclusion is relatively homogeneous 2 the dacite host is generally higher in 87sr 86sr and lower in 143nd 144nd than the enclave but it is heterogeneous on a small scale and probably a hybrid 3 the isotopic composition in the marginal zone apparently on both host and inclusion sides of the weakly chilled interface actually shows the highest 87sr 86sr and lowest 143nd 144nd 4 large plagioclase crystals in the inclusions and host are xenocrystic with higher 87sr 86sr than any of the other samples these observations are reconciled with a model of magma evolution in a crustal magma chamber in such a scenario the mafic magma is overlain by a cap of rhyolite a partial melt of the dacitic ignimbrites which now underlie the purico chascon complex overturn of such a magma system gives rise to a hybrid dacite containing discrete mafic inclusions

the 16 september 1986 eruption of lascar volcano north chile satellite investigations landsat thematic mapper tm images acquired in 1984 and 1985 revealed a pronounced thermal anomaly on lascar volcano north chile subsequent images showed that the anomaly was persistent but variable and that after a significant eruption on 16 september 1986 it was weaker and divided into several sources tm studies and other observations of lascar indicate that the persistent thermal anomaly may be due to high temperature fumaroles within the summit crater goes weather satellite images and field investigations confirm that the 16 september event was a short lived vulcanian type eruption which produced an ash column that reached 15 km altitude the ash cloud can be tracked on geos images to about 400 km downwind and covered an area 112 000 km2 transport occurred in the upper troposphere at speeds up to 180 km h ash fall from the plume was well sorted and moderately fine grained md 200 m formation and fallout of ash as aggregates was unimportant in the deposition of the ash layer although small the lascar 16 september eruption is significant because few historic eruptions have been recorded in the central andes little would have been known of the eruption in the absence of remote sensed data

a comparison of different tl techniques on loess samples from rheindahlen f r g abstract 9 tl samples of the loess profile rheindahlen lower rhine area germany covering the time span of the last 300 ka were studied systematic investigation was carried out using different filters and preheating procedures ed determinations were done by the additive dose and the regeneration method the annual dose was determined by aas alpha counting naa and gamma spectrometry in the laboratory and in the field the results show that the weichselian loess is datable whereas no tl age differentiation between loesses of stage 6 and stage 8 is possible if the accumulated dose ed is in the 600 gy region every apparent tl age between 100 and 300 ka can be obtained this leads to the conclusion that in rheindahlen no reliable tl ages are available for loess deposits underneath the eemian soil stage 5e

a review of current research on tl dating of loess abstract the thick loess deposits of china central europe and north america are particularly suitable for the application of the thermoluminescence tl dating method because individual grains are likely to have travelled large distances and thus been well exposed to light before deposition wind blown silt grains collected close to glacial rivers in alaska have been shown to give a zero age of not more than 2 ka demonstrating the efficiency of the zeroing mechanism differences in laboratory procedures can cause differences in the tl ages reported particularly for loess over 100 ka tl ages for interstadial soils in europe are in agreement with the very few radiocarbon dates on reliable material such as charcoal on the other hand tl dates from sites in belgium and north western germany indicate that the previously accepted chronology which was based on two radiocarbon dates on humic rich sediments is incorrect the use of the last interglacial palaeosol for assessing the tl dates on loess above and below it is limited by the uncertainty in the timing of termination of soil forming processes 107 and 71 ka are the limits suggested by the astronomically derived time scale results on deposits from china north america alaska and europe are discussed in this context

discrimination of iron alteration minerals in visible and near infrared reflectance data field and laboratory studies were conducted to relate the mineralogy of rock and soil samples containing hematite fe2o3 goethite feooh and jarosite kfe3 so4 2 oh 6 to their reflectance properties in visible and near infrared wavelengths field reflectance measurements of regolith containing one or more of these minerals were made in the goldfield nevada mining district with a four channel radiometer the mineralogy and reflectance properties of regolith samples collected from these field measurement sites were then determined by laboratory studies mossbauer spectroscopy was used to identify the iron minerals present and their relative proportions the reflectance spectra of samples containing hematite and goethite were characterized by a reflectance minimum near 900 nm the location of this minimum could be accounted for by the relative proportions of hematite and goethite present in the samples under certain conditions it may be feasible to estimate the relative proportions of hematite and goethite on the earth s surface by determining the location of this near infrared reflectance minimum in high spectral resolution remote sensing data in addition the field measurements suggest that the ratio of band passes at 852 and 982 nm may be used to distinguish qualitatively among hematite goethite and jarosite thus maps of the distribution of these minerals may be derived from scanner images acquired in those band passes

reinterpreting climate proxy records from late quaternary chinese loess a detailed osl investigation abstract numerous authors have utilised physical properties of chinese loess and red clay deposits to develop apparently detailed and continuous past climate records from the miocene into the holocene many of these studies have further suggested that the principal climatic agent responsible for the aeolian emplacement and diagenesis of chinese loess the east asian monsoon has fluctuated rapidly on millennial to sub millennial timescales in concert with dramatic changes in the north atlantic dansgaard oeschger cycles and heinrich events and the western pacific el nino southern oscillation much of this evidence is based on reconstructions and age models that are tied to assumptions concerning the nature of loess sedimentation and diagenesis for example the belief that loess sedimentation can be viewed as essentially continuous some authors have however cast doubt on these assumptions and suggest that the application of radiometric techniques may be required to determine their validity recent studies utilising optically stimulated luminescence osl methods have reinforced these doubts and here osl dates obtained at 10 cm intervals from three sites along a transect across the chinese loess plateau have been used in combination with climate proxy evidence to test the existing assumptions that underpin many palaeoclimatic reconstructions from loess in this way the first time continuous and independently dated late quaternary climate reconstruction is developed from loess the data indicate that sedimentation is episodic and that once emplaced loess is prone to pedogenic disturbance diagenetic modification and in some cases erosion the relationships between proxies and sedimentation rates are also assessed and climatic interpretations based on different age models compared the implications of these findings for reconstructions of climate from loess are explored and comparisons are made between the developed palaeoclimate records and evidence from ice and ocean cores this exercise also highlights important information concerning the relative influence of forcing mechanisms behind east asian monsoon change over the late quaternary

lithospheric structure beneath the northern central andean plateau from the joint inversion of ambient noise and earthquake generated surface waves the central andean plateau cap as defined by elevations in excess of 3 km extends over 1 800 km along the active south american cordilleran margin making it the second largest active orogenic plateau on earth the uplift history of this high plateau with an average elevation around 4 km above sea level remains uncertain as paleoelevation studies along the cap suggest a complex non uniform uplift history as part of the central andean uplift and the geodynamics of high topography caught project we image the s wave velocity structure of the crust and upper mantle using surface waves measured from ambient noise and teleseismic earthquakes to investigate the upper mantle component of plateau uplift we observe three main features in our s wave velocity model including 1 a positive velocity perturbation associated with the subducting nazca slab 2 a negative velocity perturbation below the subandean crust that we interpret as anisotropic brazilian cratonic lithosphere and 3 a high velocity feature in the mantle above the slab that extends along the length of the altiplano from the base of the moho to a depth of 120 km a strong spatial correlation exists between the lateral extent of this high velocity feature and the relatively lower elevations of the altiplano basin suggesting a potential relationship determining if this high velocity feature represents a small lithospheric root or foundering of orogenic lithosphere requires more integration of observations but either interpretation implies a strong geodynamic connection with the uppermost mantle and the current topography of the northern cap

systematic thermoluminescence dating of two loess profiles from the middle rhine area f r g abstract systematic investigation of 104 loess samples from the well studied loess sequences at ariendorf and toenchesberg middle rhine area f r g was carried out to study the reliability of tl ages of the last 150 ka the samples were investigated by the additive dose regeneration and partial bleach methods using integral and plateau ranges for determination of accumulated dose the results show that in ariendorf all the loess deposits of the last glaciation are contaminated with reworked loesses from older glaciations at toenchesberg the tl ages are in good agreement with the stratigraphy up to about 90 ka but no tl age over 110 ka was obtained underneath the interglacial soil at toenchesberg

loess correlations between myth and reality abstract the correlation of loess sequences across global hemispheric regional and local scales is one of the most fundamental aspects to loess research however despite recent progress in stratigraphic and chronometric methods the correlation of many loess sequences is often still based on untested assumptions over loess deposition preservation soil type and age as such the aim of this overview is to provide an adequate framework for evaluation of the accuracy of loess correlations applied on different temporal and spatial scales across eurasia this opens up possibilities for detailed temporal and spatial environmental reconstructions across the huge loess provinces of the eurasia and provides a framework for future extension of this to north america additionally we evaluate the potential development of appropriate sub millennial scale loess correlations as well as essentially important chronological approaches for establishing valid correlations between different loess records such as current improvements in tephrochronology 14c and luminescence dating techniques

a critical review of the glaciomarine model for irish sea deglaciation evidence from southern britain the celtic shelf and adjacent continental slope in support of their glaciomarine model for the deglaciation of the irish sea basin eyles and mccabe cited the occurrence of distal glaciomarine mud drapes onshore in the isles of scilly and north devon and of arctic beach face gravels and sands around the shores of the celtic sea glacial and sea level data from the southern part of the irish sea in the terminal zone of the ice stream and the adjacent continental slope are reviewed here to test this aspect of the model the suggestion that the glacial sequences of both the isles of scilly and fremington in north devon are glaciomarine mud drapes is rejected an actively calving tidewater margin only occurred early in the deglacial sequence close to the terminal zone in the south central celtic sea relative sea levels were lower and therefore glacio isostatic depression less than envisaged in the glaciomarine model geochronological sedimentological and biostratigraphical data indicate that the raised beach sequences around the shores of the celtic sea and english channel were deposited at or during regression soon after interglacial eustatic highstands evidence for ice rafting at a time of high relative sea levels is restricted to a phase s earlier than the late devensian these data indicate that the raised beach sequences have no bearing on the style of irish sea deglaciation copyright 2001 john wiley sons ltd

the southernmost quaternary niche glacier system in great britain until recently the scientific consensus has been that the uplands of south west britain remained unglaciated throughout the quaternary with glacial ice sheet limits lying to the north of the south west peninsula however recent work has shown that small glaciers and ice caps existed in the uplands of exmoor and dartmoor during the late quaternary demonstrating that the consensus of an unglaciated south west britain requires considerable revision here we report geomorphological and sedimentary evidence supported by glacier climate modelling for a quaternary niche glacier from west cornwall south west england this niche glacier represents the southernmost such system from mainland great britain and provides evidence for the presence of extra glacial niche glaciers probably during the last glacial maximum of the devensian glaciation and well outside the limits of the main british irish ice sheet

thermoluminescence dating of late devensian loesses in southern england scattered across southern england are many isolated deposits of loess like material1 a few such as that at pegwell bay in kent are highly calcareous and unweathered but most have been reworked by fluvial or colluvial processes there is good stratigraphical evidence for a few pre devensian loesses also in kent but dating of more recent loess has so far been based on indirect evidence much work has been done on the pegwell bay loess as it is the most extensive truly aeolian loessic deposit in britain kerney2 compared the late devensian deposits in the isle of thanet and at pegwell bay with similar deposits in holland and belgium where radiocarbon dates have been obtained for interstadial deposits correlation of the east kent deposits with these in northern europe indicates that the loesses in kent were formed between 30 000 and 14 000 yr ago i report here dates for six of the more recent deposits in southern britain from the scilly isles to kent the dates have been obtained on the loess itself using a recently developed thermoluminescence tl dating technique3 4 and confirm the ages as being late devensian

thermoluminescence ages of loess and associated sediments in central nebraska usa abstract thick deposits of quaternary loess maximum 60 m more typically 20 30 m occur in the loess hills and south of the platte river in central nebraska a programme of field sampling and thermoluminescence dating has provided new age estimates for the younger aeolian stratigraphic units in the upper part of the sequence dates from aeolian sands below the gilman canyon formation at two sites indicated ages ranging from 64 7 to 48 5 ka providing a maximum age for this unit a date of 35 3 ka was obtained from near the top of a truncated gilman canyon sequence in one section but radiocarbon evidence from other sites suggests that slow accumulation of dust accompanied by pedogenesis and syn depositional reworking continued in some areas until at least 23 ka ago the gilman canyon formation is overlain by up to 25 m of grey peoria loess which accumulated between c 22 ka and 10 5 ka ago between c 10 5 ka and 9 ka ago the rate of dust accumulation decreased apparently due to a reduction in sediment supply from the great plains river valleys thereby allowing the widespread development of a soil the brady soil after 9 ka ago the rate of dust deposition again accelerated resulting in the accumulation of up to 5 m of bignell loess the main source of bignell loess was probably also the valleys of ephemeral great plains rivers during periods when the region experienced a drier climate than present dating evidence suggests that some time after 3 2 ka ago the rate of dust accumulation again slowed allowing development of the modern soil it is suggested that this change reflected a reduction in dust availability related to a change towards slightly wetter climate and associated changes in river regime

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

new age constraints for the limit of the british irish ice sheet on the isles of scilly the southernmost terrestrial extent of the irish sea ice stream isis which drained a large proportion of the last british irish ice sheet impinged on to the isles of scilly during marine isotope stage 2 however the age of this ice limit has been contested and the interpretation that this occurred during the last glacial maximum lgm remains controversial this study reports new ages using optically stimulated luminescence osl dating of outwash sediments at battery tresco 25 5 1 5 ka and terrestrial cosmogenic nuclide exposure dating of boulders overlying till on scilly rock 25 9 1 6 ka which confirm that the isis reached the isles of scilly during the lgm the ages demonstrate this ice advance on to the northern isles of scilly occurred at 26 ka around the time of increased ice rafted debris in the adjacent marine record from the continental margin which coincided with heinrich event 2 at 24 ka osl dating 19 6 1 5 ka of the post glacial hell bay gravel at battery suggests there was then an 5 ka delay between primary deposition and aeolian reworking of the glacigenic sediment during a time when the isis ice front was oscillating on and around the ll n peninsula 390 km to the north

chronological separation of interglacial raised beaches from northwestern europe using thermoluminescence thermoluminescence tl age estimates have been obtained on coarse grained detrital feldspar from eemian beach sand substage 5e early weichselian dune sands substages 5d and 5b and pre eemian beach sand the past radiation dose is obtained using the additive dose method even for the oldest samples which date to 300 000 yr b p by other methods the tl signal is not in saturation and can be doubled by the addition of laboratory radiation doses without saturation being achieved this is contrasted with the behavior of polymineral silt sized grains from loess in the adjacent area the tl age estimates are systematically underestimated by about 40 when compared with the expected geological ages however they are in correct stratigraphic order and demonstrate that stage 5 beach deposits can be distinguished from those resulting from earlier high sea levels using tl signals from potassium feldspars

tl geochronology of brickearths from south east england abstract the results of a study of brickearths from 29 sites in south east england are presented tl provides a powerful tool for age correlation of sites the use of tl has begun to unravel a geochronology of unexpected complexity although many sites contain material dating to the late devensian 10 25 ka bp the present study also reveals clusters of sites dating to 40 ka bp 50 100 ka bp and 120 ka bp

infrared surveillance of crater lakes using satellite data abstract under optimum circumstances thermal infrared data recorded from satellites can measure water surface temperatures to accuracies of a few tenths of a degree celsius such techniques are applied here to evaluate volcanic crater lake temperatures at present band 6 of the landsat thematic mapper tm is the most pertinent sensor in this respect although its nominal 120 120 m footprint only permits useful measurements of circular lakes exceeding 340 m in diameter in addition the radiative properties of the atmosphere between sensor and target at the instant of observation should be well characterised in order to make confident measurements of surface temperatures with single band infrared data an analysis is presented of three tm band 6 images of the crater lake at poas volcano costa rica recorded on february 6 1986 march 13 1987 and may 10 1988 in the february 1986 scene the band 6 derived water surface temperature is 36 c which is 3 c less than a field measurement made in the same month since the satellite measurement was integrated over some 14 400 m 2 of the lake surface while the field measurement was obtained at a single point below the surface the former may be more representative of surface heat losses subsequent tm data reveal an increasing discrepancy between contemporaneous field and satellite observations probably because the lake diameter had decreased to 250 m by march 1987 and to less than 200 m by mid 1988 greatly reducing the likelihood of obtaining a pure lake pixel the advanced spaceborne thermal emission and reflection radiometer aster which is earmarked for orbit on the first of nasa s earth observing system satellite platforms later this decade has five discrete spectral bands in the thermal infrared region and will produce data composed of 90 90 m pixels these specifications could enable the determination of water surface temperatures of 250 m diameter crater lakes by algorithms that implicitly account for atmospheric effects

spot satellite monitoring of the eruption of nevado sabancaya volcano southern peru abstract the nevado sabancaya volcano southern peru began a phreatomagmatic eruptive process on 28 may 1990 after 4 years of weak seismic activity and fumarolic emission spot images were acquired on 21 july 1986 and 1 july 1989 differences between the two dates in snow and ice cover and morphology of the crater allowed us to foresee an increase in activity and possible change in the eruptive process after the beginning of the eruptive stage five spot images were provided by the cnes france the last one dated 12 december 1990 they show variations of ash cover the opening of fractures an increase of the crater size and new mudflows the 10 m ground resolution and stereoscopic capabilities of panchromatic spot imagery permitted us to follow the major changes of geomorphic features during a volcanic eruptive stage

thermoluminescence dating and geochemistry of loessic deposits in southeast england the results of a thermoluminescence tl dating and geochemical survey of loessic deposits in southeast england involving sampling at 26 localities demonstrate that the loessic deposits appear to be the product of at least three depositional phases of aeolian silt during the late pleistocene namely 10 25 ka bp 50 125 ka bp and 170 ka bp the majority of localities sampled date to the late devensian but isolated pockets of older material were found throughout the area the majority of the samples analysed were of decalcified material the results of geochemical analyses of major oxide and trace element concentrations indicate the uniformity of material and suggest a common provenance

using the landsat thematic mapper to detect and monitor active volcanoes an example from lascar volcano northern chile the landsat thematic mapper tm offers a means of detecting and monitoring thermal features of active volcanoes using the tm we have discovered a prominent thermal anomaly on lascar volcano northern chile data from two short wavelength infrared channels of the tm show that material within a 300 m diameter pit crater was at a temperature of at least 380 c on two dates in 1985 the thermal anomaly closely resembles in size and radiant temperature the anomaly over the active lava lake at erta ale in ethiopia an eruption took place at lascar on september 16 1986 tm data acquired on october 27 1986 revealed significant changes within the crater area we find that lascar is in a much more active state than any other volcano in the central andes and for this reason it merits further careful monitoring our studies show that the tm is capable of confidently identifying thermal anomalies less than 100 m in size at temperatures of above 150 c and thus it offers a valuable means of monitoring the conditions of active or potentially active volcanoes particularly those in remote regions

stratigraphy geochemistry and thermoluminescence ages of lower mississippi valley loess four periods of loess deposition in the lower mississippi valley can be identified on the basis of geochemical and mineralogical criteria radiocarbon dating and thermoluminescence dating these are designated loess units 1 2 3 and 4 in order of increasing age carbonate rich unit 1 loess comprises more than 70 per cent of the thickness of the loess profiles 14c and tl dates indicate this loess was deposited between 9 000 and 20 000 years ago a maximum sedimentation rate of 2 17 mm yr 1 has been recorded near vicksburg just after the last laurentide glacial maximum between 17 190 and 15 580 years ago the unit 2 loess which is thin and partly decalcified was deposited slowly between about 25 000 and 20 000 years ago the unit 3 and unit 4 loess formations which are both highly weathered have yielded tl ages of 76 000 85 000 years and 119 000 132 000 years suggesting they were deposited during the altonian substage of the early wisconsinan and the illinoian glacial stage respectively the four loess units are stratigraphically equivalent to the peoria farmdale roxana and loveland loess formations previously recognized in illinois the source of dust in both areas was glacial outwash in the mississippi valley during interglacials and interstadials when the supply of glacial debris was reduced and the mississippi river changed from a braided to a meandering regime dust sedimentation in southern mississippi virtually ceased allowing weathering and pedogenesis to proceed

heterogeneous agglutinitic glass and the fusion of the finest fraction f3 model evidence in favor of the model fusion of the finest fraction f3 for the origin of lunar agglutinitic glass has been accruing they include 1 theoretical expectations that shock pulses should engulf and melt smaller grains more efficiently than larger grains 2 experimental results of impact shock albeit at lower than presumed hypervelocity impacts of micrometeorites on the lunar regolith and 3 new analyses confirming previous results that average compositions of agglutinitic glass are biased towards that of the finest fraction of lunar soils from which they had formed we add another reason in support of the f3 model finer grains of lunar soils are also much more abundant hence electrostatic forces associated with the rotating terminator region bring the finest grains that are obviously much lighter than courser grains to the surface of the moon this further contributes to the preferential melting of the finest fraction upon micrometeoritic impacts new backscattered electron imaging shows that agglutinitic glass is inhomogeneous at submicron scale composition ranges of agglutinitic glass are extreme and deviate from that of the finest fraction even by more than an order of magnitude for some components additionally we show how an ilmenite grain upon impact would produce tio2 rich agglutinitic glass in complete disregard to the requirements of fusion of the finest fraction we propose an addition to the f3 model to accommodate these observations i e that micrometeorite impacts indiscriminately melt the immediate target regardless of grain size or grain composition we therefore suggest that 1 agglutinitic glass is the sum of a the melt produced by the fusion of the finest fraction of lunar soils and b the microvolume of the indiscriminate target which melts at high shock pressures from micrometeoritic impacts and that 2 because of the small volume of the melt and incorporating cold soil grains the melt quenched so rapidly that it did not mix and homogenize to represent any preferential composition for example that of the finest fraction

thermoluminescence dating of sediments abstract the potential for using the thermoluminescence behaviour of sediments for dating them was first recognized by soviet scientists g v morozov and v n shelkoplyas and for over a decade their tl dates obtained from a variety of sediments have appeared in the soviet literature since 1977 tl sediment dates have been published by six additional groups using a variety of methods in this review we describe the principles of tl dating the various methods used and contrast tl dating of sediments with the now well accepted tl dating of pottery we conclude that while tl dating has the potential to solve many sedimentary problems more fundamental research needs to be carried out before such dates should be accepted a set of criteria for acceptable dates is proposed

tl stratigraphy of pre weichselian loess from nw europe using feldspar coarse grains abstract a new feldspar relative tl dating method is proposed that enables dating of pre weichselian loess older than 130 ka by applying the additive dose technique and the mejdahl s exponential extrapolation to alkali feldspar coarse grains the method is applied to loess deposits from various reference loessic sections of nw europe our relative tl age estimates are consistent with the information provided by the regional stratigraphy furthermore they lead to a clear separation of the pre weichselian periods of loess deposition in the time period 130 ka 300 ka

pattern and timing of retreat of the last british irish ice sheet during the last glacial the ice sheet that subsumed most of britain ireland and the north sea attained its maximum extent by 27 ka bp and with an ice volume sufficient to raise global sea level by ca 2 5 m when it melted we reconstruct the demise of this british irish ice sheet biis and present palaeo glaciological maps of retreat stages between 27 and 15 ka bp the whole land area was investigated using remote sensing data and we present maps of moraines meltwater channels eskers and drumlins and a methodology of how to interpret and bring them together for the continental shelf numerous large moraines were discovered recording an extensive pattern of retreat stretching from sw ireland to the shetland isles from an integration of this new mapping of glacial geomorphology 26 000 landforms with previously published evidence compiled in the britice database we derive a pattern of retreat for the whole biis we review and compile relevant dates 881 examples that constrain the timing of retreat all data are held within a geographic information system gis and are deciphered to produce a best estimate of the combined pattern and timing of retreat pattern information reveals an ice sheet mainly comprised of a shelf parallel configuration from sw ireland to ne scotland but it spread far enough to the south to incorporate outlying ice domes over wales the lake district and kerry final disintegration was into a number of separate ice caps rather than reduction as a single mass and paradoxically retreat was not always back to high ground by 23 ka bp ice withdrew along its northern boundaries at the same time as the southern margins were expanding including transient ice streaming down the irish sea and advances of lobes in the cheshire basin vale of york and east coast of england ice divides migrated south by 19 ka the ice sheet was in crisis with widespread marine based ice losses particularly in the northern north sea and the irish sea considerable dynamic thinning occurred during this phase final collapse of all marine sectors occurred by 17 ka bp and with most margins beginning to back step onshore disintegration of the north sea ice bridge between britain and norway remains loosely constrained in time but the possibility of catastrophic collapse of this sector is highlighted the north channel and irish sea ice streams had finally cleaved the ice sheet into separate irish and scottish ice sheets by 16 ka bp rates of ice loss were found to vary widely over space and time e g 65 260 km3 per year the role of ice streams and calving losses of marine based sectors are examined retreat rates of up to ca 150 ma 1 were found for some ice stream margins that large parts 2 3 of the biis were marine based drained by ice streams and possibly with fringing ice shelves in places makes it a useful analogue for the west antarctic ice sheet wais this is especially so because the biis deglaciated in response to rising temperatures and a rising sea level driven by melting of other ice masses which are the current forcings that might cause collapse of the wais our reconstruction when viewed from the opposite perspective documents when fresh land became exposed for exploitation by plants animals and man and records for how long such land has been available for soil and geochemical development and ecological succession

effusive eruption of viscous silicic magma triggered and driven by recharge a case study of the cerro chascon runtu jarita dome complex in southwest bolivia the cerro chascon runtu jarita complex is a group of ten late pleistocene 85 ka lava domes located in the andean central volcanic zone of bolivia these domes display considerable macroscopic and microscopic evidence of magma mixing two groups of domes are defined chemically and geographically a northern group the chascon consists of four lava bodies of dominantly rhyodacite composition these bodies contain 43 48 phenocrysts of plagioclase quartz sanidine biotite and amphibole in a microlite poor rhyolitic glass rare mafic enclaves and selvages are present mineral equilibria yield temperatures from 640 to 750 c and log o2 of 16 geochemical data indicate that the pre eruption magma chamber was zoned from a dominant volume of 68 to minor amounts of 76 sio2 this zonation is best explained by fractional crystallization and some mixing between rhyodacite and more evolved compositions the mafic enclaves represent magma that intruded but did not chemically interact much with the evolved magmas a southern group the runtu jarita is a linear chain of six small domes 1 km3 total volume that probably is the surface expression of a dike the five most northerly domes are composites of dacitic and rhyolitic compositions the southernmost dome is dominantly rhyolite with rare mafic enclaves the composite domes have lower flanks of porphyritic dacite with 35 vol phenocrysts of plagioclase orthopyroxene and hornblende in a microlite rich rhyodacitic glass sieve textured plagioclase mixed populations of disequilibrium plagioclase compositions xenocrystic quartz and sanidine with ternary composition reaction rims indicate that the dacite is a hybrid the central cores of the composite domes are rhyolitic and contain up to 48 vol phenocrysts of plagioclase quartz sanidine biotite and amphibole this is separated from the dacitic flanks by a banded zone of mingled lava macroscopic microscopic and petrologic evidence suggest scavenging of phenocrysts from the silicic lava mineral equilibria yield temperatures of 625 727 c and log o2 of 16 for the rhyolite and 926 1000 c and log o2 of 9 5 for the dacite the rhyolite is zoned from 73 to 76 sio2 and fractionation within the rhyolite composition produced this variation most of the 63 73 sio2 compositional range of the lava in this group is the result of mixing between the hybrid dacite and the rhyolite eruption of both groups of lavas apparently was triggered by mafic recharge a paucity of explosive activity suggests that volatile and thermal exchanges between reservoir and recharge magmas were less important than volume increase and the lubricating effects of recharge by mafic magmas for the runtu jarita group the eruption is best explained by intrusion of a dike of dacite into a chamber of crystal rich rhyolite close to its solidus the rhyolite was encapsulated and transported to the surface by the less viscous dacite magma which also acted as a lubricant simultaneous effusion of the lavas produced the composite domes and their zonation reflects the subsurface zonation the role of recharge by hotter more fluid mafic magma appears to be critical to the eruption of some highly viscous silicic magmas

an experimental investigation of agglutinate melting mechanisms shocked mixtures of apollo 11 and 16 soils mixtures of chemically contrasting lunar soils from a 11 and a 16 have been shocked at pressures ranging from 18 2 62 0 gpa 182 620 kb other than the generation of impact melts modal and textural changes caused by shock include destruction of pore space and fused soil clasts and conversion of plagioclase to maskelynite the loss of the fused soil component in these runs indicates that low agglutinate contents in shocked and or compacted regolith breccias cannot be considered by themselves to be evidence of formation from immature regolith from the petrographic and chemical data it appears that the impact glass formed mainly from the fine fraction and the fused soil component in the target with relatively minor contributions from the other coarse clasts the impact glasses exhibit the same chemical enrichments and depletions as their corresponding fine fractions and plot on or near a mixing line between the bulk and fine fraction of the soil in which they were formed from this as well as several other studies it appears that the fusion of the finest fraction f3 model is valid and that it accurately predicts the chemical systematics of impact glass formed from lunar soil in addition fusion of agglutinates present in the target soil is an important process

paired 26al and 10be exposure ages from lundy new evidence for the extent and timing of devensian glaciation in the southern british isles lundy lies in a strategic geographical position for understanding the glacial history of the british isles the island bears evidence of glaciation largely in the form of ice moulded bedrock and glaciallytransported boulders e an unusual occurrence this far south in the british isles irish sea ice penetrated the western bristol channel overriding lundy from the northwest during the last phase of glaciation in this area the results of paired terrestrial cosmogenic nuclide analyses 26al 10be constrain the timing of this extensive glaciation and provide for the first time an age for the exposure of lundy granite following deglaciation the results from nine paired samples yield 26al 10be exposure ages of 31 4e48 8 ka 10be and 31 7e60 0 ka 26al this challenges the view that any glaciation this far south must belong to middle pleistocene glaciations such as the anglian stage c 480e420 ka and a devensian age for the last glaciation is consistent with findings from the isles of scilly further south however the findings suggest early mid devensian marine isotope stage mis 4e3 glaciation of lundy it also implies that the island was exposed or covered for a short time by non erosive cold based ice at the global last glacial maximum lgm during mis 2 26e21 ka the potential exposure of the island throughout mis 2 contrasts with the evidence from the isles of scilly and the celtic sea which were glaciated at the lgm

thermoluminescence dating of coarse grain quartz from the malan loess at zhaitang section china thermoluminescence tl ages were obtained for five loess samples taken from the zhaitang section near beijing china using the coarse grain quartz technique the paleodose values have been determined by the method of total sample bleaching and regeneration of the tl growth curve the method appears to be suitable for the age determination of loess samples up to about 150 000 yr where the annual dose rate values are of the order 3 4 mgy yr this limit is a function of the total accumulated dose the ages are in good agreement with those obtained by a fine grain tl technique and are consistent with geological and geomagnetostratigraphic evidence

application of the landsat thematic mapper to the identification of potentially active volcanoes in the central andes abstract landsat thematic mapper tm images have been used to make the first comprehensive study of the central andean volcanic province 14 s 28 s one of the world s largest zones of active volcanism more than 60 major volcanoes have been identified as potentially active whereas only 16 had been previously cataloged most of these are large composite cones up to 6000 m in height some of which threaten nearby settlements apart from its consistent coverage the chief merit of the landsat tm in making this study has been spatial resolution provided by the 30 m pixel size this has been particularly important for the recognition of subtle glacial morphological features such as valley and terminal moraines which can be used to determine relative ages of the volcanoes on the tm images we have classified a volcano as potentially active if it has i a well preserved summit crater ii pristine lava flow texture and morphology iii flank lava flows with low albedo and iv evidence of post glacial

abrupt last glacial dust fall over southeast england associated with dynamics of the british irish ice sheet loess deposits in southern britain contain a record of dust climate and landscape dynamics over the last glacial yet their age and accumulation rate remain poorly known furthermore the environm

the origin of heinrich layers evidence from h2 for european precursor events recent well dated isotopic sr nd fingerprinting of heinrich layer ice rafted detritus ird on the european margin indicates supply from european ice sheets as precursors to laurentide ice sheet lis supply f e grousset et al geology 28 2000 123 126 h snoeckx et al mar geol 158 1999 197 208 these precursorevents lead lis input by up to 1 5 ka f e grousset et al geology 28 2000 123 126 and have been interpreted to indicate lis collapse during heinrichevents stimulated by events originating on the european side of the atlantic f e grousset et al geology 28 2000 123 126 such phasing of ird supply from different sources within heinrich layers therefore has implications for the origin and mechanics of heinrichevents we present evidence here that the ird comprising heinrich layer 2 h2 20 21 14c ka bp on the european continental margin contains detrital campanian upper chalk deriving from bedrock sources eroded on the celtic shelf by the british ice sheet bis in addition to lithic material sourced from the lis high resolution radiocarbon chronology indicates chalk grain deposition as discrete pulses both before and coincident with supply of lis sourced detritus the specificity of the chalk fingerprint to the bis enables a 700 1000 yr lag between the bis and lis events to be identified this phasing indicates a more rapid response of the outlet lobes draining the smaller bis than those draining the lis and implicates external climatic forcing of heinrichevents it is unlikely that this precursorevent represents ird event 18 the recently identified 1 2 ka ird cycle event which immediately precedes h2 because the lag between precursor and main event is here less than 1 5 ka and because such pervasive periodicity is not apparent in european continental margin ird records the later synchroneity between the bis and lis input in h2 identifies glacio eustatic sea level rise associated with lis discharges as a possible feedback mechanism causing destabilisation of ice streams elsewhere during heinrichevents

the chronology palaeogeography and archaeological significance of the marine quaternary record of the west sussex coastal plain southern england u k abstract the quaternary sediments of the west sussex coastal plain have produced a wide range of floral faunal and archaeological remains these sediments consist of marine sands and gravels exhibiting transgressive and regressive trends which occur from present day sea level to c 43 0 m o d and are overlain by terrestrial silts and cold climate periglacial sediments at the present day coastline channel fill deposits occur below modern beach levels new field observations coupled with a re investigation of old sites and literature suggest that five discrete high stands of sea level may be preserved in the area of the west sussex coastal plain age estimates for these deposits suggest that they span large parts of the middle and upper pleistocene oxygen isotope stages 13 to 5 conformable relationships between many of the marine and terrestrial sediments suggest that the potential exists within the area to correlate the marine and terrestrial quaternary stratigraphic records in addition sediments associated with two of these high sea level stands are associated with extensive buried landsurfaces covering large areas of the coastal plain at some locations these intact landsurfaces are associated with evidence for human activity and represent stratigraphic and cultural resources of international importance

thermoluminescence dating of periods of loess deposition and soil formation in normandy the least incomplete records of pleistocene climate change come from the study of deep sea sediments in which the stratigraphic record of oxygen isotope variations reflecting terrestrial ice volume is the primary correlation medium on continents the available record is far less complete because many of the characteristics of glaciation are erosional rather than depositional the areas of loess deposition may provide the best deposits in which to develop relatively complete regional stratigraphies that may be compared with the deep sea record1 2 in this study we use thermoluminescence tl dating of loess and of soil developed on loess to test this model we have confined ourselves to the last complete glacial cycle within which the reproducibility of the age determinations is similar to the time resolution of most deep sea core records

analysis of active volcanoes from the earth observing system abstract a study of volcanic activity and its effects on the atmosphere is one of 28 interdisciplinary investigations for the earth observing system eos due to be launched in 1997 and 1999 the volcanology investigation will include long and short term monitoring of selected volcanoes the detection of precursory activity associated with unanticipated eruptions and the detailed study of on going eruptions the data collected will allow us to address two aspects of volcanism volcanic padforms and the atmospheric effects of eruptions a variety of instruments on the two nasa eos platforms together with supplemental data from the japanese and european platforms will enable the study of local to regional scale thermal and deformational features of volcanoes and the chemical and structural features of volcanic eruption plumes and aerosols this investigation fits well within the overall goal of the eos project which is to study the regional and global interrelationships between components of the earth system because it specifically investigates the links between volcanism atmospheric chemistry and short term 1 3 year climate change