spatial and temporal patterns of aeolian activities in the desert belt of northern china revealed by dune chronologies abstract as a part of the inqua project a global digital database and atlas of quaternary dune field and sand seas 337 age records from the desert dunes of china and 20 from mongolian dune fields have been compiled in the database this has opened the possibility of exploring and synthesizing the quaternary environmental changes in the asian mid latitudes dune fields directly from the on site aeolian sand archives this paper assessed the sand dune chronologies in terms of geographical distribution data quality and their implications for late quaternary palaeoenvironmental reconstructions the available ages are concentrated mainly in the last 20 ka and many are from the fields of stabilized dunes in the eastern portion of the desert belt in northern china the number of records and the ratio between the records of stable state and the total records could act as a proxy for the palaeoenvironmental interpretation the aeolian sand activities deciphered from the chronological data in the eastern portion of the desert belt in northern china show a reasonable correlation with the general global climatic curves at the glacial interglacial timescales the limited aeolian sand records from the glacial period however hamper the understanding of the detailed features e g forms and processes of the dune fields during glacial times in the last two millennia however there has not been any meaningful correlation between aeolian dune activity and climatic variation at the centennial time scales probably due to the complexity of the aeolian sand systems and human interventions extending the coverage of dune chronology both temporally and spatially is urgently needed for a full understanding of the environmental changes in the dune fields

controls on alluvial fan long profiles water and debris flows exiting confined valleys have a tendency to deposit sediment on steep fans on alluvial fans where water transport of gravel predominates channel slopes tend to decrease downfan from 0 10 0 04 to 0 01 across wide ranges of climate and tectonism some have argued that this pattern reflects grain size fining downfan such that higher threshold slopes are required just to entrain coarser particles in the waters of the upper fan whereas lower slopes are required to entrain finer grains downfan threshold hypothesis an older hypothesis is that slope is adjusted to transport the supplied sediment load which decreases downfan as deposition occurs transport hypothesis we have begun to test these hypotheses for alluvial fan long profiles using detailed hydraulic and particle size data in sediment transport models on four alluvial fans in the western u s we find that channel hydraulic radiiare largely 0 5 0 9 m at fan heads decreasing to 0 1 0 2 m at distal margins we find that median gravel diameter does not change systematically along the upper 60 80 of active fan channels as slope declines so downstream gravel fining cannot explain most of the observed channel slope reduction however as slope declines channel bed sand cover increases systematically downfan from areal fractions of 20 above fan heads to distal fan values in excess of 70 as a result entrainment thresholds for bed material might decrease systematically downfan leading to lower slopes however current models of this effect alone tend to underpredict downfan slope changes this is likely due to off channel gravel deposition calculations that match observed fan long profiles require an exponential decline in gravel transport rate so that on some fans approximately half of the load must be deposited off channel every 0 20 1 4 km downfan this leads us to hypothesize that some alluvial fan long profiles are statements about the rate of overbank deposition of coarse particles downfan a process for which there is currently no mechanistic theory

is there evidence for global scale forcing of southern hemisphere quaternary desert dune accumulation a quantitative method for testing hypotheses of dune system development luminescence dating of desert dune sediments has generated many hundreds of ages many used in reconstructions of quaternary environmental changes others in attempts to elucidate dune processes environmental and climatic interpretations of these records have proved problematic and it remains challenging to test hypotheses of the systematic response of dunefields to changes in external forcing in the past and to make predictions of the future we use a method that quantifies dune sediment accumulation to interpret dune luminescence age datasets rather than simply using the ages themselves as proxies of change the accumulation intensity method allows periods of dune sediment accumulation here over the timescale 102 105 years to be identified from compilations of dated sand sea stratigraphic sequences we apply this approach to two of the largest dune age datasets from southern africa and australia testing whether or not dunefield accumulation has co varied in the late quaternary and whether systematic relationships to external drivers at global hemispheric regional and local scales can be identified

comment on generation and exhumation of granitoid intrusions in the penjween ophiolite complex nw zagros of the kurdistan region of iraq implications for the geodynamic evolution of the arabia eurasia collision zone by ismail et al 2020 v 376 377 105714

numerical dating of a late quaternary spit shoreline complex at the northern end of silver lake playa mojave desert california a comparison of the applicability of radiocarbon luminescence terrestrial cosmogenic nuclide electron spin resonance u series and amino acid racemization methods a late quaternary spit shoreline complex on the northern shore of pleistocene lake mojave of southeastern california usa was studied with the goal of comparing accelerator mass spectrometry ams radiocarbon luminescence electron spin resonance esr terrestrial cosmogenic radionuclide tcn surface exposure amino acid racemization aar and u series dating methods the pattern of ages obtained by the different methods illustrates the complexity of processes acting in the lakeshore environment and highlights the utility of a multi method approach tcn surface exposure ages mostly 20 30 ka record the initial erosion of shoreline benches whereas radiocarbon ages on shells determined in this and previous studies within the spit supported by aar data record its construction at fluctuating lake levels from 16 to 10 ka luminescence ages on spit sediment 6 7 ka and esr ages on spit shells 4 ka are anomalously young relative to radiocarbon ages of shells within the same deposits the significance of the surprisingly young luminescence ages is not clear the younger esr ages could be a consequence of post mortem enrichment of u in the shells high concentrations of detrital thorium in tufa coating spit gravels inhibited the use of single sample u series dating detailed comparisons such as this provide one of the few means of assessing the accuracy of quaternary dating techniques more such comparisons are needed

magnetostratigraphy of the loess palaeosol key palaeolithic section at korolevo transcarpathia w ukraine abstract a total of 213 oriented samples were taken for palaeomagnetic investigations from 11 m of loess palaeosol sediments cropping out in the korolevo new section w ukraine as the background of our palaeomagnetic investigations we present the results of granulometric chemical content of humus and iron oxides mineralogical heavy minerals and structural analyses of loess and soil deposits the matuyama brunhes boundary was found at a depth of 8 7 m in the upper part of the illuvial horizon of the soil s7 the second well developed soil from the bottom the bottom part of the oldest sediment studied here relict palaeosol of cambisol type was magnetized by the normal polarity geomagnetic field that can be correlated with the top of the jaramillo subchron the oldest cultural chronological assemblages vii and viii from the korolevo site can be dated at the period between the b m boundary 780 ka and the top of the jaramillo subchron 986 ka but this conclusion must be supported by further more extensive palaoemagnetic investigations of the bottom part of quaternary deposits in different places in the korolevo site three zones of the korolevo section containing anomalous directions inside the normal polarity record of the brunhes chron can be interpreted as possible places with destructed record of palaeomagnetic excursions

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

luminescence ages for alluvial fan deposits in southern death valley implications for climate driven sedimentation along a tectonically active mountain front abstract controversy exists over whether alluvial fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause alluvial fan deposits in death valley and throughout the arid southwestern united states have long been the subjects of study but their ages have generally eluded researchers until recently most mapping efforts have recognized at least four major relative age groupings q1 oldest q2 q3 and q4 youngest using observed changes in surface soils and morphology relation to the drainage net and development of desert pavement obtaining numerical age determinations for these morphologic stages has proven challenging we report the first optically stimulated luminescence osl ages for three of these four stages deposited within alluvial fans along the tectonically active black mountains of death valley deposits showing distinct remnant bar and swale topography q3b have osl ages from 7 to 4 ka whereas those with moderate to poorly developed desert pavement and located farther above the active channel q3a have osl ages from 17 to 11 ka geomorphically older deposits with well developed desert pavement q2d have osl ages 25 ka using this osl based chronology we note that alluvial fan deposition along this tectonically active mountain front corresponds to both wet to dry and dry to wet climate changes recorded globally and regionally these findings underscore the influence of climate change on alluvial fan deposition in arid and semi arid regions

thermoluminescence dating of quaternary red sand beds a case study of coastal dunes in sri lanka red sand beds that occupy extensive tracts of coastal humid tropics have conventionally been considered undatable results of a first successful attempt to provide an absolute chronology to these sediments based on thermoluminescence dosimetry are presented along with a discussion on the importance of an understanding of ambient geochemistry in the application of the thermoluminescence technique the results on the sri lankan coastal region indicate that the sea level in the region may have been affected by regional tectonics during the past 70 000 years based on in situ finds of geometric microliths in the red sands a date of ca 25 000 years is ascribed to them suggesting them to be substantially older than believed so far

numerical analysis of laterally loaded 3 3 to 7 3 pile groups in sands the coupled bridge foundation superstructure finite element code flpier was employed to predict the lateral response of the single piles and 3 3 to 7 3 pile groups founded in both loose and medium dense sands the p multiplier factors suggested by mcvay et al for laterally loaded pile groups with multiple pile rows were implemented for the predictions the soil parameters were obtained through a back analysis procedure based on single pile test results the latter as well as the numerical predictions of both the single and group tests are presented it was found that the numerical code flpier did an excellent job of predicting the response of both the single piles and the 3 3 to 7 3 pile groups the latter involved the predictions of lateral load versus lateral deflection of the group the shears and bending moments developed in the individual piles and the distributions of the lateral loads in each pile row which were all in good agreement with the measured results

limitations of infra red stimulated luminescence in dating high arctic marine sediments abstract the accuracy of infra red stimulated luminescence irsl dating was evaluated for modern late glacial 11 to 13 ka and older 70 10 ka and 125 10 ka nearshore marine sediments from west spitsbergen despite the increased sensitivity of the irsl signal to solar reduction compared with thermoluminescence the irsl signal of these sediments was not totally reset resulting in overestimates of a few 1000 to 10 000 years subtraction of residuals determined after 10 or 60 minutes of filtered light exposure wavelengths

thermoluminescence dating studies of glacial silts from ontario to develop procedures for the direct dating of glacially related silts by thermoluminescence tl i have applied previously proposed techniques to three polymineralic 4 11 m samples from the toronto area furthermore one of these samples was studied in detail by isolating some mineral fractions the principal conclusion is that the tl of the lodgment halton till from woodbridge was not significantly reset during deposition whereas the tl of the waterlaid upper thorncliffe silt from the scarborough bluffs was reset as was the tl of the third sample wc st a massive silt from woodbridge that has been generally correlated with the glaciolacustrine sunnybrook diamict at the bluffs this conclusion follows from the observation of feldspar tl apparent ages of 140 ka for the 12 ka bp halton till and of 36 and 66 ka for the upper thorncliffe and wc st samples respectively the four laboratory factors that contributed most to inaccuracies in the tl apparent ages were 1 anomalous fading in the felds

late quaternary linear dune accumulation and chronostratigraphy of the southwestern kalahari implications for aeolian palaeoclimatic reconstructions and predictions of future dynamics abstract the linear dunes of the kalahari now largely inactive have long been identified as having potential palaeoenvironmental significance the application of optically stimulated luminescence osl dating to these dunes in the 1990s provided the first chronology of aeolian accumulation in this region though field methodologies and time consuming multiple aliquot laboratory protocols limited both the depth of sampling in dune bodies and the total number of samples dated in order to permit a more thorough investigation of the potential of these dunes to preserve long chronological records this intensive study presents 71 osl ages from the linear dunes of the southwestern kalahari at witpan south africa sampled with coring equipment at regular and frequent intervals down to bedrock the earliest sand accumulation recorded at witpan is at 104 ka and in spatially discrete locations other evidence of dune activity is recorded at 77 76 57 52 and 35 27 ka although an inherently discontinuous archive the linear dunes of the southwestern kalahari have the potential to record multiple phases of dune construction following the last glacial maximum there is near continuous evidence of dune building with a peak of accumulation recorded from 15 to 9 ka at five individual sites this latter period is generally recognised from other proxy evidence as being unusually arid in this region and such periods of dune activity are likely to be related to intensification of the continental anticyclone during the holocene accumulation has continued at most sites sampled albeit at a lesser intensity this may imply that these dunes are presently not far from thresholds of activation

thermoluminescence age determinations for the mungo iii human burial lake mungo southeastern australia abstract thermoluminescence dating work was carried out on quartz from unburnt sediment associated with the mungo iii human burial site in southeastern australia using selective bleach and total bleach methods a comparison of the techniques showed that in some cases incomplete removal of the thermoluminescence tl signal used for dating sediments had occurred and in these cases selective bleach was the more reliable of the two methods the selective bleach results indicate the age of the burial to be older than 24 6 2 4 ka and younger than 43 3 3 8 ka while the total bleach results give ages for the burial between 34 0 3 9 ka and 43 1 6 7 ka the ages place the mungo iii human remains with the same population or older than the previously discovered human remains of mungo i

thermoluminescence and new 14c age estimates for late quaternary loesses in southwestern nebraska abstract loess of late quaternary age mantles most of nebraska south of the platte river valley at least five late quaternary loesses are recognized from oldest to youngest one or more undifferentiated pre illinoian loesses the loveland loess the gilman canyon loess which exhibits a well developed soil and rests unconformably on the sangamon soil the peoria loess capped by the brady soil and the bignell loess which is distributed discontinuously previous research shows that the loveland loess is illinoian the gilman canyon loess and peoria loess are wisconsin and the bignell loess is holocene we present here the first thermoluminescence tl age estimates and new 14 c ages for these late quaternary loesses at two key sections in southwestern nebraska the eustis ash pit and the bignell hill road cut tl age estimates from all samples collected from eustis ash pit and bignell hill were internally consistent tl and 14 c age estimates from these two sections generally agree and support previous age determinations the tl age estimate on loveland loess indicates deposition at 163 ka tl and radiocarbon age estimates indicate that gilman canyon loess believed to be deposited during the farmdale interstade first began to accumulate at about 40 ka the lower part of the gilman canyon loess is 36 ka at eustis and the middle of the unit is 30 ka at bignell hill the lower and upper parts of the peoria loess give age estimates of 24 ka and 17 ka respectively tl age estimates for deposition of the bignell loess are 9 ka near the base in agreement with radiocarbon age estimates and 6 ka immediately below the modern soil substantiating its holocene age comparisons of tl age estimates with 18 o and insolation curves which show loess deposition during interglacial and interstadial as well as glacial periods indicate that loess deposition on the great plains can occur under a variety of climatic conditions

challenges involved in obtaining luminescence ages for long records of aridity examples from the arabian peninsula abstract in the last 35 years luminescence dating has provided a large database of ages for the deposition of dunes in desert environments over 380 ages have been generated for dunes from the arabian peninsula and demonstrate episodic dune deposition in the late quaternary but give a less clear pattern prior to 50 ka interpreting databases of luminescence ages faces two issues first the precision of luminescence ages in the last 50 ka is between 5 and 10 but for older ages the uncertainties may be much larger as luminescence signals reach saturation second different luminescence signals from quartz and from feldspar have been used over the last 35 years as the method has developed and expanded these different signals have different saturation limits and different rates at which they are reset by exposure to daylight at deposition approaches which focus on the most light sensitive signals e g quartz osl are better suited to dating recent events while those which show growth of the luminescence signal over the largest dose range e g the thermally transferred osl tt osl signal from quartz and the post infrared infrared stimulated luminescence pir irsl from feldspars have the potential to date much older events

the stranded beach dune sequence of south east south australia a test of thermoluminescence dating 0 800 ka the remarkable sequence of stranded beach dunes in south east south australia deposited during the past 800 ka has provided us with a rare set of samples for testing thermoluminescence sediment dating methods here we report thermoluminescence ages obtained from quartz separated from the dunes and compare them with accepted ages for the high sea levels responsible for the dunes the independent ages of the dunes were obtained from earlier work by schwebel which has been extended and refined by modelling the dune formation using sea level variations derived from the oceanic 18o record the work is unusual in extending thermoluminescence dating to an 800 ka sequence with modest geological control of the age the agreement between thermoluminescence and geological ages is satisfactory for eight dunes with ages in the range 120 800 ka quartz is not usually thought to be useful for thermoluminescence dating in this time span two factors contribute to our success the first is that the dose rates are low about 0 5 gy ka 1 or one quarter of that typical of sediments the second is that the thermoluminescence vs dose response continues to rise monotonically above the saturation region at doses above 300 gy

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

earthquake geology of the bulnay fault mongolia the bulnay earthquake of 23 july 1905 mw 8 3 8 5 in north central mongolia is one of the world s largest recorded intracontinental earthquakes and one of four great earthquakes that occurred in the region during the twentieth century the 375 km long surface rupture of the left lateral strike slip n095 e trending bulnay fault associated with this earthquake is remarkable for its pronounced expression across the landscape and for the size of features produced by previous earthquakes our field observations suggest that in many areas the width and geometry of the rupture zone is the result of repeated earthquakes however in those areas where it is possible to determine that the geomorphic features are the result of the 1905 surface rupture alone the size of the features produced by this single earthquake are singular in comparison to most other historical strike slip surface ruptures worldwide along the 80 km stretch between 97 18 e and 98 33 e the fault zone is characterized by several meters width and the mean left lateral 1905 offset is 8 9 0 6 m with two measured cumulative offsets that are twice the 1905 slip these observations suggest that the displacement produced during the penultimate event was similar to the 1905 slip morphotectonic analyses carried out at three sites along the eastern part of the bulnay fault allow us to estimate a mean horizontal slip rate of 3 1 1 7 mm yr over the late pleistocene holocene period in parallel paleoseismological investigations show evidence for two earthquakes prior to the 1905 event with recurrence intervals of 2700 4000 yrs

paleoearthquakes and eolian dominated fault sedimentation along the hubbell spring fault zone near albuquerque new mexico the hubbell spring fault zone forms the modern eastern margin of the rio grande rift in the albuquerque basin of north central new mexico knowledge of its seismic potential is important because the fault zone transects kirtland air force base sandia national laboratories and underlies the southern albuquerque metropolitan area no earthquakes larger than m l 5 5 have been reported in the last 150 years in this region so we excavated the first trench across this fault zone to determine its late quaternary paleoseismic history our trench excavations revealed a complex 16 m wide fault zone overlain by four tapered blankets of mixed eolian sand and minor colluvium that we infer were deposited after four large magnitude surface rupturing earthquakes although the first oldest rupture event is undated we used luminescence thermoluminescence and infrared stimulated luminescence ages to determine that the subsequent three rupture events occurred about 56 6 29 3 and 12 1 ka these ages yield recurrence intervals of 27 and 17 k y between events and an elapsed time of 12 k y since the latest surface rupturing paleoearthquake slip rates are not well constrained but our preferred average slip rate since rupture event 2 post 56 ka is 0 05 mm yr and interval slip rates between the last three events are 0 06 and 0 09 mm yr respectively vertical displacements of 1 2 m per event and probable rupture lengths of 34 43 km indicate probable paleoearthquake magnitudes m s or m w of 6 8 7 1 future earthquakes of this size likely would cause strong ground motions in the albuquerque metropolitan area

single grain optical dating of grave infill associated with human burials at lake mungo australia abstract recent age constraints on australia s oldest human remains mungo i and iii found at lake mungo in western new south wales relied on optical dating of sands from the same stratigraphic units as those into which the remains had been inserted 42 3 ka and those that overlay the graves 38 2 ka giving a burial age of 40 2 ka this indirect means of dating the burials was necessary because the original site from which the remains had been excavated had been completely eroded away at the time of the original excavation of the mungo iii grave blocks of sediment from the grave infill were collected for sediment fabric analysis these sediment blocks were impregnated with polyester resin sectioned for analysis and the remaining resin impregnated sediment blocks were then stored in a cupboard where they have lain for the last 30 years here we report on optical dating of single grains of quartz extracted from one of these sediment blocks grains extracted from the centre of the block show a wide distribution of equivalent doses 0 0 0 3 to 43 7 8 3 gy indicating that not all of the grains have remained hidden from light light safe following excavation we show that the population of grains with the maximum equivalent dose produces an age consistent with that of the previous study indicating that some of the grains have remained light safe we also use linearly modulated optically stimulated luminescence to identify light safe grains these yield an age of 41 4 ka which represents a direct optical age for the grave infill and which is consistent with the age obtained in the previous study for sands from the same stratigraphic unit as that containing the burial the results reported here demonstrate the potential of applying optical dating to archived sediment samples that have not been stored in a light safe environment

palaeoclimatic evidence from sand seas abstract sand seas can be an important source of information on the quaternary history of many deserts because sand seas appear to react sensitivity to climatic changes the quality of palaeoenvironmental information obtained from them is frequently much better than that from adjacent rocky desert areas patterns of dune alignments may be used to reconstruct the wind directions that formed currently inactive or fixed dunes and thus can provide information on palaeocirculation patterns the climatic conditions under which these dunes formed can be examined using palaeoclimatic models to explore the combinations of wind velocity rainfall and evaporation rates required to reactivate them choice of appropriate values for these parameters may be hampered by the problems of dating episodes of dune activity in many sand seas the best palaeoclimatic information comes from studies of interdune lacustrine or playa deposits which may reflect increased local rainfall or higher groundwater discharge or greater penetration of the sand sea by rivers with headwaters outside the desert caution should be taken in the interpretation of such deposits for juxtaposition of aquatic and aeolian environments can occur even in modern hyperarid and seas the record of climatic changes preserved in the deposits of modern sand seas suggests that periods of dune formation may have been interrupted by long periods of stability which may also have included deposition of interdune lacustrine deposits for example within the past 40 000 years active dune formation in many sand seas appears to have been restricted to the interval between about 20 000 and 12 000 yr b p and to the late holocene approximately 1 4 to 1 3 rd of the time

loess paleosol sequence at korshiv ukraine chronology based on complementary and parallel dating tl osl and litho pedosedimentary analyses abstract the paper concerns the issues of age as well as lithological and pedological development of the loess paleosol sequence available for direct research at the korshiv site in the volhynian upland west ukraine for dozens of identical samples a series of comparative laboratory tl dating gdansk lublin and osl dating gliwice was performed supplemented by the physicochemical and micromorphological analyses due to the different dating techniques used in individual laboratories the details of their methodology were also presented the resulting series of dates confirmed the lithological and pedostratigraphic diagnosis of the sediments during the last two loess forming cycles additionally the age of the loess layer at the base of the available sequence was established it was defined as loess l5 and correlated with mis 12 the resulting age of the mineral substrate in different laboratories shows considerable similarity upper sequence but also clear differences lower part the osl dates were younger than the tl dates two high rank fossil soil complexes investigated in the profile represent mis 7 and 5 for the eemian early weichselian pedocomplex s1 the tripartite structure of the younger paleosol represents early weichselian glaciation mis 5 4 5 1 the dates helped to conclude that there is a possibility of stratigraphic separateness of the dubno soil mis 3 the whole youngest sedimentary sequence is dated from 20 to 14 ka and correlates well with the period when the last glacial ice sheet advanced during its main stadial in poland

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

limitations of thermoluminescence to date waterlain sediments from glaciated fiord environments of western spitsbergen svalbard abstract a fundamental problem in the tl dating of waterlain sediments particularly in the arctic is the accurate determination of the level of solar resetting prior to deposition this study determined the effect of wavelength on the solar resetting of the tl signal and concomitant effects on the accuracy of tl age estimates for late glacial and modern glacial and nearshore marine sediments from fiords on spitsbergen the reduction in tl level decreases with filtering of wavelengths above 400 nm modern and late weichselian tills have tl levels at saturation probably received no light exposure prior to deposition and thus cannot be dated by tl glacial marine sediments deposited within 0 5 km of a glacier terminus yielded tl age estimates 10 times the known age presumably because these sediments received limited light exposure prior to deposition modern sublittoral sediments and fiord muds yielded tl apparent ages between

stable isotopic composition of pedogenic carbonates from the eastern margin of the thar desert rajasthan india pedogenic carbonates in a 19 m thick dune section 16r at didwana and several shorter profiles from the eastern margin of the thar desert rajasthan were studied for their stable isotope composition carbon isotope results show the c4 biomass grasses has dominated local vegetation for most of the 250 000 years represented by the 16r section our results display a decrease in 18o and 13c values during the last interglacial and early glacial periods the higher 13c values in our dune records correlate to episodes in the strong upwelling and decreased sedimentation rates in indian ocean cores probably the result of a strong asian monsoon the high 13c values may therefore denote the expansion of c4 vegetation in response to warm wetter monsoon circulation conversely low 18o and 13c values mark the expansion of c3 vegetation probably caused by enhanced winter rains and lower temperatures

late quaternary chronology of major dune ridge development in the northeast rub al khali united arab emirates the northeastern sector of the rub al khali desert in the eastern united arab emirates uae is dominated by large ne sw trending dune ridges orientated perpendicular to the currently prevailing northwesterly wind regime in this study extensive use has been made of artificially exposed sections through these major dune ridges that reveal internal sedimentary structures and allow an intensive high resolution sampling programme to be carried out here we present the optical dating results for samples from 7 sections the results indicate that dune activity and preservation occurred within the periods 7 3 ka 16 10 ka and 22 20 ka with evidence of earlier preservation during marine oxygen isotope stages mis 3 and 5 with net accumulation rates in the range 2 2 25 m ka 1 in several instances hiatuses in the preserved record of dune accumulation coincide with stratigraphic bounding surfaces visible in the exposed section profiles with associated truncation of internal sedimentary structures caution must be exercised when interpreting such gaps in the recorded accumulation chronologies of these dunes since these may simply constitute phases of low preservation potential rather than phases of low aeolian activity other factors such as sediment supply and availability in relation to sea level dynamics may be significant and are also considered

thermoluminescence dating study of quartz in aeolian sediments from southeastern australia abstract using 90 125 m grains of quartz extracted from sediments the equivalent dose absorbed since burial was derived by exposing aliquots of quartz to a sunlamp regenerating the tl growth curve by artificial irradiation and comparing the natural tl of the sample being dated as well as that of an adjacent surface sample to this curve the age can then be calculated once the dose rate is known the method is tested successfully on known age aeolian sediments retaining their original bedding but reveals some difficulties in trying to use tl to date aeolian sediments for which the original bedding has been destroyed anomalous fading of tl in quartz is reported this latter difficulty was circumvented by using a delay of several weeks between the irradiation and heating of the quartz

thermoluminescence and excess 226ra decay dating of late quaternary fluvial sands east alligator river australia thermoluminescence tl dating was applied to seven samples of siliceous fluvial sands from the east alligator river of northern australia giving ages ranging from modern to 6000 yr b p two methods of estimating the equivalent dose ed total bleach and regenerative were applied to the 90 to 125 m quartz fraction of the samples in order to determine the reliability and internal consistency of the technique high resolution and spectroscopy were used to measure radionuclide contents these measurements revealed an excess 226ra activity compared with 230th this excess decreased with depth and was used directly to derive mean sedimentation rates and thus sediment ages both this method and one 14c date confirmed the validity of the tl values which increased systematically with depth and were consistent with site stratigraphy tl was of limited use in the dating of these late holocene deposits because of age uncertainties of 500 to 1600 yr resulting from a significant residual ed this residual probably resulted from incomplete bleaching during reworking upstream of the sampling site for pleistocene deposits the residual ed will be less significant because of higher total eds and tl dates will be correspondingly more accurate

luminescence chronology of the northeastern bulgarian loess paleosol sequences viatovo and kaolinovo abstract the key reference loess sequence of viatovo in ne bulgaria lying within the lower danube basin records climatic and environmental changes over the last 800 ka this 20 m thick loess sequence consists of seven loess units l1 to l7 intercalated by six paleosols s1 to s6 below the modern soil s0 the matuyama brunhes palaeomagnetic boundary has been identified in the lowest loess unit l7 this reference loess sequence remains so far undated by radiometric techniques its chronostratigraphy relies only on pedostratigraphic and magnetostratigraphic evidence this contrasts with the adjacent reference loess sequences of se romania tuzla mostistea mircea vod whose luminescence chronology is now securely established up to mis 8 the aim of this study is to validate the chronostratigraphic framework of the viatovo loess sequence using the luminescence dating method for this purpose the luminescence method is applied to the three upper loess units l1 l2 l3 from two adjacent sites the reference site of viatovo and the nearby site of kaolinovo both located in the ludogorie region ne bulgaria and showing the same superposition of loess l1 to l7 and interbedded paleosols luminescence dating infrared stimulated luminescence irsl was carried out using the feldspar fine sand size grain fraction 60 80 m applying the irsl50 and the pirir290 dating techniques for the equivalent dose de determination we used both the sar post infrared infrared pirir290 protocol on single aliquots and the multiple aliquot additive dose maad irsl50 protocol the pirir290 ages and the fading corrected maad irsl50 ages are self consistent it demonstrates for the first time that the three upper loess layers l1 l2 l3 at viatovo and kaolinovo were deposited during the marine isotope stages mis 2 4 6 and 8 thus constraining the youngest well developed paleosol s1 a chernozem to the last interglacial these irsl50 and pirir290 ages are in good agreement with the luminescence ages obtained for 1 the two upper loess layers l1 l2 from the harletz sequence in nw bulgaria and 2 the three upper loess units l1 l2 l3 from the adjacent se romanian loess sequences the luminescence chronology of the loess sequences is presented along with the pedogenic and magnetic property data the pedostratigraphic records of the ne bulgarian and se romanian loess sequences show the same palaeoclimatic trends with progressive aridification during interglacial periods from s6 to s0

th u ratios in metamorphic zircon this is the peer reviewed version of the following article yakymchuk c kirkland c l clark c 2018 th u ratios in metamorphic zircon journal of metamorphic geology which has been published in final form at https doi org 10 1111 jmg 12307 this article may be used for non commercial purposes in accordance with wiley terms and conditions for self archiving

lateral load behavior of full scale pile group in clay a static lateral load test was performed on a full scale pile group to determine the resulting pile soil pile interaction effects the 3 3 pile group at three diameter spacing was driven into a profile consisting of soft to medium stiff clays and silts underlain by sand the piles were instrumented with inclinometers and strain gages the load carried by each pile was measured a single pile test was conducted for comparison the pile group deflected over two times more than the single pile under the same average load group effects significantly reduced load capacity for all rows relative to single pile behavior trailing rows carried less than the leading row and middle row piles carried the lowest loads maximum moments in the group piles were 50 100 higher than in the single pile p multipliers were 0 6 0 38 and 0 43 for the front middle and back row piles respectively good agreement between the measured and computed pile group responses was obtained using the p multiplier approach design c

evolution of the nw zagros fold and thrust belt in kurdistan region of iraq from balanced and restored crustal scale sections and forward modeling abstract we present the first regional balanced and restored sections across the northwestern part of the zagros fold and thrust belt in kurdistan region of iraq and a 2d kinematic model that illustrates the evolution of the belt since late cretaceous time the balanced cross section based on surface and sub surface data is characterized by multi detachment folds detached above a lower triassic basal ductile level with intermediate detachment levels that induced internal complexities like accommodation thrusting and or disharmonic folding our work suggests that the two main structural steps in the detachment level in the high folded zone may be related to low angle thrusts rooted at the brittle ductile transition growth strata of late cretaceous and paleocene times have been recognized for the first time in the kurdistan fold and thrust belt this allows us to constrain timing of deformation and to estimate the evolution of the shortening and the advance of the deformation front since late cretaceous deformation of the zagros belt is characterized by a combination of thin and thick skinned tectonics that reactivated the late cretaceous paleogene obduction belt

optical dating of holocene dune sands in the ferris dune field wyoming abstract optical dating of late quaternary quartz dune sands from the clear creek portion of ferris dune field wyoming demonstrates the considerable potential of the technique as a chronostratigraphic tool a sequence of radiocarbon dated holocene interdune strata permit optical dating of the intercalated dune sand to be tested the concordance is good the optical dates for the aeolian deposits not datable by radiocarbon suggest that aeolian sedimentation at clear creek peaked during two relatively short phases at ca 8500 and 4000 yr b p the dates indicate that aeolian accumulation maxima at least in the clear creek area may not be synchronous with previously defined phases of marked aridity

the potential of using thermoluminescence to date buried soils developed on colluvial and fluvial sediments from utah and colorado u s a preliminary results the natural tl intensity for surface and buried holocene and pleistocene a horizons developed on flood plain silts near denver colorado exponentially decreases with time this signal is approaching saturation by ca 130 ka the a horizon of the modern flood plain soil is not fully light bleached the tl properties and age estimates are presented for radiocarbon dated eolian enriched buried a horizons developed on fault derived colluvium from the american fork segment of the wasatch fault zone utah dating of these buried soils provide a close age estimate on paleoearthquake events mean tl age estimates by regeneration and total bleach techniques for buried a horizons are 0 5 0 1 ka and 2 7 0 4 ka which are in agreement with corresponding radiocarbon dates of 980 70 years bp and 2620 70 years bp a surface sag pond mud formed within an antithetic grabben is well light bleached and yielded a tl age estimate by the total bleach method of 240 60 years bp in agreement with its known age of 300 years bp this study indicates that relatively brief periods of pedogenesis are not sufficient to light bleach sediment and that eolian additions enhance the reduction of tl in soils

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

thermoluminescence dating of the holsteinian marine formation of herzeele northern france thermoluminescence dating of potassium feldspar coarse grains from the fossiliferous holsteinian marine formation of herzeele at the southern limit of the north sea basin yields a minimum age of 228 30 ka a tentative correction for the long term fading of the tl signal in potassium feldspar is proposed assuming a lifetime of 711 ka this correction would yield a preliminary age estimate of 271 36 ka these results support a minimum oxygen isotope stage 7 age but do not preclude at this stage of our research a possible correlation with late oxygen isotope stage 9 these results are in agreement within the error of the method with independent absolute dates u th and esr obtained on in situ marine shells which range from 225 ka to 348 ka this study provides evidence of the reliability of tl age estimates on potassium feldspar coarse grains from shallow marine sediments older than the last interglacial

geochemistry and ar ar muscovite ages of the daraban leucogranite mawat ophiolite northeastern iraq implications for arabia eurasia continental collision abstract daraban leucogranite dykes intruded discordantly into the basal serpentinized harzburgite of the mawat ophiolite kurdistan region ne iraq these coarse grained muscovite tourmaline leucogranites are the first leucogranite dykes identified within the mawat ophiolite they are mainly composed of quartz k feldspar plagioclase tourmaline muscovite and secondary phologopite while zircon xenotime corundum mangano ilemnite and cassiterite occur as accessories the a cnk value of the granite dyke samples varies from 1 10 to 1 22 indicating a strongly peraluminous composition cao na2o ranges from 0 11 to 0 15 and al2o3 tio2 from 264 to 463 similar to the strongly peraluminous sp granites exposed in high pressure collision zones such as the himalayas ar ar muscovite step heating dating yields 37 57 0 25 and 38 02 0 53 ma plateau ages for two samples which are thought to reflect either their magmatic emplacement or resetting during collision related metamorphism mineral chemistry shows evidence of both primary and secondary types of muscovite with cores favouring the magmatic interpretation and slight effects of a late syn serpentinization fluid seen at the rims geochemical features of daraban leucogranite dykes favour a syn collisional tectonic setting they probably formed in response to the continental collision between eurasia and arabia during the initial stage of the opening of the gulf of aden at 37 ma the muscovite ages and geochemical features of daraban leucogranite are strong evidence for the timing of the continental collision between northeastern arabia and eurasia in kurdistan region of iraq

extending the geochronometry of arctic lake cores beyond the radiocarbon limit by using thermoluminescence reconstructing detailed paleoclimatic paleoenvironmental histories from pleistocene sediments in the arctic is an ongoing challenge because of the difficulty of measuring accurate timescales beyond the range of radiocarbon 14c dating important archives of such histories are arctic lakes that exist outside the known extent of the last major glaciations to develop reliable geochronometry of sediment cores from arctic and other lakes we applied thermoluminescence tl sediment dating methods to 24 samples 8 reported earlier but some reanalyzed here selected from cores from squirrel and joe lakes in northwestern alaska a sequence of 23 14c ages from the upper parts of these cores permitted tests of the zeroing assumption of tl dating that all fine silt grains were exposed to daylight before final burial we performed multiple tl tests on most samples to isolate stable tl signals and measured tl emissions spectra to help characterize samples tl ages generally agree with the 30 kyr age depth trend derived from 14c dating and extend the timescale apparently to 180 ka for squirrel lake and to at least 60 ka for joe lake an anomalously old tl result from squirrel lake is attributed to failure of the tl zeroing assumption within that sediment horizon in the lower joe lake core we assign a timing of 45 ka to 50 ka for the beginning of an apparently climatic warming interval these results identify and quantify the main tl sources of tl age inaccuracy and the preferred tl protocols for accurate tl sediment dating in northern high latitude lake deposits they also provide the first direct chronology beyond the 14c dating range for these lakes

late pleistocene lake level history of lake mungo australia abstract lake mungo is a currently dry lake basin in the semi arid zone of southeastern australia the transverse dune system on the downwind side contains a record of human occupation of international importance it also contains one of the most continuous records of climate change over the last glacial cycle in the australia desert in this paper we provide a framework for the interpretation of lake level history from before the arrival of people 41 ka until after the establishment of the pastoral industry in the area we present 83 optically stimulated luminescence ages from the lake mungo lunette the lake level history is reconstructed from 34 stratigraphic sections along three transects through the lunette the dating reveals considerable lake level fluctuations through time which occur over a depth range of 10 m in the basin at its height probably at multiple times before 20 ka the lake held more than 1 km3 of water and at its final level at 19 ka contained only 0 03 km3 the inception of lake mungo appears to have taken place during the mid pleistocene between 256 and 369 ka during the last glacial cycle lake mungo was almost continuously wetter than present from shortly after 60 ka until 19 ka the upper mungo arumpo and zanci units represent a succession of lake filling and drying events briefly interspersed by soils the final zanci unit does not represent a single high lake phase but an initial lake filling followed by a series of short lived lake level events within a brief period of a few thousand years at the conclusion of this event the lake remained dry until the present day four osl ages from a linear dune upwind of lake mungo indicates regional aeolian activity from 30 ka until present widespread erosion that produces the characteristic topography of the lunette began after the arrival of british pastoralists and traditional aboriginal ways of life overlapped briefly with this erosion the presence of water in lake mungo closely corresponds to periods when regional surface temperature was colder than present during the late pleistocene our new data supports a model that decreased evaporation and increased runoff were primarily responsible for increased availability of surface water in the hydrological cycle

depositional history and archaeology of the central lake mungo lunette willandra lakes southeast australia abstract lake mungo presently a dry lake in the semi arid zone of southeastern australia preserves a unique record of human settlement and past environmental change within the transverse lunette that built up on its downwind margin the lunette is 30 km long and the variable morphology along its length suggests spatial variability in deposition over time consequently this presents differential potential for the preservation of past activity traces of different ages along the lunette earlier work at lake mungo focused primarily on the southern section of the lunette where two ritual burials of considerable antiquity were found here we describe the depositional history of the central section of the lake mungo lunette together with the first single grain optically stimulated luminescence osl chronology of the full stratigraphic sequence and of three hearths we thereby lay the foundation for systematic investigation of the distribution of archaeological traces through the sedimentary record the older depositional units lower and upper mungo were deposited ca 50 40 ka and 34 ka respectively and are substantially thinner in the central section of the lunette compared with the south by contrast the overlying unit of interbedded sands and clayey sands arumpo zanci units deposited ca 25 14 ka is markedly thicker and dominates the stratigraphic sequence in the central portion of the lunette although the sequence broadly reflects previous models of the lunette s depositional history and changing hydrological conditions our results indicate spatially variable deposition of sediments possibly as a result of changes in prevailing wind regimes archaeological traces are exposed in all stratigraphic units deposited after ca 50 ka including sediments deposited after the final lake drying ca 15 ka indicating human occupation of the area under a range of palaeoenvironmental conditions dating and stratigraphical examination of individual hearth features demonstrates that even within individual stratigraphic units human occupation persisted under variable conditions mid holocene occupation of the area following the final lake retreat took place during a period of relatively humid climate

luminescence dating using feldspars a test case from southern north island new zealand abstract luminescence dating using coarse grain potassium rich feldspars is applied to a suite of 12 dune sands collected from southern north island new zealand the expected ages of the samples range from modern to 350 ka luminescence ages were calculated using thermoluminescence and infra red stimulated luminescence measurements to determine total bleach and regeneration equivalent doses for each sample no systematic difference was observed between any of these different methods withstanding the uncertainties in the independent ages of some samples comparison of the luminescence ages with those suggested by the independent age control suggests that reliable luminescence ages can be obtained for samples younger than 130 ka luminescence ages for older samples appear to underestimate the true age and it is suggested that this may be due to long term fading of the luminescence signal as suggested by mejdahl 1989