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Arnold, L. J., Roberts, R. G., MacPhee, R. D. E., Haile, J. S., Brock, F., Möller, P., Froese, D. G., Tikhonov, A. N., Chivas, A. R., Gilbert, M. T. P. & Willerslev, E. 2010: Paper II - Dirt, dates and DNA: OSL and radiocarbon chronologies of perennially frozen sediments in Siberia, and their implications for sedimentary ancient DNA studies. Boreas, Vol. 40, pp. 417-445. 10.1111/j.1502-3885.2010.00181.x. ISSN 0300-9483 The sedimentary ancient DNA ( sedaDNA) technique offers a potentially invaluable means of investigating species evolution and extinction dynamics in high-latitude environments. An implicit assumption of the sedaDNA approach is that the extracted DNA is autochthonous with the host deposit and that it has not been physically transported from older source deposits or reworked within the sedimentary profile by postdepositional mixing. In this paper we investigate whether these fundamental conditions are upheld at seven perennially frozen wetland sites across the Taimyr Peninsula and coastal lowlands of north-central Siberia. Optically stimulated luminescence (OSL) and radiocarbon (C) dating are used to constrain the ages of both the inorganic and organic fractions of perennially frozen deposits from which sedaDNA of extinct and extant species have been recovered. OSL and C age/depth profiles, as well as single-grain equivalent dose (D) distribution characteristics, are used to assess the stratigraphic integrity of these sedaDNA sequences by (i) identifying the presence of primary or reworked organic and inorganic material, and (ii) examining the types of depositional and postdepositional processes that have affected specific sedimentary facies. The results of this study demonstrate that even though DNA preservation and stratigraphic integrity are commonly superior in perennially frozen settings, this does not, in itself, guarantee the suitability of the sedaDNA approach. The combined OSL and C chronologies reveal that certain perennially frozen sites may be poorly suited for sedaDNA analysis, and that careful site selection is paramount to ensuring the accuracy of any sedaDNA study - particularly for 'latest appearance date' estimates of extinct taxa. [ABSTRACT FROM AUTHOR]

Arnold, L. J. & Roberts, R. G. 2011: Paper I - Optically stimulated luminescence (OSL) dating of perennially frozen deposits in north−central Siberia: OSL characteristics of quartz grains and methodological considerations regarding their suitability for dating. Boreas, Vol. 40, pp. 389-416. 10.1111/j.1502-3885.2011.00209.x. ISSN 0300−9483. Optically stimulated luminescence (OSL) dating of coarse-grained quartz is increasingly being used as the main chronological tool in late Quaternary palaeoenvironmental reconstructions of Siberia. However, relatively little information has been published on the suitability of OSL dating for the various types of perennially frozen sediments found in this region. Here we provide a systematic examination of the quartz luminescence characteristics of 21 perennially frozen samples from the Taimyr Peninsula and adjacent coastal lowlands of north-central Siberia, and discuss their implications for the reliability of single-grain and multi-grain OSL chronologies in such contexts. The results of this study suggest that the quartz luminescence characteristics of these samples are, in principle, favourable for OSL dating but, in practice, require that a series of validation checks are made of the chosen experimental conditions. If these tests are satisfied, then reliable OSL chronologies should be obtained for sedimentary deposits in this region. Importantly, however, the single-grain and multi-grain aliquot equivalent dose (D) distribution characteristics for our samples reveal that there are advantages in targeting certain types of depositional settings for OSL dating studies of Siberian sediments. We also show that samples from the same depositional settings, and even from the same sites, do not necessarily display similar D distribution characteristics. The latter complication favours the use of single-grain analysis to unravel the bleaching and burial histories of young (mid- to late Holocene) sediments in these Arctic environments. [ABSTRACT FROM AUTHOR]

This paper presents a study of past coastline dynamics and their consequences for prehistoric societies living in the glacio‐isostatically uplifted central Limfjord area, northern Denmark. The consequences of the gradual relative sea level (RSL) changes have been investigated to develop a local RSL curve, study settlement patterns on newly exposed marine foreland, and estimate changes in the area and quality of grazing and forage for livestock. This was achieved by a multidisciplinary approach involving existing regional and local beach ridges dated by optically stimulated luminescence, a comprehensive database of archaeological finds, and extrapolation based on a digital elevation model. The beach‐ridge dates suggested a near‐linear local RSL change in the study area of ~1.2±0.2 m per 1000 years for the last 3000 years. Based on this, a palaeo‐coastline development model was produced that correlated well with a comprehensive database of archaeological finds. The model indicates that (i) few human settlements moved to the newly exposed marine foreland prior to modern times, though clusters of burial mounds (barrows) suggest that some of the new lands were colonized during the Late Roman Iron Age until 400 CE, (ii) winter‐flooded marine foreland with high‐quality livestock grazing increased steadily until c. 750 CE and then remained stable at approximately 150 km2, and (iii) due to high salinity of the inundating water, the palaeo‐Limfjord probably had Wadden Sea‐like fertile saltmarshes until c. 1 CE. The improved chronologies yield a better understanding of the spatial and temporal prehistoric human–nature interactions in the study area. The findings highlight the need for accurate local RSL curves in order to interpret concomitant terrestrial environment drivers and trajectories, and thereby understand causal relationships and consequences for prehistoric human–environment interactions in coastal areas. [ABSTRACT FROM AUTHOR]

This paper reports an investigation into palaeoflooding along the upper reaches of the Hanjiang River valley, China. Based on the sedimentary evidence of the palaeohydrological regime, two bedsets of palaeoflood slackwater deposits (SWDs) were identified interbedded within the Holocene loess-soil sequence along the riverbanks of the Ankang east reach. Optical Stimulated Luminescence (OSL) dating and stratigraphical correlation with previously dated sites were used to reconstruct the chronology of the palaeoflood events. The results show that the palaeoflood events represented by SWD1 occurred between 13 000 and 12 400 a, coincident with the climatic transition from the Bølling-Allerød (BL+AL) stage to the Younger Dryas (YD) event. The palaeoflood events recorded by SWD2 were dated to 1000-800 a, corresponding to the later stages of the North Song Dynasty (AD 960-1127) and the subsequent South Song Dynasty (AD 1127-1279), which was a time of climatic decline according to historical documents. Palaeoflood discharges were estimated using the step-backwater method, and the peak discharges were estimated to be in the range 35 200-47 400 m3 s-1. These results are of significance to our understanding of the regional hydrological response to global climatic change, the utilization of water resources, hydraulic engineering, flood control and disaster reduction. [ABSTRACT FROM AUTHOR]

Denmark has been subject to complex interactions of isostatic uplift and eustatic sea level changes since the last deglaciation. Prominent coastal beach ridges as well as lagoonal and lake deposits from this period have been investigated at a number of sites in the region to constrain the relative sea level (RSL) changes. However, despite the common occurrence of former coastal lagoons and lakes in proximity to raised beach ridges, they have rarely been studied in combination. In this study, we use a multiproxy approach including geospatial data, lake sediment coring, ground penetrating radar and optically stimulated luminescence dating to investigate the Holocene coastal evolution and RSL history at Rugård in Mols Bjerge National Park, on the east coast of the Jutland Peninsula. Our results show that the coastal area at Rugård was transgressed between c. 7.6 and 7.0 cal. ka BP and that RSL was ~4.5 m higher than present between c. 6.6 and 5.9 ka ago, when the highest section of the beach ridge plain was deposited. The elevation and timing of this relative highstand are in good agreement with previous estimates of the Littorina transgression and contribute to our combined knowledge about RSL history and coastal evolution in the southern Kattegat. Subsequently, isostatic adjustment has caused uplift and erosion of the beach ridge plain, but renewed progradation and deposition of a lower beach plain have taken place since c. 1740 CE. Our results demonstrate the value of using a multiproxy approach to study RSL changes and coastal evolution. [ABSTRACT FROM AUTHOR]

This paper focuses upon the youngest terraces of the Moselle and its tributary the Meurthe ( NE France and SW Germany). It includes research on several sections, in particular the key sections of Golbey- Pré Droué and Thörnich- Hochrech (located in the vicinity of the Vosges Massif and in the Rhenish Massif, respectively), and the use of the Optically Stimulated Luminescence ( OSL) dating method. Our investigations made it possible to obtain a more robust chronostratigraphical framework and to update the previous model of fluvial response to climate change. The results demonstrate that the Moselle terrace M3 (first terrace formed after the capture of the Upper Moselle by the Palaeo- Meurthe) has the same age from the Vosges to the Rhenish Massif. The formation of this terrace included two main periods of sedimentation attributed to the Late Saalian ( MIS 6) and the Early Weichselian ( MIS 5), respectively. They were separated by a major episode of fluvial erosion that may be allocated to the MIS 6-5 transition on the basis of chronological and sedimentological evidence. This erosion led to the removal of most of the MIS 6 deposits, whereas the MIS 5 deposits have been widely preserved following the subsequent ( MIS 5-4) terrace incision. This evolution somewhat contrasts with that observed in the Sarre valley, the main tributary of the Moselle, and with many fluvial systems in western Europe, which show better preservation of deposits from cold periods. This atypical behaviour is explained by the relationship between the fluvial evolution and the glaciers covering the upper Moselle catchment ( Vosges Massif) during the Pleistocene cold periods. [ABSTRACT FROM AUTHOR]

The varved sediment of Lake Suigetsu (central Japan) provides a valuable opportunity to obtain high-resolution, multi-proxy palaeoenvironmental data across the last glacial/interglacial cycle. In order to maximize the potential of this archive, a well-constrained chronology is required. This paper outlines the multiple geochronological techniques being applied - namely varve counting, radiocarbon dating, tephrochronology (including argon-argon dating) and optically stimulated luminescence ( OSL) - and the approaches by which these techniques are being integrated to form a single, coherent, robust chronology. Importantly, we also describe here the linkage of the floating Lake Suigetsu ( SG06) varve chronology and the absolute ( Int Cal09 tree-ring) time scale, as derived using radiocarbon data from the uppermost (non-varved) portion of the core. This tie-point, defined as a distinct (flood) marker horizon in SG06 (event layer B-07-08 at 1397.4 cm composite depth), is thus derived to be 11 255 to 11 222 Int Cal09 cal. years BP (68.2% probability range). [ABSTRACT FROM AUTHOR]

Buylaert, J.-P., Huot, S., Murray, A.S. & Van den haute, P.: Infrared stimulated luminescence dating of an Eemian (MIS 5e) site in Denmark using K-feldspar. Boreas, 10.1111/j.1502-3885.2010.00156.x. ISSN 0300-9483. Infrared stimulated luminescence (IRSL) dating of K-feldspars may be an alternative to quartz optically stimulated luminescence (OSL) dating when the quartz OSL signal is too close to saturation or when the quartz luminescence characteristics are unsuitable. In this paper, Eemian (MIS 5e) coastal marine sands exposed in a cliff section on the coast of southern Jutland (Denmark) are used to test the accuracy and precision of IRSL dating using K-feldspars. This material has been used previously to test quartz OSL dating (): a small systematic underestimation of <10% compared to the expected age of ∼130 ka was reported. In our study, a single-aliquot regenerative-dose (SAR) IRSL protocol is used to determine values of equivalent dose (D) and the corresponding fading rates ( g values). A significant age underestimation (of up to ∼35%) is observed; this is attributed to anomalous fading. Using a single site-average fading rate of 3.66 ± 0.09%/decade to correct the IRSL ages for all samples provides good agreement between the average fading-corrected K-feldspar age (119 ± 6 ka) and the independent age control (132-125 ka). This is despite the reservations of that their fading correction method is not expected to work on samples older than ∼20-50 ka. This fading-corrected feldspar result is not significantly different from the overall revised quartz age (114 ± 7 ka) also presented here. We conclude that fading-corrected IRSL ages measured using K-feldspar may be both precise and accurate over a greater age range than might be otherwise expected. [ABSTRACT FROM AUTHOR]

In this study, we analysed a ~54‐m sediment core consisting of Quaternary sediments overlying the Neoproterozoic Muhos Formation in central western Finland, adjacent to the Gulf of Bothnia. The sediments recovered were logged, and their sedimentological characteristics defined. Two fine‐grained sediment units were subjected to biostratigraphical studies using pollen and diatom analyses. In addition, two sand‐rich units and a wooden stick were dated by the optically stimulated luminescence (OSL) and 14C‐AMS methods. The core sediments were divided into six units, where several diamicton, sand and gravel, and silt‐and‐clay‐dominated beds were studied. The results indicate that the sediment succession of the core beneath the Holocene Litorina Sea and the Ancylus Lake sediments of the Baltic Basin were deposited in glacial and lacustrine environments that existed in the Oulu River valley during the time period between the Saalian glaciation (MIS 6) and the Holocene. The stratigraphical evidence, supported by the OSL ages, suggests that the Scandinavian Ice Sheet (SIS) entered the Muhos area during the Saalian glaciation, and at least during three separate time intervals in the Weichselian stage. Stratigraphically controlled and age‐bracketed evidence shows that the first Weichselian SIS advance extended further south in the eastern part of Fennoscandia than previously estimated, and that this ice growth phase occurred during the Early Weichselian Herning Stadial (MIS 5d). The subsequent ice growth phases occurred during the Middle (MIS 4) and Late (MIS 2) Weichselian substages. The lacustrine and littoral sediments of the Muhos core were correlated with the late Eemian interglacial (MIS 5e) and two Weichselian interstadials (MIS 5c and MIS 3). [ABSTRACT FROM AUTHOR]

In this study, we reconstruct the style and timing of the late Quaternary glaciation pattern in a monsoon‐influenced precipitation‐deprived region (Dhauliganga basin) of the Central Himalaya, India. We present detailed glacial geomorphological mapping, aided by topographic maps, satellite data, Google Earth images, global positioning system survey, and fieldwork (2012–2016), supported by optically stimulated luminescence dating. Our estimations for the magnitude and timing of glaciations in the Dunagiri Glacier valley suggest five sets of glacial advances. The oldest and most extensive glaciation in the valley is Dunagiri Glacial Stage‐I (DGS‐I), represented by a discontinuous moraine ridge that extends down to ~10 km (~2700 m a.s.l.) from the present‐day snout and formed 13±3 ka ago. The DGS‐II stage is present in the form of a small moraine ridge (~3000 m a.s.l.) that formed 10±2 ka ago. The DGS‐III and DGS‐IV glacial stages are 5–6 and 3.5 ka old, respectively. The youngest stage (DGS‐V) of glaciation belongs to the neoglaciation episode ~1 ka old. DGS‐I was the most extensive glaciation in the valley and corresponds to the global Last Glacial Maximum. The glaciation pattern has been correlated with the estimates of present‐day glacial sensitivity to climate and explained as forcing factors sensitive to temperature and/or precipitation changes in the region. The observations based on prevailing climate correlations aided with available glacial chronologies underline the fact that the glacial valleys situated in precipitation‐deprived regions have preserved a delayed response of glaciations to regional climatic events. Estimates for the timing and pattern of glaciation in the present study suggest a different glacial response for modern climatic changes than previously assumed. We suggest that individual glacier advances differ regionally and, therefore, should not be interpreted as being reflective of a change in the whole geographical belt. [ABSTRACT FROM AUTHOR]

Aeolian dunes, coversands, glacifluvial deltas and paraglacial mass-movement deposits in Bon€asheden and Skattungheden in Dalarna, central Sweden were dated by optically stimulated luminescence (OSL) on quartz. The OSL ages confirm that the majority of the dunes started forming directly after deglaciation, as suggested by previous investigators. Dune formation seems to have lasted at least 1500 years, until c. 9 ka. Four younger episodes of sand drift resulting in coversand deposition were dated by OSL and/or radiocarbon to 4100±200 a, 1569-1412 cal. a BP, 970±60 a and 150±10 a. The youngest one is related to changes in land use, while the older ones may be due to regional climatic changes. The dated quartz had excellent luminescence characteristics; the luminescence was bright and dominated by the fast signal component, which made it possible to successfully analyse even untreated material, so-called range-finder dating. These characteristics are most likely inherited from one of the source rocks of the Quaternary deposits - the Mesoproterozoic Dala sandstone, which we show to also have very good luminescence properties. [ABSTRACT FROM AUTHOR]

Analysis of a high-resolution suite of modern glacial sediments from Jostedalen, southern Norway, using a portable optically stimulated luminescence ( OSL) reader, provides insights into the processes of sediment bleaching in glacial environments at the catchment scale. High-magnitude, low-frequency processes result in the least effective sediment bleaching, whereas low-magnitude, high-frequency events provide greater bleaching opportunities. Changes in sediment bleaching can also be identified at the scale of individual bar features: tails of braid-bars and side-attached bar deposits have the lowest portable reader signal intensities, as well as the smallest conventional OSL residual doses. In addition to improving our understanding of the processes of sediment bleaching, portable reader investigations can also facilitate more rapid and comprehensive modern analogue investigations, which are commonly used to confirm that the OSL signals of modern glacial sediments are well bleached. [ABSTRACT FROM AUTHOR]

In the Northeastern Tibetan Plateau ( NETP), the courses of the Huang Shui and Huang He near their confluence are characterized by alternating gorges and wide depressions, segmenting the fluvial systems. The river valleys have developed terrace staircases, which are used to infer relative tectonic motions between the segments. The terrace staircases are correlated by means of relative height and optically stimulated luminescence ( OSL) dating. At least eight terraces are present, two of which have been dated by OSL (the sixth and the third ones; c. 70 and c. 24 ka, respectively). The correlated longitudinal terrace profiles show no distinct relative tectonic movements within the confluence area, demonstrating that this area behaved as one tectonic block. The correlation of the terrace staircase of this block with areas upstream ( Xining area) and downstream (eastern Lanzhou area) indicates relative tectonic movements, which therefore represent different tectonic blocks. The fluvial incision rate since c. 70 ka was much higher in the confluence area than in the blocks upstream and downstream, possibly indicating relative uplift. This relatively strong uplift provided more space for differentiation within the terrace staircase as a result of climatic changes, leading to six terraces formed as a response to minor climatic fluctuations (103-104 year timescale) since the last interglacial. This may indicate that the stronger the tectonic movement the better the climatic imprint as expressed in the form of terrace development. Over a shorter timescale, two accumulation terraces with thick stacked deposits (>18 m) may indicate relative subsidence in the confluence, occurring sometime between 20 and 70 ka. This indicates changes in relative vertical crustal motions at timescales of tens of thousands of years. We speculate that the inferred tectonic motions are related to transpression movements in the NETP as a result of the collision of the Indian and Asian plates. [ABSTRACT FROM AUTHOR]

Two fluvial sediment cores taken from a floodplain of the Hawkesbury- Nepean River system in the Sydney region, eastern Australia are dated using Optically Stimulated Luminescence ( OSL) to provide a reliable chronology essential for the management and planning of water resources. Nine charcoal 14 C ( AMS) dates constrain these OSL ages. Quartz extracted from seven OSL samples from each of the cores was measured using both single-grain and multi-grain OSL techniques. Three of the single-grain natural dose distributions appear to be well bleached, but the others appear to be incompletely bleached to various degrees. Three minimum-age models ( MAM, MAMUL and IEU) are applied to the single-grain dose distributions. We conclude that these models give consistent age estimates. For one of the cores it appears to be necessary to use a minimum-age model to obtain accurate ages, but in the other core incomplete bleaching is probably less important than postdepositional mixing and mixing during sampling. As a result, the burial age is probably best estimated using the weighted average of the individual single-grain dose estimates. The application of multi-grain OSL techniques to these samples results in an average apparent age overestimation of ∼200 years, which is significant for these samples, but negligible for sediments older than a few thousand years. The intention is that the chronology obtained in this study will be used in conjunction with a proxy flood record, derived from floodplain sediments, to gain an understanding of the long-term variability in periods of high and low rainfall in eastern Australia. [ABSTRACT FROM AUTHOR]

The lithostratigraphy of pre- Late Weichselian sediments and OSL-dating results from four localities in the Suupohja area of western Finland, adjacent to the centre of the former Scandinavian glaciations, are presented. The studied sections expose glacifluvial, quiet-water, littoral and aeolian deposits overlain by Middle and/or Late Weichselian tills. Litho- and biostratigraphical results together with seven OSL age determinations on buried glacifluvial sediment at Rävåsen (94±15 ka) and on till-covered littoral and aeolian sediments at Risåsen, Rävåsen, Jätinmäki and Kiviharju (79±10 to 54±8 ka), accompanied by previous datings and interpretations, suggest that the glacifluvial sediments at Risåsen were deposited at the end of the Saalian Stage ( MIS 6) and those at Risåsen were deposited possibly in the Early Weichselian Substage (MIS 5d?). Palaeosol horizons and ice-wedge casts together with the dated littoral and aeolian sediments between the Harrinkangas Formation ( Saalian) and the overlying till(s) indicate that western Finland was ice-free during most of the Weichselian time. Littoral deposits, dated to the Middle Weichselian ( MIS 4-3), occur at altitudes of 50-90 m a.s.l., which indicates significant glacio-isostatic depression. The depression resulted from expansion of the ice sheet in the west of Finland at that time. [ABSTRACT FROM AUTHOR]

The fine-grained (4-11 μm) quartz Optically Stimulated Luminescence ( OSL) dating technique was applied to the Weinan section on the southeastern Chinese Loess Plateau ( CLP) with a high luminescence sampling resolution (10- and 20-cm intervals). Fifty-eight OSL ages, spanning c. 1-74 ka, were obtained for the 10-m loess-palaeosol sequences. The reliability of the OSL dating and the constructed chronology was confirmed by comparing the OSL ages with independent dates from other studies and by correlation with palaeoclimatic time series. The closely spaced OSL ages at Weinan indicate that the mean dust accumulation rate ( DAR) of L1-1 ( MIS 2, 7.0±0.9 cm ka−1) is lower than those of L1-3 ( MIS 4, 19.1±6.1 cm ka−1) and L1-2 ( MIS 3, 16.0±0.7 cm ka−1) and that the mean DAR c. 30-20 ka ago (11.4±2.4 cm ka−1) is higher than that c. 20-10 ka ago (3.0±0.1 cm ka−1) in L1-1. The subsequent calculation of the mass accumulation rate ( MAR) indicates that the MAR of L1-1 (107 g m−2 a−1) is much lower than those of L1-2 (247 g m−2 a−1) and L1-3 (307 g m−2 a−1). By comparing the mean DAR results during the Last Glacial at Weinan with those at a further six sites from other studies, we observed that the mean DAR of L1-2 is higher (lower) than that of L1-1 on the eastern (western) CLP, and that the mean DAR during MIS 2 has an evident transition from high to low at c. 20 ka on the entire CLP. Possible mechanisms for the above mean DAR changes at orbital and sub-orbital time scales are presented. [ABSTRACT FROM AUTHOR]

A database consisting of radiocarbon ( 14C), optically stimulated luminescence ( OSL), thermoluminescence ( TL) and beryllium ( 10Be) dates was used for timing the advance of the Late Weichselian Scandinavian Ice Sheet ( SIS), determining the age of the Last Glacial Maximum ( LGM) and the rate of deglaciation. The study area encompasses the southeastern sector of the last SIS between the Baltic Sea and the LGM position in the western part of the East European Plain, covering the Karelian Ice-Stream Complex ( ISC) area in the east and the Baltic ISC area in the west. The linear advance and recession rates of the last SIS were estimated to be between 110 and 330 m a−1 and between 50 and 170 m a−1, respectively. The onset of the last SIS in the Karelian ISC area reached the western shores of Latvia not before 26 OSL ka, and in the Baltic ISC area, on the southern shores of the Gulf of Finland, not before 21 OSL ka. The last SIS reached close to the LGM position earliest in NW Belarus, not earlier than 22.6 cal. 14C ka BP, and latest in the NE of Belarus, not earlier than 19.1 cal. 14C ka BP. The Baltic ISC area between the LGM position and the western shores of Latvia was deglaciated in about 8 ka, and in the Karelian ISC area, between the LGM position and the southern shores of the Gulf of Finland, in about 2.6 ka. The whole area between the LGM position and the Baltic Sea was deglaciated between 14.2 10Be ka and 13.3 cal. 14C ka BP. [ABSTRACT FROM AUTHOR]

Two sand wedge structures and their host sediments, from Jonzac in SW France, were successfully dated using Optically Stimulated Luminescence ( OSL) measurements on both small aliquots and single grains of quartz from the 180-212 μm size fraction. One of the sand wedges clearly contains primary infilling. However, grain-size analysis and field observations do not clearly indicate whether the other feature represents a primary sand wedge or a composite sand wedge with primary and secondary infilling. OSL results and the geological setting justify using the Central Age Model ( CAM) for the calculation of age estimates. Grain-size analysis and detailed investigations of OSL results revealed the contamination of one sand wedge sample with host sediment. However, age calculation using the Finite Mixture Model ( FMM) provided what is considered to be a reliable age estimate for the contaminated sample. The age estimates for all samples correspond to Marine Isotope Stage ( MIS) 3. While fine-grained sediments were deposited in the middle of MIS 3 ( c. 43-55 ka), the sand wedges unexpectedly correspond to the end of this period ( c. 33 ka) or the onset of MIS 2 ( c. 27 ka). The sand wedges were probably formed during intense but short cold periods, possibly correlated with a Heinrich event ( H2 and/or H3). The results help us to assess how effective luminescence dating is on sand wedges and the limitations involved in correlating sand wedge ages with Heinrich events, and contribute to the debate on the timing of cryogenic formation processes and the permafrost distribution in SW France. [ABSTRACT FROM AUTHOR]

Sand wedges and ice-wedge casts in the Qinghai Lake area on the northeastern Qinghai- Tibetan Plateau ( QTP) occur within alluvial gravel or river terrace deposits. In this study, we report the results of quartz Optically Stimulated Luminescence ( OSL) dating of the infill of five relict sand wedges and one ice-wedge cast. Combining our dating results with previously published luminescence ages of permafrost wedges in the Qinghai Lake area, we show that sand/ice wedges formed at c. 62 ka, c. 45 ka and between 30 and 15 ka, and that the mean annual air temperature ( MAAT) was depressed by at least ∼3° C relative to present during the sand/ice-wedge formation periods. This new work is partially corroborated by post- LGM proxy records from lakes and aeolian deposits reported from the northeastern QTP. It also significantly extends the palaeoenvironmental record in the region in the period before the LGM, when other proxy records are rare, allowing a better understanding of the palaeoenvironmental conditions on the northeastern QTP. [ABSTRACT FROM AUTHOR]

In this study we present optically stimulated luminescence ( OSL) dating results obtained at one of the most important open-air Middle Palaeolithic sites in the Sierra de Atapuerca foothills - Hotel California. We also assess the possibility of obtaining extended-range OSL chronologies for a nearby Middle Pleistocene fluvial deposit using several novel methods, namely OSL dating of individual quartz 'supergrains', multi-grain aliquot thermally transferred OSL ( TT-OSL) dating and the first application of a single-grain TT-OSL dating procedure. Four single-grain OSL ages constrain the Middle Palaeolithic occupation of Hotel California to between 71±6 and 48±3 ka. The Hotel California single-grain equivalent dose ( De) distributions are highly overdispersed and contain several dose populations, which are probably attributable to post-depositional sediment mixing, partial bleaching and intrinsic scatter. The reliability of multi-grain aliquot OSL dating is compromised by the complex underlying De dispersion affecting these samples, as well as by biasing multi-grain averaging effects. Extended-range OSL and TT-OSL chronologies for the nearby Pico River terrace are consistent with each other and with broad independent age control. These experimental approaches yield a weighted average age of 348±16 ka for terrace TA9 of the Arlanzón River sequence. Our results highlight the benefits of comparing ages obtained using several OSL methodologies to improve the robustness of luminescence chronologies. They also demonstrate the potential that single-grain OSL techniques offer for establishing improved age constraints on the many other Middle Palaeolithic sites found at Atapuerca and elsewhere across north-central Spain. [ABSTRACT FROM AUTHOR]

In central and northern Sweden, glacial sediments and landforms, formed during Early and Middle Weichselian stadials and their transition into interstadials, are often preserved in spite of having been overridden by later glacial advances. This study presents an OSL-dated glacial stratigraphy from Idre in west-central Sweden, expanding the area in which Middle Weichselian ice-free conditions have been identified. Three sedimentary units were identified, with the lowermost unit consisting of glaciolacustrine sand, deposited in a stagnant water-body. Nine OSL samples gave ages ranging from 54 to 41 ka, suggesting deposition during a deglacial phase in MIS 3. Normal faults and silt veins, formed after deposition, indicate that the area was ice-free for a prolonged period, enabling the melting of buried stagnant ice. Above an erosional unconformity is a sediment unit characterized by gravels and sands deposited in a proximal braided-river environment. OSL ages range from 180 to 41 ka, indicating poor sediment bleaching during deposition. We thus consider them to give a maximum age of the sedimentation, indicating deposition at or after 41 ka. The uppermost unit consists of a stacked succession of subglacial traction tills and glaciotectonite beds, representing the Late Weichselian glaciation of the area, probably during the inception phase with a wet-based glacier regime. At the last deglaciation of the area there was extensive meltwater erosion, eroding all sedimentary units and forming a landscape with terraces and channels, and erosional remnants of the uppermost diamict as free-standing hummocks. [ABSTRACT FROM AUTHOR]

The Middle Weichselian ( OIS 4-3) and the transition from Early to Middle Weichselian are the most problematic and disputed time intervals of the Late Pleistocene with regard to the palaeogeography of the Fennoscandian glaciations. The number of sites with sediments of Middle Weichselian age in the Baltic region is very limited. An extensive area (77 km2) of lacustrine sediments (sand, clay, silt with humus and interlayers of peat), under the relief-forming Upper Weichselian till, was discovered in the vicinity of the Venta settlement, northwestern Lithuania, and named the Venta Palaeolacustrine Basin. The Svirkanciai outcrop (56°18′05″ N, 22°53′00″ E) (15 m in height) of this palaeobasin is composed of two sediment complexes of different genesis and age. The lower part consists of silt and very fine-grained sand of lacustrine origin. According to palynological data, the lacustrine sediments accumulated under boreo-arctic climatic conditions. The pollen records suggest that local vegetation was sparse forest with open areas. An Optically Stimulated Luminescence ( OSL) date of the lacustrine sand yielded an age of >79±6 ka, which indicates that lacustrine conditions may have occurred during part of the Early Weichselian Odderade Interstadial ( Jonionys 2). However, the palynological data from Svirkanciai suggest a Middle Weichselian age, possibly correlating with the Oerel Interstadial ( Jonionys 3) 55 ka ago. No traces of early Middle Weichselian Schalkholz ( Nemunas 2a) stadial glacial advance have been found in the Venta sections. This also suggests a Middle Weichselian age for the Svirkanciai lacustrine sediments. [ABSTRACT FROM AUTHOR]

Luminescence dating is used extensively to provide absolute chronologies for Late Pleistocene sediments. Nowadays, most optical dates are based on quartz optically stimulated luminescence ( OSL). However, the application of this signal is usually limited to the last ∼100 ka because of saturation of the quartz luminescence signal with dose. In contrast, the feldspar infrared stimulated luminescence ( IRSL) dose-response curve grows to much higher doses; this has the potential to extend the datable age range by a factor of 4-5 compared with quartz OSL. However, it has been known for several decades that this IRSL signal is unstable, and this instability often gives rise to significant age underestimation. Here we test against independent age control the recently developed feldspar post- IR IRSL approach to the dating of sediments, which appears to avoid signal instability. A physical model explaining our observations is discussed, and the method is shown to be accurate back to 600 ka. The post- IR IRSL signal is reduced by exposure to daylight more slowly than that from quartz and low-temperature IRSL, preventing its general application to young (e.g. Holocene) sediments. Nevertheless, this new approach is widely applicable (feldspar of appropriate luminescence behaviour is even more ubiquitous than quartz). These characteristics make this a method of great importance for the dating of Middle and Late Pleistocene deposits. [ABSTRACT FROM AUTHOR]

Alexanderson, H., Landvik, J. Y. & Ryen, H. T. 2010: Chronology and styles of glaciation in an inter-fjord setting, northwestern Svalbard. Boreas, 10.1111/j.1502-3885.2010.00175.x. ISSN 0300-9483. A 30-m-thick sedimentary succession at Leinstranda on the southwestern coast of Brøggerhalvøya, northwestern Svalbard, spans the two last glacial-interglacial cycles and reveals information on glacial dynamics, sea-level changes and the timing of these events. We investigated the deposits using standard stratigraphical and sedimentological techniques, together with ground-penetrating radar, and established an absolute chronology based mainly on optically stimulated luminescence dating. We identified facies associations that represent depositional settings related to advancing, overriding and retreating glaciers, marine and littoral conditions and periglacial surfaces. The environmental changes show an approximate cyclicity and reflect glaciations followed by high sea levels and later regression. The luminescence chronology places sea-level highstands at 185 ± 8 ka, 129 ± 10 ka, 99 ± 8 ka and 36 ± 3 ka. These ages constrain the timing of recorded glaciations at Leinstranda to prior to c. 190 ka, between c. 170 and c. 140 ka (Late Saalian) and between c. 120 ka and c. 110 ka (Early Weichselian). The glaciations include phases with glaciers from three different source areas. There is no positive evidence for either Middle or Late Weichselian glaciations covering the site, but there are hiatuses at those stratigraphic levels. A high bedrock ridge separates Leinstranda from the palaeo-ice stream in Kongsfjorden, and the deposits at Leinstranda reflect ice-dynamic conditions related to ice-sheet evolution in an inter-fjord area. The environmental information and the absolute chronology derived from our data allow for an improved correlation with the marine record, and for inferences to be made about the interaction between land, ocean and ice during the last glacial-interglacial cycles. [ABSTRACT FROM AUTHOR]

Proglacial Lake Humber is of UK national significance in terms of landscape drainage and development of the British Ice Sheet (BIS) during Marine Isotope Stage 2 (MIS 2), yet it is poorly understood in terms of its dynamics and timing. Sands and gravels exposed at Ferrybridge, West Yorkshire, UK, are interpreted as part of the Upper Littoral sands and gravels related to a high-level Lake Humber, which inundated the Humber Basin to ∼30 m OD during MIS 2. Excavations exposed well-rounded gravels of local origin extending downslope from the 27.5 m OD contour and interbedded sands and fine gravels, which are interpreted as the coarse littoral deposits and nearshore associated deposits. A sample from the distal sands returned an Optically Stimulated Luminescence age of 16.6±1.2 kyr, providing the first direct age for the high-level lake and for when North Sea Basin ice must have blocked the Humber Gap. An underlying sequence included a diamicton dated to after 23.3 ±1.5 kyr and before 20.5±1.2 kyr, indicating that the Late Devensian ice reached at least 15 km south of the Escrick Moraine prior to the high-level lake. Previous to both the high-level lake and this ice advance, loess found at the two sites investigated indicates a long period of loess deposition earlier in MIS 2. These new data for the history of Lake Humber are discussed in the context of ice-marginal oscillations in both the Vale of York and the North Sea Basin. [ABSTRACT FROM AUTHOR]

Recent geomorphological and sedimentological investigation of the raised beach ridge plain on Anholt in the Kattegat Sea, Denmark, has demonstrated how these deposits, when combined with Optically Stimulated Luminescence (OSL) dating, can provide information about past changes in relative sea level. The southwest–northeast trending plain is divided into three topographic levels, one of which has been surveyed using Ground-Penetrating Radar (GPR). Samples retrieved from the survey line indicate that the initial part of the beach ridge plain formed about 7700 years ago in response to a mid-Holocene Littorina transgression. The raised marine deposits document a subsequent rise in relative sea level of about 9 m, and OSL dates indicate that this transgression took place about 6650 years ago. The flooding of the Kattegat Sea 7700 years ago might possibly be related to a rapid global sea-level rise peaking around 7500 years ago. [ABSTRACT FROM AUTHOR]

The Hitura open pit exposes a sedimentary sequence up to 50 m thick representing Late Saalian to Holocene glacial and non-glacial sediments. The sequence was investigated using sedimentological methods, OSL-dating and pollen and diatom analyses to reconstruct the Middle Weichselian (MWG) glacial event in the central part of the Scandinavian Ice Sheet (SIS). The results indicate that the sediment succession represents two entire glacial advance and retreat cycles. The lowermost deposits are Late Saalian esker and delta sediments overlain by sediments that correlate with the early Eemian lacustrine phase. Remnants of the Eemian soil post-dating the lacustrine phase were also observed. The area was ice-free during the entire Early Weichselian (EWG). The first glacial advance recorded in the sediments is related to the MWG. It started 79 kyr ago, deformed underlying sediments and deposited an immature till, including large detached sediment pods containing remains of organic material, soils and fluvial sediments representing allochthonous material from EWG ice-free stadials and interstadials. The glacial deposits are conformably overlain by glaciolacustrine and littoral accumulations, indicating MWG deglaciation between 62 and 55 kyr ago. Based on the fabric measurements from the till unit overlying the MWG sediments, ice advance during the Late Weichselian (LWG) was initially from the west and later from a north-northwesterly direction. The Hitura strata provide the first dating of the MWG deglaciation (55 to 62 kyr ago) from central parts of the SIS. It can be considered as a key site for studying the growth and decay of SIS during the poorly known early parts of the glaciation. [ABSTRACT FROM AUTHOR]

The chronology of two adjacent Danish Lateglacial sedimentary sequences with well-developed layering of alternating aeolian sand and organic matter has been investigated using both Optically Stimulated Luminescence (OSL) and Accelerator Mass Spectrometry (14C). Both sites are known to cover at least the period Bølling to Younger Dryas, with the so-called older and younger coversand types present at both localities. Typical overall uncertainties with the OSL data are about two to five times those of the 14C ages, but both data sets contain clear outliers. When these are excluded, OSL ages appear to be systematically slightly younger than the 14C ages, by about 10%; possible reasons for this are discussed. The investigation stresses the importance of making several age estimates from any single locality. The older coversand type makes up the pre-Bølling and most, or possibly all, of the Bølling (which also has the highest net accumulation rate). Deposits of the younger coversand type are dominant in layers younger than the Bølling. [ABSTRACT FROM AUTHOR]