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This study presents the first quantitative assessment of weathering conditions in the Tajikistan depression throughout the last full glacial cycle. We employed geochemical and magnetic susceptibility analyses to investigate various weathering indices (WIs), with the CPA and FENG indices identified as the most suitable for this region. Our results confirm the formation of a robust pedocomplex, PS2, during the OIS5 interglacial phase, while primary loess deposition occurred during the interstadials. The presence of a weak paleosol, PS1, suggests that OIS3 was not significantly pronounced, and sediment transport and deposition continued during this period. Furthermore, we assessed the effectiveness of various climatic transfer functions, including some recently developed specifically for Chinese loess. These transfer functions have also shown promising applicability to the loess of Central Asia, producing realistic climate trends that are, however, still to be taken with caution. The MAT and mean annual precipitation generated with these functions show for the last interglacial period about 13°C and 665 mm, thus higher temperatures and lower precipitation than the current conditions of 10.8°C and 730 mm. These results indicate a significant increase (c. 15%) in both temperature and precipitation compared to the stadial periods. [ABSTRACT FROM AUTHOR]

This study presents the first quantitative assessment of weathering conditions in the Tajikistan depression throughout the last full glacial cycle. We employed geochemical and magnetic susceptibility analyses to investigate various weathering indices (WIs), with the CPA and FENG indices identified as the most suitable for this region. Our results confirm the formation of a robust pedocomplex, PS2, during the OIS5 interglacial phase, while primary loess deposition occurred during the interstadials. The presence of a weak paleosol, PS1, suggests that OIS3 was not significantly pronounced, and sediment transport and deposition continued during this period. Furthermore, we assessed the effectiveness of various climatic transfer functions, including some recently developed specifically for Chinese loess. These transfer functions have also shown promising applicability to the loess of Central Asia, producing realistic climate trends that are, however, still to be taken with caution. The MAT and mean annual precipitation generated with these functions show for the last interglacial period about 13°C and 665 mm, thus higher temperatures and lower precipitation than the current conditions of 10.8°C and 730 mm. These results indicate a significant increase (c. 15%) in both temperature and precipitation compared to the stadial periods.

Late Marine Isotope Stage (MIS) 3 and MIS 2 loess–palaeosol sequences in Western Europe comprise alternating loess layer and 3‐ to 30‐cm‐thick bleached soil horizons with Fe–Mn oxide precipitations, which are usually interpreted as waterlogged active layers and referred to as 'tundra gleys'. Active layer thickness data derived from a regional climate model simulation and the fossils (shells, earthworm granules) found in 'tundra gleys' argue against such an assumption. Most of these horizons better correspond to Fe‐depleted, slightly humic topsoil horizons or subsurface eluvial horizons and should be referred to as (incipient) Ag or Eg horizons. They formed during climate ameliorations associated with vegetation (cryptogams, herbs) development, possibly limited by long‐lasting snow cover. Strong mixing usually occurred in these horizons due to the activity of anecic earthworms and frost activity. [ABSTRACT FROM AUTHOR]

In this article, a dataset of age-depth modelling data, sedimentation rates and dust mass accumulation rates (MAR) from four loess-palaeosol sequences from the Carpathian Basin is presented. The dataset is related to the article “Detailed luminescence dating of dust mass accumulation rates over the last two glacial-interglacial cycles from the Irig loess-palaeosol sequence, Carpathian Basin”, published in the journal Global and Planetary Change by Perić et al. [1].In the dataset, luminescence ages from the loess sites Irig, Nosak, Stari Slankamen and Crvenka were modeled using the r.bacon software after which the dust mass accumulation rates were calculated. For a more realistic representation the MARs were subsequently smoothed using the SigmaPlot software. For all sites, minimum, maximum, median and mean values for the modelled ages and accumulation rates are calculated and presented.

Loess provides a valuable terrestrial record of past environmental conditions, including the dynamics and trajectories of air mass circulation responsible for dust transport. Here we explore variations in the luminescence sensitivity characteristics of sedimentary quartz and feldspar as possible tools for identifying changes in source down a loess-palaeosol sequence (LPS). Luminescence sensitivity is a rapidly measurable index which is the product of interplay between source lithology and the history of the quartz or feldspar clasts. Variations in sensitivity of down profile may therefore reflect changes in sediment provenance as well as other factors such as weathering through pedogenesis. We undertake an empirical investigation of the luminescence sensitivity of quartz and feldspar from different grain-size fractions from the Schwalbenberg LPS in the German Rhine valley. We compare samples from a 30 m core spanning the last full glacial cycle with samples of oxygen isotope stage (OIS) 3–2 age exposed within nearby profile. We find an overall inverse relationship between quartz and feldspar sensitivity, as well as variability in sensitivity between different quartz grain sizes. Statistical analyses yield a significant correlation between IR50 sensitivity from unprocessed sediments and clay content, and feldspar sensitivity and Si/Al ratios down the core. Since Si/Al ratios may indicate changes in provenance, the latter correlation suggests that IR50 measurements on unprocessed samples may be used to provide a reliable, rapid scan of source variability over millennial timescales. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an independent luminescence chronology for the upper part of the important Loess Palaeolithic site at Kuldara (Khovaling Loess Plateau, Tajikistan). We applied high sampling-depth resolution (n = 85) luminescence dating to the upper ∼26 m of the sequence from loess L4 to pedocomplex PC0. Luminescence characteristics of the post-IR 200 IRSL 290 signal from coarse-silt polymineral grains are satisfactory (reproducible growth and good dose recovery). Comparison with quartz OSL for samples <50 ka and results from modern analogues (Challier et al. these proceedings) shows that the pIRIR 200,290 signal is, as expected, sufficiently bleached at deposition. The luminescence chronology extends back to ∼250 ka and shows distinct erosional hiatuses ranging in duration from ∼15 ka to a full glacial-interglacial cycle (∼100 ka); some of these breaks were not identifiable in the field. We suggest an upper dating limit of 2.5xD c ; this yields minimum ages of ∼300 ka for this material. Dust Accumulation Rates (DAR) are reconstructed for the Late Pleistocene (from ∼100 to ∼40 ka) and reveal, next to several minor dust accumulation peaks, two major peaks at the end of MIS5 (∼75 ka) and at MIS3b (∼40 ka). We conclude that detailed post-IR 200 IRSL 290 dating of loess-palaeosol sequences in Tajikistan is necessary to exploit fully the potential of this important terrestrial (dust) record. [ABSTRACT FROM AUTHOR]

Loess provides a valuable terrestrial record of past environmental conditions, including the dynamics and trajectories of air mass circulation responsible for dust transport. Here we explore variations in the luminescence sensitivity characteristics of sedimentary quartz and feldspar as possible tools for identifying changes in source down a loess-palaeosol sequence (LPS). Luminescence sensitivity is a rapidly measurable index which is the product of interplay between source lithology and the history of the quartz or feldspar clasts. Variations in sensitivity of down profile may therefore reflect changes in sediment provenance as well as other factors such as weathering through pedogenesis. We undertake an empirical investigation of the luminescence sensitivity of quartz and feldspar from different grain-size fractions from the Schwalbenberg LPS in the German Rhine valley. We compare samples from a 30 m core spanning the last full glacial cycle with samples of oxygen isotope stage (OIS) 3–2 age exposed within nearby profile. We find an overall inverse relationship between quartz and feldspar sensitivity, as well as variability in sensitivity between different quartz grain sizes. Statistical analyses yield a significant correlation between IR50 sensitivity from unprocessed sediments and clay content, and feldspar sensitivity and Si/Al ratios down the core. Since Si/Al ratios may indicate changes in provenance, the latter correlation suggests that IR50 measurements on unprocessed samples may be used to provide a reliable, rapid scan of source variability over millennial timescales.

The article presents the results of research on the formation conditions and the age of glaciogenic deposits left by the Scandinavian ice sheet in the Eastern Carpathian Foreland, in its part drained by the Dniester River and its tributaries (Black Sea basin). These deposits (till, erratics, glaciolacustrine and glaciofluvial sediments), preserved only in some places and occurring in the range of altitudes defined by terrace VI (Early Pleistocene) and terrace V (Middle Pleistocene), are the southernmost traces of the ice sheet in Europe. They are underlain by fluvial deposits and overlain by loess deposits, and locally occur as intraloess layers. The following research methods were used: geomorphological mapping, sedimentological, lithological, micromorphological, palaeopedological, and palaeontological analyses, as well as luminescence dating. The obtained results allowed a reconstruction to be made of the main stages of morphogenesis and the style of the ice-sheet advance at its maximum extent, defined as the Sambor Phase. The area was glaciated during MIS 12 (Elsterian II = Sanian 2 = Okanian), as indicated by the occurrence of a complete Middle/Upper Pleistocene loess–palaeosol sequence. The oldest palaeosol (S4), i.e. Sokal (=Mazovian = Zavadivka) soil that developed directly on the glaciogenic deposits or loess L5 is correlated with the Holsteinian (=Likhvinian) Interglacial (MIS 11). • The study area is the zone of maximum extent of the Elsterian Glaciation in Europe. • Main stages and styles of the Elsterian II ice-sheet advance have been reconstructed. • Pleistocene environments reconstructed based on full sequence of interglacial palaeosols. [ABSTRACT FROM AUTHOR]

Abstract The correlation of loess sequences across global, hemispheric, regional and local scales is one of the most fundamental aspects to loess research. However, despite recent progress in stratigraphic and chronometric methods, the correlation of many loess sequences is often still based on untested assumptions over loess deposition, preservation, soil type and age. As such, the aim of this overview is to provide an adequate framework for evaluation of the accuracy of loess correlations applied on different temporal and spatial scales across Eurasia. This opens up possibilities for detailed temporal and spatial environmental reconstructions across the huge loess provinces of the Eurasia and provides a framework for future extension of this to North America. Additionally, we evaluate the potential development of appropriate sub-millennial scale loess correlations, as well as essentially important chronological approaches for establishing valid correlations between different loess records, such as current improvements in tephrochronology, 14C and luminescence dating techniques. [ABSTRACT FROM AUTHOR]

Current loess research indicates a better understanding of the factors that determine the ways that loess (dust) accumulation and soil formation has responded to the rapid and variable Late Quaternary climatic changes across Europe and Western Asia. Lack of evidence of loess in the region between the Black Sea and Caspian Sea creates a critical gap in the geographical distribution of this deposit and hence inhibits our ability to examine properly the spatial distribution and processes of formation. The recent discovery of loess-palaeosol sequences in Armenia allows us to overcome this problem and preliminary investigations have yielded encouraging results. A research programme has been established to characterise, analyse and date sequences from NE-Armenia that are up to 45 m thick. This paper presents first results of this study and reports three well-developed pedocomplexes below a Holocene soil. The magnetic properties of the loess indicate mainly Caucasian sources and all palaeosols exhibit clear magnetic enhancement. Luminescence dating of the upper part of the sequences identifies deposition between 150 and 39 ka. During that period, loess deposition took place during MIS 6/4 and 3. A multiphase pedocomplex that documents progressive climate transition from initially humid to arid conditions, could be placed into MIS 5, although we found striking temporal offset between the phase of most intense soil formation and the Last Interglacial climatic optimum. Furthermore, colluvial slope deposits and erosional discordances provide information on distinct phases of landscape instability that are linked to interglacial periods and the transition to glacial conditions. [ABSTRACT FROM AUTHOR]

With one of the largest watersheds in Europe, draining complex geological terrains within the Alps, Bohemian Massif, Carpathians, Dinarides, and the Balkan Mountains, the Danube River valley has long been linked to the formation of thick loess deposits, particularly within the Middle and Lower Danube basins. However, uncertainty over the provenance of loess-palaeosol sequences along the Danube impacts our understanding of sediment generation mechanisms and hinders interpretation of paleoenvironmental proxies preserved in loess. To date, most of the studies investigating loess provenance in Europe have not attempted a standardised characterisation and synthesis of loess deposits with potential source rocks. Further, despite clear links identified between loess and rivers in Asia and Europe, detrital zircons have not yet been used systematically to investigate the relationship between loess and the fluvial sediments of the Danube and its tributaries. Finally, in European loess research, provenance fingerprinting has often been conducted using indirect approaches or bulk sample geochemical analyses, which have been shown to have a limited application in well mixed sedimentary bodies such as loess. This provenance study of loess along the Danube River integrates existing zircon U-Pb ages and Hf datasets for loess, rivers, and bedrock, with new loess zircon U-Pb and Hf results from loess sequences in Croatia, Serbia and Bulgaria. The results show that all surrounding mountain belts (i.e. the Alps, Bohemian Massif, Carpathians, Dinarides Alps, and Balkan Mountains) contribute primary sediment to loess deposits in the Danube valley via its modern tributary network. Critically sedimentary sources remain relatively homogenous along the river, with no apparent major change in source with tributary confluence, further highlighting the role of fluvial transport in homogenising sediment prior to final aeolian deposition. Whilst some small site variations can be observed, they are likely explained by contributions restricted to very local rock outcrops. Moreover, geomorphological results support floodplain sediments as the proximal sediment source and suggest that short-distance aeolian transport dominates sediment delivery to loess sequences, challenging distant sources hypotheses such as major Saharan sources. The identification of sediment sourced from lower elevation regions such as the Bohemian Massif, Dinarides, and Balkans, which did not support ice-caps, suggests that the role of glacial action in silt-size sediment production has been previously exaggerated. Therefore, the glacial and desert loess division inadequately separates and describes sediment generation processes. This research supports and furthers previous work, which suggests "mountain sourced and transported by-rivers" as a more appropriate term for the particles forming loess, at least in the Danube basin. [ABSTRACT FROM AUTHOR]

In this study we present a luminescence investigation of samples from the Požarevac loess–palaeosol sequence (LPS) in north–eastern Serbia. The pIRIR 290 signal displayed a generally good behaviour and yielded stratigraphically consistent D e values. The pIRIR 290 ages show very good agreement (within uncertainty) with the expected stratigraphic ages up to about 260 ka. The analyses of the 4–11 μm quartz extracts were performed in order to determine their applicability for luminescence dating. The optically stimulated luminescence (OSL) measurements showed that the fine–grained quartz systematically underestimates the expected equivalent doses for all measured samples. A comparison between natural and laboratory dose response curve showed no overlapping, not even in the lower dose range. Linear modulated –OSL analysis revealed large differences between individual samples where some quartz extracts displayed a different number of components and varying contribution of the fast component. The quartz OSL also shows thermal instability as demonstrated by pulse annealing experiments and thermal fading. For these reasons we do not consider the fine–grained quartz from the Požarevac LPS as a reliable dosimeter. • We investigate the applicability of the 4–11 μm quartz and polyminerals for luminescence dating. • The laboratory and natural OSL growth curves show no overlapping, not even in the lower dose range. • LM–OSL analysis showed large differences between samples and a varying fast component. • Large g 2days values for quartz extracts present a real feature, probably caused by thermal fading. • The pIRIR 290 ages show a very good agreement with the expected stratigraphic ages. [ABSTRACT FROM AUTHOR]

Recent data on the evolution of the inland lakes, loess-palaeosol sequences, and glacier variations in western China are briefly reviewed. The lake history shows three distinct stages in the Holocene, i.e., low water levels before 7500 BP, a stage of expansion during the climatic optimum between 7500 and 3500 BP, and contraction after 3500 BP. Three stages (wooded grassland, mixed woodland, wooded grassland becoming steppe) also appear indicated by the Holocene loess/palaeosol sequence in the Lanzhou region, the optimal period for soil development being between 7500 and 3500 BP. There were seven periods of glacier advance: the continental glaciers advanced at about 8300, 5700, 4000, and 400 BP in northwestern China and the maritime glaciers advanced at about 3000, 2000, 1000, and 200 BP. It is suggested that the climatic changes show two periodicities during the Holocene, namely at intervals of about 2500 and 1000 years. [ABSTRACT FROM PUBLISHER]