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The influence of different sample pretreatment methods on grain size distributions in particle size analysis has been subject to controversial discussions. Standard sample preparation typically comprises the disaggregation of aggregated and agglomerated particles into single primary particles, i.e., the organic binding material is oxidized by hydrogen peroxide (H2O2) and the contained carbonates are dissolved by hydrochloric acid (HCl). The aim of this study is to evaluate the effects of HCl treatment on grain size analyses of Late Pleistocene and Holocene loess-paleosol-sequences investigated by a Beckman Coulter LS 13320 laser particle analyzer. For this purpose, samples from two different sections with different weathering degrees and sedimentary genesis were measured: (1) the Suohuoduo section on the northeastern fringe of the Tibetan Plateau (China) containing loess and paleosols, and (2) a vibracore from Dusseldorf-Grafenberg (Germany) containing calcareous loess and intercalated interglacial, interstadial and periglacial soils and soil sediments. All samples were pretreated with hydrogen peroxide and sodium pyrophosphate. Subsequently, the samples were prepared with and without the addition of HCl. There is no significant association of the HCl-induced grain size modifications after the HCl treatment with the calcium carbonate content Conversely, a distinct dependence of the modification of grain size distributions on the content of organic matter, the weathering degree of the sediment, and the presence of stable aggregates as well as organo-mineral complexes was observed. Consequently, pretreating post-depositionally modified aeolian sediments with HCl may result in misleadinggrain size distributions and should be avoided in standard analyses of loess-paleosol-sequences. However, the HCl-induced modification of grain size distributions provides an indication of the existence of stable aggregates or organo-mineral complexes. (C) 2015 Elsevier B.V. All rights

Most studies on landscape evolution on the Tibetan Plateau during the late Quaternary have mainly focused on using lacustrine records. However, mantles of sandy silt and paleosols also provide valuable archives for reconstructing Holocene paleoenvironmental change. Yet little is known about the distribution and timing of these late Quaternary aeolian sediments. To enhance understanding and knowledge of aeolian sediments in Tibet and to help reconstruct the nature of Late Glacial through mid-Holocene landscape development, a loess-paleosol sequence, the Suohuduo section, located at the eastern margin of the Tibetan Plateau at about 4000 m above sea level is examined using sedimentological, geochemical and geochronological methods. A chronostratigraphy is established using nine optically stimulated luminescence and one radiocarbon ages. Sedimentation increased during the Late Glacial and the early Holocene with an upwards fining of sediments in the lower part of the section. Two mid Holocene paleosols that date to about 8.5 ka to 7 ka and -5.5 ka to 4 ka reflect more humid climate conditions during the mid-Holocene than earlier times. The upper part of the section is mainly silt, which reflects a more open landscape with higher aridity since 4 to 3 ka this time. These data support evidence for similar climate/paleoenvironmental change in adjacent regions on the Tibetan Plateau. (C) 2013 Elsevier B.V. All rights reserved.

The Paleolithic sites Rom (a) over cap nesti and Cosava, situated at the foothills of the Banat Mountains in Romania, provide an important testament of life of the first European modern humans (Homo sapiens sapiens) during Middle Pleniglacial. Even though these sites have been extensively excavated, little is known about the site formation of related loess-like sediments and soils. First luminescence data at the two investigated sections confirm sediments from the penultimate glacial period to the Holocene. Assigning the levels of findings is difficult, because the sediments are close to the surface and are overprinted by recent soil development. Albeluvisols, influenced by stagnic features, are the typical surface soils in the study area and on comparable morphological positions in the region. Laboratory analysis has revealed that this soil has a complex genesis from hydrolysis weathering, which is connected with the development of a fragic soil horizon, overprinting the major find horizons at both sites. By using sedimentological and geochemical methods in combination, this study aims to reconstruct sedimentary evolution and soil processes at the sites, as well as to evaluate the state of preservation and the actual content of the archeological contexts. Initial results indicate hints for a forest step and higher vegetation during MIS 3 at the foothills of the Carpathian Mountains in the Western Plain of Romania. These natural factors offer a local attractiveness of the region which could be the most important reason for the occurrence of first Anatomically Modern Humans. Our investigations lend a better understanding of the paleoenvironment as well as a first age control of Paleolithic levels for the region. (C) 2014 Elsevier Ltd and INQUA. All rights reserved.

Upper Pleistocene sediments at Wadi Sabra (Ma'an District, Jordan) were geoarcheologically investigated from 2008-2010. The Wadi Sabra valley system, situated east of the Dead Sea Rift and south of the ancient Nabataean capital of Petra, has preserved sedimentary deposits which are connected with several Upper Paleolithic sites. First results from sedimentological and geochemical analysis supported by archeological and radiometric dating provide evidence of fluvial and fluvio-eolian sedimentation during Marine Isotope Stage (MIS) 3 and 2 from at least 38 ka to 18 ka, followed by at least one erosional event that finally determined the recent valley morphology. Several calcretes, buried surfaces and initial soil horizons indicate phases of landscape stability and potentially moister climatic conditions than today. Inferred favorable environment of the time allowed for human occupation of the Wadi Sabra attested throughout the cultural stages of the Initial. Early, and evolved Upper Paleolithic and the early Epipaleolithic, thus illustrating the occurrence of Homo sapiens in the Near East. Field work at Wadi Sabra is expected to further elucidate the Out of Africa II movement of our species, leading modern humans to Europe, possibly via the Middle East and the Balkan Peninsula, both regions now under comparative investigation by the Cologne-Aachen B1 project group of the CRC 806. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.

Mantles of silt- and sand-size particles, paleosols and fluvial deposits preserve valuable information on Holocene environmental change. These archives were used to reconstruct the landscape history in the upper Orkhon Valley close to the former capitals of the Uighurs (Kharbalgasin Tuur) and the Mongolian Empire (Karakorum) near the recent town of Kharkhorin, Central Mongolia. A holistic approach involving the use of high spatial resolution geomorphological mapping, sedimentological and geochemical analysis, palynology, and geochronology shows several phases of landscape activity and stability in the region. This includes phases of fluvial erosion, aeolian sedimentation, and soil formation. By using luminescence and radiocarbon dating, phases of landscape change, indicated by soil formation, occurred mainly at around 6.5-6 ka. Pollen data and a weakly humic horizon at around 1.0 ka probably indicate enhanced moisture supply in the region and a reduction of human activity between the time of the reigns of the Uighurs (8th-9th century AD) and the Mongols (1220-1388 AD). Since 3 ka, especially within the last two millennia of Historical Time (300 B.C.-present), a more intensified human occupation in the Upper Orkhon Valley occurred in this region. This included a more densely grazing of cattle to supply the growing population demands of the Uighurs and Mongols. This overgrazing caused an increase in erosion and the formation and deepening of fluvial gullies. together with soil deflation and subsequent deposition of aeolian sediments. Human activity, in addition to climate, has been dominant in driving landscape evolution of this region since the late Holocene. (C) 2011 Elsevier B.V. All rights reserved.