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Beryllium-10 cosmic-ray exposure (CRE) dating has revolutionized our understanding of glacier fluctuations around the globe. A key prerequisite for the successful application of this dating method is the determination of regional production rates of in situ accumulated 10 Be, usually inferred at independently dated calibration sites. Until now, no calibration site has been available for the mid-elevation mountain ranges of central Europe. We fill this gap by determining in situ 10 Be concentrations in large boulders on moraines and by applying radiocarbon and infrared-stimulated luminescence (IRSL) dating to stratigraphically younger lake sediments in the southern Black Forest, SW Germany. The dating methods yielded concordant results, and, based on age–depth modelling with 14 C ages, the age of a cryptotephra, and IRSL ages, we deduced a regional 10 Be production rate in quartz. Calibrating the Black Forest production rate (BFPR) in the Cosmic-Ray Exposure program (CREp) resulted in a spallogenic sea-level and high-latitude (SLHL) production rate of 3.64±0.11 atoms 10 Be g -1 quartz a -1 when referring to time-dependent Lal–Stone scaling, the European Reanalysis (ERA)-40 atmosphere model, and the atmospheric 10 Be-based geomagnetic database in CREp. The BFPR turned out to be ∼11 % lower than both those at the nearest calibration site in the Alps (4.10±0.10 atoms 10 Be g -1 quartz a -1 at SLHL) and the canonical global 10 Be production rate (4.11±0.19 atoms 10 Be g -1 quartz a -1 at SLHL) in CREp. A stronger weathering and snow cover bias and a higher impact of forest, soil, moss, and shrub cover at the study site likely explain this discrepancy. [ABSTRACT FROM AUTHOR]

Beryllium-10 cosmic-ray (CRE) exposure dating has revolutionised our understanding of glacier fluctuations around the globe. A key prerequisite for the successful application of this dating method is a thorough understanding of local production rates of in-situ accumulated 10Be, usually inferred from independently dated regional reference sites. For the mid-elevation (Variscan) mountain ranges of central Europe, no production rate reference site has been available so far. We fill this gap by determining in-situ 10Be concentrations in large boulders on moraines and by applying radiocarbon and luminescence dating to stratigraphically younger lake sediments in the southern Black Forest, SW Germany. The dating methods yielded concordant results and, based on age-depth modelling with 14C ages, we deduced a local 10Be production rate. The resulting Black Forest (BF) production rate is ~11 % lower than both those at the nearest reference site in the Alps and the canonical global 10Be production rate. A stronger weathering and snow cover bias and a higher impact of soil, moss and shrub cover at the stud site likely explain this discrepancy. Due to its internal robustness, we suggest applying the BF production rate in future CRE dating studies in Central Europe and for revising existing age estimates which will have crucial implications for understanding past atmospheric circulation patterns. [ABSTRACT FROM AUTHOR]

While timing and ice extent of the last glacial maximum are generally well known, the courses of earlier glaciations have remained poorly constrained, with one of the main reasons being the scarcity of sedimentary archives. This study introduces a new palaeolake record from a Mid‐Pleistocene glaciofluvial channel system in the Lower Aare Valley (Northern Switzerland). The record of Rinikerfeld comprises a >40 m long succession of Quaternary deposits that are targeted by multi‐method sedimentological analysis. Sedimentary facies together with geochemical and geotechnical parameters, pollen content, as well as luminescence ages allow the reconstruction of the establishment, evolution and infilling of the early Marine Isotope Stage 6‐aged Rinikerfeld Palaeolake. A drastic change in lake sediment composition and structure indicates cessation of the initial glacially derived input, which is explained by landscape modification and drainage rerouting during the Penultimate (Beringen) Glaciation. Geochemical and palynological data further reveal cold, initially periglacial but slightly ameliorating, climate conditions, while the lake was progressively filled up by local runoff, before being buried by periglacial colluvial diamicts, and potentially overridden by ice. It is therefore concluded that the onset of the Beringen Glaciation was an environmentally as well as geomorphically dynamic time period in the Northern Alpine Foreland. [ABSTRACT FROM AUTHOR]

Pyroclastic currents are catastrophic flows of gas and particles triggered by explosive volcanic eruptions. For much of their dynamics, they behave as particulate density currents and share similarities with turbidity currents. Pyroclastic currents occasionally deposit dune bedforms with peculiar lamination patterns, from what is thought to represent the dilute low concentration and fluid‐turbulence supported end member of the pyroclastic currents. This article presents a high resolution dataset of sediment plates (lacquer peels) with several closely spaced lateral profiles representing sections through single pyroclastic bedforms from the August 2006 eruption of Tungurahua (Ecuador). Most of the sedimentary features contain backset bedding and preferential stoss‐face deposition. From the ripple scale (a few centimetres) to the largest dune bedform scale (several metres in length), similar patterns of erosive‐based backset beds are evidenced. Recurrent trains of sub‐vertical truncations on the stoss side of structures reshape and steepen the bedforms. In contrast, sporadic coarse‐grained lenses and lensoidal layers flatten bedforms by filling troughs. The coarsest (clasts up to 10 cm), least sorted and massive structures still exhibit lineation patterns that follow the general backset bedding trend. The stratal architecture exhibits strong lateral variations within tens of centimetres, with very local truncations both in flow‐perpendicular and flow‐parallel directions. This study infers that the sedimentary patterns of bedforms result from four formation mechanisms: (i) differential draping; (ii) slope‐influenced saltation; (iii) truncative bursts; and (iv) granular‐based events. Whereas most of the literature makes a straightforward link between backset bedding and Froude‐supercritical flows, this interpretation is reconsidered here. Indeed, features that would be diagnostic of subcritical dunes, antidunes and 'chute and pools' can be found on the same horizon and in a single bedform, only laterally separated by short distances (tens of centimetres). These data stress the influence of the pulsating and highly turbulent nature of the currents and the possible role of coherent flow structures such as Görtler vortices. Backset bedding is interpreted here as a consequence of a very high sedimentation environment of weak and waning currents that interact with the pre‐existing morphology. Quantification of near‐bed flow velocities is made via comparison with wind tunnel experiments. It is estimated that shear velocities of ca 0·30 m.s−1 (equivalent to pure wind velocity of 6 to 8 m.s−1 at 10 cm above the bed) could emplace the constructive bedsets, whereas the truncative phases would result from bursts with impacting wind velocities of at least 30 to 40 m.s−1. [ABSTRACT FROM AUTHOR]

Rock surface dating, a relatively new approach within luminescence dating, determines when a rock surface was last exposed to sunlight by measuring the amount of latent OSL signal accumulated after burial. However, the potential and applicability of rock surface dating in glaciofluvial settings of the Alps has seen very limited application so far (Rades et al., 2018). Therefore, different luminescence methods including rock surface dating have been applied in a unique setting at the Hartheim gravel pit in the southern Upper Rhine Graben to establish a chronological frame for distal glaciofluvial deposits. First, a detailed field study was conducted in order to gather a comprehensive understanding of the different sediment types present. Fine grain sand, cobbles, pebbles and matrix sediments embedded within large clasts were collected and analyzed using a combination of OSL and IRSL dating. Conventional OSL dating of fine sand quartz is considered as robust age control compared to the other sediment types. A substantial amount of luminescence measurement has been done on the sand lens and gravel matrix sediment collected from Hartheim. OSL ages range around from ca. 19 ka to 32 ka for the different sediment types. Feldspar IRSL has been measured using a MET-pIRIR protocol to avoid problems with fading. Furthermore, a detailed dosimetry study was conducted to measure the varying levels of radionuclide concentration within materials of different grain size, in order to obtain accurate depositional ages. Overall, the purpose of this research contributes to our existing knowledge in the field of luminescence dating by showing the potential and versatility of different luminescence methods in different sediment types and environments that provide an ideal framework for future studies in similar contexts. [ABSTRACT FROM AUTHOR]

The present‐day landscape of the northern Alpine foreland is marked by the cumulated impact of weathering during interglacial, and of erosion and deposition during glacial periods of the Quaternary. Direct traces of the earliest phases of ice advance, as well as thorough studies thereof, exist only sporadically. Here, a succession of diamictic deposits, which has been interpreted as the infill of an Early Pleistocene overdeepened basin, is investigated with a combined sedimentological‐geotechnical approach including analysis via μCT scans, and standard tests of the water uptake, consistency, and compaction properties. The diamicts are exposed along a 4.5‐m‐deep profile, and are subdivided into a yellowish‐brown lower unit with a variable, carbonaceous, silty to sandy matrix, and a reddish‐brown upper unit that is free from carbonate and appears largely homogeneous. Although the lower unit is rather loose and surficially bioturbated, it contains microstructures indicative of subglacial deformation, which are lacking in the compact and clay‐rich upper unit. The lower part is interpreted as a secondary glacial deposit (i.e. it has been affected by limited sorting in water) that was overridden and sheared by a glacier briefly after deposition, and recently bioturbated. The upper part is less sorted, more massive and compact, and thus likely of a primary glacial nature. It is further characterized by a strong pedogenetic overprint typical of prolonged warm periods. This suggests that it is separated from the overlying glacifluvial gravel, which has an equivalent petrographic composition, by a full interglacial at least. Thus, the combination of geotechnical testing and CT‐based micromorphology offers a new, practical and cost‐effective approach to the characterization of glacially derived sediments. [ABSTRACT FROM AUTHOR]