Alexandra Hilgers

The potential of OSL and TL for dating lateglacial and Holocene dune sands tested with independent age control of the Laacher See tephra (12 880 a) at the Section "Mainz-Gonsenheim"

Abstract Optically stimulated luminescence (OSL) and Thermoluminescence (TL) are applied in this study to date a Lateglacial and Holocene aeolian sediment sequence. Quartz and potassium rich feldspars extracted from dune sands from western Germany were dated using both multiple-aliquot (MA) and single-aliquot (SA) protocols for luminescence dating. This particular dune section was chosen for this test study, because an independent age control is provided by a horizon of the Laacher Seetephra (12,880 a). In contrast to the results for potassium feldspars, which show underestimation of up to 25%, the quartz fraction provides promising results with respect to the presumed geological ages.

ESR dating of raised coral reefs from Kish Island, Persian Gulf

Electron spin resonance (ESR) dating of raised coral reefs from Kish Island, Persian Gulf, Iran, was used for the calculation of uplift rates. From the methodological point of view, it has been demonstrated that concentrations of uranium, as needed for the calculation of dose rates, determined by instrumental neutron activation analyses were significantly lower than the results of inductively coupled plasma—mass spectrometry and are probably systematically underestimated. The ESR ages for the corals show no increase with elevation as was expected due to field observations. This apparent discrepancy is explained by the dicyclic nature of the palaeo-reef. Average uplift rates for Kish Island are between ∼0.13 and ∼0.24 mm a−1. This is consistent with previous estimates based on 230Th/234U dating of raised marine deposits from the nearby Iranian mainland and Qeshm Island, Strait of Hormuz, but contrary to results based on 14C dating that predicted uplift rates as high as 3 mm a−1 in that area. It is once more demonstrated that 14C dates >20 ka from this context often have to be interpreted as minimum ages.

A Lateglacial palaeosol cover in the Altdarss area, southern Baltic Sea coast (northeast Germany): investigations on pedology, geochronology and botany

A new site with Lateglacial palaeosols covered by 0.8 - 2.4 m thick aeolian sands is presented. The buried soils were subjected to multidisciplinary analyses (pedology, micromorphology, geochronology, dendrology, palynology, macrofossils). The buried soil cover comprises a catena from relatively dry (’Nano’-Podzol, Arenosol) via moist (Histic Gleysol, Gleysol) to wet conditions (Histosol). Dry soils are similar to the so-called Usselo soil, as described from sites in NW Europe and central Poland. The buried soil surface covers ca. 3.4 km 2 . Pollen analyses date this surface into the late Allerod. Due to a possible contamination by younger carbon, radiocarbon dates are too young. OSL dates indicate that the covering by aeolian sands most probably occurred during the Younger Dryas. Botanical analyses enables the reconstruction of a vegetation pattern typical for the late Allerod. Large wooden remains of pine and birch were recorded.

Luminescence dating of loess deposits from the Remagen-Schwalbenberg site, Western Germany

Abstract This study describes the luminescence characteristics of quartz of Upper Pleistocene loess of the Middle Rhine area. The loess/palaeosol sequence of the Schwalbenberg near Remagen com-prises a multitude of interstadial soils and soil sediments that have been dedicated to the Marine Iso-tope Stage 3 (MIS 3). These weak calcaric cambisols and their derivates are underlain by loess and soil sediments of MIS 4 to MIS 5 and covered by loess sediments and intercalated gelic gleysols of MIS 2. We applied luminescence dating of quartz and feldspar of drill core samples and observed an age discrepancy within both data sets. The quartz ages were clearly younger than the feldspar ages, because of thermally unstable signal components of the quartz luminescence signal. Therefore, we re-garded the quartz samples of the lower parts of the drill core as unsuitable for luminescence dating. This underestimation did not affect the quartz samples of the upper part of the drill core which was indicated by age control that was provided by the Eltville tephra layer. Geochemical analysis based on X-ray fluorescence showed that the sediments in the upper part and the lower part of the drill core have different geogenic finger prints most likely due to changing source areas of dust and sediment allocation. We assumed that these different facies types were the reason for the luminescence behav-ior of the quartz samples.

Dealul Guran: evidence for Lower Palaeolithic (MIS 11) occupation of the Lower Danube loess steppe

Owing to a thick blanket of loess and other later geological disruptions, the earliest hominins to reach Europe are hard to find. To a handful of possible sites, our authors add a new assemblage of lithics with a clear local context and corroborated OSL ages. Ancient humans were present in what is now Romania between 300 000 and 400 000 years ago.

The earliest Aurignacian in Romania: New investigations at the open air site of Româneşti-Dumbrăviţa I (Banat)

Previous archaeological research in the Banat area (South-western Romania) resulted in the definition of a chronologically late Krems-Dufour type Aurignacian, followed by the isolated find of several considerably old anatomically modern human (AMH) remains at Oase Cave, several decades later. The last find set the stage for new stratigraphic, chronological and archaeological reassessment of Banat Aurignacian settlements at Tincova, Coşava and RomâneştiDumbrăviţa. This study presents the attribute analysis of the Aurignacian lithic assemblage at Româneşti-Dumbrăviţa I, involving both old and recently excavated collections. Alongside the more accurate identification of the main technological and typological features, pointing to a Protoaurignacian/Early Aurignacian assignation of the Early Upper Palaeolithic industry here, new chronological landmarks, much older than previously considered, became available. Preliminary thermoluminescence results point to an estimated age between 45 and 40 ka for the main accumulation in GH3 at Româneşti, thus indicating a possible contemporaneity of the Banat Aurignacian and the Oase AMH finds. A brief comparative outline of the Banat Aurignacian settlements is also provided, followed by and attempt at placing the local Aurignacian into the European Early Upper Palaeolithic landscape. Zusammenfassung Bisherige Forschung zum Beginn des Jungpaläolithikums im Banat ergaben widersprüchliche Ergebnisse. Nachdem die von dort bekannt gewordenen Aurignacien-Freilandfundstellen Tincova, Coşava und Româneşti-Dumbrăviţa zunächst chronologisch an das Ende dieses Technokomplexes gestellt worden waren, wurde nach der Entdeckung der Überreste früher anatomisch moderner Menschen in der Oase-Höhle angenommen, es handele sich um ein Proto-Aurignacien. In dem vorliegenden Artikel werden diese Widersprüche anhand neuer Grabungen und erster absoluter Datierungen sowie einer detaillierten Analyse der Altund Neufunde an der Fundstation Româneşti-Dumbrăviţa aufgelöst. Demnach handelt es sich an diesem Fundplatz um eine Steingeräteindustrie, die sowohl Merkmale des Proto-Aurignacien als auch des klassischen Aurignacien aufweist. Erste Thermolumineszenz-Alter zwischen 45 kyr BP im Liegenden und 40 kyr BP im Hangenden deuten auf eine frühe Zeitstellung von Româneşti-Dumbrăviţa innerhalb des älteren Jungpaläolithikums und eine zeitliche Überschneidung mit den Menschenresten aus der Oase-Höhle. Vor diesem Hintergrund wird die Bedeutung des Banat im Rahmen der Ausbreitung des frühen modernen Menschen nach Europa diskutiert.

A contribution to the dating of the northern boundary of the Weichselian Loess Belt in Northern Germany by luminescence dating and pedological analysis

Abstract Sedimentological examination of the sediments in the area along the northern margin of the loess belt in Northern Germany show a typical stratigraphic sequence of at least five phases of aeolian sedimentation. As a contribution to the chronostratigraphic classification of the sedimentary sequence in this zone, 15 samples from a section close to Denstorf, near Braunschweig in Lower Saxony, Northern Germany, were dated, using thermoluminescence (TL) as well as optically stimulated luminescence (OSL). The age estimates obtained by dating the potassium-rich feldspars and quartz-rich extracts lead to the assumption that the northernmost Last Glacial loess accumulation occurred during the Late Glacial period. This confirms earlier suggestions that the northernmost loess deposits in Northern Germany represent the return of strong aeolian processes under the cold and dry conditions of the Late Glacial.

Luminescence Dating of Fluvial Deposits in the Rock Shelter of Cueva Antón, Spain

Abstract The fluvial sediments at Cueva Antón, a Middle Palaeolithic rock shelter located in the valley of the River Mula (Southeast Spain), produced abundant lithic assemblages of Mousterian affinities. Radiocarbon dates are available for the upper part of the archaeological succession, while for the middle to lower parts chronometric data have been missing. Here we present luminescence dating results for these parts of the succession. Quartz OSL on small aliquots and single grain measurements yield ages ranging from 69 ± 7 ka to 82 ± 8 ka with a weighted mean of 72 ± 4 ka for sub-complexes AS2 to AS5. Equivalent dose estimates from large aliquots were highest and inconsistent with those from single grains and small multiple grain aliquots. This is probably caused by the presence of over-saturating grains, which have been quantified by single grain measurements. Additional post-IR IRSL measurements on coarse grained feldspar give strong support to a well-bleached quartz OSL signal. While independent chronometric control is missing, the results are within the expected age range and support the notion of a rapid accumulation of the fluvial deposits.

Reconstructing fluvial, lacustrine and aeolian process dynamics in Western Mongolia

At the eastern rim of the Mongol Els, the largest dune field of Mongolia, the rivers Shurgyn Gol and Zavkhan Gol converge and form a flood plain at the dune front. Interfingering fluvio-lacustrine and aeolian sediments are found in different spatial contexts in the area. By investigating the chronostratigraphy of these sediments, valuable information can be derived for the reconstruction of geomorphological processes and forcing-response relations in the past. The flood plain is locally covered by lacustrine sediments representing an Early to Mid-Holocene lake only a few meters deep. This can be deduced from several 14C and OSL dates and tachymetric measurements, and is in accordance with high stands of other lakes in Western Mongolia. Relics of a lake sediment on top of an old dune 17 m above the floodplain have been OSL-dated to 114 10, 119 10, and 127 10 ka, indicative of an Eemian age. At that time a large and deep lake must have covered the plain. There is evidence of two causes of lake formation: increased discharge of the rivers due to increased precipitation in the mountainous catchment areas and, at the same time, ponding of the rivers by strong dune advance due to persistingly arid conditions in the foreland. The transition phase to more humid con ditions, together with a relatively high humidity gradient, appears to have been morphodynamically very efficient. No evidence could be found of the assumed modern climate change. Recent reduction of the sparse grass cover of the region reflects overgrazing, and the reduction of river discharge is due to water-consuming irrigation.

Origin and age of the Lower Bavarian sand dune landscape around Abensberg and Siegenburg

The Lower Bavarian aeolian sand areas and sand dune landscape in the Abensberg/Siegenburg area (county/Landkreis Kelheim, Lower Bavaria) originated in an area where the Late Tertiary deltaic sediments of the Ur-Naab are overlain by a complex system of Pleistocene Danube gravels as well as those of the Abens river, deposited by in parts widely-shifting Quaternary river courses, mainly during the Riss glacial. This explains the absence of any significant loess cover of the area. The sand dunes and aeolian sands occurring there have been known for a long time, and their mostly late glacial age origin can be stratigraphically inferred. During the Holocene there were repeated phases of aeolian remobilisation, each of them related to an overexploitation of the carrying capacity of the landscape. It can be excluded that remobilisation was caused by changing climate. Today the dune fields, up to 10 m high, have partly been set aside as nature reserves, or are being used for agriculture and forestry. Based on geophysical prospection, at four selected dune chains and their surroundings, a distinction has been made between the underlying aeolian sand sheet, the dune cores, and younger aeolian accumulation bodies, and they have been sedimentologically characterised. The dune sands have been dated by OSL, macro-remains and the humous material of fossilised soil horizons by the radiocarbon method. Forest clearing of much of the landscape began during the Neolithic period, related to the operation of a flintstone mine at Arnhofen. Two significant phases of sand dune growth have been dated to the Bronze Age and the High Middle Ages, largely determining the aspect of the present dune landscape. There is evidence of younger remobilisation phases up to the 1950s. With reduced settlement pressure, each time the dune landscape returned to a phase of morphodynamic stability, without any evidence of directed reforestation or dune stabilisation measures of the sands. Today, under the name of Durnbucher Forest, the former hunting preserve of the Wittelsbach noble family, the Abensberg/Siegenburg dune landscape is one of the largest contiguous forest areas of Bavaria.