Lumineszenzdatierung von äolischen und fluvialen Archiven im mittleren und unteren Donaueinzugsbietes und die Implikationen für die Paläoumwelt : Luminescence dating of eolian and fluvial archives in the Middle and Lower Danube catchment and the paleoenvironmental implications

• Main Author: Bösken, Janina Johanna
• Format: Thesis
• Language: English
• Published: RWTH Aachen University 2018
• Subjects: loess-paleosol sequences; southestern Europe; Carpathian Basin; post-IR-IRSL; OSL; Lower Danube Basin; a-value; grain-size; geochemistry; Aurignacian; Tundra
• Online Access: https://dx.doi.org/10.18154/rwth-2018-01253; http://publications.rwth-aachen.de/record/713554

Dissertation, RWTH Aachen University, 2017; Aachen, 1 Online-Ressource (xxi, 195 Seiten) : Illustrationen, Karten (2018). = Dissertation, RWTH Aachen University, 2017 : The presented doctoral dissertation uses luminescence dating techniques to reconstruct the paleoenvironmental and paleoclimatic conditions in the Middle and Lower Danube catchments, especially during the period of anatomically modern human emergence. It is embedded in the Collaborative Research Center 806 "Our Way to Europe - Culture-Environment Interaction and Human Mobility in the Late Quaternary". To increase ones understanding of the environmental conditions during the last 150 ka, four loess-paleosol sequences and one fluvial section were investigated. The research area is located at the junction of Atlantic, Mediterranean and continental climatic regimes, which makes it sensitive to climatic changes. Moreover, the geographical position between Asia, Near East and Central Europe and the vast river network connecting these regions, make the area a favorable pathway for anatomically modern human migration. The sediments of the five investigated sites cover various time frames from the penultimate interglacial (MIS 7) to the Holocene. The methodological approach focused on optically stimulated luminescence dating, but for some of the sections the geochronological methods were combined with physical, biological, and geochemical proxy data to reconstruct the paleoenvironmental conditions. In the Middle Danube Basin three sites were investigated. The Ságvár loess-paleosol sequence is located in the central basin and its sediments accumulated during the last glacial maximum from approximately 25 − 17 ka. The sequence can be correlated to two Gravettian occupation layers. Paleoenvironmental conditions changed from short grassland (25 − 24 ka), to a mosaic of mammoth steppe, forest steppe, continental steppe, and tundra (25 − 18 ka), towards continental grassland (< 18 ka). The data indicates that the Gravettian occupation took place during a typically cold LGM phase. The Bodrogkeresztúr loess-paleosol sequence is located in the foothills of the Carpathians in the northern part of the Middle Danube Basin. It is located in the vicinity of the Gravettian Bodrogkeresztúr-Henye site. The chronological data indicates rather high sediment accumulation rates, in particular between 33.5 ± 2.5 and 28.0 ± 2.1 ka. Moreover, generally more humid conditions during late MIS 3 and early MIS 2 in comparison to other regions in the Carpathian Basin were deduced. Nevertheless, two loess layers with high sand abundance in the profile suggest colder and dryer conditions with increased eolian dynamics during short periods within MIS 2. The findings highlight the unique microclimatic conditions at the foothills of the Carpathian Mountains, which may have offered a favorable environment for Upper Paleolithic populations. Another research site investigated in the Middle Danube Basin is the Crvenka-At site. This site contains fluvial sediments and Aurignacian artifacts. Investigations here focused on the reconstruction of a geochronology for the Early Upper Paleolithic occupation. The Aurignacian artifacts were found in sediments with an age between 33.9 ± 2.9 ka and 41.3 ± 3.6 ka. This age range fits well to other dated Aurignacian findings in the Banat region and points to a more widespread occurrence of anatomically modern humans in the Banat region during this time frame than previously thought. It demonstrates that not only the upland regions, but also lowland areas were attractive for early modern human occupation. Moving to the southern part of the Middle Danube catchment, the Stalac section was investigated. It is located in the interior of the Central Balkan region, south of the typical loess distribution, in a zone of paleoclimatic shifts between continental and Mediterranean climate regimes. Detailed investigations on the luminescence signal of a quartz sample, which is unsuitable for dating, are presented. A firm chronology framing the last two glacial cycles was established using fine-grained polyminerals and the post-infrared infrared stimulated luminescence (pIRIR) protocol. The characteristics of the dated paleosols indicate similar climatic conditions during the last interstadial and interglacial phases, which were different from the penultimate interglacial period. Finally, the Urluia loess-paleosol sequence in the Lower Danube Basin was investigated. This 16 m long sequence contains one paleosol at the bottom of the profile and a vast accumulation of loess above. The section was dated from 20.98 ± 1.6 ka to 144.9 ± 12.2 ka. While the chronology of the upper 7 m of the section is supported by independent age control in form of the Campanian Ignimbrite / Y-5 tephra, the lower part of the sequence remains less well constrained. A rapid increase in ages between ~7 and 9 m is followed by rather constant ages > 130 ka in the lower 7 m of the profile. These ages are in contrast with the expectation of a well developed MIS 5 paleosol in the lowermost part of the section. Several hypothesis trying to explain these findings were explored, but could not be solved satisfactorily.The doctoral dissertation demonstrates that a detailed investigation is necessary in order tobuild robust age models. For quartz samples, the importance of preheat plateau and dose recovery tests are pointed out. Some samples of Stalac and Urluia, that have high equivalent doses, show falling preheat plateaus, while the quartz samples of Crvenka-At are already in saturation at very low doses. These findings indicate that these samples cannot be dated reliably using the SAR protocol. Most samples of this dissertation were dated with the pIRIR protocol. The necessary first IR stimulation temperature tests, dose recovery tests, fading experiments and residual dose measurements are presented. It is demonstrated that polymineral and kalifeldspar samples can be dated with higher doses than quartz. However, it remains unclear up to which dose range age estimates are reliable. E.g. at Urluia, the lowermost samples approach saturation even within the polymineral fraction and at Stalac the lowermost two ages underestimate the accepted correlative stratigraphy. Overall, this doctoral dissertation highlights the importance of luminescence dating in paleoenvironmental and geoarcheological studies. It demonstrates how the combination of multiple proxy data enhances the paleoenvironmental interpretations, and identifies remaining challenges. The paleoclimatic dynamics in the research area at the junction of Atlantic, Mediterranean and continental climatic regimes are discussed. Finally, paleoenvironmental conditions during phases of Upper Paleolithic occupation were equally diverse highlighting anatomically modern humans’ ability to adapt to changing paleoenvironments. : Published by Aachen