CRC806-Database Publications Feed (Atom) http://crc806db.uni-koeln.de/ Multi-proxy-approach in palaeoenvironmental reconstructions using terrestrial sequences from southeastern Transylvania http://crc806db.uni-koeln.de/dataset/show/multiproxyapproach-in-palaeoenvironmental-reconstructions-using-terrestrial-sequences-fr1544700665/ 2018-12-13T11:31:04+01:00 Tephrochronology in terrestrial sediments gained increased attention throughout the last years. Volcanic layers in loess-palaeosol-sequences can be used to enhance the chronostratigraphy and to correlate miscellaneous archives. In southeastern Europe this correlative dating is frequently used, since the region lies in the dispersal area of several regional and supra-regional marker tephra layers. They can be used to put e.g. palaeo-environmental data in a temporal framework. The polygenetic sediment sequence of Bodoc north of Sfântu Gheorghe (Transylvania) and at the bank of the Olt River contains several of such tephra layers. These layers were deposited either subaerial or subaqueous, since this 15 m sequence is of aeolian and fluvial origin. Based on tephra geochemical data and correlations with proximal deposits, we assume the sequence to cover the last glacial cycle. Peculiarly, the sequence shows periglacial features such as ice-wedge casts and cryoturbation, albeit the permafrost boundary during the LGM is thought to be further north (Vandenberghe et al., 2014). Geochemical, magnetic, granulometric and photometric analyses are conducted to reconstruct the local palaeoenvironmental conditions and their implications for southern Transylvanian palaeoclimate. Moreover, the tephra layers are investigated as well as radiocarbon and luminescence dating are applied to obtain a high-resolution chronostratigraphy. References Vandenberghe, J., French, H.M., Gorbunov, A., Marchenko, S., Velichko, A.A., Jin, H., Cui, Z., Zhang, T., Wan, X., 2014. The Last Permafrost Maximum (LPM) map of the Northern Hemisphere: permafrost extent and mean annual air temperatures, 25-17 ka BP: The Last Permafrost Maximum (LPM) map of the Northern Hemisphere. Boreas 43, 652–666. https://doi.org/10.1111/bor.12070 Jonas Viehweger;Janina Bösken Chances and challenges in dating tephra marker horizons by luminescence dating techniques http://crc806db.uni-koeln.de/dataset/show/chances-and-challenges-in-dating-tephra-marker-horizons-by-luminescence-dating-technique1544699575/ 2018-12-13T11:12:53+01:00 Tephra layers are excellent time markers in paleoenvironmental archives. These can be used for correlation between different archives and give stratigraphic control independent of the applied dating techniques. Terrestrial archives such as loess-paleosol sequences are often dated by luminescence or radiocarbon dating, depending on the material available. While radiocarbon dating is only applicable for younger timescales, luminescence ages overcome this problem to a certain extent. However, they are accompanied by wider errors that are often too imprecise for some geochronological and paleoenvironmental questions. It is thus often useful to apply different dating techniques to cross-validate their results. Since tephra layers can sometimes be dated directly and very precisely (e.g. by 40Ar/39Ar dating), they can be used as a reference to validate the results of other chronological methods such as luminescence dating. Here, we present the Stalać and the Urluia loess-paleosol sequences and their geochronological investigations. The Stalać section in southern Serbia contains the “L2-Tephra” and a cryptotephra related to the Campanian Ignimbrite/Y-5 tephra (cf. Bösken et al., 2017; Obreht et al., 2016). The L2-Tephra is preserved in several loess-paleosol sequences in southeastern Europe (cf. Laag et al., INTAV conference abstract). Its labelling is related to its deposition within the L2 loess package, usually correlated to marine isotope stage 6 (e.g. Marković et al., 2015). Furthermore, also the Urluia section contains the Campanian Ignimbrite/Y-5 tephra (Obreht et al., 2017) that is widely distributed in southeastern Europe (e.g. Fitzsimmons et al., 2013) and dated to 39.85 ± 0.14 ka (Giaccio et al., 2017). This contribution identifies challenges in dating tephra layers by luminescence dating techniques and highlights its possibilities and prospects. References Bösken, J., Klasen, N., Zeeden, C., Obreht, I., Markovic, S.B., Hambach, U., Lehmkuhl, F., 2017. New luminescence-based geochronology framing the last two glacial cycles at the southern limit of European Pleistocene loess in Stalać. Geochronometria 44, 150–161. https://doi.org/10.1515/geochr-2015-0062 Fitzsimmons, K.E., Hambach, U., Veres, D., Iovita, R., 2013. The Campanian Ignimbrite Eruption: New Data on Volcanic Ash Dispersal and Its Potential Impact on Human Evolution. PLoS ONE 8, e65839. https://doi.org/10.1371/journal.pone.0065839 Giaccio, B., Hajdas, I., Isaia, R., Deino, A., Nomade, S., 2017. High-precision 14C and 40Ar/39Ar dating of the Campanian Ignimbrite (Y-5) reconciles the time-scales of climatic-cultural processes at 40 ka. Sci Rep 7, 45940. https://doi.org/10.1038/srep45940 Laag, C., Hambach, U., Botezatu, A., Baykal, Y., Veres, D., Schönwetter, T., Viola, J., Zeeden, C., Radaković, M., Obreht, I., Jovanović, M., Bösken, J., Lehmkuhl, F., Marković, S.B., 2018. The geographical extent of the “L2-Tephra”: a widespread marker horizon for the penultimate glacial (MIS 6) on the Balkan Peninsula. INTAV conference abstract. Marković, S.B., Stevens, T., Kukla, G.J., Hambach, U., Fitzsimmons, K.E., Gibbard, P., Buggle, B., Zech, M., Guo, Z., Hao, Q., Wu, H., O’Hara Dhand, K., Smalley, I.J., Újvári, G., Sümegi, P., Timar-Gabor, A., Veres, D., Sirocko, F., Vasiljević, D.A., Jary, Z., Svensson, A., Jović, V., Lehmkuhl, F., Kovács, J., Svirčev, Z., 2015. Danube loess stratigraphy - Towards a pan-European loess stratigraphic model. Earth-Science Reviews 148, 228–258. https://doi.org/10.1016/j.earscirev.2015.06.005 Obreht, I., Hambach, U., Veres, D., Zeeden, C., Bösken, J., Stevens, T., Marković, S.B., Klasen, N., Brill, D., Burow, C., Lehmkuhl, F., 2017. Shift of large-scale atmospheric systems over Europe during late MIS 3 and implications for Modern Human dispersal. Scientific Reports 7, 5848. https://doi.org/10.1038/s41598-017-06285-x Obreht, I., Zeeden, C., Hambach, U., Veres, D., Marković, S.B., Bösken, J., Svirčev, Z., Bačević, N., Gavrilov, M.B., Lehmkuhl, F., 2016. Tracing the influence of Mediterranean climate on Southeastern Europe during the past 350,000 years. Scientific Reports 6, 36334. https://doi.org/10.1038/srep36334 Jonas Viehweger;Janina Bösken Temperature accuracy in luminescence measurements – Results from an interlaboratory comparison http://crc806db.uni-koeln.de/dataset/show/temperature-accuracy-in-luminescence-measurements--results-from-an-interlaboratory-compa1544698155/ 2018-12-13T10:49:14+01:00 Jonas Viehweger;Janina Bösken Lower Danube loess and millennial-scale paleoclimate changes: new approach, new outcome and new perspectives http://crc806db.uni-koeln.de/dataset/show/lower-danube-loess-and-millennialscale-paleoclimate-changes-new-approach-new-outcome-and1544697090/ 2018-12-13T10:31:29+01:00 Loess-paleosol sequences are the most widespread terrestrial archives of Quaternary paleoclimate. Recent research carried out on multiple profiles from the Danube loess basins significantly improved our understanding of past environments, especially in the Lower Danube area, where loess-paleosol sequences and alluvial archives represent almost exclusively the main Pleistocene paleoenvironmental records. Here we present a synopsis of the latest research carried out using detailed high-resolution sedimentological, geochemical and chronological approaches, including multi-method luminescence dating and tephrochronology of several loess profiles from the Lower Danube area. We provide detailed records of grain-size and loess geochemical composition, with the aim of reconstructing the paleoenvironment as well as complementing the luminescence based age models of these records through comparisons with other records, aided by the presence of volcanic ash beds (particularly the Campanian Ignimbrite), that allow for the building of reliable correlative age models. A series of environmental magnetic proxies provide information on the magnetic mineralogy, grain-size variations and trace the amplitude of past pedological influences that modulate the paleoclimatic significance of proxy data. Most parameters show distinct down-core oscillations that correlate well with regional shifts in paleoclimate. These features, visible also in the grain-size data are complemented by information from geochemical proxies that provide important insights into the nature of the depositional environment and origin of sediments. Our new records are compared with regionally representative speleothem and marine stacks from the Black Sea, Mediterranean and the high-latitudes of the Northern Hemisphere. The comparison reveals consistent millennial-scale variability (e.g., fluctuations that resemble stadial-interstadial events) archived within the proxy data and identification of common features that may allow for the synchronization of records for most of the last glacial cycle, but also intriguing differences. The results also illustrate the value of a multiproxy approach in understanding sediment dynamics and variations in physical and chemical processes influencing/controlling loess-paleosol formation during rapid climate changes such as stadials and interstadials. Jonas Viehweger;Janina Bösken Luminescence dating of the lacustrine record of Vršac (Carpathian Basin, Serbia) – implications for a palaeoenvironmetal reconstruction http://crc806db.uni-koeln.de/dataset/show/luminescence-dating-of-the-lacustrine-record-of-vrac-carpathian-basin-serbia--implicatio1544696328/ 2018-12-13T10:18:46+01:00 The Carpathian Basin is one of the key areas to investigate the influence of the continental, Mediterranean and Atlantic climate interaction over Europe. The available Upper Pleistocene and Holocene geoarchives in the region are mainly loess-paleosol records. Long lacustrine records are sparse and do not always span the whole last glacial cycle. In the area around Vršac, we drilled a 10 m core to contribute to the palaeoenvironmental reconstruction of the Carpathian Basin. Electrical Resistivity Tomography (ERT) was used to find the best-suited drilling location. We applied luminescence and radiocarbon dating, because a robust chronology is important for the interpretation of the sedimentary record. Pulsed OSL measurements were carried out to identify the best sampling positions. We expect runoff from the catchment being the main source of the lacustrine sediments, because coarse fluvial input is absent. Knowledge about the depositional conditions is important in luminescence dating to evaluate partial bleaching prior to deposition, which may cause age overestimation. Therefore, we compared infrared stimulated luminescence (IRSL) signals with post infrared infrared stimulated luminescence (pIRIR) signals, which bleach at different rates. Estimation of a representative water content has major influence on the age estimate, but remains challenging in luminescence dating. We measured the present day water content as well as the saturation water content, to account for variations over time. Luminescence and radiocarbon ages differ greatly from each other. According to the laboratory experiments, luminescence dating was reliable and we conclude that radiocarbon ages were underestimated because of an intrusion of younger organic material. The initial results demonstrated the potential of the drill core. Integrating more proxy data will be useful to enhance the importance of the geoarchive at Vršac for a better understanding of the last glacial cycle in the Carpathian Basin. Jonas Viehweger;Janina Bösken