| 1. |
- Markovic, Slobodan B., et al.
(författare)
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Danube loess stratigraphy - Towards a pan-European loess stratigraphic model
- 2015
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252 .- 1872-6828. ; 148, s. 228-258
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Tidskriftsartikel (refereegranskat)abstract
- The Danube River drainage basin is the second largest river catchment in Europe and contains a significant and extensive region of thick loess deposits that preserve a record of a wide variety of recent and past environments. Indeed, the Danube River and tributaries may themselves be responsible for the transportation of large volumes of silt that ultimately drive loess formation in the middle and lower reaches of this large catchment However, this vast loess province lacks a unified stratigraphic scheme. European loess research started in the late 17th century in the Danube Basin with the work of Count Luigi Ferdinand Marsigli. Since that time numerous investigations provided the basis for the pioneering stratigraphic framework proposed initially by Kukla (1970, 1977) in his correlations of loess with deep-sea sediments. Loess-palaeosol sequences in the middle and lower reaches of the Danube River basin were a key part of this framework and contain some of the longest and most complete continental climate records in Europe, covering more than the last million years. However, the very size of the Danube loess belt and the large number of countries it covers presents a major limiting factor in developing a unified approach that enables continental scale analysis of the deposits. Local loess-palaeosol stratigraphic schemes have been defined separately in different countries and the difficulties in correlating such schemes, which often change significantly with advances in age-dating, have limited the number of basin-wide studies. A unified basin-wide stratigraphic model would greatly alleviate these difficulties and facilitate research into the wider significance of these loess records. Therefore we review the existing stratigraphic schemes and define a new Danube Basin wide loess stratigraphy based around a synthetic type section of the Mosorin and Stari Slankamen sites in Serbia. We present a detailed comparison with the sedimentological and palaeoclimatic records preserved in sediments of the Chinese Loess Plateau, with the oxygen isotope records from deep-sea sediments, and with classic European Pleistocene stratigraphic subdivisions. The hierarchy of Danubian stratigraphic units is determined by climatically controlled environmental shifts, in a similar way to the Chinese loess stratigraphic scheme. A new unified Danube loess stratigraphic model has a number of advantages, including preventing confusion resulting from the use of multiple national schemes, a more transparent basis, and the potential to set Pleistocene palaeoenvironmental changes recorded in the Danube catchment area into a global context. The use of a very simple labelling system based on the well-established Chinese loess scheme facilitates interpretation of palaeoenvironmental information reported from the Danube Basin loess sites in a wider more accessible context that can be readily correlated world-wide. This stratigraphic approach also provides, for the first time, an appropriate framework for the development of an integrated, pan-European and potentially pan-Eurasian loess stratigraphic scheme.
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| 2. |
- Heyman, Jakob, 1979-
(författare)
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Palaeoglaciology of the northeastern Tibetan Plateau
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study concerns the palaeoglaciation of the northeastern Tibetan Plateau, with emphasis on the Bayan Har Shan (Shan = Mountain) in the headwaters of Huang He (Yellow River). To reconstruct past glacier development multiple techniques, including remote sensing, field investigations, cosmogenic exposure dating, and numerical modelling have been employed. Analysis of the large-scale geomorphology indicates that glacial erosion has been dominant in the elevated mountain areas on the low-relief plateau, whereas fluvial erosion outpaces glacial erosion along the plateau margin. Landform and sediment records yield evidence for multiple local glaciations, restricted to the highest mountain areas, and a maximum glaciation beyond the mountain front. Absence of data supporting the former presence of proposed ice sheets, plateau-wide or regional, tentatively indicates that no ice sheet glaciation occurred on the northeastern Tibetan Plateau. Cosmogenic exposure dating of boulders, surface pebbles, and sediment sections in central Bayan Har Shan indicates that its record of past glaciations predates the global Last Glacial Maximum (LGM). Based on a world-wide analysis, yielding that wide age disparity within apparent exposure age datasets is most likely caused by post-glacial shielding processes, the Bayan Har Shan exposure ages constrain four periods of glaciation with minimum ages of 40-65 ka, 60-100 ka, 95-165 ka, and undetermined oldest stage. Similar to Bayan Har Shan, the plateau-wide distribution of boulders with pre-LGM exposure ages close to present-day glaciers shows that its LGM glaciers were generally not much larger than today. The results of a high resolution glacier model applied to nine regions across the plateau indicates that temperature depressions of 2-4 K are enough to expand glaciers beyond their global LGM extent, implying that during periods of Northern Hemisphere glaciation the Tibetan Plateau was not much colder than today or became exceedingly dry.
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| 3. |
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| 4. |
- Markovic, Slobodan B., et al.
(författare)
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Geomorphological evolution of the Petrovaradin Fortress Palaeolithic site (Novi Sad, Serbia)
- 2021
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Ingår i: Quaternary Research. - : Cambridge University Press. - 0033-5894 .- 1096-0287. ; 103, s. 21-34
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Tidskriftsartikel (refereegranskat)abstract
- Two phases of archaeological investigation were performed in the Novi Sad City Museum at Petrovaradin Fortress. In this study, we summarize the results of geo-archaeological investigations of the second period of excavation inside the Novi Sad City Museum building. The fortress is situated on a Danube terrace with the top of the bedrock at ca.123 m asl. The investigated section consists of undisturbed fine-sandy silt. The grain-size distribution of the sediments indicates clearly its alluvial reworking but shows also a general similarity with typical primary loess in the region. All analyzed proxies indicate slightly stronger weathering in the upper part of the profile. Luminescence ages suggest that the investigated sequence covers the last glacial period and the terrace presumably formed during MIS 4. Subsequently, the Danube started its incision at the start of the next warmer period (MIS 3) onward. This terrace age and elevation enable us to derive an uplift rate of the terrace of ca. 0.73 mm/a for the last 60 ka, which seems to increase towards the present. Basal loessic material, in which artifacts occur, likely in the reworked position, indicate that the area close to today's Petrovaradin Fortress was already inhabited in MIS 5.
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| 5. |
- Obreht, Igor, et al.
(författare)
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Shift of large-scale atmospheric systems over Europe during late MIS 3 and implications for Modern Human dispersal
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the past dynamics of large-scale atmospheric systems is crucial for our knowledge of the palaeoclimate conditions in Europe. Southeastern Europe currently lies at the border between Atlantic, Mediterranean, and continental climate zones. Past changes in the relative influence of associated atmospheric systems must have been recorded in the region’s palaeoarchives. By comparing high-resolution grain-size, environmental magnetic and geochemical data from two loess-palaeosol sequences in the Lower Danube Basin with other Eurasian palaeorecords, we reconstructed past climatic patterns over Southeastern Europe and the related interaction of the prevailing large-scale circulation modes over Europe, especially during late Marine Isotope Stage 3 (40,000–27,000 years ago). We demonstrate that during this time interval, the intensification of the Siberian High had a crucial influence on European climate causing the more continental conditions over major parts of Europe, and a southwards shift of the Westerlies. Such a climatic and environmental change, combined with the Campanian Ignimbrite/Y-5 volcanic eruption, may have driven the Anatomically Modern Human dispersal towards Central and Western Europe, pointing to a corridor over the Eastern European Plain as an important pathway in their dispersal.
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| 6. |
- Perić, Zoran M., et al.
(författare)
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Detailed luminescence dating of dust mass accumulation rates over the last two glacial-interglacial cycles from the Irig loess-palaeosol sequence, Carpathian Basin
- 2022
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Ingår i: Global and Planetary Change. - : Elsevier. - 0921-8181 .- 1872-6364. ; 215
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Tidskriftsartikel (refereegranskat)abstract
- Mineral dust records distant from dust sources are crucial in establishing wider atmospheric dust loads in the past. However, detailed, independent chronologies for loess-palaeosol sequences distant from local dust sources are still rare in Europe. In this study we present a high-resolution OSL and pIRIR(290) chronology and multi-proxy investigation of the Irig loess-palaeosol sequence (LPS), Vojvodina, Serbia. Our results show that 4-11 mu m quartz is a reliable dosimeter only up to similar to 59 ka (179 Gy), after which the OSL ages underestimate the expected ages based on stratigraphy. The pIRIR 290 signal displays generally good luminescence behaviour and resultant ages show good agreement with the expected stratigraphic ages, although with apparent 15 kyr and 35 kyr age underestimations at the L2-52 and 52-L3 boundaries, respectively. The calculated dust mass accumulation rates (MAR) reveal large fluctuations during the last two glacial-interglacial cycles. During the penultimate glacial, the highest MARs were observed between 171 and 181 ka, subsequently decreasing rapidly during MIS 5. During the last glacial period, dust MARs display maximum values during MIS 2 and MIS 4, while the lowest dust input was observed during the Holocene, followed by MIS 3. Dust MAR and grain-size shifts appear to lead changes in magnetic susceptibility by several kyr. Our results imply that changes in dust availability and wind dynamics occurred prior to changes in climate-controlled soil moisture conditions at the Irig LPS. Moreover, our results reveal a close coupling of the dust MAR and grain-size variations during the Mid-Late Pleistocene. These patterns suggest that the Irig site is likely representative of regional dust dynamics, which separates it from more source proximal loess sites, such as those close to major rivers, which are likely more affected by local dust availability and river discharge.
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| 7. |
- Peric, Zoran, et al.
(författare)
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Quartz OSL dating of late quaternary Chinese and Serbian loess : A cross Eurasian comparison of dust mass accumulation rates
- 2019
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 502:Part A, s. 30-44
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Tidskriftsartikel (refereegranskat)abstract
- Reconstructing dust Mass Accumulation Rate (MAR) from loess deposits is critical to understanding past atmospheric mineral dust activity and requires accurate independent age models from loess deposits across Europe and Asia. Previous correlations of loess in Europe and China have tended to focus on multi-millennial timescales, with no detailed examination of dust MAR at the two ends of the Eurasian loess belt on shorter, sub-orbital scales. Here we present a detailed quartz optically stimulated luminescence (OSL) chronology from the Serbian Titel Loess Plateau (Veliki Surduk loess core) and the Chinese Loess Plateau (Lingtai section). The luminescence ages pass internal tests and show consistent increases in age with depth, with no obvious major hiatuses. However, as reported before, it seems the quartz OSL technique is only capable of accurate age determination up to accrued doses of ca. 150 Gy (ca. 30–40 ka) due to approaching field saturation of the quartz OSL signal. Two age-depth models were used to reconstruct dust MARs, where one utilises OSL data solely and the other additionally makes assumptions about sedimentation rates. Although short-term fluctuations in MAR are model dependent, general MAR patterns between the two sites are very similar, with peak MAR occurring rather late in the last glacial (ca. 13–25 ka). This suggests that at least broad scale trends in dust activity within the last glacial period may be similar at a continental scale.
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| 8. |
- Potter, Stephan, et al.
(författare)
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Disentangling Sedimentary Pathways for the Pleniglacial Lower Danube Loess Based on Geochemical Signatures
- 2021
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Ingår i: Frontiers in Earth Science. - : Frontiers Media S.A.. - 2296-6463. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The source of aeolian sediments such as loess has been investigated since decades. Reliable knowledge on potential dust sources is crucial to understand past climatic and environmental conditions accompanying the dispersal of early modern humans (EMH) into Europe. Provenance studies are usually performed on small sample sets and most established methods are expensive and time-consuming. Here, we present the results of high-resolution geochemical analyses performed on five loess-palaeosol sequences from the Lower Danube Basin (LDB), a region, despite its importance as a trajectory for EMH, largely underrepresented in loess provenance studies. We compare our results with geochemical data of loess-palaeosol sequences from Austria, Hungary, Serbia, and Ukraine. Based on published literature, we thus evaluate five plausible sedimentary pathways for the LDB loess: 1) the Danube alluvium (DA) pathway, which constrains the transport and re-deposition of detrital material by the Danube and its tributaries; 2) the Carpathian Bending (CB) pathway, where sediment is mainly transported from the Cretaceous to Neogene flysch of the Eastern Carpathian Bending; 3) the Eastern Carpathian (EC) pathway, in which sediment is eroded from the flysch of the Outer Eastern Carpathians, transported by rivers, and deflated by northwesterly to westerly winds; 4) the glaciofluvial (GF) pathway, where dust is deflated from glacial outwash plains in nowadays Ukraine, and 5) the Black Sea (BS) pathway, where dust originates from the exposed shelf of the Black Sea. Based on geochemical data, we consider the DA pathway to be the major sediment trajectory for loess in the LDB. Especially the sequences located close to the Danube and the Dobrogea show similarities to sites in Central and Northeast Hungary as well as Northern Serbia. For the northeastern part of the LDB, we demonstrate that dust input is mainly sourced from primary material from the Eastern Carpathians. Mineralogical estimations and geochemical data render the CB pathway as an additional substantial source of detrital material for the loess of this area. We consider the influence of the GF pathway in the LDB as negligible, whereas some minor influences of the BS pathway cannot be ruled out based on geochemical data.
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| 9. |
- Schaetzl, Randall J., et al.
(författare)
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Approaches and challenges to the study of loess : Introduction to the Loess-Fest Special Issue
- 2018
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 89:3, s. 563-618
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In September 2016, the annual meeting of the International Union for Quaternary Research's Loess and Pedostratigraphy Focus Group, traditionally referred to as a LoessFest, met in Eau Claire, Wisconsin, USA. The 2016 LoessFest focused on thin loess deposits and loess transportation surfaces. This LoessFest included 75 registered participants from 10 countries. Almost half of the participants were from outside the United States, and 18 of the participants were students. This review is the introduction to the special issue for Quaternary Research that originated from presentations and discussions at the 2016 LoessFest. This introduction highlights current understanding and ongoing work on loess in various regions of the world and provides brief summaries of some of the current approaches/strategies used to study loess deposits.
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| 10. |
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| 11. |
- Sümegi, Pál, et al.
(författare)
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Comparison of High-Resolution 14C and Luminescence-Based Chronologies of the MIS 2 Madaras Loess/Paleosol Sequence, Hungary : Implications for Chronological Studies
- 2022
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Ingår i: Quaternary. - : MDPI. - 2571-550X. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- Numerous loess/paleosol sequences (LPS) in the Carpathian Basin span the period of Marine Isotope Stage (MIS) 2 and the last glacial maximum (LGM). Nevertheless, only two known records-Madaras and Dunaszekcso-preserve highly resolved records with absolute chronologies with minimal uncertainties, which enable the meaningful assessment of feedbacks and short-term climatic fluctuations over this period. The Madaras profile is located at the northern margin fringe of the Bacska loess plateau; Dunaszekcso, located on the Danube to its west, yields a chronology built on over 100 C-14 dates yet spans only part of MIS 2, missing half of the LGM including its peak. Here, we add to the previously published C-14 chronology for Madaras (15 dates) with an additional 17 C-14 and luminescence ages. Resulting age models built solely on quartz OSL and feldspar pIRIRSL data underestimate the C-14 based chronology, which is likely based on inaccuracies related to luminescence signal behavior; we observe age underestimations associated with unusual quartz behavior and significant signal loss, a phenomenon also observed in Serbian and Romanian loess, which may relate to non-sensitized grains from proximal sources. Our new chronology provides higher resolution than hitherto possible, yielding consistent 2 sigma uncertainties of similar to 150-200 years throughout the entire sequence. Our study indicates that the addition of further dates may not increase the chronological precision significantly. Additionally, the new age model is suitable for tackling centennial-scale changes. The mean sedimentation rate based on our new age-depth model (10.78 +/- 2.34 years/cm) is the highest yet recorded in the Carpathian Basin for MIS 2. The resolution of our age model is higher than that for the Greenland NGRIP ice core record. The referred horizons in our profile are all characterized by a drop in accumulation and a higher sand input, the latter most likely deriving from nearby re-exposed sand dunes.
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| 12. |
- Vinnepand, Mathias, et al.
(författare)
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Decoding geochemical signals of the Schwalbenberg Loess-Palaeosol-Sequences — A key to Upper Pleistocene ecosystem responses to climate changes in western Central Europe
- 2022
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Ingår i: Catena. - : Elsevier BV. - 0341-8162. ; 212
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Tidskriftsartikel (refereegranskat)abstract
- Loess deposits are the most extent continental archives of climatic- and environmental change and represent important components of local and global dust systems. Consequently, their geochemistry provides an excellent basis for studying climate oscillations on land and how these affect processes in the terrestrial system. It is, however, challenging to assess information archived in loess records due to complexities in their formation, causing interfering geochemical signatures. In particular, the use of element ratios to derive weathering indices may be complicated since dust sources change through time, and since ecosystems respond differently to changing conditions. Whilst this complexity appears as limiting factor, the explanatory potential of proxies increases when the diversity of geochemical processes is acknowledged. To make use of this potential, we integrate the decadic logarithm of element ratios indicative for provenance shifts, mineral sorting during transport and sediment reworking as well as weathering into multivariate statistical analysis. We test, if the sensitivity of Principal Component Analyses (PCA) and Linear Discriminant Analysis (LDA) can be increased by applying both to sub-datasets of diagnostic Stratigraphic Units (SU) of the Schwalbenberg Loess-Palaeosol-Sequences (Middle Rhine valley, Germany). The selected site recorded sub-millennial Upper Pleistocene ecological changes in an unprecedented resolution for Central European LPS. Differences in operating functions of PCA and LDA and our age model highlight timing and intensity of provenance shifts, sediment relocation, decalcification, redox dynamic and clay-mineral formation associated with Atlantic-driven climate oscillations. Based on this we provide evidence for the accretionary character of interstadial palaeosols caused by a close interplay of dust input and soil formation. Automated re-detection of SU across the site using LDA functions contributes important insights into slope dynamics through regional erosion events. Overall, our approach provides a key for tracing ecological changes during climate oscillations across continents.
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