75 research outputs found
The Crvenka loess-paleosol sequence (Vojvodina, Northern Serbia)- a record of continuous domination of the Late Pleistocene grasslands
In this study we present a comparison of two independent paleo-environmental evidences: novel n-alkane biomarkers and traditional land snails assemblages, associated with widely used proxy records such as the low field magnetic susceptibility, grain size and various isotopic and geochemical indices. These paleo-environmental proxy records provide evidence for the continued predominance of the different grassland vegetation types during the entire Late Pleistocene. The results presented in this study highlight the spatial differences in the environmental conditions during the Late Pleistocene across the European loess belt. Contrary to other European loess provinces characterized by high diversity of the Late Pleistocene environments (ranging from tundra-like to deciduous forest habitats), our investigations indicate a continued dominance of grassland-dominated ecosystems in the southeastern Carpathian Basin. This uninterrupted presence of Late Pleistocene grassland zone in the southeastern part of the Carpathian Basin may have played an important role in the preservation of exceptional biodiversity of the Balkan region, as well as in the migration of anatomically modern humans into Europ
A post-IR IRSL chronology and dustmass accumulation rates of the Nosak loess-palaeosol sequence in northeastern Serbia
In the Middle Danube Basin, Quaternary deposits are widely distributed in the Vojvodina region where they cover
about 95% of the area.Major research during the last two decades has been focused on loess deposits in the Vojvodina
region. During this period, loess in the Vojvodina region has become one of the most important Pleistocene European
continental climatic and environmental records.Herewe present the dating results of 15 samples taken from theNosak
loess-palaeosol sequence in northeastern Serbia in order to establish a chronology over the last three glacial–
interglacial cycles. We use the pIRIR290 signal of the 4–11 lm polymineral grains. The calculated ages are within the
error limits partially consistent with the proposed multi-millennial chronostratigraphy for Serbian loess. The average
mass accumulation rate for the last three glacial–interglacial cycles is 265 g m�2 a�1
, which is in agreement with the
values of most sites in the Carpathian Basin. Our results indicate a highly variable deposition rate of loess, especially
during the MIS 3 and MIS 6 stages, which is contrary to most studies conducted in Serbia where linear sedimentation
rates were assume
Palaeoclimate record in the Late Pleistocene loess-paleosol sequence at Miseluk (Vojvodina, Serbia)
Climatic fluctuations inferred for the Middle and Late Pleniglacial (MIS 2) based on high-resolution (∼ca. 20 y) preliminary environmental magnetic investigation of the loess section of the Madaras brickyard (Hungary)
Abstract
The Madaras brickyard section found at the northernmost fringe of the Backa loess plateau is one of the thickest and best-developed last glacial loess sequences of Central Europe. In the present work high-resolution magnetic susceptibility measurements (at 2 cm) were implemented on samples from the 10 m-section corresponding to a period between 29 and 11 KY cal b2K. One aim was to compare the findings with the ice core records of northern Greenland in order to establish a high-resolution paleoclimatic record for the last climatic cycle and with findings documented in other biotic and abiotic proxies so far. Our results revealed a strong variability of loess/paleosol formation during MIS 2. Millennial time-scale climatic events that characterize the North Atlantic during the last climatic cycle have been identified. From 29 ka up to the start of the LGM, the recorded MS values show a weak, negative correlation with the temperature proxy, and a weak positive correlation with the dust concentration of Greenland. A strong correlation was observed with the local paleotemperatures. Local climatic factors must have had a more prominent effect here on loess/paleosol development than the climate shifts over Greenland. During the LGM the same pattern is seen with a stronger correlation with the dust concentrations and a weaker correlation with the local temperature. Local climatic factors, plus dust accumulation, must have had a prominent influence on loess/paleosol development here. From the terminal part of the LGM a strong positive correlation of the MS values with the temperature proxy for Greenland accompanied by a strong negative correlation with the dust concentration values is observed. Correlation with local paleotemperatures is positive and moderate, strong. Here climate shifts over Greenland, as well as local endowments equally had an important role on the development of the MS signal
Two possible source regions for Central Greenland last glacial dust
Dust in Greenland ice cores is used to reconstruct the activity of dust-emitting regions and atmospheric circulation. However, the source of dust material to Greenland over the last glacial period is the subject of considerable uncertainty. Here we use new clay mineral and <10 µm Sr–Nd isotopic data from a range of Northern Hemisphere loess deposits in possible source regions alongside existing isotopic data to show that these methods cannot discriminate between two competing hypothetical origins for Greenland dust: an East Asian and/or central European source. In contrast, Hf isotopes (<10 µm fraction) of loess samples show considerable differences between the potential source regions. We attribute this to a first-order clay mineralogy dependence of Hf isotopic signatures in the finest silt/clay fractions, due to absence of zircons. As zircons would also be absent in Greenland dust, this provides a new way to discriminate between hypotheses for Greenland dust sources
Loess Correlations – Between Myth and Reality
Abstract The correlation of loess sequences across global, hemispheric, regional and local scales is one of the most fundamental aspects to loess research. However, despite recent progress in stratigraphic and chronometric methods, the correlation of many loess sequences is often still based on untested assumptions over loess deposition, preservation, soil type and age. As such, the aim of this overview is to provide an adequate framework for evaluation of the accuracy of loess correlations applied on different temporal and spatial scales across Eurasia. This opens up possibilities for detailed temporal and spatial environmental reconstructions across the huge loess provinces of the Eurasia and provides a framework for future extension of this to North America. Additionally, we evaluate the potential development of appropriate sub-millennial scale loess correlations, as well as essentially important chronological approaches for establishing valid correlations between different loess records, such as current improvements in tephrochronology, 14C and luminescence dating techniques
Cardiopoietic cell therapy for advanced ischemic heart failure: results at 39 weeks of the prospective, randomized, double blind, sham-controlled CHART-1 clinical trial
Cardiopoietic cells, produced through cardiogenic conditioning of patients' mesenchymal stem cells, have shown preliminary efficacy. The Congestive Heart Failure Cardiopoietic Regenerative Therapy (CHART-1) trial aimed to validate cardiopoiesis-based biotherapy in a larger heart failure cohort
An enthusiasm for loess: Leonard Horner in Bonn and Liu Tungsheng in Beijing
Liu Tungsheng featured on the list of twelve notable loess investigators prepared for the great LoessFest meeting, held in Heidelberg and Bonn in 1999. He fully deserved his position on this list of eminent loess scholars; in fact it might be argued that his was the major contribution. His contribution was a true paradigm shift in the world of loess investigation.Obruchev and Richthofen had produced an earlier paradigm shift when they propagated the idea that loess deposits form by aeolian deposition- a paradigm shift away from the earlier Lyellian idea of lacustrine or fluvial deposition. But that was a fairly simple shift, a tweak of the sedimentological event structure. Liu, and his co-workers in China, produced a new vision, a new way of looking at loess, not so much a paradigm shift as a paradigm enlargement. Post-Liu the Quaternary era was a new land, a new place with a real chronology and a landscape of events and amazing happenings
Loess and fragipans: Development of polygonal-crack-network structures in fragipan horizons in loess ground
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