G. Újvári

G. Újvári
Research Centre for Astronomy and Earth Sciences, Institute for Geological and Geochemical Research

PhD

About

85
Publications
23,247
Reads
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2,000
Citations
Citations since 2017
38 Research Items
1465 Citations
20172018201920202021202220230100200300
20172018201920202021202220230100200300
20172018201920202021202220230100200300
20172018201920202021202220230100200300
Introduction
Gábor Újvári is an Earth scientist with major research interests in Quaternary geology and paleoclimate, low temperature isotope geochemistry and absolute radiometric dating of sedimentary rocks (dust deposits) of the last 5 million years and provenance fingerprinting of aerosols/mineral dust using Hf, Sr, Nd and U-Pb isotopes.
Additional affiliations
October 2018 - September 2020
University of Vienna
Position
  • PostDoc Position
October 2017 - August 2018
Hungarian Academy of Sciences
Position
  • Senior Researcher
April 2017 - September 2017
Technical University of Denmark
Position
  • Senior Researcher

Publications

Publications (85)
Article
Full-text available
Significance Atmospheric dust is a major component of climate change. However, the relationship between glacial continental dust activity and abrupt centennial–millennial-scale climate changes of the North Atlantic is poorly known. Recent advances in high-precision radiocarbon dating of small gastropods in continental loess deposits provide an oppo...
Article
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The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to divide geologic time. The reliability of these records is fundamental to understand past global change. Here we use the most detailed luminescence dating age model yet published to show that the ICS chronology for the Quaternary terrestrial type section at...
Article
Full-text available
RATIONALE Complete decomposition of silicate rock matrices is crucial in determining their isotopic compositions, but acid dissolution in high‐pressure steel‐jacketed bomb, which has been the only powerful, effective technique thus far, is time‐consuming and expensive. Rock dissolution using ammonium bifluoride (ABF) is a viable alternative, which...
Article
Full-text available
Last glacial North Atlantic climate is characterized by abrupt, centennial-millennial scale climate oscillations, called Dansgaard-Oeschger (D-O) events. Understanding the cause and propagation of these D‒O events into Eurasia is hampered by the scarcity of quantitative paleotemperature estimates from continental archives with precise, independent...
Article
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Abrupt and large-scale climate changes have occurred repeatedly and within decades during the last glaciation. These events, where dramatic warming occurs over decades, are well represented in both Greenland ice core mineral dust and temperature records, suggesting a causal link. However, the feedbacks between atmospheric dust and climate change du...
Article
There is an increasing need for paleoclimate records from continental settings to better understand the climatic changes during critical periods such as the Pliocene and Early Pleistocene. Present data indicates a transition from a warmer than present-day climate to a substantially different cooler climate. This study reviews the oxygen and carbon...
Article
Poor understanding of the differential evolution of interglacial climate over various regions in Eurasia greatly limits our ability to predict the specific local impacts of future climate change. Here we demonstrate starkly opposing trends in interglacial intensities in Asia and Europe over the early Middle Pleistocene and Mid-Brunhes Transitions b...
Article
The climate and environmental conditions in the Carpathian Basin and the adjacent northern Italy/Adriatic region during the Last Glacial Maximum (LGM) exhibit some major differences, as compared to present-day conditions. For instance, high accumulation rates recorded in loess deposits point to an active dust cycle during the LGM. Here, we investig...
Article
Magnetic susceptibility measurements play a key role in Quaternary studies. Magnetic proxies, such as low field and frequency-dependent magnetic susceptibility, are widely applied in the reconstruction of terrestrial paleoclimate, e.g., in the study of loess-paleosol successions. In general, the interpretation of loess magnetic susceptibility signa...
Article
The role of environmental change in the evolution of cultural traits is a topic of long-standing scientific debate with strongly contrasting views. Major obstacles for assessing environmental impacts on the evolution of material culture are the fragmentary nature of archaeological and – to a somewhat lesser extent – geoscientific archives and the i...
Article
A summary of approximately three decades and greater than thirty loess magnetic fabric studies is presented here. The revised studies cover various loess regions from the Chinese Loess Plateau across the European Loess Belt to Alaska. Although there is still an ongoing argument about the feasibility of the magnetic fabric of loess in paleowind rec...
Article
Full-text available
Plio-Pleistocene silt/clay-rich deposits and paleo-karst fissure sediments from sites of the northern and southern parts of the Carpathian Basin were investigated. These materials were supposed to be mixed during transport before being captured in karstified fissures. Evidence that the eolian fissure sediments of Plio-Pleistocene age in the older T...
Conference Paper
Full-text available
Mineral dust in ice cores provides insight into past atmospheric circulation patterns provided that the source(s) of these aerosols can be identified. Isotopes of strontium, neodymium and lead are frequently used for source discrimination in ice cores, while those of hafnium much less so. This is because of the extremely low (1-5 ng) amounts of Hf...
Article
We describe the Late Pliocene paleoenvironment and paleoclimate of the Pula fossil site of the western Pannonian Basin, Hungary, which occurs within a lacustrine succession deposited in a volcanic crater (maar). Radiometric dating of adjacent volcanic bodies hosting the fossil-bearing sedimentary assemblages gives an age of 4.25 ± 0.17 Ma (K-Ar). T...
Article
Laser diffraction grain size data and size distributions of paleosols are widely used in paleoenvironmental reconstructions as physicochemical alteration-related proxies of past changes of the sedimentary environment. Different laser diffraction devices, optical theories, and optical settings are being applied nowadays, and ignorance of several unc...
Article
Full-text available
Glacial settings are considered to be the most challenging context for the application of luminescence dating. The optically stimulated luminescence (OSL) signal of quartz is often preferred for luminescence dating in partially-bleached settings as it resets (or bleaches) more rapidly in response to sunlight than the post-IR IRSL (pIRIR) signal of...
Article
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 multimillennial timescales, with no detailed exam...
Article
Quantitative paleotemperature reconstructions for the continents, including East Central Europe, over marine isotope stage 5 (MIS 5) and specifically the last interglacial (LIG, MIS 5e) are scarce and mostly based on pollen assemblages. Here we provide soil and air temperature reconstructions for the summer season of MIS 5e (5c) using carbonate clu...
Article
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Grain size proxies of aeolian dust deposits have widely been applied in environmental and sedimentary studies. However, large body of research papers are not taking into consideration that a complex grain size distribution curve cannot be an indicator of a single one environmental factor (e.g. wind speed/strength, transportation distance, aridity)....
Article
During field work at the Ibn Battuta Mars analogue sites, two research questions were analyzed: (1) How do we identify sampling sites using remote and local imaging and (2) what kind of information can be gained from shallow subsurface exploration? While remote images help in targeting field activities in general, the connection between observation...
Article
Full-text available
Previous work has been unable to establish a relationship between K concentration and De in single-grains of feldspar. Here we use four well-bleached sediments with low external dose rate (typically ≤1.5 Gy ka⁻¹) to investigate this relationship. Single and multi-grain pIRIR measurements and μ-XRF analyses are made on Na- and K-rich extracts; μ-XRF...
Article
The particle size, shape, surface texture and composition of aeolian and fluvial sedimentary samples were analyzed and compared using optical microscope-based automatized image analysis, in order to suggest indicators that could discriminate these two modes of transport on Mars. The principal goal is to assess if such indicators – established on Ea...
Article
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...
Article
We describe magnetic fabric and depositional environments of aeolian (loess) deposits from Paks, Hungary, and develop a novel, complex conceptual sedimentation model based on grain size and low-field magnetic susceptibility anisotropy data. A plot of shape factor (magnetic fabric parameter) and dry deposition velocity estimated from grain-size reve...
Data
R script associated with the manuscript 'Quartz OSL dating of late Quaternary Chinese and Serbian loess: a cross Eurasian comparison of dating results and mass accumulation rates' by Zoran Peric et al.
Data
Equivalent dose measurements (De, recycling ratio and recuperation), dose recovery tests (Dr) and luminescence ages for the Titel loess core and the the Lingtai loess section. The file also includes the grain-size distribution data for the Lingtai loess section and the Loess Mass Accumulation Rate (MAR g m-2 a-1) calculated for Titel and Lingtai ba...
Article
Full-text available
Combined Sr-Nd-Hf isotopic data of two reference materials (AGV-1/BCR2) and 50, 10 and 5 mg aliquots of carbonate-free fine grain (<10 μm) separates of three loess samples (Central Europe/NUS, China/BEI, USA/JUD) are presented. Good agreement between measured and reference Sr-Nd-Hf isotopic compositions (ICs) demonstrate that robust isotopic ratios...
Article
Full-text available
Great advances are expected during the analysis of drilled material acquired from 2 m depth by ExoMars rover, supported by the comparison to local context, and the joint use of different instruments. Textural information might be less detailed relatively to what is usually obtained at outcrops during classical geological field work on the Earth, pa...
Article
Loess deposits are recorders of aeolian activity during past glaciations. Since the size distribution of loess deposits depends on distance to the dust source, and environmental conditions at the source, during transport, and at deposition, loess particle size distributions and derived statistical measures are widely used proxies in Quaternary pale...
Article
Full-text available
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 deposit...
Article
Full-text available
Loess sediments in Austria deposited ca. 30–20 ka ago yield different zircon age signatures for samples collected around Krems (SE Bohemian Massif; samples K23 and S1) and Wels (halfway between the Bohemian Massif and the Eastern Alps; sample A16). Cathodoluminescence (CL) imaging reveals both old, multistage zircons with complex growth histories a...
Article
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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...
Article
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The paper describes the investigation of the mass movements of one of the most dangerous high banks along the River Danube at Dunaszekcso in Hungary. Cracks appeared on this part of the high bank in 2007, indicating the beginning of a new landslide. In autumn of the same year, a geodetic network for observation of the movements was created. The net...
Conference Paper
Full-text available
Particle size data are holding crucial information on the sedimentary environment at the time the aeolian dust deposits were accumulated. Various aspects of aeolian sedimentation (wind strength, distance to source(s), possible secondary source regions and modes of sedimentation and transport) can be reconstructed from proper grain size distribution...
Article
Full-text available
Millennial scale warm-cold oscillations in air temperature over Greenland and rapid sea surface temperature changes were recorded in ice cores and North Atlantic sediments for the last glaciation. These events must have been associated with profound environmental changes in Europe, and indeed, millennial scale oscillations in grain size records hav...
Article
Five years of geodetic monitoring data at Dunaszekcső, Hungary, are processed to evaluate recurrent landsliding, which is a characteristic geomorphological process affecting the high banks of the Middle Danube valley in Hungary. The integrated geodetic observations provide accurate three dimensional coordinate time series, and these data are used t...
Article
We outline how the data from the drilled samples by the ExoMars rover will provide information on the source, tranport, and paleoenvironment of the particles.
Article
The Paks loess-paleosol sequence is one of the most important terrestrial records of Middle and Late Pleistocene environmental changes in East Central Europe, spanning the last ca. 0.8 Ma. While geochemical proxies demonstrate a general decreasing chemical weathering trend over the last 0.8 Ma in the Carpathian Basin, mineralogy and derived indices...
Article
Trace element (Cr, Nb, Zr) geochemistry and U-Pb geochronology of detrital rutile grains provide constraints on the nature of potential metamorphic sources of loess in Austria. Cr and Nb compositions reveal rutile sources with a predominance of metapelitic lithologies for all three loess samples. By contrast, Zr-in-rutile geothermometry indicates t...
Article
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Geochemical and mineralogical studies of palaeosols provide essential information for palaeoclimatic and palaeoenvironmental interpretation of continental deposits and can present a proxy for palaeoclimate. Red clays in the central Carpathian Basin (Hungary) (Tengelic Red Clay Formation; Kerecsend Red Clay Formation), overlain by loess-palaeosol se...
Article
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Previous studies on detrital rutiles in sandstones demonstrated that rutile trace element geochemistry (especially Cr and Nb contents) and Zr-in-rutile thermometry may yield diagnostic data on the lithology and metamorphic facies of possible source rocks. U-Pb geochronology of detrital rutiles is as yet rare in spite of its potential to date metamo...
Article
Full-text available
Geochemical and mineralogical studies of paleosols provide essential information for paleoclimatic and paleoenvironmental interpretation of continental deposits and can present a high-resolution proxy for paleoclimate. Consequently, paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that inf...
Article
Aeolian dust particles and dust storms play substantial role in climatic and other environmental processes of the Earth system. The largest and most important dust source areas are situated in the Sahara, from where several hundred thousand tons of mineral dust is emitted each year and transported towards the European continent. Here we show that 1...
Article
Full-text available
In September 2007 a geodetic network based on GPS measurements, precise levelling and continuous borehole tilt measurements was established for surface displacement monitoring on the high bank of the River Danube at Dunaszekcső where a serious landslide began to develop at that time. The landslide took place on February 12, 2008. After rapid, enorm...
Article
Stable carbon and oxygen isotope values (δ13C, δ18O) of structural carbonate were determined in the bioapatite component of fossil teeth from the Czech Republic, Slovakia and Hungary. Oxygen isotope compositions of enamel and dentin samples provide new quantitative records of the Late Pleistocene climate in East Central Europe (ECE). These δ18O dat...
Article
Full-text available
Aeolian dust deposits can be considered as one of the most important archives of past climatic changes. Alternating loess and paleosol strata display variations of the dust load in the Pleistocene atmosphere. By using the observations of recent dust storms, we are able to employ Late Pleistocene stratigraphic datasets (with accurate chronological f...
Article
Multiple competing hypotheses have been proposed to explain the source of loess dust in the Carpathian Basin yet none has been demonstrated. Here bulk and grain-size differentiated Nd and Sr isotopic and bulk and clay mineralogical compositions, together with detrital zircon ages and morphologies from loess along the Danube in the Carpathian Basin...
Article
Paleosols and Pleistocene loess-paleosol sequences preserve important information on landscape stability and soil formation, paleoclimate, and paleoenvironment. The nature of clay mineral assemblages (mineral composition of the clay fraction, <2 μm) is primarily a function of climate. Therefore, clay mineralogy is considered to be a powerful tool f...
Article
Full-text available
Terrestrial red clays underlying Quaternary loess deposits, or filling fissures and recently existing caves in limestone are named Tengelic Red Clay Formation and Kerecsend Red Clay Formation (Middle Pliocene to Lower Pleistocene). They occur in three types in Hungary. (1) The oldest red clays are mainly in situ weathering crusts rich in kaolinite,...
Article
The role of two major factors, climate and tectonism, in controlling loess–paleosol evolution has been evaluated in the present study based on a multi-proxy dataset comprising mollusc, bulk and clay mineralogical, and geochemical data. A recent trend has been to use chemical indices such as the chemical index of alteration (CIA) for paleoclimate re...
Article
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The Mende loess-palaeosol sequence is one of the type profiles in Hungary, which records the evolution of middle and late Pleistocene environments at the Gödöllő Hills. A rudimentary age-depth model has been created for the youngest part (30 kyr) of the profile by using previous TL-IRSL data. According to this model, the mean sedimentation rate (SR...
Article
Loess–paleosol sequences are significant records of the mineral dust cycle of glacial–interglacial periods. As dust particles give rise to direct and indirect radiative forcing, obtaining a reliable picture of the global and regional patterns of mineral dust fluxes during glacial periods can lead to a better understanding of the contribution of min...
Article
Full-text available
Origin and formation characteristics of loess deposits in the Carpathian Basin have long been debated and remain unresolved. Previous work [1, 2] identified 3 main sources of loess deposits in this region: (I) glacial materials carried through the Moravian Depression by glacial floodwaters, (II) weathering products of the Carpathian Flysch deposits...
Article
After more and more significant deformations and accelerating displacements, rapid movements took place on the right bank of the Danube at Dunaszekcső (Hungary) in February, 2008 as the main phase of an enormous slope failure. It had a dimension of 220×20×60 m (length×width×depth) and the sliding mass was estimated at 0.3 million m3. Moving blocks...
Article
The banks of the River Danube are one of the most susceptible areas to mass wasting in Hungary. In 2007, a large slump began to develop along the Danube at Dunaszekcső and jeopardized properties on land and navigation in the river. Several factors such as geological, hydrogeological and morphological conditions, recurrent flooding and erosion by th...
Article
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According to the most continuous loess-palaeosol sequences of the World (e.g. China, Tajikistan, etc.) the climatic and environmental conditions allowed the formation of the oldest loess deposits at about 2.6 Ma BP. The loess layers are generally underlain by red clay, which is wind-blown in origin. So the oldest loess horizons in many regions can...
Article
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Relationships between regional tectonics, subsurface structures and mass movements are investigated on the high loess bank of the River Danube at Dunaföldvár based on remote sensing data, gravity and tilt measurements. The geology and morpho-tectonics of the area were derived from remote sensing images. The basement structure under the high loess b...