János Kovács
Working on Late Miocene-Quaternary sedimentology, paleontology and stratigraphy mostly in Central Europe.
Address: Ifjusag u. 6
H-7624 Pecs, Hungary
Address: Ifjusag u. 6
H-7624 Pecs, Hungary
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Papers by János Kovács
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 paleoenvironmental
studies. However, the interpretation of these proxies often only consider dust transport
processes. To move beyond such overly simplistic proxy interpretations, and toward proxy
interpretations that consider the range of environmental processes that determine loess particle
size distribution variations we provide a comprehensive review on the physics of dust particle
mobilization and deposition. Furthermore, using high-resolution bulk loess and quartz grain
size datasets from a last glacial/interglacial sequence, we show that, because grain size
distributions are affected by multiple, often stochastic processes, changes in these
distributions over time allow multiple interpretations for the driving processes. Consequently,
simplistic interpretations of proxy variations in terms of only one factor (e.g. wind speed) are
likely to be inaccurate. Nonetheless using loess proxies to understand temporal changes in the
dust cycle and environmental parameters requires (i) a careful site selection, to minimize the
effects of topography and source distance, and (ii) the joint use of bulk and quartz grain size
proxies, together with high resolution mass accumulation rate calculations if possible.
Comparison of geodetic datasets and field observations with the timing of rainfall and water level changes of the Danube suggested that hydrological properties (subsurface flow processes, soil physical properties, infiltration, and perched water table) were primarily responsible for initiation of the studied slump. A model of slope failure evolution is proposed here based on the monitoring and field observations.
the central Carpathian Basin (Hungary) (Tengelic Red Clay Formation; Kerecsend Red Clay Formation), overlain by loess–palaeosol sequences, were studied. Results from geochemical climofunctions applied to Upper Pliocene–Lower Pleistocene red clays and palaeosols located in the Carpathian Basin, and clay mineralogy, indicate that the palaeoclimate was considerably more humid and warmer during the Late Pliocene–Early Pleistocene in comparison to modern values."
Comparison of geodetic datasets and field observations with the timing of rainfall and water level changes of the Danube suggested that hydrological properties (subsurface flow processes, soil physical properties, infiltration, and perched water table) were primarily responsible for initiation of the studied slump. A model of slope failure evolution is proposed here based on the monitoring and field observations."
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 paleoenvironmental
studies. However, the interpretation of these proxies often only consider dust transport
processes. To move beyond such overly simplistic proxy interpretations, and toward proxy
interpretations that consider the range of environmental processes that determine loess particle
size distribution variations we provide a comprehensive review on the physics of dust particle
mobilization and deposition. Furthermore, using high-resolution bulk loess and quartz grain
size datasets from a last glacial/interglacial sequence, we show that, because grain size
distributions are affected by multiple, often stochastic processes, changes in these
distributions over time allow multiple interpretations for the driving processes. Consequently,
simplistic interpretations of proxy variations in terms of only one factor (e.g. wind speed) are
likely to be inaccurate. Nonetheless using loess proxies to understand temporal changes in the
dust cycle and environmental parameters requires (i) a careful site selection, to minimize the
effects of topography and source distance, and (ii) the joint use of bulk and quartz grain size
proxies, together with high resolution mass accumulation rate calculations if possible.
Comparison of geodetic datasets and field observations with the timing of rainfall and water level changes of the Danube suggested that hydrological properties (subsurface flow processes, soil physical properties, infiltration, and perched water table) were primarily responsible for initiation of the studied slump. A model of slope failure evolution is proposed here based on the monitoring and field observations.
the central Carpathian Basin (Hungary) (Tengelic Red Clay Formation; Kerecsend Red Clay Formation), overlain by loess–palaeosol sequences, were studied. Results from geochemical climofunctions applied to Upper Pliocene–Lower Pleistocene red clays and palaeosols located in the Carpathian Basin, and clay mineralogy, indicate that the palaeoclimate was considerably more humid and warmer during the Late Pliocene–Early Pleistocene in comparison to modern values."
Comparison of geodetic datasets and field observations with the timing of rainfall and water level changes of the Danube suggested that hydrological properties (subsurface flow processes, soil physical properties, infiltration, and perched water table) were primarily responsible for initiation of the studied slump. A model of slope failure evolution is proposed here based on the monitoring and field observations."
The Late Miocene to Pleistocene Bakony–Balaton Highland Volcanic Field (BBHVF) in western Hungary is a typical small sized (< 50 eruption centres), basaltic, intraplate “monogenetic” volcanic field. Generally, initial eruptions of the BBHVF were phreatomagmatic (n = ~ 28); however, a lesser number (n = ~ 14) of predominantly scoria cone forming eruptions are also inferred. The temporal distribution of the Strombolian style scoria cones was concentrated mostly between 3 and 2.5 Ma. A detailed study of the changes in eruption styles recorded in the pyroclastic sequences suggested a change from a conventional phreatomagmatic to a magmatic fragmentation style during the activity of the volcanic field. A clear correlation has been identified between the long-term environmental changes of the region that resulted in a gradual shift from a more phreatomagmatic eruption style to a more magmatic eruption style. Detailed examination of the temporal distribution of K–Ar and Ar–Ar radiometric data, Digital Elevation Model and Dense Rock Equivalent-based volume calculations of eruptive products and origin of pyroclastic rocks (e.g. phreatomagmatic or magmatic) preserved in variously eroded monogenetic volcanoes were utilized to integrate available volcanological and climatological data to identify potential links between external and internal controlling parameters that responsible for long-term eruption style changes."