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Horvath F.,ELTE Foldrajz Es Foldtudomanyi Intezet | Dombradi E.,ELTE Foldrajz Es Foldtudomanyi Intezet | Dombradi E.,VU University Amsterdam
Foldtani Kozlony | Year: 2010

Early concepts in Hungarian tectonics were born about a century ago as a result of exploration of Lake Balaton and its surroundings conducted by Lajos LÓCZY. The papers collected in the present volume deal with the tectonic studies of the past decade around Lake Balaton. Therefore, it was considered necessary to review the early tectonic concepts in the light of contemporary knowledge in a comparative manner. First, an overview of the fundamentals of the fixistic median mass (Zwischengebirge) concept is given and its early mobilistic alternative is also presented. Some of the subsequent geological results favouring a mobilistic interpretation are analyzed, and the major contribution of seismic surveys and deep drillings for establishing the Alpine nappe structure of the Transdanubian Range is emphasized. Another early concept explained the formation of the Pannonian Basin in terms of the subsidence of blocks bounded by a longitudinal and a meridional set of faults. It was also thought that the present surface morphology, particularly a meridional system of valleys and ridges, was controlled by these faults. An early alternative view rejected this block-faulting and, instead, suggested regional scale-folding in the basin, and wind erosion as a primary mechanism of surface evolution. The new data gathered on the neotectonic evolution of the Pannonian Basin relies on seismic mapping of the young deformational features and the determination of the present day stress field. It is concluded that reactivation of Miocene synrift faults and/or Cretaceous compressional detachment planes has occurred and has resulted in folding at the south-western periphery, andregional strike-slip faulting all over the basin and surrounding mountains. Thus wind erosion as a main mechanism of Holocene surface evolution in the Pannonian Basin can be regarded as undegoing a process of revival. Source

Reka L.,ELTE Foldrajz Es Foldtudomanyi Intezet | Szabolcs H.,ELTE Foldrajz Es Foldtudomanyi Intezet | Gyula R.,Magyar Allami Foldtani Intezet | Marianna K.,ELTE Foldrajz Es Foldtudomanyi Intezet | And 2 more authors.
Foldtani Kozlony | Year: 2010

The nearly continuous drilling cores of the boreholes Miskolc-7, Miskolc-8 and Nyékládháza-1 provide a unique opportunity to investigate the nature of the thick Miocene volcanic formations present in the boreholes. The large number of volcanic layers implies there was repeated, intense volcanic activity from 19 Ma to 12 Ma. This work focuses on the volcanological, petrologic, geochemical and geochronological characterization of the thickest volcanic units. Most of the pyroclastic products were formed during the course of deposition from pumiceous pyroclastic flows under subaerial conditions, and therefore they are ignimbrites. The 18-19 Ma-old non-welded to welded ignimbrite shows many features similar to the pumiceous pyroclastic deposits which occurred over a wide area in the northern Pannonian Basin beneath the Ottnangian-Karpathian coal-bearing sequence. The large thickness (>140 metres) in the studied boreholes indicates an eruption of significant magnitude, possibly accompanied with the formation of a caldera or repeated explosive eruptions in the proximity of the area of the boreholes. The borehole Nyékládháza-1 revealed a 250 metre-thick volcanic suite above the coal-bearing sedimentary series. The data indicate a large temporal difference (ca. 3 Myr) between the lower and upper portion of this sequence! The respective volcanological nature and composition of the phenocrysts of the lower, 15-16 Ma-old ignimbrite are different from those characterize the ignimbrites of the middle volcanic suite of the Bükkalja. Therefore, an eruption of compositionally different silicic magmas could have occurred almost contempor-aneously in the northern Pannonian Basin during the Middle Miocene. In contrast, the 12-13 Ma-old ignimbrite found in the upper part of this thick volcanic sequence can be unambiguously correlated with the Harsány ignimbrite unit from the eastern part of the Bükkalja. The results obtained strongly suggest that the well-defined regional volcanic key-horizons in the Pannonian Basin should be revised. In contrast earlier suppositions, the present study emphasizes repeated volcanic eruptions throughout the Miocene and additionally, compositionally different magmas could have erupted frequently and contemporaneously, even in spatially restricted areas. Source

Breuer H.,ELTE Foldrajz Es Foldtudomanyi Intezet | Acs F.,ELTE Foldrajz Es Foldtudomanyi Intezet | Laza B.,ELTE Foldrajz Es Foldtudomanyi Intezet | Matyasovszky I.,ELTE Foldrajz Es Foldtudomanyi Intezet | And 3 more authors.
Agrokemia es Talajtan | Year: 2012

In this study, the relationship between the planetary boundary layer (PBL) and the hydraulic properties of the soil was analysed. Special attention was paid to the sensitivity of the PBL height to the dataset used for determining soil parameters. The simulations were performed using the MM5 meso-scale modelling system. The PBL height was estimated using both the Janjic's Eta PBL and MRF schemes, while the soil properties were calculated using soil datasets from Hungary and the USA. The model domain covered the Carpathian Basin, i.e. Hungary and certain territories belonging to neighbouring countries. Six days were analysed, three of them in detail (one day each in summer, autumn and winter). High pressure systems influenced the weather on most of the chosen days, so they were mostly cloud-free, leading to more intense insolation and stronger local convection, making it possible to detect the impact caused by soil differences. Each simulation was performed for 24 hours, starting at 0:00 UTC, and the outputs were displayed every 15 minutes. The results of the sensitivity test were also subjected to a significance test. When the Eta scheme was applied, 60-90% of the model domain was found to be significantly sensitive to the soil dataset used on five of the six days. Only on the winter day was this value below 50%, though when the MRF scheme was applied, the results for the same winter day showed a sensitivity of 89%, suggesting that changes in the height of PBL were more sensitive to the method used to parameterize the PBL height than to the soil database used. Nevertheless, it became clear that soil hydraulic properties could influence the weather not only in the case of rainfall, but also in rain-free weather situations of the convective type. The results obtained could be useful for the meso-scale modelling of soil-atmosphere feedback processes. Source

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