Marton acute; E.,Institute of Hungary |
Zampieri D.,University of Padua |
Kazmer M.,Eotvs University |
Dunkl I.,University of Gottingen |
Frisch W.,University of Tübingen
Tectonophysics | Year: 2011
From the "undeformed" foreland of the Southern Alps Paleocene through Early Miocene rocks, mostly biostratigraphically well-dated sediments with sub-horizontal bed attitude were collected for a paleomagnetic study from 23 geographically distributed localities. The samples were subjected to standard paleomagnetic measurements and evaluation. While the Miocene samples are unstable, most of the older localities yielded statistically well-defined paleomagnetic directions. These are interpreted as primary for the compact marls, supported by positive between-locality tilt and reversal tests. This large group of localities is characterized by CCW rotated declinations with respect to the present north. Combined with paleomagnetic directions of corresponding age from stable Istria, these allow definition of the APW for stable Adria for the 61.6-33.9. Ma interval, which is significantly displaced from the coeval segment of the African APW due to the decoupling of the former to the latter by a moderate CCW rotation. This post-Eocene final separation (exact age is not constrained directly, but estimated as end-of-Miocene) was preceded by a small CW rotation of Adria with respect to Africa, suggested by unchanged orientation of the former across the Cretaceous-Paleocene boundary, while the latter continued its CCW rotation. © 2011 Elsevier B.V.
Szendrei G.,Hungarian Natural History Museum |
Toth T.,Hungarian Academy of Sciences |
Kovacs-Palffy P.,Institute of Hungary
Agrokemia es Talajtan | Year: 2014
The aim of the present study is a better understanding of the distribution and formation of salt efflorescences by mineralogical examination. Dominant sodium sulphate and sodium chloride surface efflorescences were selected for investigation. 24 samples were collected between 1999 and 2005 from 16 sites. The soil types were solonchak and meadow solonetz.Basic soil and groundwater analyses were performed according to the standard methods. Minerals were determined by X-ray diffractometry and SEM combined with microanalysis. The evaporation experiments were carried out in a Sanyo Versatile 350 HT environmental test chamber.It was concluded that common sulphate salts form rare and unique mineral associations on salt affected soils in Hungary.Comparing the groundwater compositions and the mineral associations of surface efflorescences or that of precipitated evaporites of groundwaters, the conclusion can be drawn that groundwater composition is reflected much better by the mineral association of experimentally precipitated evaporates of the groundwater than by the mineral associations of surface efflorescences. These differences suggest that the soil matrix may have an effect on the crystallization of minerals (e.g. gypsum, thenardite) in the efflorescences. The differences also suggest that in the surface efflorescences the precipitation process does not come to the end in all cases (minerals with high solubility are missing).Concerning the data on groundwater level depths in case of different (sodium carbonate versus sodium sulphate and sodium chloride) efflorescences, there is a tendency of declining groundwater table in the sequence of these soils. This difference can be explained by the difference (increase) in the solubility of various salt minerals.It was recognized that the change in the major component of surface efflorescenes in time (i.e. the sodium carbonate and sodium carbonate chloride versus sodium sulphate efflorescences before and after 1998) can be explained by the decline of the groundwater level and by the decreasing hydromorphic influence in the lowland area during the 19 and 20 century.Finally it can be stated that the presented research-which mainly focused on mineralogical aspects-has contributed to the earlier knowledge on surface salt efflorescences, which was based only on their chemical composition.
Balog K.,Hungarian Academy of Sciences |
Kuti L.,Institute of Hungary |
Szabo A.,Hungarian Academy of Sciences |
Toth T.,Hungarian Academy of Sciences
Agrokemia es Talajtan | Year: 2014
Related to ongoing (re)forestation in the Great Hungarian Plain the short-term influence of changing land cover was studied on the grains of skeletal sandy soils. In three sampling areas with forest and grassy/arable control plots, the 0.1-0.2 mm grain size fraction of samples taken every 20 cm from the 0-100 cm sandy soil layer (totalling 22,509 grains) were separated and described with optical mineralogical microscope. In order to distinguish sand grains of forest-covered and control areas (grassland/arable land), the results of mineralogical and morphological observations were compared. It was revealed that the amount of feldspar grains is 8-9 times less than the amount of the quartz ones. The increase in the quartz/feldspar (q/fp) ratio is tied to the "consumption" of feldspars: the intense consumption of potassium by trees. Under the forest-covered fields, the number of in-situ crushed grains increased. Grains with etch pits are frequent in samples from the grasslands (except in Hajdúsámson). In samples of forest-covered areas a greatly increased number of brown grains with limonite and/or humus films were observed. The gained results can be useful in proving earlier land use in forested fields.
Scholtz P.,Institute of Hungary
Leading Edge | Year: 2013
Optimized pseudo-random sequences proved effective, both theoretically and empirically, in increasing data quality while reducing possible damage to buildings by vibratory sources during seismic reflection data acquisition. The linear sweeps commonly used for vibratory measurements can cause resonance in nearby infrastructure; hence, there is a potential for property damage. A pseudo-random sweep signal can be designed to decrease resonance effects and therefore reduce damage thresholds. The sweep sequences produced by simple random number generators, like the ones given by the vibrator manufacturers, have marked disadvantages, such as high correlation noise, large fluctuations in spectral amplitudes, and reduced seismic energy. To overcome some of these problems, an optimization process can be developed to produce pseudo-random sweeps for site-specific conditions. Two strategies are considered for preprocessing: crosscorrelation and deterministic deconvolution. Analysis of examples for an optimum pseudo-random sweep and simple pseudo-random sweep demonstrates that the total seismic energy is increased, while side-lobe energy is decreased and spectral fluctuations are reduced when the pseudo-random sweep is optimized. A limited-scope field test reveals that the peak particle velocity values are lowered substantially, while correlated and deconvolved records generated by the optimized pseudo-random sweep are of similar quality to a linear-sweep record. Application of optimized pseudo-random sweeps has the potential to increase productivity, while maintaining data quality and reducing resonance in surveys of built-up areas. © 2013 © 2013 by The Society of Exploration Geophysicists.