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Martin Danišík Milan Kohút István Dunkl L’ubomír Hraško Wolfgang Frisch 《Swiss Journal of Geoscience》2008,101(1):225-233
The thermal evolution of the only known Alpine (Cretaceous) granite in the Western Carpathians (Rochovce granite) is studied by low-temperature thermochronological methods. Our apatite fission track and apatite (U-Th)/He ages range from 17.5 ± 1.1 to 12.9 ± 0.9 Ma, and 12.9 ± 1.8 to 11.3 ± 0.8 Ma, respectively. The data thus show that the Rochovce granite records a thermal event in the Middle to early Late Miocene, which was likely related to mantle upwelling, volcanic activity, and increased heat flow. During the thermal maximum between ~17 and 8 Ma, the granite was heated to temperatures ? 60 °C. Increase of cooling rates at ~12 Ma recorded by the apatic fission track and (U-Th)/He data is primarily related to the cessation of the heating event and relaxation of the isotherms associated with the termination of the Neogene volcanic activity. This contradicts the accepted concept, which stipulates that the internal parts of the Western Carpathians were not thermally affected during the Cenozoic period. The Miocene thermal event was not restricted to the investigated part of the Western Carpathians, but had regional character and affected several basement areas in the Western Carpathians, the Pannonian basin and the margin of the Eastern Alps. 相似文献
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Statistical approach to the analysis of the relationship between the frequency of flood events and land cover (LC) changes
in small catchments of Slovakia is presented in this paper. The data for identification of LC changes were taken from the
1990 and 2006 CORINE LC (CLC) data layers. They were derived by computer-aided visual interpretation of satellite images under
the CLC Projects. The data about frequency of flood events in small catchments are from the period 1996–2006. Two hypotheses
were formulated: (1) the greater the area of LC changes, the more frequent flood events; (2) in catchments where LC changes
accelerating formation of direct runoff (e.g. urbanization, deforestation, farming) dominates, flood events are more frequent
than in catchments where the prevailing LC changes (e.g. afforestation) reduce formation of direct runoff. Validity of hypotheses
was tested in the framework of flood potential of catchments by two-factor ANOVA method. The obtained results indicate that
(1) flood event frequency increases with the increasing total area of LC changes in a catchment. This tendency clearly manifests
itself in catchments with very high flood potential. It is somewhat less distinct in catchments with moderate and high flood
potentials. (2) There were no differences in flood event frequency between the group of catchments, where LC changes accelerating
the formation of the direct runoff prevailed and the group of catchments where LC changes decelerating the formation of direct
runoff were dominated. 相似文献
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The study aimed to assess the response of ep- and hemiedaphic Collembola communities （activity, richness, community structure） to a disturbance, the subsequent management regime and to the season （summer, winter） in a High Tatra Mountainsspruce forest destroyed by a windstorm. Fire and clear-cut resulted in an initial increase in the activity of Collembola inhabiting open areas, opportunistic or generalist species, while forest specialists diminished in numbers or disappeared. Our results indicated that treatment with non-extracted fallen trees （NEX） provided a better chance for forest species to survive compared with their survival in open habitats of extracted （EXT） and wildfire （FIR） treatments. Great species’ potential of NEX treatment was indicated by Chao2 estimator and activity/species rarefaction curves. Communities of NEX treatment were more similar to the reference （REF） treatment, documented by ordination and cluster analyses. Thus, leaving fallen timber after a windthrow to natural process of succession is suitable for survival of forest species and maintenance of diversity in forests restoration than timber extraction. Community structure in wildfire （FIR） stands was the most dissimilar to the other treatments. Most of the species trapped in this treatment belonged to hemiedaphic life forms, while the activity of larger epedaphic species diminished. In contrast, the highest number of trapped Collembola in EXT treatment was connected with the larger-bodied epigeic species with fast dispersal ability. The trapping period affected both the number of individuals and species richness; Collembola activity and species diversity in the individual treatments were lower in winter compared with the summer period. Several species increased activity during the winter period, namelyFolsomia penicula, Friesea mirabilis, F. truncata,Hypogastrura socialisand Protaphorura aurantiaca. 相似文献
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Geometrical changes induced by cation substitutions {Si4+/Al3+}[Mg2+/Al3+], {2Si4+/2Al3+} [2Mg2+/2Al3+], {Si4+/Fe3+} [Mg2+/Al3+] or [Mg2+/Fe3+], where {} and [] indicate tetrahedral and octahedral sheet in lizardite 1T, are studied by ab-initio quantum chemistry calculations. The majority of the models are based on the chemical compositions
reported for various lizardite polytypes with the amount of Al in the tetrahedral sheets reported to vary from 3.5% to 8%
in the 1T and 2H
1, up to ~30% in the 2H
2 polytype. Si4+ by Fe3+ substitution in the tetrahedral sheet with an Al3+ (Fe3+) in the role of a charge compensating cation in the octahedral sheet is also examined. The cation substitutions result in
the geometrical changes in the tetrahedral sheets, while the octahedral sheets remain almost untouched. Substituted tetrahedra
are tilted and their basal oxygens pushed down from the plane of basal oxygens. Ditrigonal deformation of tetrahedral sheets
depends on the substituting cation and the degree of substitution. 相似文献
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Ľubor Kresák 《Earth, Moon, and Planets》1980,22(1):83-98
The dynamics of larger interplanetary bodies is reviewed, with emphasis on evolutionary problems, interrelations, and open questions. Observational biases distinguishing the sample of known objects from the whole population are briefly discussed. A schematic division of the solar system into zones with different regimes of motion, and a rough taxonomy of orbit types are attempted. The role of individual major planets in controlling the dynamical evolution of interplanetary objects, in particular by stabilizing resonances and destabilizing close encounters, is compared. There are significant evolution asymmetries due to boundary conditions and preferential evolutionary paths; individual major displacements in the phase space of orbital elements conserve the Tisserand invariant with respect to the planet responsible, thus favouring certain evolutionary sequences against others. Very limited lifetimes of some orbit types imply a long-term balance between source and sink, and require a continuous supply of objects from other types of orbits. In this respect, the ultimate fate of extinct comets is of particular interest. Under very specific conditions, nongravitational effects of mass loss can result in stabilization of a formerly unstable orbit. Since the dividing line between the two basic interplanetary populations distinguished by origin and composition — the asteroids and the comets — is essentially that between stable and unstable motion, orbital data can be used to specify which of the known asteroid-like objects may be devolatilized cometary nuclei.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy. 相似文献
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Peter Sekula Edgar Hiller Peter Šottník Ľubomír Jurkovič Tomáš Klimko Jaroslav Vozár 《Environmental Earth Sciences》2018,77(13):518
The main aim of this paper was to investigate the removal efficiency of antimony (Sb) and arsenic (As) from circum-neutral mine drainage in the former Sb mine in Popro? (Slovakia) using a simple field treatment system based on the adsorption onto iron fillings. The treatment system consisted of two batch reactors with a volume of 1 m3: the first was used for settling of spontaneously precipitated ochreous sediments and the second, filled with reactive iron material, was designed to remove Sb and As from mine water. This passively operated treatment system contained 150 kg of low-cost iron fillings and was able to treat approximately 360 l of mine drainage per hour. The average removal efficiency of Sb and As reached 84 and 89% during a period of 2.3 years of the system operation, respectively. On average, dissolved Sb and As concentrations in mine drainage decreased from 175 to 24.3 µg/l and from 452 to 50.6 µg/l, respectively. Based on the electron microprobe (EMP) analyses of corrosion products developed on the surfaces of iron fillings, average Sb and As contents were 0.28 and 0.73 wt%, respectively. The chemical analyses of precipitated HFOs in the settling reactor showed that these ochreous precipitates contained up to 19.3 g/kg Sb and 65.8 g/kg As, indicating their natural role in the removal of the two metalloids from circum-neutral mine drainage. The results of transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses confirmed the presence of ferrihydrite and goethite in ochreous sediments. 相似文献
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L’ubomír Smr?ok Alexander I. Kolesnikov Milan Rieder 《Physics and Chemistry of Minerals》2012,39(9):779-787
Inelastic neutron scattering (INS) was used to study the vibrational dynamics of the hydrogen atoms in natural trioctahedral phlogopite, K0.93Na0.03(Mg2.47Fe0.22Al0.16Fe0.04Tl0.06)[Si2.84Al1.16]O10OH1.71F0.28Cl0.01, within the 50–1,000?cm?1 energy range. The INS spectra collected using direct geometry spectrometer SEQUOIA (ORNL) were interpreted by means of the solid-state DFT calculations covering both normal mode analysis and molecular dynamics. To optimize the structure and to calculate the vibrational modes under harmonic approximation, both a hybrid PBE0 and the AM05 functional were used, while the molecular dynamics calculations (60?ps/1?fs) were performed only with the computationally less-demanding AM05 functional. The main contributions to the dominant band within ~750–550?cm?1 are symmetric and antisymmetric Mg–O–H bending modes, overlapping with the skeletal stretching and bending modes causing weaker secondary movements of H atoms of inner hydroxyl groups. Signatures of the Mg–O–H bending modes appear down to ~400?cm?1, where a region of octahedra deformation modes starts. These deformations cause just shallow movements of the hydrogen atoms and are mirrored by the modes with close vibrational energies. The region from ~330?cm?1 down to the low-energy end of the spectrum portrays induced vibrations of the H atoms caused by deformation of individual polyhedra, translational vibrations of the parts of the 2:1 layer relative one to another, and librational and translational vibrations of the layer. The main difference between the INS spectrum of dioctahedral Al-muscovite and trioctahedral Mg-phlogopite is that the Mg–O–H modes are all assigned to in-plane vibrations of the respective hydrogen atoms. 相似文献
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Ľubomír Smrčok Daniel Tunega Anibal Javier Ramirez-Cuesta Eva Scholtzová 《Physics and Chemistry of Minerals》2010,37(8):571-579
The dynamics of the hydrogen atoms in the highly ordered kaolinite was studied by vibrational spectroscopy based on inelastic
neutron scattering method with the focus on the spectral region of 100–1,250 cm−1. The experimental spectrum was interpreted by means of the solid state density functional theory calculations covering both
normal mode analysis and molecular dynamics going beyond the harmonic approximation. The Al–O–H bending modes were found to
be spread over the large interval of 100–1,100 cm−1, with the dominant contributions located between 800 and 1,100 cm-1. The shapes of the individual hydrogen spectra depend on the strengths of the individual interlayer O–H···O hydrogen bonds
involving the inner surface hydroxyl groups. The modes assigned to the in-plane movements of the respective hydrogen atoms
are well-defined and always appear on the top of the intervals of energy transfer. In contrast, the modes generated by the
out-of-plane movements are spread over large intervals of energies spanning down to the region of external (lattice) modes. 相似文献
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