Titanium-rich biotite from granodiorite belonging to redwitzite suite of the Slavkovský les Mts. alters to mixture of low-Al titanite, Mn-enriched ilmenite, REE-fluorocarbonate (parisite) and very fine-grained mixture of chlorite and clay minerals. Titanite consists from 1.1 to 2.3 wt. % Al2O3 and from 0.4 to 1.0 wt. % Fe2O3. Titanite shows some Al+Fe3+ excess over F with significant amount of (Al+Fe3+)-OH titanite component (4-9 mol. %). Ilmenite contains considerable amount of pyrophanite component (5-8 mol. %). The retrograde assemblage of titanite with considerable amount of (Al+Fe3+)-OH titanite component and presence of ilmenite, together with chlorite, argued for low-temperature breakdown of biotite in reducing conditions., Miloš René., and Obsahuje bibliografii
An assemblage of Al-bearing titanite, ilmenite and magnetite is present in polymetamorphic metabasite environment of the Varied group of the Moldanubian Zone. Titanite is characterized by coupled substitution (Al, Fe3+)+ (F, OH) - Ti + O, with a slight excess of (Al, Fe3+)-F component. Complex reaction rims of titanite around ilmenite occur in some cases. Ilmenites have FeTiO3 amounts usually above 96 mol.%, with some enrichment by MnTiO3 component (max. 8 mol.%). Magnetite has a negligible ulvöspinel component (max. 1 mol.%)., Miloš René., and Obsahuje bibliografii
In this article we solve the non-standard situation that arose after publishing our paper "Crustal deformations in the epicentral area of the West Bohemia 2008 earthquake swarm in central Europe" (Schenk et al., 2012). Horálek and Fischer wrote a statement regarding our publication, sent it to specialists interested in research in the West Bohemia swarm area, and questioned the reliability of the seismic data used in our work. Since the statement regarding the reliability of our work was not directly sent to us we are using this journal to return to professional discussion regarding our results. In this paper we review scientific arguments made in their statement and provide review of various studies on West Bohemia tectonics and related seismicity., Vladimír Schenk and Zdeňka Schenková., and Obsahuje bibliografii
A study of displacements relating to geodynamical processes involves a use of accurate measurement equipment. Better and better accuracy of field surveys neglecting a survey environment can be insufficient in a reliable study. One of the environmental aspects is discussed in the paper. That is a geotechnical condition of a ground - an environment of benchmarks, which changes of position are observed in geodetic surveys. The conditions determine a ground stability affected by weather or geological processes. The main idea of the paper is to consider geotechnical and geological aspects in geodetic reasoning carried on the base of displacement analysis within a study of geodynamics. There are presented examples illustrating the problem. The first relates to former levelling observations carried in an area of Wieliczka, well geologically surveyed due to mining activity in a salt deposit. There are presented results obtained on the base of a numerical analysis. The seasonal variations of benchmarks’ heights are explained in a background of geology. The changes of ground properties induced by atmospheric conditions are suggested as the main cause of the displacements. The survey data processing provided values of displacements caused by seasonally expanding grounds. The second examples concerns ongoing observations in the area of Inowroclaw (located above the salt dome) bring similar variations of heights that can not be related to that cause. The estimated linear trend of height changes proves an uplift process of the salt dome. Derived conclusions suggest a certain methodology helpful in reliable analysis of geodetic surveys. The conclusions prove that geodetic surveys carried out for investigations of displacements in geodynamics require quite extensive geological data., Zbigniew Szczerbowski., and Obsahuje bibliografii
Soubor dvanácti nečíslovaných původních mědirytů zhotovených uznávaným mnichovským rytcem Johannem Poppelem na základě Schinkelových kreseb, vycházejících ze skic Alexandra Humboldta, zobrazujících sopky jižní a střední Ameriky., von Alexander von Humboldt, gezeichnet von Schinkel nach einer Skizze von A. v. Humboldt* Karl Friedrich Schinkel, gestochen von J. Poppel in München* Johann Poppel, and Pomocné vědy geologické. Geoastronomie. Geofyzika. Geochemie. Geobiologie. Všeobecná geologie. Teorie o vzniku Země. Geodynamika. Zemětřesení. Glaciologie. Geomorfologie. Speleologie. Oceánografie. Historická geologie. Geologie oblastní. Vulkanická činnost. Podmořská fotografie. Stratigrafie.
Dynamic soil properties are important parameters for the design of structures subjected to various dynamic/cyclic loading such as earthquake which can be obtained by in situ and laboratory measurements. Numerous empirical and mathematical models have been proposed to predict the dynamic properties of soils, including maximum shear modulus (Gmax), normalized shear modulus (G/Gmax - γ) curve, reference shear strain (γr), minimum damping ratio (Dmin) and damping ratio (D - γ) curve. However, the majority of the existing models were proposed for specific soil types, loading characteristics, initial soil fabrics and strain ranges. This paper proposes five universal models to estimate the Gmax, γr and Dmin values, and also G/Gmax - γ and D - γ curves using a database that contains 117 tests on 5 different granular soils. The proposed models include the effect of grading characteristics, void ratio, mean effective confining pressure, consolidation stress ratio (KC) and specimen preparation method. The models are validated using experimental data from previous studies for granular soils. The results indicate that the proposed models are capable of evaluating the dynamic properties of granular soil., Meysam Bayat., and Obsahuje bibliografii
The harmonic oscillations of water level changes with several hundred nanometers amplitudes and 10-3 [Hz] frequencies are irregularly observed with the water-tube tiltmeter. The effects are observed only by one of four gauges - the one closest to the entrance to underground. The other three gauges of water-tube tiltmeters are situated at the ends of the corridors and are significantly more distant from the entrance to the underground. The atmospheric pressure signals affect level of water in the instrument by inverse barometric effect. The water-tube tiltmeters can register water level variations associated with inverse barometric effects, which were produced by air pressure signals until 10-5 [Pa] magnitude. The amplitude of harmonic oscillations of water level is significantly large and amounts to 1/10 of tidal amplitude, that is 300 to 500 nanometers, which corresponds to 5 x 10-3 [Pa] of air pressure variations. Harmonic oscillations appear irregularly and their time of duration changes from few days until several weeks. The length of atmospheric wave of 10-3 [Hz] frequencies is of 1000 [km] and cannot be explained by any phenomenon from the outside surroundings or the inside of the underground. Resonance frequencies of air column in the hundred meters long underground corridors are of the order of single Hz. Absence of similar signals in measurements from the other three gauges suggests that the harmonic signals are not propagated through the Earth’s solid body but through the atmospheric medium. The observed micro-vibrations of air pressure are very low infrasounds which can be produced in large dimension space of thousand kilometers size. The open question is what is the origin of micro-vibrations registered by the water-tube tiltmeter., Marek Kaczorowski., and Obsahuje bibliografii