Sandstones have been widely used as a building material since the medieval time all around the Europe. Porosity is one of the main factors affecting the resistance to weathering processes and consequently to the changes of mechanical and physical properties of these stones. Rock material is generally negatively influenced especially during the winter period when frost action takes place. Effect of salt crystals and ice formation depends on the character of pore space, including the pore size distribution. Mercury porosimetry is well known method which provides information about porosity and pore size distribution of samples, but as any other method, it has its own limitations. X-ray microtomography can be used as a complementary method enabling another "view" into the pore space. Main aim of this paper has been to provide the information about the use of these two mentioned methods and comparison of obtained results, within the study of sandstone weathering. The research was focused on two commonly used Czech Cretaceous sandstones - Hořice and Božanov. The stones were exposed to the accelerated durability test which is based on the meteorological data measured in Prague winters from 1998 to 2008. There were described the changes in the area of pores diameters > 5 μm. Use of mercury porosimetry together with X-ray microtomgraphy enabled more detailed understanding of the processes inside the stone structure., Kateřina Kovářová, Robert Ševčík and Zuzana Weishauptová., and Obsahuje bibliografické odkazy
The values of density and velocity in the samples of the predominant rocks from the Archaean section of the Kola superdeep borehole (SG-3) drilled in the northern frame of the Pechenga palaeorift structure have been studied. The main part of rocks of the SG-3 Archaean section is represented by gneisses, schists and amphibolites. Their main rock-forming minerals are plagioclase, hornblende, mica and quartz. The texture of the rocks is mainly medium-grained, the structure is nematogranoblastic and lepidogranoblastic. The parameters of elastic anisotropy were estimated by the acoustopolariscopy method, the density and velocity of compression and shear waves were determined in the lab and the mentioned characteristics were calculated by mineral composition. The measured sample velocities are unusually low, which can be explained by the decompaction effect of deep rocks. The values of the velocity characteristics that are close to those for the conditions of the rock deep occurrence were obtained by calculation with regard to their specific mineral composition. The average values of the velocity of compression and shear waves for gneisses were calculated by mineral composition are 6.38 ± 0.16 km/s and 3.52 ± 0.14 km/s, respectively. The average of the compression wave velocity for schists is 6.40 ± 0.13 km/s, of the shear wave velocity - 3.46 ± 0.09 km/s and for amphibolites 6.84±0.13 km/s and 3.82±0.08 km/s, respectively. The dynamic moduli in different rocks are lower in schists, medium in gneisses and higher in amphibolites., Olga Trishina, Feliks Gorbatsevich and Mikhail Kovalevskiy., and Obsahuje bibliografii
The development of knowledge on geodynamic processes is one of the most important issues in the Earth’s science. Over decades, geodetic techniques have been applied to study the geodynamics. The Global Navigation Satellite Systems (GNSS) have been reliably used for monitoring geodynamic processes. The satellite gravimetric missions such as GRACE (Gravity Recovery And Climate Experiment) and GRACE Follow-On (GRACE-FO) missions have provided numerous valuable information concerning temporal mass variations within the Earth system which can subsequently be converted to surface deformations of the Earth. The main aim of this study is to compare vertical deformations of the Earth's surface over the area of SouthEastern Poland obtained from GNSS data with the corresponding ones determined from GRACE data. The GNSS data for the period between 2008 and 2013 from 25 permanent GNSS stations operating in South-Eastern Poland and the latest release of GRACE-based Global Geopotential Models (GGMs) were used. GNSS data and GRACE-based GGMs were processed with the GAMIT/GLOBK and the IGiK‒TVGMF (Institute of Geodesy and Cartography - Temporal Variations of Gravity/Mass Functionals) packages, respectively. The results obtained indicate that monthly vertical deformations of the Earth’s surface determined using GNSS data are generally in a good agreement with the corresponding ones obtained from GRACE satellite mission data. Coefficients of correlation between these vertical deformations range from 0.60 to 0.90 and standard deviations of their differences are in the range of 2.6 - 5.7 mm., Walyeldeen Godah, Malgorzata Szelachowska, Jagat Dwipendra Ray and Jan Krynski., and Obsahuje bibliografii
This paper reports an investigation into the composition of gypsum from Kobeřice locality (Czech Republic). The X-ray diffraction along with FTIR spectroscopy and thermal analysis show that almost pure gypsum occurs mainly in autochthonous horizons. While allochthonous clastic deposition is represented by gypsum containing also calcite, quartz, clay minerals and organic matter., Pavel Konečný, Eva Plevová, Lenka Vaculíková, Alena Kožušníková, Janka Peterková and Marianna Hundáková., and Obsahuje bibliografii
Since October 2011, the Russian GLObal NAvigation Satellite System (GLONASS) has been revitalized and is now fully operational with 24 satellites in orbit. It is critical to assess the benefits and problems of using GLONASS observations (i.e. GLONASS-only or combined Global Positioning System (GPS) and GLONASS) for precise positioning and zenith total delay (ZTD) retrieval on a global scale using precise point positioning (PPP) technique. In this contribution, extensive evaluations are conducted with Global Navigation Satellite System (GNSS) data sets collected from 251 globally distributed stations of the International GNSS Service (IGS) network in July 2016. The stations are divided into 30 groups by antenna/radome types to investigate whether there are ante nna/radome-dependent biases in position and ZTD derived from GLONASS-only PPP. The positioning results do not show obvious antenna/radome-dependent biases except the stations with JAV_RINGANT_G3T/NONE. For these stations, the averaged biases in horizontal component, especially in the north component, can achieve as high as -9.0 mm. The standard de viation (STD) and root mean square (RMS) are used as indicators of positioning repeatability and accuracy, respectively. The averaged horizontal STD and RMS of GLONASS-only PPP are comparable to GPS-only PPP, while in vertical component, those for GLONASS-only P PP are larger. Furthermore, the STD and RMS of GPS+GLONASS combined PPP solutions are the smallest in horizontal and vertical components, indicating that adding GLONASS observations can achieve better positioning performance than GPS-only PPP. With the IGS final ZTD as reference, we find that ZTD biases and accuracy of GLONASS-only are latitude - and antenna/radome-independent. The ZTD accuracy of GLONASS-only PPP is slightly worse than that of GPS-only PPP. Compared with GPS-only PPP, the ZTD accuracy is only improved by 1.3% from 7.8 to 7.7 mm by adding GLONASS observations., Feng Zhou, Shengfeng Gu, Wen Chen and Danan Dong., and Obsahuje bibliografické odkazy
The study of the mechanical properties of frozen rock is a basic problem that humans have to face in artificial low-temperature rock engineering and cold region rock engineering. There are few literatures on the dynamic constitutive models of frozen rocks under low-temperature gradients at home and abroad. In this paper, the constitutive model of water-saturated marble under the coupling effects of uniaxial impact compressive load and low-temperature is studied by theoretical analysis and experimental verification. Based on the theory of mechanical element combination, a rock constitutive model considering strain rate effect, damage softening effect and low-temperature effect is established, and the model parameters are determined by fitting method. The dynamic stress-strain curve of water-saturated marble at -30 °Cis predicted. The predicted results are in good agreement with the experimental results and the concordance correlation coefficient is 0.984092. The relevant results of this paper can provide a theoretical reference for the excavation and protection of rock engineering under negative temperature., Junzhe Li, Guang Zhang, Mingze Liu, Shaohua Hu and Xinlong Zhou., and Obsahuje bibliografii
Clays (2005) and the Handbook of Clay Science (2006) are new textbooks. Clays, written by Alain Meunier, is for those studying earth sciences. The Handbook of Clay Science, edited by Faїza Bergaya, Benny Theng and Gerhard Lagaly, is concerned particularly with the industrial application of clay mineral science. Both books ar e timely and could fill important gaps in the library of mineral science. Their quality as textbooks is discussed. Critical an alysis of editorial accuracy, indexes and user-friendliness indic ate that both books fall short of the high standards that should be the hallmark of academic publication. Their shortcomings seem to be related to widespread problems that may beset commercial publica tion of scientific books., Christopher V. Jeans., and Obsahuje bibliografické odkazy
The paper presents selected results of seismological observations in Silesia and northern Moravia between 01/2004 - 08/2008, which are based on interpretation of three-component digital recordings at solitary seismic stations operated by the Institute of Geonics of the ASCR Ostrava (IGN) distributed in the region under investigation. Five seismic stations had recorded local tectonic seismic events in a continuous regime until 12/2005, when the grant project GA CR No. 205/03/0999 terminated. Meanwhile, the Ostrava - Krásné Pole (OKC) seismic station have continued in operation as a part of the Czech regional seismological network since 1983 up to present. Other three stations have been operating in a so-called triggered regime. At the mid-January 2007, seismic station in Klokočov village was re-opened in continuous regime. During 55 months of observation, 90 tectonic events have been detected at one or more seismic stations mentioned above. However, database of the Institute of Physics of the Earth of the MU contains more than 640 microearthquakes during the same time. This discrepancy is caused mainly due to a higher concentration of microearthquake foci distributed all over the western part of the region under investigation where the IPE seismic stations are situated. On the other hand, the IGN seismic stations are spread predominantly within the eastern part of the territory, i.e. relatively far from the recent foci, and moreover, some stations are operated using the triggered regime., Karel Holub, Zdeněk Kaláb, Jaromír Knejzlík and Jana Rušajová., and Obsahuje bibliografii
Experimental geomechanical and seismological measurements are performed in the medieval Jeroným Mine near Čistá (Sokolov district). The main aim of this activity is geomech anical stability evaluation of this monument. Periodical monitoring was started in 2001 whereas quarterly period was applied (measurement of crack development in the mine working, development in changes in convergence cross-sections of linear and spatial workings and fluctuations of water levels in underground spaces). Seismological monitoring was started during reconstruction of partly impassable drainage adit. At present, selected parts of described geomechanical system are newly instrumented to obtain continuous information. Data obtained from periodical and continuous monitoring are presented in this contribution. Interpretation of seismological data on both natural and technical seismicity and fluctuations of water levels is presented in details., Zdeněk Kaláb, Jaromír Knejzlík, Robert Kořínek, Radovan Kukutsch, Markéta Lednická and Petr Žůrek., and Obsahuje bibliografické odkazy
A morphologically distinct intrusive massif emerges from sedimentary Mesozoic/Tertiary cover in Eastern Socotra forming the high Haggier Mts. It is mostly composed of peralkaline a nd hypersolvus granite partly accompanied by gabbroic rocks. Amphibole, the sole mafic mineral of th e granite, shows predominately the arfvedsonite composition, while riebeckite, for which Socotra is reported in most manuals of mineralogy as the "locus typicus", occurs subordinately only. Either Paleozoic or Tertiary age has been assumed for this massif for a long time. In the last decade, however, K/Ar datings have been published clearly showing Precambrian (Ne oproterozoic) age. The present authors confirm with somewhat modified results this statement by five new radiometric measurements of monomineral amphibole fractions yiel ding values of 687 to 741 Ma for granites and 762 Ma for gabbroic rocks. The massif represents an isolated segment of numerous late postorogenic Pan-African A-granite bodies piercing the Nubian-Arabian Shield an d is explained as the result of partial melting of Pan-African calc-alkaline shield rocks in the closing stage of the orogeny., Ferry Fediuk and Kadosa Balogh., and Obsahuje bibliografické odkazy