Objective analysis by means of the optimum interpolation and automatic data processing of aerological reports     

Miroslav Škoda 《Studia Geophysica et Geodaetica》1967,11(1):80-89

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Accuracy limits of palaeomagnetic chronology     

Miroslav Krs 《Mineralium Deposita》1968,3(2):155-161

The paper deals with palaeomagnetic chronology as a statistical method. Using R. Fisher's statistics, the author derived the mean virtual pole positions, beginning with the Quaternary up to the Devonian, from data published in different countries and laboratories for the Eurasian continent up to the end of the year of 1966. From the mean pole positions the divergence of palaeomagnetic directions was computed and its value for Central Europe versus time was plotted. — Palaeomagnetic research into biostratigraphically dated rocks and mineral deposits in the Bohemian Massif has reached a stage, where it is possible to study the tectonic development of mineral deposits in relation to tectonic development of various basins, grabens and rock blocks. With respect to tectonic deformations, to the natural scattering of palaeomagnetic directions and to the accuracy in deriving the mean values of palaeomagnetic divergence, it is possible to achieve an accuracy in palaeomagnetic dating within the limits of a geological period, i.e. some tens of millions of years. Some other parameters may be used in special instances to reach a higher degree of accuracy.

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Zusammenfassung Die Arbeit behandelt die paläomagnetische Chronologie als statistische Methode im Hinblick auf die Erforschung von Lagerstätten. Mit der statistischen Methode von R. Fisher berechnet der Verfasser die mittleren Lagen der virtuellen Pole vom Quartär bis zum Devon; zur Berechnung wurden die paläomagnetischen Daten ausgenutzt, die für den eurasischen Erdteil bis 1966 veröffentlicht wurden. Von den mittleren Pollagen wurde die Divergenz der paläomagnetischen Richtungen für Mitteleuropa abgeleitet und ihr Wert wurde als Zeitfunktion graphisch dargestellt. Auf diese Weise wurde durch eine objektive Methode eine chronologische Vergleichskala ermittelt, die sich auf ein umfangreiches statistisches Material vom gesamten eurasischen Erdteil stützt. — Die paläomagnetische Erforschung der biostratigraphisch datierten Gesteine und Lagerstätten von Mineralrohstoffen auf dem Gebiet des Böhmischen Massivs ist so weit fortgeschritten, daß es möglich ist, die tektonische Entwicklung der Lagerstätten mit Bezug auf die tektonische Entwicklung verschiedener Becken, Gräben, ganzer Gesteinsblöcke usw. zu untersuchen. Mit Rücksicht auf die tektonischen Deformationen, auf den natürlichen Streubereich der paläomagnetischen Richtungen und auf den Genauigkeitsgrad der Ableitung der mittleren Werte der paläomagnetischen Divergenz besteht die Möglichkeit, bei der paläomagnetischen Datierung die Genauigkeit im Bereich von einigen zehn Millionen Jahren zu erreichen. In speziellen Fällen ist es zweckmäßig, auch andere Parameter zum Erreichen eines höheren Genauigkeitsgrades zu benützen.

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The properties of macerals in Czechoslovak coals rich in inertinite     

Miroslav Košina  Jan Hrnčiř 《International Journal of Coal Geology》1983,3(2):145-156

Czechoslovak bituminous coals rich in inertinite contain a considerable amount of inertinite with a reflectance range displaced towards and partly overlapping that of the vitrinite reflectance. Together with the existence of the transitional maceral group of semivitrinite, this causes difficulties in maceral analysis as well as in the technological evaluation of these coals. The relationship between the volatile matter of vitrinite and its reflectance is very close for both vitrinite- and inertinite-rich coals. The analogous relationship between the vitrinite reflectance and the volatile matter of inertinite displays a considerable scatter due to the effects of some higher values of the volatile matter of inertinite — related to the presence of inertinite with relatively low reflectance. The results of investigations into the coking properties of coals rich in inertinite, however, do not supply any proof of a higher fusibility of these coals.  相似文献   

Geochronological aspects of polar wandering derived from Czechoslovak hydrothermal deposits     

Miroslav Krs 《Pure and Applied Geophysics》1964,57(1):96-102

Summary The present contribution contains a brief review of palaeomagnetic investigation carried out in Czechoslovak hydrothermal deposits. So far polar wandering has been considered on the basis of palaeomagnetism of lavas and red sediments; to first approximation it agrees with palaeoclimatic data. Since the products of hydrothermal mineralizations have displayed a high stability of the magnetic parameters used in palaeomagnetism, the treatment of a greater amount of statistical material yielded data for deriving the polar wandering path during geological history. By analyzing the curve obtained it is possible to derive some geochronological conclusions concerning the age of the ore-yielding processes in the principal Czechoslovak metallogenic areas. In this way a new dating technique for products of hydrothermal mineralizations is presented based on the study of palaeomagnetic properties. At the same time, these new results are consistent with the geophysical interpretation of the polar wandering curve for Europe.  相似文献   

Textural evidence of magma decompression, devolatilization and disequilibrium quenching: an example from the Western Krušné hory/Erzgebirge granite pluton     

Miroslav Štemprok  David Dolejš  Axel Müller  Reimar Seltmann 《Contributions to Mineralogy and Petrology》2008,155(1):93-109

We report new occurrences of “two-phase” granitic textures from the Western Krušné hory/Erzgebirge pluton (central Europe) and use crystal-size distribution data and thermodynamic modeling to interpret their crystallization conditions. The two-phase texture consists of (1) early phenocrysts of quartz, plagioclase, K-feldspar and biotite, (2) medium-grained matrix of the same phases and (3) interstitial channels and patches of a late-stage, very fine-grained matrix. The porphyritic two-mica microgranites, which host two-phase textures, occur as minor intrusions in early low-F biotite granites or as marginal parts of evolved high-F Li-mica granites. Measurements of the crystal-size distribution of quartz revealed three grain populations: (1) early phenocrysts (0.5–3.0 mm) showing partial resorption by residual melt, (2) a medium-grained population of the equigranular rock matrix (0.05–0.50 mm) that experienced minor coarsening by subsolidus annealing and (3) a fine-grained population (<0.03 mm) in the interstitial channels and patches formed during rapid devolatilization; this quartz group shows no or poor grain coarsening. All samples exhibit similar fraction of the fine-grained population (44–52%) but proportions of phenocrysts to medium-grained matrix vary significantly. Thermodynamic modeling of liquidus equilibria and experimental data in the hydrous haplogranite system require: (1) ascent of a granitic suspension (15–25% phenocrysts) under H₂O-undersaturated conditions at 25–45 bar/°C and a cooling rate of 40 J/(g kbar) in order to produce partial resorption of quartz phenocrysts and continued growth of feldspar phenocrysts, followed by (2) emplacement as discrete intrusions or bodies along pluton roof accompanied by sudden devolatilization. At the onset of matrix nucleation, disequilibrium undercooling of 70–85°C was inferred from the presence of micrographic intergrowths of quartz and K-feldspar. The two-phase granites in the Western Krušné hory/Erzgebirge pluton and in the Southeast Asian batholith form compositionally narrow groups with high-silica and moderate volatile enrichments but they differ in peraluminosity and phosphorus concentrations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Gravity in the expansive nondecelerative universe     

Vladimír Skalský  Miroslav Súkeník 《Astrophysics and Space Science》1992,193(2):329-331

The gravity in the expansive nondecelerative universe originates in the process of permanent constant maximum possible creation of matter .  相似文献   

P-wave dispersion and attenuation in fractured and porous reservoirs – poroelasticity approach     

Boris Gurevich  Miroslav Brajanovski  Robert J. Galvin  Tobias M. Müller  Julianna Toms-Stewart 《Geophysical Prospecting》2009,57(2):225-237

Natural fractures in hydrocarbon reservoirs can cause significant seismic attenuation and dispersion due to wave induced fluid flow between pores and fractures. We present two theoretical models explicitly based on the solution of Biot's equations of poroelasticity. The first model considers fractures as planes of weakness (or highly compliant and very thin layers) of infinite extent. In the second model fractures are modelled as thin penny-shaped voids of finite radius. In both models attenuation is a result of conversion of the incident compressional wave energy into the diffusive Biot slow wave at the fracture surface and exhibits a typical relaxation peak around a normalized frequency of about 1. This corresponds to a frequency where the fluid diffusion length is of the order of crack spacing for the first model and the crack diameter for the second. This is consistent with an intuitive understanding of the nature of attenuation: when fractures are closely and regularly spaced, the Biot's slow waves produced by cracks interfere with each other, with the interference pattern controlled by the fracture spacing. Conversely, if fractures are of finite length, which is smaller than spacing, then fractures act as independent scatterers and the attenuation resembles the pattern of scattering by isolated cracks. An approximate mathematical approach based on the use of a branching function gives a unified analytical framework for both models.  相似文献   

Geoelectrical and geological structure of the crust in Western Slovakia     

Vladimír Bezák  Josef Pek  Ján Vozár  Miroslav Bielik  Jozef Vozár 《Studia Geophysica et Geodaetica》2014,58(3):473-488

Electrical resistivity of the Earth’s crust is sensitive to a wide range of petrological and physical parameters, and it particularly clearly indicates crustal zones that have been tectonically or thermodynamically disturbed. A complex geological structure of the Alpine nappe system, remnants of older Hercynian units and Neogene block tectonics in Western Slovakia has been a target of recent magnetotelluric investigations which made a new and more precise identification of the crustal structural elements of the Western Carpathians possible. A NW-SE magnetotelluric profile, 150 km long, with 30 broad-band and 3 long-period magnetotelluric sites, was deployed, crossing the major regional tectonic elements listed from the north: Brunia (as a part of the European platform), Outer Carpathian Flysch, Klippen Belt, blocks of Penninic or Oravicum crust, Tatricum and Veporicum. Magnetotelluric models were combined with previous seismic and gravimetric results and jointly interpreted in the final integrated geological model. The magnetotelluric models of geoelectrical structures exhibit strong correlation with the geological structures of the crust in this part of the Western Carpathians. The significant resemblance in geoelectrical and crustal geological structures are highlighted in shallow resistive structures of the covering formations represented by mainly Tertiary sediments and volcanics. Also in the deeper parts of the crust highly resistive and conductive structures are shown, which reflect the original building Hercynian crust, with superposition of granitoids or granitised complexes and lower metamorphosed complexes. Another important typical feature in the construction of the Western Carpathians is the existence of young Neogene steep fault zones exhibited by conductive zones within the whole crust. The most significant fault zones separate individual blocks of the Western Carpathians and the Western Carpathians itself from the European Platform.  相似文献   

Oscillations and Waves in Radio Source of Drifting Pulsation Structures     

Marian Karlický  Ján Rybák  Miroslav Bárta 《Solar physics》2018,293(4):62

Drifting pulsation structures (DPSs) are considered to be radio signatures of the plasmoids formed during magnetic reconnection in the impulsive phase of solar flares. In the present paper we analyze oscillations and waves in seven examples of drifting pulsation structures, observed by the 800?–?2000 MHz Ond?ejov Radiospectrograph. For their analysis we use a new type of oscillation maps, which give us much more information as regards processes in DPSs than that in previous analyses. Based on these oscillation maps, made from radio spectra by the wavelet technique, we recognized quasi-periodic oscillations with periods ranging from about 1 to 108 s in all studied DPSs. This strongly supports the idea that DPSs are generated during a fragmented magnetic reconnection. Phases of most the oscillations in DPSs, especially for the period around 1 s, are synchronized (“infinite” frequency drift) in the whole frequency range of DPSs. For longer periods in some DPSs we found that the phases of the oscillations drift with the frequency drift in the interval from ?17 to \(+287~\mbox{MHz}\,\mbox{s}^{-1}\). We propose that these drifting phases can be caused (a) by the fast or slow magnetosonic waves generated during the magnetic reconnection and propagating through the plasmoid, (b) by a quasi-periodic structure in the plasma inflowing to the reconnection forming a plasmoid, and (c) by a quasi-periodically varying reconnection rate in the X-point of the reconnection close to the plasmoid.  相似文献   

The Lateglacial and Holocene in Central Europe: a multi‐proxy environmental record from the Bohemian Forest,Czech Republic          下载免费PDF全文

Klára Vočadlová  Libor Petr  Pavla Žáčková  Marek Křížek  Lenka Křížová  Simon M. Hutchinson  Miroslav Šobr 《Boreas: An International Journal of Quaternary Research》2015,44(4):769-784

The Hercynian mountain ranges were islands of mountain glaciation and alpine tundra in a Central European ice‐free corridor during the Late Pleistocene. Today they are notable areas of glacial landforms, alpine‐forest free areas, peatlands and woodlands. However, our knowledge of the Lateglacial and early Holocene environmental changes in this region is limited. We present a new multi‐proxy reconstruction of a mid‐altitude environment in the Bohemian Forest spanning this period. A core (5.2 m length) in the ?erné Lake cirque (1028 m a.s.l.) was subjected to lithological, geochemical, pollen and macrofossil analysis supplemented by two optically stimulated luminescence (OSL) and 10 AMS radiocarbon dates. We determined the impact of regional and supraregional climate changes on the environment. The two most significant changes in sedimentation during the Lateglacial (17.6 and 15.8–15.5 cal. ka BP) were synchronous with regional glacial chronostratigraphy. Unlike Central European mountain ranges, in the Bohemian Forest the Younger Dryas was not coincident with glacier re‐advance, but was a dry, cold episode with low lake levels, which prevailed until the early Preboreal. Plant macrofossils indicate local establishment of Betula nana and Betula pendula/pubescens at 15.4–13.4 cal. ka BP. Comparison with Holocene records from Central Europe shows a similar immigration history of vegetation at mid and higher altitudes. The tree line exceeded an altitude of ~1000 m a.s.l. around 10.5 cal. ka BP and coincided with rapid geochemical changes in the sediment. The 8.2 ka BP event did not have any response in the sedimentary record, but corresponded to stabilization of the Picea abies population and expansion of Fagus. Fagus colonized the Bohemian Forest earlier than other Hercynian mid‐mountains, but never predominated in the composition of the forest at higher elevations. Abies alba was the last tree species that immigrated to the study area.  相似文献