The connection between chromospheric flares and geomagnetic activity in the IGY     

Jaroslav Halenka 《Studia Geophysica et Geodaetica》1960,4(4):361-377

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Book review     

Jaroslav Feda 《Rock Mechanics and Rock Engineering》1989,22(1):65-66

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A possible long-term solar impact on air temperature in relation to solar motion     

Ivanka Charvátová  Jaroslav Střeštík 《Studia Geophysica et Geodaetica》1992,36(4):338-348

Summary Using the long-term relations between solar motion and solar activity, long-term relations between solar activity and air temperature variations on the Earth's surface have been studied. A long-term periodicity in the period range from 25 to 250 years, corresponding to the periodicity of solar motion and solar activity, has been found in four very long European surface air temperature series. The positions of the spectral peaks approximately obey the relation p_i=178.7/i, i=1, 2, ... . Similar long-term patterns of solar and geomagnetic activity and of global surface air temperature have been found in the years 1861 to 1990. The results indicate that the solar activity impact on the climate could be significant, and that the prolonged minimum of solar activity, predicted from solar motion for the next 2 – 3 decades, could decreace global air temperatures.  相似文献   

A contribution to the exploitation of the diagram of a radar antenna for meteorological measurements     

Jaroslav Sychra 《Studia Geophysica et Geodaetica》1966,10(4):467-471

Резюме Были выведены выражения для коэффициента заполнения радиолокационного луча малой ленточной, прямоугольной и круглой метеорологической целью с учетом формы диаграммы антенны. Далее был дредложен метод оценки угловых размеров или же толшины облачного слоя, зондированного под малым углом, посредством анализа изменений эха. Последняя часть работы посвящена рассмотрению проблематики измерения высоты основания облаков или верхней границы облачного слоя.

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Address: Boční II, Praha 4-Spořilov.  相似文献   

Observations of acoustic-gravity waves in the ionosphere generated by severe tropospheric weather     

Tereza Šindelářová  Dalia Burešová  Jaroslav Chum 《Studia Geophysica et Geodaetica》2009,53(3):403-418

Atmospheric waves influence the dynamics and energetic budget of the upper atmosphere. Using the continuous HF Doppler sounder, we study the wave activity in the ionosphere during tropospheric convective storms in western and central part of the Czech Republic. The study is focused on acoustic-gravity waves in the period range 2–30 minutes. We discuss possible methods of distinguishing the waves emitted by meteorological sources from waves of different origin, particularly waves of geomagnetic origin. In two cases out of twenty-five analysed, we found waves in the infrasonic period range which might be generated by exceptionally intense meteorological activity in the troposphere. The results differ considerably from those previously obtained in North America. In the central part of the United States, infrasonic waves were frequently observed during convective storms. As a possible reason, we discuss different intensity and dynamics of weather systems in both regions.  相似文献   

On methods used for determining the effect of a solar eclipse on the geomagnetic field     

Jaroslav Tauer 《Studia Geophysica et Geodaetica》1964,8(1):72-81

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Epithermal gold veins in a caldera setting: Banská Hodruša, Slovakia     

Peter Koděra  Jaroslav Lexa  Andrew Hugh Rankin  Anthony Edward Fallick 《Mineralium Deposita》2005,39(8):921-943

The central zone of the large Miocene tiavnica stratovolcano in the Western Carpathians hosts epithermal Au mineralization of intermediate-sulfidation type, located at deep levels of the historic Rozália base-metal mine at Banská Hodrua. The Au mineralization occurs as subhorizontal veins at the base of pre-caldera andesites, close to the roof of a subvolcanic granodiorite intrusion. The veins are dismembered by a set of quartz–diorite porphyry sills and displaced by the younger, steeply dipping, Rozália base-metal vein, and parallel structures. The base-metal vein structures are related to resurgent horst uplift in the caldera center. The Au mineralization formed during two stages. Based on fluid inclusion evidence, both stages formed from fluids of low salinity (0–3 wt% NaCl eq.), which underwent extensive boiling at moderate temperatures (280–330°C). Variable pressure conditions (39–95 bars, neglecting the effect of CO₂) indicate continual opening of the system and a transition from suprahydrostatic towards hydrodynamic conditions at shallow depths (~550 m). The fluid inclusions of the Rozália base-metal vein show homogenization temperature peaks at ~285 and 187°C and salinities between 1 and 4 wt% NaCl eq. Precipitation of Au is considered to be the result of prolonged boiling of fluids and associated decrease in Au solubility. Oxygen and hydrogen isotope data for quartz and carbonate from the Au veins show a relatively homogeneous fluid composition (–2.7 to 1.1¹⁸O, –78 to –62D). The combined ¹⁸O_fluid and D_fluid values suggest a mixed character of fluids, falling between the fields of typical magmatic and meteoric water influenced by ¹⁸O_fluid shift due to fluid–rock isotopic exchange. End stages of open-system boiling and fractionation could have been reached, at least locally. Significantly lower isotopic composition of meteoric fluids associated with Au mineralization compared to those associated with the intrusion-related mineralizations could have resulted from changing paleoclimate and/or analytical problems of extraction of water from fluid inclusions. The proposed genetic model for the Au deposit at Rozália mine highlights the importance of hydrothermal activity during the early stage of caldera collapse. Caldera subsidence established new, convective, fluid-flow paths along marginal caldera faults, which acted as infiltration zones. Major metal precipitation occurred within subhorizontal structures that formed as the result of a collapse-related stress field. A shallow, differentiated magma chamber at the base of the volcano was the likely source of heat and magmatic components for the mineralizing fluids.Editorial handling: S. Nicolescu  相似文献   

Collocations and thirtieth order resonant harmonics     

Jan Kostelecký  Jaroslav Klokočník 《Planetary and Space Science》1983,31(8):829-841

The method of collocations (LSC) has been compared with traditional least-squares adjustments (LSA) for determining the values of the individual harmonic coefficients in the expansion for the Earth gravitational potential from the lumped geopotential coefficients of order 30, accumulated from previous analyses of satellite orbits near the 15th-order resonance. The computations are based on the data from King-Hele and Walker (1982b), where the 30th-order harmonic coefficients were determined from the lumped values by means of the usual least-squares method. We take into account the correlation coefficients among the lumped coefficients; we do not omit higher degree harmonics but on the contrary, they are statistically estimated as the signal in LSC. Four groups of runs have been performed: from LSA (similar to that in King- Hele and Walker, 1982b) to as general LSC as possible. The resulting harmonic coefficients are compared mutually, with the resonant solution by King-Hele and Walker (1982b), with our older trials (Kostelecký and Kloko?ník, 1979) and with recent comprehensive Earth models (GEM 10 B(C), ‘Rapp 77’ and GRIM 3). The comparison by harmonic coefficients is in Tables 4 and 5 and on Fig. 1, that via lumped coefficients for arbitrary inclination is in Figs. 2–7. The first few pairs of the 30th-order harmonic coefficients, at least C?_{30, 30}and S?_{30, 30}, are now well determined. King-Hele and Walker (1982b) used better data than we had in our previous solution (Kostelecký and Kloko?ník, 1979), so that the LSC does not play so important a role in the determination as played in the older solution. Although our evaluations serve as an example where more complicated LSC is not necessary, LSC ought to be preferred in a situation where LSA does not achieve optimal utilization of the data base.  相似文献   

1: Subduction, slab detachment and mineralization: The Neogene in the Apuseni Mountains and Carpathians     

Franz Neubauer  Andor Lips  Kalin Kouzmanov  Jaroslav Lexa  Paul Ivacanu 《Ore Geology Reviews》2005,27(1-4):13

The Inner Carpathians comprise several distinct Neogene late-stage orogenic Pb–Zn–Cu–Ag–Au ore districts. The mineral deposits in these districts are closely related to volcanic and subvolcanic rocks, and represent mainly porphyry and epithermal vein deposits, which formed within short periods of time in each district. Here, we discuss possible geodynamic and structural controls that suggest why some of the Neogene volcanic districts within the Carpathians comprise abundant mineralization, while others are barren. The Neogene period has been characterized by an overall geodynamic regime of subduction, where primary roll-back of the subducted slab and secondary phenomena, like slab break-off and the development of slab windows, could have contributed to the evolution, location and type of volcanic activity. Structural features developing in the overlying lithosphere and visible in the Carpathian crust, such as transtensional wrench corridors, block rotation and relay structures due to extrusion tectonics, have probably acted in focusing hydrothermal activity. As a result of particular events in the geodynamic evolution and the development of specific structural features, mineralization formed during fluid channelling within transtensional wrench settings and during periods of extension related to block rotation.In the Slovakian ore district of the Western Carpathians, Neogene volcanism and associated mineralization were localized by sinistral, NE-trending wrench corridors, which formed part of the extruding Alcapa block. The Baia Mare ore district, in the Eastern Carpathians, reflects a transtensional wrench setting on distributed oversteps close to the termination of the Dragos Voda fault. There, mineralization was spatially controlled by the transtensional Dragos Voda master fault and associated cross-fault systems. The Golden Quadrangle Cu–Au ore district of the Southern Apuseni Mountains reflects an unusual rotated transtensional/extensional setting close to the termination of a graben system. There, fluid flow was probably localized by fault propagation at the inner tip of the graben system.The spatial and temporal evolution of the magmatism and its changing geochemical signature from (N)W to (S)E strongly suggests a link with the contemporaneous northeastward roll-back of the subducted slab and a progressive southeastward detachment during accelerating roll-back. This geodynamic evolution is further supported by the present-day overall and detailed mantle lithospheric density images, the present-day heat flow patterns, the crustal architecture and its interpreted evolution, and the spatial and temporal evolution of depocentres around the Carpathian arc. In contrast to all these features, the mineral deposits in the West Carpathians, East Carpathians and Apuseni Mountains are too synchronous with respect to their individual volcanic history and contrast too much with younger volcanics of similar style, but barren, in southeastern parts of the Carpathians to simply link them directly to the slab evolution. In all three districts, the presence of magmatic fluids released from shallow plutons and their mixing with meteoric water were critical for mineralization, requiring transtensional or extensional local regimes at the time of mineralization, possibly following initial compressional regimes.These three systems show that mineralization was probably controlled by the superposition of favourable mantle lithospheric conditions and partly independent, evolving upper crustal deformation conditions.In the 13 to 11 Ma period the dominant mineralization formed all across the Carpathians, and was superimposed on structurally favourable crustal areas with, at that time, volcanic–hydrothermal activity. The period may reflect the moment when the (upper part of the) crust failed under lithospheric extension imposed by the slab evolution. This crustal failure would have fragmented the overriding plate, possibly breaking up the thermal lid, to provoke intensive fluid flow in specific areas, and allowed subsequent accelerated tectonic development, block rotation and extrusion of a “family of sub-blocks” that are arbitrarily regarded as the Tisia–Dacia or Alcapa blocks, even though they have lost their internal entity.  相似文献   

The Malé Vrbno magnetite occurrence of the Velké-Vrbno Unit, Czech Republic: petrology, mineralogy, geochemistry and genesis     

Arno Mücke  Bohus Fojt  Jaroslav Skcel 《Chemie der Erde / Geochemistry》2006,66(2):109-127

The mineralization investigated is that of a stretched magnetite-rich body consisting of three subparallel layers. These layers are each 200 m long, have in total a thickness of close to 2 m and are asymmetrically enveloped by amphibolite which is the host rock. Both, host rock and ore body belong to the Velké-Vrbno Unit which is a constituent of the Prevariscian Orogen and lie at the NW margin of the Bohemian Massif about 500 m SW of the village Malé Vrbno close to the town of Staré-Mešto (Czech Republic).The host rocks are composed of amphiboles (up to 90 vol%) with Mg# of 0.54–0.62 (pargasite, tschermakite and magnesiohornblende), Ab₆₄An₃₅K_0.1 feldspar (up to 50 vol%), mica (eastonite) and Mg-dominated chlorite. The only oxide mineral is manganese-rich ilmenite. The ore body is composed of homogeneous, nearly pure magnetite (up to 50 vol%), amphibole with Mg# of 0.14–0.26 (ferrotschermakite, ferrogedrite and ferroanthophyllite), garnet (almandine-dominated with varying proportions of grossularite, andradite and pyrope), mica (annite), local Ab₆₅₋₇₂An₂₈₋₃₄K_0.5−0.8 feldspar, apatite, secondary Fe_tot-dominated chlorite and quartz.Deduced from REE distribution patterns, the distribution of the HFS elements and the SPIDER diagram, host rocks and ore body originated from continental tholeiitic magmas. The magmatic origin is also supported by the occurrence of chromite and the abundance of apatite in the ore body. The rocks derived from two subvolcanic emplaced partial melts that originated from a deep-seated intrusion. The first melt, identical to the protolith of the host rocks, emplaced in an early stage of differentiation in which the Mg/Fe ratio was relatively high. In an advanced stage of differentiation a second melt was released from the deep-seated intrusion leading to the emplacement of the ore-body protolith. In this stage, the Mg/Fe ratio was remarkably lower and the oxygen fugacity higher causing not only the formation of Fe-rich minerals, but also the crystallization of magnetite. After their emplacement and consolidation, both rock types suffered the same geological development during which they were overprinted by various tectono-metamorphic events (which were not separately investigated).  相似文献