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Résumé Après un bref aperçu sur les types intrusifs de roches plutoniques, sont décrits les divers types d'associations min7'erales isogénétiques d'origine hydrothermale du Massif de bohême, sur le territoire de la Tchécoslovaquie. L'étude de la répartition spatiale de certaines associations minérales conduit à la différenciation de 2 zones et de 7 sous-provinces, dans la province du Massif de Bohême. Du point de vue chronologique, trois époques de minéralisation sont distinguées: antéhercynienne, hercynienne et posthercynienne, qui comportent plusieurs sous-époques distinctes de minéralisation. En conclusion, une distinction est faite entre: 1°) des associations hydrothermales montrant des relations chronologiques et spatiales nettes avec des granitoïdes voisins; 2°) des associations ne montrant que des relations spatiales; 3°) des associations, les plus nombreuses, qui sont sans aucun rapport évident avec les massifs connus de granitoïdes.
After a brief survey of intrusive types of plutonic rocks, the present paper contains a review of isogenetic mineral associations of hydrothermal origin occurring in the Bohemian Massif in the territory of Czechoslovakia; further, the distribution of some mineral associations is discussed; the result is the differentiation of 2 zones and 7 subprovinces of the province of the Bohemian Massif. From the chronological point of view three epochs can be distinguished: pre-Variscan, Variscan and post-Variscan which include marked mineralisation subepochs. In conclusion the authors discern: 1°) hydrothermal associations showing spatial and chronological relations to the surrounding granitoids; 2°) associations displaying spatial relations only; 3°) those — the most numerous — which do not show any distinct relations to the known massifs of granitoids.相似文献
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Jiří Borovička Juraj Tóth Antal Igaz Pavel Spurný Pavel Kalenda Jakub Haloda Ján Svoreň Leonard Kornoš Elizabeth Silber Peter Brown Marek Husárik 《Meteoritics & planetary science》2013,48(10):1757-1779
The Ko?ice meteorite fall occurred in eastern Slovakia on February 28, 2010, 22:25 UT. The very bright bolide was imaged by three security video cameras from Hungary. Detailed bolide light curves were obtained through clouds by radiometers on seven cameras of the European Fireball Network. Records of sonic waves were found on six seismic and four infrasonic stations. An atmospheric dust cloud was observed the next morning before sunrise. After careful calibration, the video records were used to compute the bolide trajectory and velocity. The meteoroid, of estimated mass of 3500 kg, entered the atmosphere with a velocity of 15 km s?1 on a trajectory with a slope of 60° to the horizontal. The largest fragment ceased to be visible at a height of 17 km, where it was decelerated to 4.5 km s?1. A maximum brightness of absolute stellar magnitude about ?18 was reached at a height of 36 km. We developed a detailed model of meteoroid atmospheric fragmentation to fit the observed light curve and deceleration. We found that Ko?ice was a weak meteoroid, which started to fragment under the dynamic pressure of only 0.1 MPa and fragmented heavily under 1 MPa. In total, 78 meteorites were recovered in the predicted fall area during official searches. Other meteorites were found by private collectors. Known meteorite masses ranged from 0.56 g to 2.37 kg. The meteorites were classified as ordinary chondrites of type H5 and shock stage S3. The heliocentric orbit had a relatively large semimajor axis of 2.7 AU and aphelion distance of 4.5 ± 0.5 AU. Backward numerical integration of the preimpact orbit indicates possible large variations of the orbital elements in the past due to resonances with Jupiter. 相似文献
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The aim of this study is to date by the archaeomagnetic method the last heatingcooling cycle of one Roman and two Medieval tile kilns, discovered in Belgium. The investigation demonstrates the limitations when well-documented local directional secular variation curves of the geomagnetic field in the past are used for dating and the difficulties when trying to determine field intensities from “in situ” baked clays from the kilns. The three kilns yielded very well defined ancient field directions but two possible dating solutions for each of them when no a priori time constraints are taken into account, due to field direction recurrence. As an increase of the dating accuracy and reduction of the number of dating solutions can be expected using the full field vector information, also field intensity determinations on burnt clays from the kilns were attempted. Field intensities from samples of the Roman and of one of the Medieval kilns are quite scattered. On the other hand, results obtained applying the Thellier-Thellier method and the modified method developed by Dekkers and Böhnel on sister samples from the Roman kiln agree fairly well. Rock magnetic properties reveal high variance in the kilns that point to varying spatial heating and cooling conditions in the kilns. Even well burnt material from the kilns shows irreversible changes when heated in air in the laboratory. Reliable field intensities on “in situ” baked materials from kilns themselves can therefore only be obtained when measuring sufficient number of samples from different parts of the kiln, taking into account the spatial-temporal conditions during kiln operation and cooling history. More reference intensity data is needed in our regions in order to improve dating based on directional reference data only. 相似文献
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Standard secular variation curves of the geomagnetic field direction for the last few millennia for different countries in Europe, based mainly on baked materials discovered in archaeological sites, are reaching sufficient accuracy and reliability that archaeomagnetic dating within this timespan in these areas is becoming feasible now. Orientation errors during sampling and sample preparation can be kept to a minimum and measurement errors of baked materials are in general very small. Nevertheless, even when the secular variation in the site to be dated is similar to that in the reference site, systematic or regular deviations between the remanence vector and geomagnetic field direction in kilns, due to internal and external factors, may result in biased average magnetisation directions and consequently in diverging archaeomagnetic dates. In more or less circular kilns, important non-random deviations of the remanence direction in the walls, in function of the relative azimuth as seen from the centre of the kilns, have been noticed in spite of precise and highly reliable average kiln magnetisation directions. The effect was revealed in the walls of the combustion chambers of roman pottery kilns and of mediaeval brass melting and working kilns, of different shape, lined with refractory bricks. Several hypotheses for the origin of these deviations were examined and anisotropy and/or magnetic refraction are unlikely to be the principal causes. The regular component of these deviations may be responsible for a strongly biased average magnetisation direction when only part of the kiln wall is preserved or when sampling is limited to certain parts of it and consequently result in unreliable dates when applying the archaeomagnetic dating method. 相似文献
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In the loess plateau of China, the stratigraphical position of the Brunhes / Matuyama boundary was not found in loess unit L8 at Luochuan and Jixian as is commonly accepted. The interbedded palaeosols may be differentiated from the parent loess not only by their high magnetic susceptibility but also by their enhanced remanence properties. These contrasts mainly result from concentration changes of the inherited magnetic minerals, grain-size changes and authigenic formation of magnetic minerals, which are all linked to climate-controlled soil formation processes. 相似文献
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Juraj Tóth Ján Svoreň Jiří Borovička Pavel Spurný Antal Igaz Leonard Kornoš Peter Vereš Marek Husárik Július Koza Aleš Kučera Pavel Zigo Štefan Gajdoš Jozef Világi David Čapek Zuzana Krišandová Dušan Tomko Jiří Šilha Eva Schunová Marcela Bodnárová Diana Búzová Tereza Krejčová 《Meteoritics & planetary science》2015,50(5):853-863
We provide the circumstances and details of the fireball observation, search expeditions, recovery, strewn field, and physical characteristics of the Ko?ice meteorite that fell in Slovakia on February 28, 2010. The meteorite was only the 15th case of an observed bolide with a recovered mass and subsequent orbit determination. Despite multiple eyewitness reports of the bolide, only three videos from security cameras in Hungary were used for the strewn field determination and orbit computation. Multiple expeditions of professionals and individual searchers found 218 fragments with total weight of 11.3 kg. The strewn field with the size of 5 × 3 km is characterized with respect to the space distribution of the fragments, their mass and size‐frequency distribution. This work describes a catalog of 78 fragments, mass, size, volume, fusion crust, names of discoverers, geographic location, and time of discovery, which represents the most complex study of a fresh meteorite fall. From the analytical results, we classified the Ko?ice meteorite as an ordinary H5 chondrite. 相似文献
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Ladislav Husár 《Studia Geophysica et Geodaetica》1990,34(1):56-64
Summary The paper outlines some new approaches to discovering refraction anomalies using available meteorological data which characterize the vertical condition of the atmosphere in the neighbourhood of an observatory. Due to the limited number of data and the methods of processing, the resultant refraction anomalies refer to only a part of the atmosphere, approximately 10 km in height. 相似文献