Ordovician and Cretaceous tectonothermal history of the Southern Gemericum Unit from microprobe monazite geochronology (Western Carpathians,Slovakia)     

Anna Vozárová  Patrik Konečný  Katarína Šarinová  Jozef Vozár 《International Journal of Earth Sciences》2014,103(4):1005-1022

The Southern Gemericum basement in the Inner Western Carpathians experienced a polyphase regional deformation. Differences in the pre-Alpine and Alpine events have been constantly discussed. To address this, monazites from metapelites and acid metavolcanic rocks were dated using the Th–U–Pb electron microprobe method. Three monazite generations, such as Precambrian, Early Paleozoic, and Alpine, have been recognized in the greenschist facies pelites and acid metavolcanic rocks of the Southern Gemericum basement. Both inherited magmatic monazite grains in metavolcanites and rare relics of detrital monazites within the polyphase monazite grains in metapelites yielded the Precambrian age in the time span of 550–660 Ma. They prove the provenance and derivation from deeper crustal Cadomian fragments. High-Y magmatic monazites of Early Paleozoic age (444 ± 13 and 477 ± 7 Ma) have been recorded in the acid metavolcanites and their metavolcaniclastics. These ages roughly fit within the previously published magmatic zircon age determinations (at 494 ± 1.7 and 464 ± 1.7 Ma) that clearly indicate two-phase volcanic activity in the Early Paleozoic Southern Gemericum basin. The Early Paleozoic magmatic monazites were partly overprinted by the low-Y Alpine monazites (133 ± 5 and 184 ± 16 Ma) at their rims. In Al-rich metapelites, the newly formed low-Y monazites of Alpine age commonly occur, reflecting the polystage compression geodynamic evolution with three distinct peaks at 100 ± 8, 133 ± 5, and 190 ± 16 Ma, respectively. No data as the evidence of the pre-Alpine metamorphic events were observed in metapelites. Only some monazites yield the age indications for the Permian extensional thermal re-heating (260–290 Ma). The monazite age data from the Southern Gemericum basement indicate the strong overprinting due to the polyphase Alpine deformation at least in the greenschist facies conditions.  相似文献   

Arsenic mobility from anthropogenic impoundment sediments – Consequences of contamination to biota, water and sediments, Poša, Eastern Slovakia     

Edgar Hiller  L&#x;ubomír Jurkovi   Jozef Kordík  Igor Slaninka  Michal Jankulr  Juraj Majzlan  Jrg Gttlicher  Ralph Steininger 《Applied Geochemistry》2009,24(11):2175-2185

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Preservation of a heavily bored belemnite rostrum from the upper Maastrichtian of north-east Belgium     

Stephen K. Donovan  John W.M. Jagt  Mart J.M. Deckers  Johan Laffineur 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(2):227-231

The robust calcite rostra (or guards) of belemnites were attractive substrates for some boring organisms in the Mesozoic. The rostra of belemnitellid coleoids are common at certain levels within the Gulpen and Maastricht formations of the extended type area of the Maastrichtian Stage (Upper Cretaceous) in the south-east Netherlands and north-east Belgium. A range of episkeletozoans have been reported from these substrates hitherto. A new specimen preserved as a natural mould in flint from the province of Liège, north-east Belgium, is distinctive, preserving a dense three-dimensional infestation of long, slender, unbranched and unsculptured borings of constant diameter, Trypanites? isp. These may be the spoor of polychaetes. Variations in diameter between borings suggests that the traces in this specimen may represent four separate infestations.  相似文献   

Regional groundwater flow modeling of the Geba basin,northern Ethiopia     

Gebreyohannes  Tesfamichael  De Smedt  Florimond  Walraevens  Kristine  Gebresilassie  Solomon  Hussien  Abdelwassie  Hagos  Miruts  Amare  Kassa  Deckers  Jozef  Gebrehiwot  Kindeya 《Hydrogeology Journal》2017,25(3):639-655

Hydrogeology Journal - The Geba basin is one of the most food-insecure areas of the Tigray regional state in northern Ethiopia due to recurrent drought resulting from erratic distribution of...  相似文献   

Archaeomagnetic investigation of two mediaeval brick constructions in north Belgium and the magnetic anisotropy of bricks     

Jozef Hus  Souad Ech‐Chakrouni  Diana Jordanova  Raoul Geeraerts 《Geoarchaeology》2003,18(2):225-253

Archaeomagnetic dates derived from geomagnetic field direction records in baked materials are proposed for a mediaeval brick kiln (from inclination I and declination D) and for bricks from a brick wall (from I only) in northern Belgium. They are used to verify whether a brick chronology based on the format of bricks is feasible in Flanders. The brick kiln yielded a highly reliable average magnetization direction corresponding to an archaeomagnetic date around A.D. 1650, using the British and French geomagnetic field secular variation curves as a reference, at least half a century younger than expected from historical data. The fidelity of the geomagnetic records was controlled by measuring the magnetic anisotropy of the bricks. Anisotropy of magnetic susceptibility (AMS) measurements demonstrate that the bricks have a shape related magnetic fabric, which is induced during the molding process. A test to control whether AMS can substitute for the anisotropy of thermo‐remanent magnetization (ATRM) failed because of induced changes during laboratory heating. © 2003 Wiley Periodicals, Inc.  相似文献   

Computation of amplification factor of earthquake ground motion for a local sedimentary structure     

Jozef Kristek  Peter Moczo  Pierre-Yves Bard  Fabrice Hollender  Svetlana Stripajová 《Bulletin of Earthquake Engineering》2018,16(6):2451-2475

We present methodology of calculating acceleration and corresponding earthquake ground motion characteristics at a site of interest assuming acceleration at a reference site for two basic configurations. In one configuration we assume that the reference ground motion is not affected by the local structure beneath the site of interest. In the other configuration we assume that the reference ground motion is affected by the local structure. Consequently, the two configurations differ from each other by the presence of the reference site within the computational model. For each of the two configurations we assume two wavefield excitations: a vertical plane-wave incidence and a point double-couple source. We illustrate the methodology on the example of the Grenoble valley. The extensive investigation of effects of local surface sedimentary structures based on the developed methodology is presented in the accompanying article by Moczo et al. (Bull Earthq Eng, 2018) in this volume.  相似文献   

The stability of stars with potential-dependent masses     

Vladimír Majerník  Jozef Gembarovič 《Astrophysics and Space Science》1990,172(1):147-153

We calculate the effective mass of a spherical star-like object under the assumption that the mass of an object represents a function of the gravitational potential in which it occurs. We show that due to this mass-dependence on the gravitational potential, it is not possible that a star of a larger mass than that of a neutron star shrinks to a point singularity. We present the value of the upper limits to the mass of spherical mass bodies as a function of their radii in a large range of their mass densities.  相似文献   

Mineralogy,petrography, geochemistry,and classification of the Košice meteorite          下载免费PDF全文

Daniel Ozdín  Jozef Plavčan  Michaela Horňáčková  Pavel Uher  Vladimír Porubčan  Pavel Veis  Jozef Rakovský  Juraj Tóth  Patrik Konečný  Ján Svoreň 《Meteoritics & planetary science》2015,50(5):864-879

The Ko?ice meteorite was observed to fall on 28 February 2010 at 23:25 UT near the city of Ko?ice in eastern Slovakia and its mineralogy, petrology, and geochemistry are described. The characteristic features of the meteorite fragments are fan‐like, mosaic, lamellar, and granular chondrules, which were up to 1.2 mm in diameter. The fusion crust has a black‐gray color with a thickness up to 0.6 mm. The matrix of the meteorite is formed mainly by forsterite (Fo_80.6); diopside; enstatite (Fs_16.7); albite; troilite; Fe‐Ni metals such as iron and taenite; and some augite, chlorapatite, merrillite, chromite, and tetrataenite. Plagioclase‐like glass was also identified. Relative uniform chemical composition of basic silicates, partially brecciated textures, as well as skeletal taenite crystals into troilite veinlets suggest monomict breccia formed at conditions of rapid cooling. The Ko?ice meteorite is classified as ordinary chondrite of the H5 type which has been slightly weathered, and only short veinlets of Fe hydroxides are present. The textural relationships indicate an S3 degree of shock metamorphism and W0 weathering grade. Some fragments of the meteorite Ko?ice are formed by monomict breccia of the petrological type H5. On the basis of REE content, we suggest the Ko?ice chondrite is probably from the same parent body as H5 chondrite Morávka from Czech Republic. Electron‐microprobe analysis (EMPA) with focused and defocused electron beam, whole‐rock analysis (WRA), inductively coupled plasma mass and optical emission spectroscopy (ICP MS, ICP OES), and calibration‐free laser induced breakdown spectroscopy (CF‐LIBS) were used to characterize the Ko?ice fragments. The results provide further evidence that whole‐rock analysis gives the most accurate analyses, but this method is completely destructive. Two other proposed methods are partially destructive (EMPA) or nondestructive (CF‐LIBS), but only major and minor elements can be evaluated due to the significantly lower sample consumption.  相似文献   

The effect of land‐use changes on the hydrological behaviour of Histic Andosols in south Ecuador     

W. Buytaert  G. Wyseure  B. De Bivre  J. Deckers 《水文研究》2005,19(20):3985-3997

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Electromagnetic Radiation and Motion of a Particle   总被引：2，自引：2，他引：0  

Jozef Klačka 《Celestial Mechanics and Dynamical Astronomy》2004,89(1):1-61

We consider the motion of uncharged dust grains of arbitrary shape including the effects of electromagnetic radiation and thermal emission. The resulting relativistically covariant equation of motion is expressed in terms of standard optical parameters. Explicit expressions for secular changes of osculating orbital elements are derived in detail for the special case of the Poynting-Robertson effect. Two subcases are considered: (i) central acceleration due to gravity and the radial component of radiation pressure independent of the particle velocity, (ii) central acceleration given by gravity and the radiation force as the disturbing force. The latter case yields results which may be compared with secular orbital evolution in terms of orbital elements for an arbitrarily shaped dust particle. The effects of solar wind are also presented. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献