Alpine metamorphism of low-grade schists from the Slavonian Mountains (Croatia): new P-T and geochronological constraints     

Dražen Balen  Hans-Joachim Massonne  Iva Lihter 《International Geology Review》2018,60(3):288-304

Low-grade schists from the Slavonian Mountains (Tisia Mega-Unit, Mt Papuk, Croatia), previously assigned to Precambrian to Lower Palaeozoic metamorphism, have been subjected to geochemical investigations, P-T modelling, and in situ age dating of monazite. The studied fine-grained metasediments consist of chlorite (5–15 vol.%), K white-mica (40–55 vol.%), quartz (20–35 vol.%), feldspar (albite 15–20 vol.%), opaques (<2 vol.%), and accessory minerals. According to their whole-rock geochemistry, the detritus of the former sediments came from upper crustal felsic rocks as they occur, for instance, at Mt Papuk. The schists show a complex microtectonic fabric, including well-developed schistosity systems. P-T pseudosections in the system MnNCKFMASHTO, constructed for typical schists of the study area, resulted in peak P-T conditions of 445–465 °C and 4.6–6.0 kbar for a sample from Kutjevo (eastern part of the study area) and 450–460 °C and 5.2–6.0 for a Vranovo sample (western part). Electron microprobe (EMP) dating of monazite in the schists gave a weighted average age of 109.0 ± 13.1 Ma (2σ) eventually with three subgroups of ages at 225 ± 63 (two analyses), 114 ± 24 and 83 ± 22 Ma. We conclude that the metamorphism of the studied schists at depths of c. 20 km is due to an Alpine collisional event.  相似文献   

Impoverishment of recent floodplain forest mollusc fauna in the lower Ohře River (Czech Republic) as a result of prehistoric human impact     

Lucie Juřičková  Jitka Horáčková  Vojen Ložek  Michal Horsák 《Boreas: An International Journal of Quaternary Research》2013,42(4):932-946

Analyses of fossil mollusc successions have rarely been used to study the development of floodplain forests during the Holocene. The Oh?e River, located in a prehistorically settled chernozem area in the Czech Republic, is partly situated in Cretaceous marlstones, yielding sediments suitable for fossilization directly in floodplain deposits. We analysed five fossil mollusc successions situated in the lower stretch of the Oh?e River and compared the results with recent mollusc assemblages studied along the entire 256 km of the river. Fossil samples were composed mostly of open‐country species throughout the Holocene or the whole preserved succession. Only some samples also contained woodland assemblages, but these were always greatly impoverished, with a very low frequency of strictly woodland species. Although the natural‐looking appearance of the present‐day floodplain forests of the lower river stretch has resulted in its being declared a nature reserve, modern floodplain forest mollusc assemblages there are also impoverished. This reduction in the distribution of strictly woodland species compared with modern assemblages in the upper stretch of the river seems to be the result of an ancient human settlement and continuous disturbances of the floodplain forest development since the Neolithic. Thus, fully developed floodplain forest assemblages occur recently only in the upper non‐impacted stretch of the river. Based on the studied fossil successions we can conclude that the lower Oh?e River floodplain was probably a mosaic of open and disturbed forest habitats throughout the Holocene. This area is part of a central European landscape island, where forests probably never fully developed and open patches from the early Holocene continually developed into an agricultural landscape.  相似文献   

Impact of an inter‐basin water transfer and reservoir operation on a karst open streamflow hydrological regime: an example from the Dinaric karst (Croatia)     

Ognjen Bonacci  Ivo Andrić 《水文研究》2010,24(26):3852-3863

This paper describes the hydrological changes caused by inter‐basin water transfer and the reservoir development on the hydrological regimes of two rivers. The Sabljaki Reservoir in the Zagorska Mre?nica River and the Bukovik Reservoir in the upper Dobra River began operation in 1959. Both are part of the hydroelectric power plant (HEPP) Gojak, whose installed capacity is 50 m³/s. Their water volumes at the spillway altitudes of 320·10 and 320·15 m a. s. l. are 3·3 × 10⁶ and 0·24 × 10⁶ m³ respectively. Both the Dobra and Mre?nica Rivers are losing, sinking and underground karst rivers. A 9376‐m‐long tunnel provides water from the Sabljaki Reservoir to the HEPP Gojak, which was constructed in the Lower Dobra River. The Sabljaki Reservoir is located in the Pla?ki karst polje, while the Bukovik Reservoir is located in the neighbouring Ogulin karst polje. The consequences of the inter‐basin water transfer are strong and have caused abrupt changes in the hydrological regimes of the downstream sections of both rivers. At the same time, the construction and development of both the reservoirs have also caused hydrological changes to the upstream section of the Upper Dobra River. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

On the relation between solar motion and the long term variability of solar activity     

Ivanka Charvátová  Reviewer P. Ambrož 《Studia Geophysica et Geodaetica》1989,33(3):230-241

Summary The Sun's motion round the barycentre of the solar system was found to consist of two basic alternately repeating elements of the noose and of the arc. The mean time for solar motion around each of these elements was found to be 9.93 yr. The relation between solar motion and solar variability was determined as follows: Approximately coincident periodicities ranging from 60 to 2200 yr were traced in both phenomena and a coincidence of all prolonged minima in solar activity with the epochs of the highest deviations from the Jupiter—Saturn order was found over a time interval of 3100 yr.

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Thermo-elastic deformations due to the annual temperature variation at the tidal station in Vyhne     

Milan Hvoždara  Ladislav Brimich  Reviewer L. Skalský 《Studia Geophysica et Geodaetica》1988,32(2):129-135

Summary The thermo-elastic deformations due to the annual temperature variation are computed. The time variation of these deformations is compared with the variation of the slow deformations observed at the tidal station in Vyhne.

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u mnu ¶rt;auu, a¶rt; auau mnam nmu a nnmama. ¶rt; mu ¶rt;au a ¶rt; ¶rt; ¶rt;au, u a nuu mauu ().

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Dedicated to RNDr Jan Pícha, CSc on his 70th birthday  相似文献   

The boundary integral calculations of the forward problem for D.C. sounding and MMR methods for a 3-D body near a vertical contact     

M. Hvoždara  P. Kaikkonen 《Studia Geophysica et Geodaetica》1994,38(4):375-398

Summary The paper presents comprehensive theory based on the boundary integral method for calculations of the electric potential, electric field and corresponding magnetic field due to a pair of D.C. source electrodes near a vertical resistivity contact in the halfspace, indlucing a 3-D disturbing body in the vicinity of the contact. Special attention is paid to the case when the disturbing body touches the vertical contact. Results of numerical calculations are presented in the form of sounding curves and a set of isoline graphs for potential, components of the electric and magnetic field (total and anomalous) on the surface of the Earth. It is shown that the presence of the disturbing body at the contact is most pronounced in the electrical characteristics. Anomalies in the magnetic field are small in comparison to the field due to the electric current in the electrode cable and primary currents flowing from the electrodes.  相似文献   

The photoelectron spectra of some Tl-Sb sulphosalts     

Ivan Gržetić  Tonći Balić Žunic 《Physics and Chemistry of Minerals》1993,20(4):285-296

The results of X-ray induced photoelectron spectroscopy (XPS) experiments on several phases of the ternary system Tl-Sb-S are reported. The binding energies of the inner S, Sb and Tl electrons increase with increasing quantities of Sb and decreasing amounts of Tl in these compounds. This is explained by the influences of the proportions of the bonded metals on the effective electron affinity of S. The higher proportions of the more electronegative element bonded to S cause the increase of its effective electron affinity. The results for Tl₂S (carlinite), Tl₃SbS₃, TlSbS₂ (weissbergite), TlAsS₂ (lorandite) and Sb₂S₃ (antimonite) can be interpreted in this way. The results for Tl₄S₃ suggest a predominantly covalent character of bonding for both Tl(III) and Tl(I), which are present in this sulfide. From comparison with Tl₃SbS₄ it could be supposed that Tl(III)-S bond has a more covalent character than Sb(V)-S bond. The results for Tl₃SbS₄ are in agreement with crystal structure data and the results of Moessbauer spectroscopy. For AsS (realgar) the binding energies of the inner electrons of As and S significantly increase, showing that the electrons in molecular orbitals are less strongly bonded to individual atoms, as compared to pure elements. The results for the amorphous TlSb₅S₈ (corresponding in composition to parapierrotite) suggest that in amorphous compound the Tl-S bonding is stronger and the coordination of Tl more regular than in a crystalline one.  相似文献   

The extreme value distribution of 5-min rainfall data at Belgrade     

Unkašević Miroslava 《Theoretical and Applied Climatology》1991,44(3-4):223-228

Summary For practical applications both the parent distribution of rainfall intensities and the distribution of their annual maxima are of interest. The relationship between these two distributions cannot be obtained from classical extreme value theory because of seasonal variation and serial correlation in the data. Mathematical results for the distribution of maxima in m-dependent sequences are presented to illustrate the effect of local dependence on the extreme value distribution. The average number of exceedances in a cluster is an important parameter in the relationship between the parent and the extreme value distribution. For 5-min rainfall data from Belgrade, quantiles of the annual maxima are overestimated by about 10 mm h^–1 if the effect of serial correlation is ignored. This bias can easily be removed by taking the local clustering of large rainfall intensities in a rainy spell into account.With 4 Figures  相似文献   

Environmental capacity—Is a new scientific concept acceptable as a strategy to combat marine pollution?     

Velimir Pravdić 《Marine pollution bulletin》1985,16(7):295-296

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Some views on the geography of tourism and recreation in Yugoslavia     

Milorad Vasović 《GeoJournal》1984,9(1):83-84

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