Intraplate volcanism in the Danube Basin of NW Hungary: 3D geophysical modelling of the Late Miocene Pásztori volcano     

Pánisová  Jaroslava  Balázs  Attila  Zalai  Zsófia  Bielik  Miroslav  Horváth  Ferenc  Harangi  Szabolcs  Schmidt  Sabine  Götze  Hans-Jürgen 《International Journal of Earth Sciences》2018,107(5):1713-1730

International Journal of Earth Sciences - Three-dimensional geophysical modelling of the early Late Miocene Pásztori volcano (ca. 11–10 Ma) and adjacent area in the Little...  相似文献   

The unique environment of the most acidified permanently meromictic lake in the Czech Republic     

Tomáš Hrdinka  Miroslav Šobr  Jan Fott  Linda Nedbalová 《Limnologica》2013,43(6):417-426

Changes in the water properties and biological characteristics of the highly acidic Hromnice Lake (Western Bohemia) were investigated. This 110-year-old lake, formed as a consequence of the mining of pyritic shales, is permanently meromictic. Two chemoclines separate an extremely acidic (pH ～ 2.6) mixolimnion from a metal-rich anoxic monimolimnion. The absence of spring mixolimnetic turnover due to ice melting and very slow heat propagation through the chemocline with a 6-month delay were observed. Extreme mixolimnetic oxygen maxima (up to 31 mg l^?1) in phosphorus-rich lake (PO₄^3? up to 1.6 mg l^?1) well correlated with outbursts of phytoplankton. Phytoplankton consist of several acido-tolerant species of the genera Coccomyxa, Lepocinclis, Chlamydomonas and Chromulina. Surface phytoplankton biomass expressed as chlorophyll-a varies from 2 to 140 μg l^?1. Multicellular zooplankton are almost absent with the exception of Cephalodella acidophila, a small rotifer occurring in low numbers. Large red larvae of the midge Chironomus gr. plumosus were found at the bottom close to the shore, with larvulae in the open water. Developmental stages (protonemata) of a moss, resembling filamentous algae, dwell in the otherwise plant-free littoral zone.  相似文献   

Interactions between European agricultural policy and climate change: a Slovenian case study     

Emil Erjavec  Tina Volk  Miroslav Rednak  Barbara Zagorc  Ben Moljk 《Climate Policy》2013,13(8):1014-1030

This article analyses the interactions between agricultural policy measures in the EU and the factors affecting GHG emissions from agriculture on the one hand, and the adaptation of agriculture to climate change on the other. To this end, the article uses Slovenia as a case study, assessing the extent to which Slovenian agricultural policy is responding to the challenges of climate change. All agricultural policy measures related to the 2007–2013 programming period were analysed according to a new methodological approach that is based on a qualitative (expert evaluation) and a quantitative (budgetary transfers validation) assessment. A panel of experts reached consensus on the key factors through which individual measures affect climate change, in which direction and how significantly. Data on budgetary funds for each measure were used as weights to assess their relative importance. The results show that there are not many measures in (Slovenian) agricultural policy that are directly aimed at reducing GHG emissions from agriculture or at adaptation to climate change. Nevertheless, most affect climate change, and their impact is far from negligible. Current measures have both positive and negative impacts, but overall the positive impacts prevail. Measures that involve many beneficiaries and more budgetary funds had the strongest impact on aggregate assessments. In light of climate change, agricultural policy should pay more attention to measures that are aimed at raising the efficiency of animal production, as it is the principal source of GHG emissions from agriculture.

Policy relevance

Agricultural policy must respond to climate challenges and climate change impact assessment must be included in the process of forming European agricultural policy. Agricultural policy measures that contribute to the reduction of emissions and adaptation, whilst acting in synergy with other environmental, economic and social goals, should be promoted. The approach used in this study combines qualitative and quantitative data, yielding an objective assessment of the climate impact of agricultural policy measures and providing policy makers with a tool for either ex ante or ex post evaluations of climate-relevant policy measures.  相似文献   

An inelastic stress integration algorithm for a rock mass containing sets of discontinuities     

Nenad Grujovic  Dejan Divac  Miroslav Zivkovic  Radovan Slavkovic  Nikola Milivojevic  Vladimir Milivojevic  Dragan Rakic 《Acta Geotechnica》2013,8(3):265-278

The mechanical behaviour of a rock mass is described in this paper using a method that combines experimental and numerical techniques. A new discontinuity (joint) constitutive model is proposed based on the non-associative yield law. Constitutive relationships for an anisotropic rock mass are determined by introducing an interaction between sets of discontinuities and the monolith in which they occur. The model is based on the concept that deformation of the monolith and its associated sets of discontinuities are coupled. An experimental investigation of the concrete foundations of the Bogovina Dam on the Crni Timok River in Serbia has been used to verify the presented numerical model. The tests included discontinuity and monolith sample investigations and large-scale field tests.  相似文献   

Radiative cooling within illuminated layers of dust on (pre)-planetary surfaces and its effect on dust ejection     

M. Kocifaj  J. Kla?ka 《Icarus》2011,211(1):832-838

Temperature gradients in dust beds embedded in a low pressure gaseous environment induce a lift of particles under certain conditions. This effect can erode planetesimals and enables entrainment of dust into the martian atmosphere. Here, we consider a numerical model to calculate the temperature profile in a dust bed which is subject to illumination. We consider the situation when the illumination is switched on and heats the dust bed’s surface and when it is switched off again after a certain time. The calculations focus on the heat transfer by infrared radiation within the dust layer. We find that radiative transfer within the dust bed modifies the absolute temperatures and temperature gradients significantly. This is important for effects which are sensitive to absolute temperatures, i.e. ice sublimation or melting of solids. For low thermal conductivity dust beds of 0.001 W m⁻¹ K⁻¹ it determines the temperature structure of the dust. For higher thermal conductivities the modifications are moderate with respect to dust eruptions as the order of magnitude of temperature gradients stays the same.  相似文献   

Cross-borehole flow analysis to characterize fracture connections in the Melechov Granite, Bohemian-Moravian Highland, Czech Republic     

Frederick L. Paillet  John H. Williams  Joseph Urik  Joseph Lukes  Miroslav Kobr  Stanislav Mares 《Hydrogeology Journal》2012,20(1):143-154

Application of the cross-borehole flow method, in which short pumping cycles in one borehole are used to induce time-transient flow in another borehole, demonstrated that a simple hydraulic model can characterize the fracture connections in the bedrock mass between the two boreholes. The analysis determines the properties of fracture connections rather than those of individual fractures intersecting a single borehole; the model contains a limited number of adjustable parameters so that any correlation between measured and simulated flow test data is significant. The test was conducted in two 200-m deep boreholes spaced 21?m apart in the Melechov Granite in the Bohemian-Moravian Highland, Czech Republic. Transient flow was measured at depth stations between the identified transmissive fractures in one of the boreholes during short-term pumping and recovery periods in the other borehole. Simulated flows, based on simple model geometries, closely matched the measured flows. The relative transmissivity and storage of the inferred fracture connections were corroborated by tracer testing. The results demonstrate that it is possible to assess the properties of a fracture flow network despite being restricted to making measurements in boreholes in which a local population of discrete fractures regulates the hydraulic communication with the larger-scale aquifer system.  相似文献   

Depth-Recursive Tomography of the Bohemian Massif at the CEL09 Transect—Part B: Interpretation     

Miroslav Novotný 《Surveys in Geophysics》2012,33(2):243-273

In the accompanying paper (Part A), depth-recursive tomography was applied to the CEL09 refraction data. A deblurred P-wave velocity image was obtained down to a depth of 20 km. This paper (Part B) is devoted to the interpretation of the upper- and middle-crustal structures of the Bohemian Massif imaged in the CEL09 section. Because of inherent ambiguity of the refraction method in imaging low-velocity zones, other well-known results based on other geophysical data sets are also used to independently verify the interpreted velocity features. Comparison with the density and velocity models previously obtained indicates that the presented P-wave velocity image has superior resolution revealing or verifying a number of geological features. The prominent lateral velocity changes encountered in the CEL09 pattern across the imaged crustal section were used to delineate the main terranes and deep regional fault zones such as the Kru?né hory Fault, the SW continuation of the Litomě?ice Fault Zone, the West and Central Bohemian Shear Zones, the Blanice-Rodl Fault, the P?ibyslav-Vitis Fault and the Boskovice-Diendorf Fault. The 450-km-long CEL09 transect reveals seven major deeply rooted high-velocity (HV) anomalies identified as Variscan massifs intruded near or within these deep fault zones. They form buried ridges mostly parallel to the SW-NE trending Variscan strike. Their discovery allows new insights into a number of phenomena such as the West Bohemian earthquake swarms, the Saxothuringian paradox, the character of the Saxothuringian-Barrandian contact zone, the detachment surface due to the slab of the Saxothuringian crust subducting beneath the Teplá-Barrandian zone in the Devonian, the depth extent of the Mariánské-Lázně Complex (MLC) as an equivalent unit of the Zone Erbendorf-Vohenstrauss (ZEV), the subsidence of the Barrandian syncline, the root zones of the Central and South Bohemian Plutons, the accretionary wedge formed along the Moravo-Moldanubian suture and its link with the Gföhl terrane, the Carpathian foreland relief and the subsidence observed in the Vienna Basin.  相似文献   

Depth-Recursive Tomography Along the Eger Rift Using the S01 Profile Refraction Data: Tested at the KTB Super Drilling Hole,Structural Interpretation Supported by Magnetic,Gravity and Petrophysical Data     

Miroslav Novotný  Zuzana Skácelová  Jan Mrlina  Bedřich Mlčoch  Bohuslav Růžek 《Surveys in Geophysics》2009,30(6):561-600

The refraction data from the SUDETES 2003 experiment were used for high-resolution tomography along the profile S01. The S01 profile crosses the zone Erbendorf-Vohenstrauss (ZEV) near the KTB site, then follows the SW–NE oriented Eger Rift in the middle part and continues toward the NE across the Elbe zone and the Sudetic structures as far as the Trans-European Suture Zone. To get the best resolution in the velocity image only the first arrivals of Pg waves with minimum picking errors were used. The previous depth-recursive tomographic method, based on Claerbout’s imaging principle, has been adapted to perform the linearized inversions in iterative mode. This innovative DRTG method (Depth-Recursive Tomography on Grid) uses a regular system of refraction rays covering uniformly the mapped domain. The DRTG iterations yielded a fine-grid velocity model with a required level of RMS travel-time fit and the model roughness. The travel-time residuals, assessed at single depth levels, were used to derive the statistical lateral resolution of “lens-shaped” velocity anomalies. Thus, for the 95% confidence level and 5% anomalies, one can resolve their lateral sizes from 15 to 40 km at the depths from 0 to 20 km. The DRTG tomography succeeded in resolving a significant low-velocity zone (LVZ) bound to the Franconian lineament nearby the KTB site. It is shown that the next optimization of the model best updated during the DRTG iterations tends to a minimum-feature model with sweeping out any LVZs. The velocities derived by the depth-recursive tomography relate to the horizontal directions of wave propagation rather than to the vertical. This was proved at the KTB site where pronounced anisotropic behavior of a steeply tilted metamorphic rock complex of the ZEV unit has been previously determined. Involving a ~7% anisotropy observed for the “slow” axis of symmetry oriented coincidentally in the horizontal SW–NE direction of the S01 profile, the DRTG velocity model agrees fairly well with the log velocities at the KTB site. Comparison with the reflectivity map obtained on the reflection seismic profile KTB8502 confirmed the validity of DRTG velocity model at maximum depths of ~16 km. The DRTG tomography enabled us to follow the relationship of major geological units of Bohemian Massif as they manifested in the obtained P-wave velocity image down to 15 km. Although the contact of Saxothuringian and the Teplá-Barrandian Unit (TBU) is collateral with the S01 profile direction, several major tectonic zones are rather perpendicular to the Variscan strike and so fairly imaged in the S01 cross-section. They exhibit a weak velocity gradient of sub-horizontal directions within the middle crust. In particular, the Moldanubian and TBU contact beneath the Western Krušné hory/Erzgebirge Pluton, the buried contact of the Lusatia unit and the TBU within the Elbe fault zone were identified. The maxima on the 6,100 ms⁻¹ isovelocity in the middle crust delimitated the known ultrabasic Erbendorf complex and implied also two next ultrabasic massifs beneath the Doupovské hory and the České středohoří volcanic complexes. The intermediate mid-crustal P-wave velocity lows are interpreted as granitic bodies. The presented geological model is suggested in agreement with available gravity, aeromagnetic and petrophysical data.  相似文献   

Geological interpretation of gravity profiles through the Karlovy Vary granite massif (Czech Republic)     

Vratislav Blecha  Miroslav Štemprok  Tomáš Fischer 《Studia Geophysica et Geodaetica》2009,53(3):295-314

We examined the shape of the Late Variscan Karlovy Vary granite massif located south of the Ohre/Eger graben in Northern Bohemia by reinterpretation of existing gravity data on two perpendicular profiles. The granite body of about 360 km² total outcrop size has the elongation ratio 0.35 with the major axis trending NE-SW. The SW part of the body was crossed in the nineties by the seismic profile 9HR which localized the bottom of granites in a depth of about 10 km. We used this value as a reference datum in our gravity profiles. We positioned one of our profiles along the seismic profile 9HR and the other one perpendicularly, i.e. parallel with the elongation of the outcrop surface. We interpret the shape of the main granite body in the vicinity of Karlovy Vary as a continuous desk whose floor is horizontal (or subhorizontal) and varies along its whole extension about a depth of 10 km. This thickness is approximately identical with that of the Saxothuringian nappes imaged by seismic reflection. The near surface upper contact of the granite body is mildly inclined, and outward dipping. It changes to steep sides or inward inclined contacts in deeper levels. The Lesny-Lysina (Kynžvart) massif is a separate granite body about 324 km thick, not continuously connected with the main Karlovy Vary massif. The gravity curve suggests that granites often enclose in their endocontact large blocks of country metasediments or metabasites the existence of which is partly evidenced by their outcrops outside the line of the profile. The granite body is found density-homogenous. Minor density differences between granite varieties are caused mainly by more intense hydrothermal alterations in younger suite granites. We interpret vertical conduits for the ascent of granitic magmas to be parallel to the Jáchymov-Gera and Ohře (Eger) lineaments or the Mariánské Lázně fault zone as indicated by the elongation of some outcrops. However, they are not clearly imaged from the gravity data. The effect of the depression of the Sokolov basin along the faults parallel with the Ohře (Eger) lineament is shallow and it is not indicated by any change in the floor depth of the granite body. Comparison of the seismicity distribution suggests that the hypocenters occur mostly outside of the granite bodies or near their contact with the country rock.  相似文献   

Moldavites from the Cheb Basin, Czech Republic     

Roman Skála  Ladislav Strnad  Miroslav ?ada 《Geochimica et cosmochimica acta》2009,73(4):1145-2158

Between 1993 and 2007, an estimated 2500-3000 individual moldavite pieces have been found in the Tertiary Cheb Basin, Western Bohemia. This identifies the area as the third most prominent source of Central European tektites, next to the South Bohemian and West Moravian strewn subfields. Basic macroscopic physical properties (weight, shape, color and sculpture) were evaluated for over 350 individual finds of tektites from 4 different localities in the Cheb Basin. All these properties are similar to those observed for the South Bohemian moldavites, particularly with respect of color and weight distribution. In total, 24 tektites from the Cheb Basin have been characterized chemically using electron microprobe. For comparison, a set of 17 moldavites from the South-Bohemian and Moravian strewn subfields was measured as well. Contents of major elements overlap between the two sample sets; the largest variation was observed for iron. The trends observed in the Harker plots, however, seem to differentiate several partial subgroups, some of them characteristic for Cheb tektites only. These results are also substantiated by cluster analysis, which reveals a tight group for most of the tektites from the Cheb Basin, forming two partial clusters. The rest of the Cheb moldavites cluster with the South Bohemian samples. Minor and trace elements were measured with an LA-ICP-MS technique; CI-normalized REE patterns compare well with those for other moldavites. Many tektites, both from Cheb and South Bohemia or Moravia, display considerable heterogeneity: they frequently show schlieren and fluidal fabric. Two samples of this kind from the Cheb Basin showed considerable enrichment in volatile elements (e.g., Zn and Cu), which is typical for Muong Nong-type Australasian tektites. Mössbauer spectroscopy confirmed the highly reducing character of 5 studied moldavites. Discovery of a new moldavite strewn subfield around Cheb substantiates the theory that moldavites were ejected from the Ries impact structure in a fan-shaped jet, although it is not clear yet if it was continuous or composed of individual rays. In addition, the chemistry of the Cheb moldavites indicates significant precursor material heterogeneity.  相似文献