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81.
P. Puelles J. I. Gil Ibarguchi A. Beranoaguirre B. ábalos 《International Journal of Earth Sciences》2012,101(7):1835-1853
The Limo harzburgites constitute a hm-thick tectonic stack where extremely elongated meter-scale sheath folds occur, bearing axes parallel to the macroscopic lineation recognized across the whole complex. They can be identified as close to L-type tectonites, with a weak foliation, a well-developed stretching, and a mineral lineation defined by the mineral assemblage in equilibrium. The linear fabric is recognizable at every scale, from aerial photos to the crystallographic orientation of the harzburgite-forming minerals measured by means of the electron back-scatter diffraction technique. These rocks registered initial deformation under high-temperature and low water fugacity conditions at low stress levels in an anhydrous mantle wedge context, as it is inferred from the activity of the [100](010) slip system in olivine. Then, the ongoing eo-Variscan subduction incorporated fluid/melts from the subducting plate into the suprasubduction mantle wedge zone. The variation in the ambient physicochemical conditions led to the operation of the [001](010) slip system in olivine, indicative of lower temperature and higher water fugacity and stress levels. These changes are recorded, too, by synkinematic recrystallization of oriented chlorite. The L-type fabric of clinopyroxene points to constriction conditions during deformation. The active deformational processes continued along the subduction conduit with the thrust of the peridotites onto the high-pressure granulites of the Bacariza Formation. Posteriorly, the whole ensemble would have shared a common deformational history related to exhumation and initial amphibolitization. Subsequent deformation processes under greenschist facies conditions took place until effective continental collision during the Early Carboniferous gave rise to the Variscan orogen. 相似文献
82.
Imprints of hydrocarbon-bearing basinal fluids on a karst system: mineralogical and fluid inclusion studies from the Buda Hills,Hungary 总被引:1,自引:1,他引:0
Zsófia?PorosEmail author Andrea?Mindszenty Ferenc?Molnár Jacques?Pironon Orsolya?Gy?ri Paola?Ronchi Zoltán?Szekeres 《International Journal of Earth Sciences》2012,101(2):429-452
Calcite veins and related sulphate–sulphide mineralisation are common in the Buda Hills. Also, abundant hypogenic caves are
found along fractures filled with these minerals pointing to the fact that young cave-forming fluids migrated along the same
fractures as the older mineralising fluids did. The studied vein-filling paragenesis consists of calcite, barite, fluorite
and sulphides. The strike of fractures is consistent—NNW–SSE—concluding a latest Early Miocene maximum age for the formation
of fracture-filling minerals. Calcite crystals contain coeval primary, hydrocarbon-bearing- and aqueous inclusions indicating
that also hydrocarbons have migrated together with the mineralising fluids. Hydrocarbon inclusions are described here for
the first time from the Buda Hills. Mixed inclusions, i.e., petroleum with ‘water-tail’, were also detected, indicating that
transcrystalline water migration took place. The coexistence of aqueous and petroleum inclusions permitted to establish the
entrapment temperature (80°C) and pressure (85 bar) of the fluid and thus also the thickness of sediments, having been eroded
since latest Early Miocene times, was calculated (800 m). Low salinity of the fluids (<1.7 NaCl eq. wt%) implies that hydrocarbon-bearing
fluids were diluted by regional karst water. FT-IR investigations revealed that CO2 and CH4 are associated with hydrocarbons. Groundwater also contains small amounts of HC and related gases on the basin side even
today. Based on the location of the paleo- and recent hydrocarbon indications, identical migration pathways were reconstructed
for both systems. Hydrocarbon-bearing fluids are supposed to have migrated north-westward from the basin east to the Buda
Hills from the Miocene on. 相似文献
83.
Parameterization of historical earthquakes in Switzerland 总被引:1,自引:1,他引:0
Sonia álvarez-Rubio Philipp K?stli Donat F?h Souad Sellami Domenico Giardini 《Journal of Seismology》2012,16(1):1-24
Macroseismic earthquake parameters of historical events have been reassessed in the framework of the update of the Earthquake
Catalogue of Switzerland ECOS-09. The Bakun and Wentworth method (Bakun and Wentworth 1997) has been used to assess location, magnitude, and, when possible, focal depth. We apply a two-step procedure. Intensity attenuation
is assessed first by fitting a model with a logarithmic and a linear term, using a set of 111 earthquakes. The magnitude range
is 3 and 5.8. Then, intensity to magnitude relation is developed. A subset of the 111 events, all having an instrumental moment
magnitude, was used to perform this intensity to magnitude calibration. Five final calibration strategies were developed based
on different intensity calibration datasets, regionalized or non-regionalized models, and fixed or variable source depth.
The final assessment of the macroseismic earthquake parameters is based on an expert judgment procedure, using the results
derived from all five strategies, and taking into consideration the historical knowledge available for the particular earthquake.
A bootstrap procedure has been applied to assess the uncertainty of parameters. Indicative lower and upper bounds of uncertainty
are derived from distributions of location and magnitude for a number of events, obtained through bootstrap sampling of the
intensity field and of the single intensity values. The final uncertainties are given in terms of parameter uncertainty classes
already used in previous versions of the earthquake catalogue of Switzerland. 相似文献
84.
Csaba Szabó Károly Hidas Enik Bali Zoltán Zajacz István Kovács Kyounghee Yang Tibor Guzmics Kálmán Török 《Island Arc》2009,18(2):375-400
In this paper we present a detailed textural and geochemical study of two equigranular textured amphibole-bearing spinel lherzolite xenoliths from Szigliget, Bakony–Balaton Highland Volcanic Field (BBHVF, western Hungary) containing abundant primary silicate melt inclusions (SMIs) in clinopyroxene rims and secondary SMIs in orthopyroxene (and rarely spinel) along healed fractures. The SMIs are dominantly composed of silicate glass and CO2 -rich bubbles. Clinopyroxene and orthopyroxene are zoned in both studied xenoliths, especially with respect to Fe, Mg, Na, and Al contents. Cores of clinopyroxenes in both xenoliths show trace element distribution close to primitive mantle. Rims of clinopyroxenes are enriched in Th, U, light rare earth elements (LREEs) and medium REEs (MREEs). Amphiboles in the Szg08 xenolith exhibit elevated Rb, Ba, Nb, Ta, LREE, and MREE contents. The composition of silicate glass in the SMIs covers a wide range from the basaltic trachyandesite and andesite to phonolitic compositions. The glasses are particularly rich in P2 O5 . Both primary and secondary SMIs are strongly enriched in incompatible trace elements (mostly U, Th, La, Zr) and display a slight negative Hf anomaly. The development of zoned pyroxenes, as well as the entrapment of primary SMIs in the clinopyroxene rims, happened after partial melting and subsequent crystallization of clinopyroxenes, most probably due to an interaction between hot volatile-bearing evolved melt and mantle wall-rocks. This silicate melt filled microfractures in orthopyroxenes (and rarely spinels) resulting in secondary SMIs. 相似文献
85.
Gbor Újvri Gyula Mentes Lszl Bnyai Jnos Kraft Attila Gyimthy Jnos Kovcs 《Geomorphology》2009,109(3-4):197-209
The banks of the River Danube are one of the most susceptible areas to mass wasting in Hungary. In 2007, a large slump began to develop along the Danube at Dunaszekcső and jeopardized properties on land and navigation in the river. Several factors such as geological, hydrogeological and morphological conditions, recurrent flooding and erosion by the Danube led to a gradual development of the large rotational slide. Slope failure has been monitored using GPS, precise levelling techniques and tiltmeters since October 2007. The expected location of the maximum lateral displacement and extrusion was indicated by GPS measurements from the middle of November 2007. The main phase of the slope failure evolution, i.e. the rapid movement on 12 February 2008 was indicated by accelerated tilting of the southern moving block prior to slumping. Small rise of the relatively stable part of the slope was measured after the rapid movements, which may be explained either by the elastic rebound along the slip surface, or by the intrusion of some plastic material into the lower section of the slope.Comparison of geodetic datasets and field observations with the timing of rainfall and water level changes of the Danube suggested that hydrological properties (subsurface flow processes, soil physical properties, infiltration, and perched water table) were primarily responsible for initiation of the studied slump. A model of slope failure evolution is proposed here based on the monitoring and field observations. 相似文献
86.
87.
Marcell Ferenc Joelle Nicolas Tonie van Dam Laurent Polidori Alexis Rigo Philippe Vernant 《Studia Geophysica et Geodaetica》2014,58(1):56-75
Surface displacements due to temporal changes in environmental mass redistributions are observable in the coordinate time series of many Global Navigation Satellite System (GNSS) sites. In this study, we investigated the effect of loading on estimates of tectonic velocity computed from campaign-style GNSS observations. The study region is in the Pyrenees mountain range between France and Spain (ResPyr campaigns). In this area, seismic activity is continuous and moderate and the expected amplitude of the horizontal tectonic velocity is less than 0.5 mm/yr. In order to determine the velocity, 4 sparse GNSS campaigns were carried out from 1995 to 2010. Considering this small rate of deformation, loading phenomena can contribute a non-negligible artifact to the velocity computation that could affect our geodynamical interpretation. In this investigation, we specifically considered the atmospheric, hydrological, and non-tidal ocean loading phenomena. The computed loading deformations for this region show the horizontal displacements are dominated by the non-tidal ocean loading (maximum 4 mm for the North and 3.1 mm for the East components); the main vertical contributions are due to the atmospheric and continental water storage loading (maximum 14.3 for the atmosphere and 8.1 mm for the hydrology, respectively). We have found that the dominant loading effect on the horizontal velocity is the non-tidal ocean loading (mean of 0.11 mm/yr), whereas the vertical component is dominated by the hydrological loading (mean of 0.21 mm/yr). Since the study area is in a mountainous region, we also analyzed the difference between the atmospheric and the topography dependent atmospheric loading models at our GNSS campaign sites. We did not find any significant difference between the two atmospheric loading models in terms of horizontal velocity. Finally, we performed simulations to identify the optimum timing and frequency of future GNSS campaigns in this area that would minimize the loading effects on tectonic velocity estimates. 相似文献
88.
Hajnalka Breuer Ferenc ács Borbála Laza ákos Horváth István Matyasovszky Kálmán Rajkai 《Theoretical and Applied Climatology》2012,109(3-4):577-590
The effects of two soil datasets on planetary boundary layer (PBL) height are analyzed, using model simulations. Simulations are performed with the MM5 weather prediction system over the Carpathian Basin, with 6?km horizontal resolution, investigating three summer days, two autumn, and one winter day of similar synoptic conditions. Two soil datasets include that of the United States Department of Agriculture, which is globally used, and a regional Hungarian called Hungarian unsaturated soil database. It is shown that some hydraulic parameter values between the two datasets can differ up to 5–50%. These differences resulted in 10% deviations in the space–time-averaged PBL height (averaged over Hungary and over 12?h in the daytime period). Over smaller areas, these relative deviations could reach 25%. Daytime course changes in the PBL height for reference run conditions were significant (p?<?0.01) in ≈70% of the grid points covering Hungary. Ensemble runs using different atmospheric parameterizations and soil moisture initialization setups are also performed to analyze the sensitivity under changed conditions. In these cases, the sensitivity test showed that irrespective of the radiation and PBL scheme, the effect of different soil datasets on PBL height is roughly the same. PBL height is also sensitive to field capacity (Θf) and wilting point (Θw) changes. Θf changes seem to be more important for loamy sand, while Θw changes for the clay soil textural class. 相似文献
89.
Summary ?Evapotranspiration characteristics on the point-scale (several hundred square meters) and the local scale (several square
kilometers) are analysed by comparing a deterministic and a statistical – deterministic surface energy balance model. The
vegetation surface variability is represented by both the surface heterogeneity and inhomogeneity. Heterogeneity means the
mosaic of wet (wif ≠ 0) and dry (1-wif) fractions of vegetation surface, while inhomogeneity addresses small scale variations of soil moisture content.
The microscale characteristics of evapotranspiration are considered in terms of analysing evapotranspiration E
v
versus soil moisture content θ, relative frequency distribution characteristics of E
v
(θ) and the aggregation algorithms for its estimation. The analyses are performed for loam soil type under different atmospheric
forcing conditions.
The main result is as follows: For dry vegetation surface (wif = 0), the relationship between the aggregated (θagg) and the area-averaged (θ
m
) soil moisture content is nonlinear and depends on both the states of the surface and the atmospheric forcing conditions.
In the study, we assumed that there are no advective effects and mesoscale circulation patterns induced by surface discontinuities.
Based on this fact it seems unlikely to be able to construct an aggregation algorithm for calculating θagg without inclusion of the atmospheric forcing conditions. This means that it will be difficult to construct a simple formula
for calculating area-averaged transpiration, if it is possible at all.
Received May 3, 2001; revised May 31, 2002; accepted June 3, 2002 相似文献
90.
G. Kovács 《Solar physics》1983,82(1-2):123-128
The accuracy of frequency determination by a least squares technique for an autoregressive spectral estimator is studied and compared with the Fourier method. Using numerical tests the probability distribution function of the peak location is calculated. The autoregressive filter order is optimized in the sense of minimum variance of the peak location. Simple sinusoidal signals with additive Gaussian noise are considered and the effect of other components is only indicated. Generally, a filter order between 1/3 and 1/2 of the total data number and a not very dense data sampling, gives the most stable spectrum. The results are numerical. 相似文献