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21.
Relu D. Roban Mihai N. Ducea Vlad I. Mihalcea Ioan Munteanu Victor Barbu Mihaela C. Melinte-Dobrinescu Cornel Olariu Mihai Vlăsceanu 《Basin Research》2023,35(1):244-270
We present new sedimentological, petrographical, palaeontological and detrital zircon U–Pb data on late Oligocene–early Miocene sedimentary rocks of the thin-skinned thrust belt of East Carpathians. These data were acquired to reconstruct the sedimentary routing system for two compositionally different turbidite fans made of the regionally extensive Kliwa and Fusaru formations. On the eastern margin of the Moldavides foreland basin, large low-gradient river systems draining the East European Platform provided well-sorted quartz-rich sand forming deltas on wide shallow shelves and thick Kliwa submarine fans. Due to the westward subduction of a thinned continental plate, the western basin margin was characterized by short, steep-gradient routing systems where sediment transport to deep water was mainly through hyperpycnal flows. The Getic and Bucovinian nappes of the East Carpathians and the exhumed Cretaceous–Early Palaeogene orogenic wedge fed Fusaru fans with poorly sorted lithic sand. The Fusaru fans trend northwards in the foredeep basin having an elongate depocentre, interfingering and then overlapping on the distal part of the Kliwa depositional system due to the eastward advance of the Carpathian fold-and-thrust belt. A smaller sediment input is supplied by southern continental areas (i.e. Moesian Platform, North Dobrogea and potentially the Balkans). In general, the sandstone interfingering between distinct basin floor fan systems is less well documented because the facies would be similar and there are not many systems that have a distinct sediment provenance like Kliwa and Fusaru systems. This case study improves the understanding of regional palaeogeography and sedimentary routing systems and provides observations relevant here or elsewhere on the interfingering turbidite fan systems. 相似文献
22.
Serban Nicolae Vlad 《Central European Journal of Geosciences》2011,3(3):318-335
Romania has a genuine accumulation of “blind” porphyry CuAuMo systems associated with Cu skarns or AuAg (PbZn) epithermal vein sets. Many such hidden structures were discovered inadvertently during state exploration based on local tradition that Romanian Carpathians are rich in vein and skarn ore types. Notable dichotomy between porphyries associated with peripheral skarns versus epithermal ores is expressed by age (Mesozoic versus Tertiary), precious metal content, alteration types and zoning, shape/size and extension of ore bodies. Preliminary conclusions on metallic/alteration assemblages around porphyries in addition to geophysical information about inferred deep-seated Alpine plutonism promote potential exploration vectors for what will be an increasingly important deposit type in the future. 相似文献
23.
A variability survey on the shape of the light curve of the classical Cepheid DL Cas has been performed on the basis of Johnson
V photometry data covering about 38 years. The input parameters (mean magnitude, pulsation frequency and period, light curve
amplitude, harmonics amplitudes, Fourier type structural parameters) for our study were determined through the Fourier decomposition
technique applied to each data set. The analysis of the outcoming time series, using different and complementary methods,
seems to indicate the constancy of these parameters within the precision limits of the available data, although the hypothesis
of the presence of a low level variability cannot be excluded. The only exception is the pulsation period, which displays
a possible increasing trend with a rate of 0.109 ± 0.037 s yr−1. This trend may be, at least partly, an effect of the unequal precision of pulsation period estimated values, corresponding
to each considered data set.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
24.
Bogdan Wszolek 《Astrophysics and Space Science》1995,227(1-2):151-155
Intergalactic gas and dust are very difficult to detect. Several methods to detect intergalactic gas have been developed. The results of these methods have provided qualitative arguments and quantitative limits on the amount of intergalactic matter in the intergalactic environment. We present here arguments as to why the density of intergalactic matter is higher than previously thought possible. 相似文献
25.
Hans C. Oskierski Judy G. Bailey Eric M. Kennedy Geraldine Jacobsen Paul M. Ashley Bogdan Z. Dlugogorski 《Mineralium Deposita》2013,48(4):525-541
Nodular, cryptocrystalline, weathering-derived magnesite deposits in the New England Orogen, Australia, provide a significant source of high-purity magnesite. Common textural features and related isotopic fingerprints indicate a close genetic relationship between weathering-derived magnesite deposits hosted by ultramafic rocks at Attunga and by sediments at Kunwarara while silica-carbonate rock alteration and rare hydrothermal magnesite vein deposits reflect contrasting conditions of formation. Localised weathering of carbonates in a soil environment shifts stable isotopic composition towards low δ 13C and high δ 18O typical for weathering-derived magnesites while intrusion-related fluids do not significantly change the isotopic composition of affected carbonates. At Attunga, magnesite consists of irregular, nodular veins and masses filling faults and cracks in the weathered serpentinite host rock as well as soft powdery magnesite in pervasive serpentinite alteration zones. The high-grade magnesite at Attunga can be contaminated by amorphous silica and serpentine relicts but does not contain dolomite or ferroan magnesite as observed for its hydrothermal equivalent, the Piedmont magnesite deposit, or other widespread deposits of silica-carbonate rock in the Great Serpentinite Belt. Heavy δ 18O values are compatible with a supergene formation from meteoric waters while low δ 13C suggests C3-photosynthetic plants as the predominant source of carbon for the Attunga magnesites. We infer that weathering-derived, nodular magnesite deposits hosted in ultramafic rocks like the Attunga magnesite deposit have formed in a two-step process involving the hypogene formation of a pre-cursor magnesite deposit and complete supergene overprinting by meteoric waters that acquired carbon from percolation through soil. 相似文献
26.
A probabilistic parametrization for geological uncertainty estimation using the ensemble Kalman filter (EnKF) 总被引:2,自引:0,他引:2
In the past years, many applications of history-matching methods in general and ensemble Kalman filter in particular have been proposed, especially in order to estimate fields that provide uncertainty in the stochastic process defined by the dynamical system of hydrocarbon recovery. Such fields can be permeability fields or porosity fields, but can also fields defined by the rock type (facies fields). The estimation of the boundaries of the geologic facies with ensemble Kalman filter (EnKF) was made, in different papers, with the aid of Gaussian random fields, which were truncated using various schemes and introduced in a history-matching process. In this paper, we estimate, in the frame of the EnKF process, the locations of three facies types that occur into a reservoir domain, with the property that each two could have a contact. The geological simulation model is a form of the general truncated plurigaussian method. The difference with other approaches consists in how the truncation scheme is introduced and in the observation operator of the facies types at the well locations. The projection from the continuous space of the Gaussian fields into the discrete space of the facies fields is realized through in an intermediary space (space with probabilities). This space connects the observation operator of the facies types at the well locations with the geological simulation model. We will test the model using a 2D reservoir which is connected with the EnKF method as a data assimilation technique. We will use different geostatistical properties for the Gaussian fields and different levels of the uncertainty introduced in the model parameters and also in the construction of the Gaussian fields. 相似文献
27.
Romania is an earthquake prone area with a few destructive earthquakes per century. The National Institute for Earth Physics carries out the seismic survey of Romania through the Romanian National Seismic Network (RNSN) consisting of 65 real-time seismic stations. Daily reports and monthly bulletins are delivered after routinely analyzing and processing the recorded data. In the present paper we applied the Seismic Network Evaluation through Simulation method for the RNSN configuration as it was in August 2011 to estimate the background noise level, assess the appropriateness of the velocity model adopted in routine location procedure, evaluate the hypocenter location uncertainty and determine the detection magnitude threshold. Areas of greater (southern Romania) and lower (Carpathians and Apuseni Mountains) background noise within the RNSN are identified by mapping the average power of noise in 1–12?Hz frequency range. The statistical study of the P and S phases residual times allow us to assess the appropriateness of the velocity model used in routine location. Both P- and S-wave velocity models can be optimized to improve the quality of the hypocenter location. As shown by our analysis, the RNSN is able to detect and locate earthquakes with M L magnitude above 2.5 anywhere on the Romanian territory, except the border areas, such as the Crisana–Maramures seismic source zone. Merging data from both sides of the border significantly improves the quality of hypocenter location in these areas. 相似文献
28.
Bogdan Saletnik Grzegorz Zaguła Dorota Grabek-Lejko Idalia Kasprzyk Marcin Bajcar Maria Czernicka Czesław Puchalski 《Environmental Earth Sciences》2017,76(16):574
Because of their physicochemical properties, biochars can be used as sorption materials for removal of toxic substances. The purpose of the present study was to determine whether biochar obtained from cones of larch (Larix decidua Mill. subsp. decidua) and spruce (Picea abies L. H. Karst) could be used as a sorbent for Cd2+, Pb2+ and Co2+ in aqueous solutions. So far, this feedstock had not been tested in this respect. The material was subjected to pyrolysis at 500 and 600 °C for the duration of 5, 10 and 15 min. The obtained pyrolysates were found to differ in terms of pH and the contents of the essential macroelements. The different values of these parameters were determined for varying temperature, duration of the pyrolysis process and type of feedstock. Sorption capacities of the biochars for removal of Cd2+, Pb2+ and Co2+ were examined using simulated contamination of aqueous solutions with salts of these metals. The findings showed the highest, nearly complete, removal for Pb2+ were maximum 99.7%, and almost three times lower value for Cd2+ and Co2+ (respectively, 35.7 and 24.8%). It was demonstrated that pyrolysis of conifer cones produced optimum sorption capacities when the process was conducted at a temperature of 500 °C for the duration of 5 min. It was shown that products of spruce cone pyrolysis were characterized by better sorption capacity in comparison with products of larch cone pyrolysis. The properties of conifer cone biochar create the possibility of using it as an adsorbent in water and wastewater treatment as well as in production of filters and activated carbon. 相似文献
29.
Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes 总被引:2,自引:1,他引:1
Vladimir Sokolov Klaus-Peter Bonjer Friedemann Wenzel Bogdan Grecu Mircea Radulian 《Bulletin of Earthquake Engineering》2008,6(3):367-388
We present the regional ground-motion prediction equations for peak ground acceleration (PGA), peak ground velocity (PGV),
pseudo-spectral acceleration (PSA), and seismic intensity (MSK scale) for the Vrancea intermediate depth earthquakes (SE-Carpathians)
and territory of Romania. The prediction equations were constructed using the stochastic technique on the basis of the regional
Fourier amplitude spectrum (FAS) source scaling and attenuation models and the generalised site amplification functions. Values
of considered ground motion parameters are given as the functions of earthquake magnitude, depth and epicentral distance.
The developed ground-motion models were tested and calibrated using the available data from the large Vrancea earthquakes.
We suggest to use the presented equations for the rapid estimation of seismic effect after strong earthquakes (Shakemap generation)
and seismic hazard assessment, both deterministic and probabilistic approaches. 相似文献
30.
Noah Brosch Elchanan Almoznino Bogdan Wszolek † Konrad Rudnicki 《Monthly notices of the Royal Astronomical Society》1999,308(3):651-663
We detected a ring-like distribution of far-infrared (FIR) emission in the direction of the centre of the Virgo cluster (VC). We studied this feature in the FIR, radio and optical domains, and deduced that the dust within the feature reddens the galaxies in the direction of the VC but does not affect stars within the Milky Way. This is likely to be a dusty feature in the foreground of the VC, presumably in the Galactic halo. The H i distribution follows the morphology of the FIR emission and shows peculiar kinematic behaviour. We propose that a highly supersonic past collision between an H i cloud and the Galactic H i formed a shock that heated the interface gas to soft X-ray temperatures. H i remnants from the projectile and from the shocked Galactic H i rain down on to the disc as intermediate-velocity gas.
Our finding emphasizes that extragalactic astronomy must consider the possibility of extinction by dust at high galactic latitude and far from the Galactic plane, which may show structure on 1° and smaller scales. This is particularly important for studies of the VC, e.g. in the determination of the Hubble constant from Cepheids in cluster galaxies. 相似文献
Our finding emphasizes that extragalactic astronomy must consider the possibility of extinction by dust at high galactic latitude and far from the Galactic plane, which may show structure on 1° and smaller scales. This is particularly important for studies of the VC, e.g. in the determination of the Hubble constant from Cepheids in cluster galaxies. 相似文献