Silver and silver-bearing minerals at the Um Samiuki volcanogenic massive sulphide deposit, Eastern Desert, Egypt     

Ibrahim M. Shalaby  Eugen Stumpfl  Hassan M. Helmy  Mahmoud M. El Mahallawi  Omar A. Kamel 《Mineralium Deposita》2004,39(5-6):608-621

The Um Samiuki Zn–Cu–Pb–Ag mineralisation, south Eastern Desert, Egypt is hosted by felsic volcanic rocks which form part of the 712-Ma-old, east-west-trending Shadli Volcanic Belt. Two major occurrences of massive sulphides are present at the top of rhyolitic breccia in the Western and Eastern mine areas. In each occurrence, a bornite-bearing zone is overlain by a pyrite-chalcopyrite-bearing zone and underlain by a disseminated, Cu-depleted zone. In the massive sulphide ore, sphalerite, chalcopyrite, pyrite, galena, bornite and tetrahedrite–tennantite are major minerals, whereas arsenopyrite, pyrrhotite, molybdenite and magnetite are accessory phases. Covellite and digenite are common secondary minerals. Bornite, tetrahedrite–tennantite and covellite contain high amounts of silver (averages of 1.97, 1.39 and 1.82 wt% respectively). Based on mineralogical balance calculations, bornite and covellite accommodate 80% of silver in the Um Samiuki deposit. Ag was incorporated in the crystal structure of the early-crystallised copper sulphides and sulphosalts and silver minerals. The temperature, sequential precipitation of the fluids and the structure of the crystallising phases control the distribution of silver. Post-depositional deformation and metamorphic processes caused liberation, remobilisation and redeposition of silver within the massive sulphides.Editorial handling: D. Lentz  相似文献   

Alfred Bentz – Erdölgeologe in schwieriger Zeit, 1938–1947     

E. Seibold  I. Seibold 《International Journal of Earth Sciences》2002,91(6):1081-1093

Alfred Bentz was the leading oil geologist in Germany during the Third Reich, the World War II and thereafter. His relevant activities are treated here mainly on the base of documents in the Geologenarchiv Freiburg. In spite of his prominent position during the Nazi Regime he can obviously not be blamed for personal guilt. As a loyal civil servant he was embedded in the tragic German fate in these years.  相似文献   

Neues aus dem Geologen-Archiv (1989)     

I. Seibold  E. Seibold 《International Journal of Earth Sciences》1990,79(2):167-170

Ohne Zusammenfassung  相似文献   

Eisbedeckung und hypolimnische Sauerstoffanreicherung im Greifensee von 1950 bis 1980     

Prof. Dr. Eugen A. Von Thomas  Dr. Christer G. Örn 《Aquatic Sciences - Research Across Boundaries》1982,44(1):117-148

Hypolimnetic oxygen in the highly eutrophic Swiss lake Greifensee (area 8 km², maximum depth 33 m) was almost entirely depleted during summer stratification. We found a strong empirical relation between wind action across the lake surface and hypolimnetic reoxygenation in the cold half year. Long periods of ice cover severely limited anemogenic reoxygenation.   相似文献   

Carbonate sediments and their diagenesis: BATHURST,Robin G.C. (1971): Developments in Sedimentology Vol. 12. 620 S., 24 Tab., 359 Abb., 1.200 Literaturhinweise. Amsterdam: Elsevier. Dfl. 90.00, US $ 28.25.     

E. Seibold 《Geoforum》1973,4(3):81-82

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Patterns and trends in the perception of seismic risk. Case study: Bucharest Municipality/Romania   总被引：1，自引：1，他引：0  

Iuliana Armaş  Eugen Avram 《Natural Hazards》2008,44(1):147-161

This research looks at the very nature of perception of seismic risk, an issue that is not only academically important, but also it can save lives and reduce injury and community costs. The background idea is that citizens in big cities, vulnerable to seismic hazard are living with latent and permanent concerns about a possible earthquake. We were interested in revealing significant aspects of Bucharest citizens’ orientations and tendencies in relation to the possible seismic event. Bucharest, the capital of Romania, is exposed to the greatest seismic hazard compared with other European capitals. The dimensions of study were: the anticipations of seism occurrence, the behavior during the event, evaluations of consequences, support factors, and individual vulnerability. This article is an example of the low cost approach on a sample of 190 citizens, understood as an exercise in attempting to relate population characteristics to various aspects of risk perception. The methodology used was based on a field investigation, where the research agents’ applied one questionnaire containing free/post codified/fan answers concerning: demographic variables, the buildings’ features, and perceptions about the possible earthquake event. The findings of this study showed that the hazard perception significantly associates with aspects concerning the subjects’ orientation toward institutional factors/human relations/negativism, and toward financial/material/moral support in case of disaster etc. It is hoped that this issue will serve to inspire further investigations into this very important and socially sensitive field, due to the fact that hazard analysis and mitigation would be more effective when it takes into account the human dimension of disasters.  相似文献   

Zur Geschichte der Umwandlungsgesteine     

Eugen Wegmann 《International Journal of Earth Sciences》1948,36(1):48-50

Ohne Zusammenfassung  相似文献   

Die Osthälfte des schwäbischen Lineaments     

Eugen Seibold 《International Journal of Earth Sciences》1951,39(1):141-142

Ohne Zusammenfassung  相似文献   

Application of periodic autoregressive process to the modeling of the Garonne river flows   总被引：1，自引：1，他引：0  

Eugen Ursu  Jean-Christophe Pereau 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(7):1785-1795

Accurate forecasting of river flows is one of the most important applications in hydrology, especially for the management of reservoir systems. To capture the seasonal variations in river flow statistics, this paper develops a robust modeling approach to identify and to estimate periodic autoregressive (PAR) model in the presence of additive outliers. Since the least squares estimators are not robust in the presence of outliers, we suggest a robust estimation based on residual autocovariances. A genetic algorithm with Bayes information criterion is used to identify the optimal PAR model. The method is applied to average monthly and quarter-monthly flow data (1959–2010) for the Garonne river in the southwest of France. Results show that the accuracy of forecasts is improved in the robust model with respect to the unrobust model for the quarter-monthly flows. By reducing the number of parameters to be estimated, the principle of parsimony favors the choice of the robust approach.  相似文献   

Estimation of effect of unequal secular variation on geomagnetic data reduction     

Eugen Vujić  Mario Brkić 《Studia Geophysica et Geodaetica》2016,60(1):162-176

The geomagnetic field components are periodically measured at repeat stations. The main objective of the repeat stations is to provide data for tracing the secular variation of the geomagnetic field components. Secular variation at the repeat station is generally different from that at geomagnetic observatory used in the data reduction. The effect of the secular variation differences on geomagnetic data reduction was estimated for the regions of Europe, North America (below 60°N) and Australia, respectively, during the period of 2000-2010. These estimations were obtained by using the monthly mean values of north, east and vertical components of geomagnetic field, recorded at geomagnetic observatories. The effects were calculated by using observatories pairs, with distances from 350 km (in Europe) to 3100 km (in North America and Australia). The maximal effects were found to be the smallest in east component in Europe and North America, and vertical component in Australia; the effects increase with time from a central reduction epoch and they are not constant during mentioned eleven years; they were less than 1 nT only in Europe, for distances between the observatories up to 1000 km in all three components and for periods spanning ±1 month from a central epoch. It was found that their year to year variability is mostly due to the non-eliminated external field residuals in the observatories monthly means; their effect is up to 3 nT for ±3 months from a central epoch. Further, the real effects were compared to those modeled by IGRF-12 model. The maximal differences between the real and the modeled values are below 4.5 nT in all three components, for ±3 months from a central epoch.  相似文献