Fluid inclusion and stable isotope characteristics of the Karalar (Gazipaşa,Antalya) barite-galena deposits,Southern Turkey     

A. Gökşe  G. Bozkaya 《Geology of Ore Deposits》2008,50(2):145-154

The Karalar galena-barite deposits are typical examples of the carbonate-hosted barite-galena deposits widely occurring in the Central Tauride Belt. These deposits are located in Permian limestones as ore veins along fault zones that are discordant to the bedding planes and as thin veinlets within hardly brecciated bottom zones of Permian limestones. The ore deposits contain mainly barite and galena and small amounts of sphalerite, pyrite, fahlore, limonite, quartz, and calcite. Barites occur during the earlier episode of mineralization and were mylonitized before the formation of galena. Galena and other minerals occur epigenetically with barite along porous zones between brecciated barite crystals and are especially abundant in the hardly mylonitized zones. Fluid inclusion studies indicate that the ore deposits of the area were developed by hydrothermal fluids with following characteristics: they contained NaCl, CaCl₂, and MgCl₂; the salinity of the fluids was relatively high and their temperature was low during the crystallization of barites in the earlier episode of mineralization; and the salinity of the fluids decreased and their temperature increased during the crystallization of sulfide minerals through the later episode of mineralization. δ₁₈O and the δD results indicate that the water in the mineralizing fluid was of meteoric origin. The deposits were formed by deep meteoric water circulating through marine sediments. Shallow circulating and slightly warmed fluids dissolved Ba and sulfate from marine sediments of the basement and transported them to the mineralization environment during the early episode, while deep circulating and more heated fluids dissolved Pb, Zn, and other elements from the basement and reached the environment during the later episode of mineralization. The text was submitted by the authors in English.  相似文献   

Dynamics of the plasmasphere in the dusk sector as observed in the outer ionosphere     

J. Bošková  F. Jiříček  J. Šmilauer  P. Tříska 《Studia Geophysica et Geodaetica》1994,38(1):82-92

Summary Direct measurements of the thermal plasma parameters in the topside ionosphere reveal variations of the plasmasphere boundary in the dusk sector. The ACTIVE satellite's near-polar orbits at altitudes of 500 – 1800 km around winter solstice 1989 were used to study the bulge region of the plasmasphere during intervals with different levels of geomagnetic agitation. The narrow, sharply defined trough in electron concentration corresponding to the plasmapause under quiet conditions situated at L = 6 – 7 moved to lower L-values with increasing geomagnetic activity. This narrow trough can be found in all main ion constituents. During periods of moderate geomagnetic activity, following the onset of a weak magnetic storm, a portion of the plasmaspheric bulge region was separated from the main plasmaspheric body. This can be seen in the outer ionosphere as an inner narrow trough at lower L-value. Troughs in light ions need no longer coincide with this in electron concentration. He⁺ is the most sensitive constituent reflecting the dusk sector plasmaspheric situation at this altitude.Dedicated to the Memory of Professor Karel P  相似文献   

Geomagnetic activity as a possible cause of changes in the middle atmosphere and troposphere; observations made in Prague in the years 1932–1987     

Josef Bochníček  Josef Pýcha 《Studia Geophysica et Geodaetica》1994,38(1):103-107

Summary A possible relation between the 10-day, 1-month, and 2-month geomagnetic as well as solar activity, characterized by Kp and Wolf's number R, and temperatures measured at the Prague-Klementinum meteorological station in January–February of the years 1932–1987 was sought. It was found that:1) Kp correlates with the temperature in Prague better than Wolf's number R.2) If the QBO phase is taken into account, the correlations improve.3) Even if the correlations improves with increasing length of the subintervals into which the individual winter periods (January-February) were derived, their statistical significance declines.  相似文献   

Magnetic properties,self-reversal remanence and thermal alteration products of smythite     

Miroslav Krs  František Novák  Marta Krsová  Petr Pruner  Jiří Jansa 《Studia Geophysica et Geodaetica》1993,37(4):382-400

Summary This study is a follow up of the investigation of some magnetic properties and metastability of greigite in samples obtained from Miocene claystones in the Kruné hory (Erzgebirge) Piedmont basins (Bohemia). Three different methods of upgrading the smythite were applied; the magnetic properties of the concentrates are compared. The thermal conversion of smythite sets in at 200°C while greigite converts at 250°C. The first intermediate products to be formed are iron sulphides, marcasite clearly dominating over pyrite and pyrrhotite. Apart from a Fe³⁺ sulphate with a composition of Fe₂(SO₄)₃, oxidation of these sulphides gives rise to -Fe₂O₃. The result of the subsequent decomposition of the mentioned sulphate is the formation of -Fe₂O₃, which retains the sulphate structure. The final product of the thermal decomposition at 800°C is -Fe₂O₃. In the smythite concentrate the conversion to Fe³⁺ sulphate and -Fe₂O₃ is about twice as intensive as in greigite. No direct conversion to -Fe₂O₃ was found. During the thermal process self-reversals of remanence were observed, in various samples as many as four reversals in the temperature interval from 340 to 590°C. The occurrences of self-reversals of remanence were only observed at high degrees of thermal demagnetization, of the order of 10^–2 down to 10^–3 in the temperature interval of sulphide origin (below 400°C), and of the order of 10^–4 down to 10^–6 in the temperature interval of Fe-oxides origin (above 400°C).Presented at the 3rd Conference on New Trends in Geomagnetism, Castle of Smolenice, Czechoslovakia, June 22–29, 1992  相似文献   

Problems connected with the tangential metric coefficient in the Schwarzschild metric: A possible solution     

Pavel Voráček 《Astrophysics and Space Science》1982,81(1-2):85-94

Four situations are shown where the Schwarzschild metric cannot be used or is subject to unsurmountable problems. The first is the question of a metric useful for PPN-formalism checking different gravitational theories. The second problem occurs in connection with Mach's principle, when the flatness of the spacetime inside a massive hollow sphere is a generally accepted solution. The metrical discontinuity on the same spherical shell is a third problem. The fourth one is the anisotropy of the mass-energy of a test particle in the gravitational field. Three principles for solution are proposed:

1. The space is not dilated, but rather contracted, in the gravitational field; then the measurement-rods are shorter and measured distances have greater magnitudes.
2. The potential energy is to be related to a potential level where a stationary observer is placed and the general relativistic potential must be used.
3. A new metric must be introduced which is distinct from the Schwarzschild metric, so that the space in the gravitational field is warped isotropically.

Then the problems stated are shown to be easily solvable.  相似文献   

Damage risk assessment of breakwaters under tsunami attack     

Ayşen Ergin  Can Elmar Balas 《Natural Hazards》2006,39(2):231-243

Turkey was struck by two major events on 17 August and 12 November 1999, named Izmit (M _w = 7.4) and Düzce (M _w = 7.2) earthquakes, respectively. Rubble mound breakwaters in Izmit Bay experienced little damage, as forecasted by the new risk assessment model in which tsunami occurrence risk was included in the damage estimations. In order to determine the occurrence probability of structural damage under design conditions, including the environmental loading parameters of tsunami and storm waves, tidal range and storm surge, the Conditional Expections Monte Carlo simulation was applied in the risk assessment model developed in this study for the Esenköy Fishery Harbour, Turkey. A tsunami was not the key design parameter when compared to storm waves for the main breakwater of the harbour, however, in places with great seismic activity, the tsunami risk should be important depending on the occurrence probability and magnitude of the tsunami.  相似文献   

The vulnerability of karst springs—a case study of the Hubelj spring (SW Slovenia)   总被引：3，自引：0，他引：3  

B. Trček  M. Veselič  J. Pezdič 《Environmental Geology》2006,49(6):865-874

The hydraulic behaviour of the karst aquifer in the Hubelj spring catchment area (SW Slovenia) was studied by using an indirect research method based on natural tracers. The variations of natural tracers (in precipitation and in groundwater) during the storm event made possible the separation of the Hubelj spring storm hydrograph by the three-component separation technique. The results produced information on the aquifer recharge, storage and discharge processes, as well as on the mechanisms that affected them. They verified the so-called epikarst hypothesis presuming that an important part of a karst aquifer recharge reaches rapidly and intensively from the epikarst zone. It was demonstrated that epikarst water could occupy up to 50% of the spring discharge during precipitation events. This phenomenon could have important consequences on protection and management of the problems of karst aquifers, including engineering problems in karst areas. With this respect the results could give way to new engineering ideas.  相似文献   

Documentary Evidence of an Economic Character as a Source for the Study of Meteorological and Hydrological Extremes and their Impacts on Human Activities   总被引：1，自引：0，他引：1  

Rudolf Brázdil  Hubert Valá&#;ek  Kate&#;ina Chromá 《Geografiska Annaler: Series A, Physical Geography》2006,88(2):79-86

This paper deals with documentary evidence of an economic character as a proxy for direct study of meteorological and hydrological extremes. Taxation records and reports of those who administrated domains and estates are described with respect to information about meteorological and hydrological extremes. Based on data from eight domains or estates from Moravia (in the Czech Republic), frequency series of floods and convective storms (including hailstorms) were developed for the period 1650–1849. One example of disastrous weather, which took place on 10 August 1694 in the Pern?tejn domain, is used to demonstrate the potential for such studies of the intensity of extremes and their impact on human activities. The importance of economic evidence in the instrumental period is shown through tax rebate data contingent upon hailstorm damage in Moravia (1896–1906). The benefits of employing documentary economic evidence for historical climatology and the study of the impact of meteorological and hydrological extremes on human activities are discussed.  相似文献   

Quantification of karst aquifer discharge components during storm events through end-member mixing analysis using natural chemistry and stable isotopes as tracers   总被引：1，自引：1，他引：1  

Daniel H. Doctor  E. Calvin Alexander Jr  Metka Petrič  Janja Kogovšek  Janko Urbanc  Sonja Lojen  Willibald Stichler 《Hydrogeology Journal》2006,14(7):1171-1191

Karst aquifer components that contribute to the discharge of a water supply well in the Classical Karst (Kras) region (Italy/Slovenia) were quantitatively estimated during storm events. Results show that water released from storage within the epikarst may comprise as much as two-thirds of conduit flow in a karst aquifer following rainfall. Principal components analysis (PCA) and end-member mixing analysis (EMMA) were performed using major ion chemistry and the stable isotopes of water (δ¹⁸O, δ²H) and of dissolved inorganic carbon (δ¹³C_DIC) to estimate mixing proportions among three sources: (1) allogenic river recharge, (2) autogenic recharge, and (3) an anthropogenic component stored within the epikarst. The sinking river most influences the chemical composition of the water-supply well under low-flow conditions; however, this proportion changes rapidly during recharge events. Autogenic recharge water, released from shallow storage in the epikarst, displaces the river water and is observed at the well within hours after the onset of precipitation. The autogenic recharge end member is the second largest component of the well chemistry, and its contribution increases with higher flow. An anthropogenic component derived from epikarstic storage also impacts the well under conditions of elevated hydraulic head, accounting for the majority of the chemical response at the well during the wettest conditions.  相似文献   

Patterns in the Turkish reinsurance claim data, 1998–2002: An application of the extreme value theory     

B. Burçak Başbuğ  Henry P. Wynn 《Natural Hazards》2006,39(2):329-342

The devastating 1999 Marmara and Düzce earthquakes led to a significant increase in the earthquake studies in Turkey in geological, engineering and financial aspects. Extreme Value Theory (EVT) has a range of applications from stock market changes to natural disasters like floods and hurricanes. Here EVT is fitted to the ordinary and earthquake reinsurance claims of Turkey.  相似文献