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111.
In the periods 1980–1986 and 1990–2007 many boreholes were sunk during hydrogeological investigations in the center of the
Karlovy Vary (Carlsbad) hot spring system. The extent and the depths reached were the greatest in the history of the geological
investigation of the discharge area of the thermal system. The results of the drilling program enabled a detailed study of
the rocks, groundwater and spring sedimentation in the area as well as the preparation of new proposals for changes in the
spring-protection zones. The spring sedimentation consists of world-renowned hot spring travertine, with a wide range of morphological
varieties of different origins and of different ages. The oldest U-series age data (230 ± 14 ka BP) have been obtained for
travertine relicts located 22 m above the present-day bottom of the narrow valley of the Teplá River. Five other travertine
deposits, partly overlapping in space and time were identified on the bottom and slopes of the valley. They were formed by
gradual growth, by river erosion and since the fourteenth century by human activities. 相似文献
112.
Bohdan Kříbek Karel Žák Petr Dobeš Jaromír Leichmann Marta Pudilová Miloš René Bohdan Scharm Marta Scharmová Antonín Hájek Daniel Holeczy Ulrich F. Hein Bernd Lehmann 《Mineralium Deposita》2009,44(1):99-128
Three major mineralization events are recorded at the Rožná uranium deposit (total mine production of 23,000 t U, average
grade of 0.24% U): (1) pre-uranium quartz-sulfide and carbonate-sulfide mineralization, (2) uranium, and (3) post-uranium
quartz-carbonate-sulfide mineralization. (1) K–Ar ages for white mica from wall rock alteration of the pre-uranium mineralization
style range from 304.5 ± 5.8 to 307.6 ± 6.0 Ma coinciding with the post-orogenic exhumation of the Moldanubian orogenic root
and retrograde-metamorphic equilibration of the high-grade metamorphic host rocks. The fluid inclusion record consists of
low-salinity aqueous inclusions, together with H2O-CO2-CH4, CO2-CH4, and pure CH4 inclusions. The fluid inclusion, paragenetic, and isotope data suggest that the pre-uranium mineralization formed from a
reduced low-salinity aqueous fluid at temperatures close to 300°C. (2) The uraniferous hydrothermal event is subdivided into
the pre-ore, ore, and post-ore substages. K–Ar ages of pre-ore authigenic K-feldspar range from 296.3 ± 7.5 to 281.0 ± 5.4 Ma
and coincide with the transcurrent reorganization of crustal blocks of the Bohemian Massif and with Late Stephanian to Early
Permian rifting. Massive hematitization, albitization, and desilicification of the pre-ore altered rocks indicate an influx
of oxidized basinal fluids to the crystalline rocks of the Moldanubian domain. The wide range of salinities of fluid inclusions
is interpreted as a result of the large-scale mixing of basinal brines with meteoric water. The cationic composition of these
fluids indicates extensive interaction with crystalline rocks. Chlorite thermometry yielded temperatures of 260°C to 310°C.
During this substage, uranium was probably leached from the Moldanubian crystalline rocks. The hydrothermal alteration of
the ore substage followed, or partly overlapped in time, the pre-ore substage alteration. K–Ar ages of illite from ore substage
alteration range from 277.2 ± 5.5 to 264.0 ± 4.3 Ma and roughly correspond with the results of chemical U–Pb dating of authigenic
monazite (268 ± 50 Ma). The uranium ore deposition was accompanied by large-scale decomposition of biotite and pre-ore chlorite
to Fe-rich illite and iron hydrooxides. Therefore, it is proposed that the deposition of uranium ore was mostly in response
to the reduction of the ore-bearing fluid by interaction with ferrous iron-bearing silicates (biotite and pre-ore chlorite).
The Th data on primary, mostly aqueous, inclusions trapped in carbonates of the ore substage range between 152°C and 174°C
and total salinity ranges over a relatively wide interval of 3.1 to 23.1 wt% NaCl eq. Gradual reduction of the fluid system
during the post-ore substage is manifested by the appearance of a new generation of authigenic chlorite and pyrite. Chlorite
thermometry yielded temperatures of 150°C to 170°C. Solid bitumens that post-date uranium mineralization indicate radiolytic
polymerization of gaseous and liquid hydrocarbons and their derivatives. The origin of the organic compounds can be related
to the diagenetic and catagenetic transformation of organic matter in Upper Stephanian and Permian sediments. (3) K–Ar ages
on illite from post-uranium quartz-carbonate-sulfide mineralization range from 233.7 ± 4.7 to 227.5 ± 4.6 Ma and are consistent
with the early Tethys-Central Atlantic rifting and tectonic reactivation of the Variscan structures of the Bohemian Massif.
A minor part of the late Variscan uranium mineralization was remobilized during this hydrothermal event. 相似文献
113.
Mineralogy and Petrology - Hafnium contents and Zr/Hf ratios were studied in zircons and their parent rocks from three magmatic suites associated with the Teplice caldera, Eastern Erzgebirge:... 相似文献
114.
Pitra Pavel Schulmann Karel Martínez Catalán José Ramón Ballèvre Michel 《International Journal of Earth Sciences》2017,106(2):395-396
International Journal of Earth Sciences - 相似文献
115.
Karel Schulmann 《地学前缘(英文版)》2017,8(2):411-412
116.
Correlation Analysis for Compositional Data 总被引:1,自引:0,他引:1
Compositional data need a special treatment prior to correlation analysis. In this paper we argue why standard transformations
for compositional data are not suitable for computing correlations, and why the use of raw or log-transformed data is neither
meaningful. As a solution, a procedure based on balances is outlined, leading to sensible correlation measures. The construction
of the balances is demonstrated using a real data example from geochemistry. It is shown that the considered correlation measures
are invariant with respect to the choice of the binary partitions forming the balances. Robust counterparts to the classical,
non-robust correlation measures are introduced and applied. By using appropriate graphical representations, it is shown how
the resulting correlation coefficients can be interpreted. 相似文献
117.
Seasonal evolution of runoff generation on agricultural land in the Belgian loess belt and implications for muddy flood triggering 总被引:1,自引:0,他引:1
Muddy floods due to agricultural runoff are a widespread and frequent phenomenon in the European loess belt, and particularly in central Belgium. These floods are triggered when high quantities of runoff are generated on cropland and cause severe erosion. Three soil surface characteristics are relevant to determine the runoff potential of cultivated soils: soil cover by crops and residues, soil surface crusting and roughness. These characteristics have been observed on 65 cultivated fields throughout 2005. A heavy rainfall event representative for events triggering muddy floods in the region (60 mm h?1 during 30 minutes) has been simulated using a 0·5 m2 simulator on fields with the 17 most observed combinations of soil surface characteristics in central Belgium. Runoff is not observed in the case of (ploughed) bare uncrusted soils, nor in the case of soils covered by crops showing a transitional crust and a moderate roughness (1–2 cm). In the cases where runoff has been observed, mean runoff coefficients ranged from 13% (wheat in July) to 58% (sugar beet or maize in May and June). Grassed buffer strips (GBSs) and grassed waterways (GWWs) show a higher runoff coefficient (62% for GBSs and 73% for GWWs) than most cultivated soils (13–58%). Furthermore, it is demonstrated that small plot measurements can be used to estimate runoff generation at the field scale. A classification of runoff generation risk based on the surveys of soil surface characteristics has been applied to common crops of central Belgium. February as well as the period between May and September are the most critical for runoff at the field scale. However, it appears from monitoring of a 16 ha catchment that the highest runoff volumes and peak discharges are recorded between May and August after heavy rainfall, explaining why 85% of muddy floods are recorded during this period in central Belgium. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
118.
Variable values of the Pcl signal transmissivity through the ionosphere, experimentally obtained from the conjugated ULF experiment GEOS-1-Husafell during a roughly 1-h interval of the micropulsation disturbance on 13 July 1977, have been compared with the results of numerical simulation. Variations of the basic physical parameters of the high-latitude outer ionosphere have been considered. Quantitative estimates of the rapid changes of the ionized particle concentration in connection with the considered changes of the ionospheric plasma temperature have been made. It is assumed that the ioncyclotron waves themselves propagating along the plasmapause give rise to the non-stationary conditions in the outer high-latitude ionosphere (Φ≈ 70°). 相似文献
119.
120.
Summary The spectral analysis of an hourly section of a synchronized conjugated record of an ULF signal made on the GEOS-1 satellite and the Husafell Observatory (Iceland) on July 13, 1977, has been carried out. The time variations of the spectral frequency-amplitude characteristics of the Pc1 wave packet in the neighbourhood of f 0.5 s–1 at both measurement sites were examined. The transmissibility of the amplitude of the total magnetic component of the wave through the ionosphere towards the Earth's surface, found in the frequency range of the packets, varies from 0.03 to 0.07. Moreover, its time behaviour with the development of the micropulsation disturbance was studied. The frequency shift of the packet spectrum centre towards higher frequencies 0.04 s–1) was determined at the Earth's surface as compared with the satellite conditions. Experimental results served to test the developed automated methods of numerical modelling of ionospheric filtration in the ULF range of Pc1 micropulsations. Good agreement between the experimental and numerical results of the two constructed limiting models of the daytime ionosphere at higher latitudes (low and high solar activity) was achieved. The values of the transmissibility calculated for the Pc1 packet frequencies vary from 0.075 to 0.3 and from 0.025 to 0.06. 相似文献