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311.
Granites and primary tin mineralization in the Erzgebirge were dated using (1) conventional U–Pb dating of uraninite inclusions
in mica, (2) Rb–Sr dating of inclusions in quartz that represent highly evolved melts, (3) Re–Os dating of magmatic–hydrothermal
molybdenite, and (4) chemical Th–U–Pb dating of uraninite. Conventional isotope dilution and thermal ion mass spectrometry
and chemical Th–U–Pb dating of uraninite in granites from the Ehrenfriedersdorf mining district provide ages of 323.9 ± 3.5
Ma (2σ; Greifenstein granite) and 320.6 ± 1.9 and 319.7 ± 3.4 Ma (2σ, both Sauberg mine), in agreement with U–Pb apatite ages of 323.9 ± 2.9 and 317.3 ± 1.6 Ms (2σ, both Sauberg mine). Rb–Sr analysis of melt inclusions from Zinnwald gives highly radiogenic Sr isotopic compositions that,
with an assumed initial Sr isotopic composition, permit calculation of precise ages from single inclusions. The scatter of
the data indicates that some quartz-hosted melt inclusions have been affected by partial loss of fluid exsolved from the melt
inclusion. Re–Os dating of two molybdenite samples from Altenberg provides ages of 323.9 ± 2.5 and 317.9 ± 2.4 Ma (2σ). Together with age data from the literature, our new ages demonstrate that primary tin mineralization and the emplacement
of the large Sn-specialized granites in the Erzgebirge fall in a narrow range between 318 and 323 Ma. Primary Sn mineralization
occurred within a short interval during post-collisional collapse of the Variscan orogen and was essentially synchronous over
the entire Erzgebirge. In contrast to earlier claims, no systematic age difference between granites of the eastern and western
Erzgebirge was established. Furthermore, our data do not support a large age range for Late-Variscan granites of the Erzgebirge
(330–290 Ma), as has been previously suggested. 相似文献
312.
Rainer Hartung Dieter Lenoir Bernhard Henkelmann Sigurd Schulte‐Hostede Karl‐Werner Schramm 《洁净——土壤、空气、水》2007,35(3):235-238
A new catalytic dehydrohalogenation method for chlorinated phenols is described, which can be used to break down chlorinated pollutants in wastewater. It uses a system of Pd‐C as catalyst with sodium formate as reducing agent. This economic method is easy to perform with a complete degradation of the pollutant within 12 to 30 h at room temperature. The ecoefficieny of the procedure is compared with eleven alternative methods showing the special advantages of the method. 相似文献
313.
Recently, increasing numbers of mobile phones are appearing on the market that feature advanced navigation capabilities: embedded GPS receivers for global positioning, integrated digital compasses for detecting the heading of the device, or accelerometer‐based tilt sensors will potentially enable upcoming and future mobile phones to measure their location and orientation in 3D space. In this paper, we present an application framework for building spatially aware mobile applications – applications that visualize, process or exchange geospatial information – on mobile phones equipped with such features. The core component of the framework is a novel, platform‐independent XML data exchange format for the interface between application server and mobile device that describes the geographic vicinity of the user. The format enables a variety of new mobile interaction styles and user interface types – from traditional text‐based local search and information interfaces to innovative real‐time user interfaces like Geo‐Wands and Smart Compasses. 相似文献
314.
Dynamic capillary effects in heterogeneous porous media 总被引:1,自引:0,他引:1
In standard multi-phase flow models on porous media, a capillary pressure saturation relationship developed under static conditions
is assumed. Recent experiments have shown that this static relationship cannot explain dynamic effects as seen for example
in outflow experiments. In this paper, we use a static capillary pressure model and a dynamic capillary pressure model based
on the concept of Hassanizadeh and Gray and examine the behavior with respect to material interfaces. We introduce a new numerical
scheme for the one-dimensional case using a Lagrange multiplier approach and develop a suitable interface condition. The behavior
at the interface is discussed and verified by various numerical simulations. 相似文献
315.
The efficiency and sustainability of carbon dioxide (CO2) storage in deep geological formations crucially depends on the integrity of the overlying cap-rocks. Existing oil and gas
wells, which penetrate the formations, are potential leakage pathways. This problem has been discussed in the literature,
and a number of investigations using semi-analytical mathematical approaches have been carried out by other authors to quantify
leakage rates. The semi-analytical results are based on a number of simplifying assumptions. Thus, it is of great interest
to assess the influence of these assumptions. We use a numerical model to compare the results with those of the semi-analytical
model. Then we ease the simplifying restrictions and include more complex thermodynamic processes including sub- and supercritical
fluid properties of CO2 and non-isothermal as well as compositional effects. The aim is to set up problem-oriented benchmark examples that allow
a comparison of different modeling approaches to the problem of CO2 leakage. 相似文献
316.
Roland Mundil Rainer Zühlke Thilo Bechstädt Arndt Peterhänsel Sven O. Egenhoff Felix Oberli Martin Meier Peter Brack Hans Rieber 《地学学报》2003,15(2):81-87
ABSTRACT Sedimentary cycles recorded in young sediments are often attributed to fluctuations of the Earth's climate on a 104 −106 -year scale which in turn is governed by periodic variations in solar insolation linked to orbital (Milankovitch) parameters. A spectacular example of cyclic stratal patterns in ancient deposits is the Middle Triassic Latemar carbonate platform (W Dolomites, N Italy). Based on spectral analyses from previous studies, a superimposition of precession (∼20 ka) and eccentricity (∼100 ka) controlled sea-level fluctuations has been suggested to account for the stacking hierarchy at Latemar, with ∼20 ka being assigned to each highest-order depositional cycle. Zircon U–Pb isotopic ages from volcanic-ash layers within the cyclic succession, corroborated by biostratigraphic constraints, suggest that the average time interval for every individual cycle is significantly smaller than the shortest Milankovitch period and therefore challenge previously published interpretations relating distinct spectral peaks to the above mentioned hierarchy. However, our new spectral data indicate that cyclicities resembling Milankovitch characteristics might exist, but on an entirely different scale. Our findings show that frequency spectra should only be interpreted in combination with robust age control. They also encourage the search for complementary mechanisms controlling carbonate deposition. 相似文献
317.
Gültekin?TopuzEmail author Rainer?Altherr Winfried?H.?Schwarz Wolfgang?Siebel Muharrem?Sat?r Abdurrahman?Dokuz 《Contributions to Mineralogy and Petrology》2005,150(4):441-455
The post-collisional Saraycık granodiorite intruded into a late Paleocene to early Eocene nappe pile that formed during collision of the Pontides in the North and the Anatolide-Tauride platform in the South, leading to the formation of the İzmir-Ankara-Erzincan suture. A relatively shallow pluton intrusion depth (∼5 to 8 km) was estimated from Al-in-hornblende geobarometry and contact metamorphic assemblages. The emplacement age is tightly constrained to ∼52 Ma by two Ar–Ar plateau and total fusion ages on biotite. The main mass of the pluton consists of metaluminous to peraluminous biotite granodiorite and hornblende-biotite granodiorite. In addition, up to 10-m thick dacitic and <25-cm thick aplitic dikes occur. Granodiorites and dacites show many close compositional similarities to high-silica adakites from supra-subduction zone settings, but tend to be slightly more felsic and to have a higher aluminium saturation index. Chondrite-normalized (cn) rare earth element patterns are characterized by high ratios of (La/Yb)cn, concave-upward shapes of the HREE and a lack of significant Eu anomalies. In conjunction with relatively high abundances of Ba and Sr as well as low abundances of Y, HREE and Sc, these patterns suggest a feldspar-poor, garnet ± amphibole-rich fractionating mineral assemblage (residue). All samples have very similar Nd–Sr isotopic characteristics, regardless of rock type. Initial εNd values range from −0.3 to −1.2 and initial 87Sr/86Sr ratios from 0.70491 to 0.70529. It is suggested that the magmas formed by partial melting of mafic lower crust at elevated pressures (∼1 to 2 GPa). 相似文献
318.
Rainer Göhring 《Solar physics》1969,8(2):271-274
The visibility, contrast and displacement of the pseudo--component of a Zeeman triplet, explained as due to saturation, is computed for the triplet at 5250 A (Fe i). Examples of the computational results are given (Figures 1–3).Mitteilungen aus dem Fraunhofer Institut Nr. 89. 相似文献
319.
Abstract We present Kr and Xe isotope data obtained by closed system stepped etching of ilmenite separates from two lunar samples exposed to the solar corpuscular radiation at different epochs. Helium, neon, and argon in the same samples were reported to consist of two components: isotopically unfractionated solar wind (SW) released in the first steps, and an isotopically heavier component (SEP) released later and, thus, sited at larger depth. The same release characteristic is now observed for the heavy noble gases. We also conclude that solar Kr and Xe consist of two isotopically different components, implanted with different energies. The SW-Kr in a recently irradiated soil has a composition very close to atmospheric Kr, which agrees with other newly reported data from stepped etch- and combustion runs. No clear evidence for temporally variable SW-Kr or SW-Xe spectra was found. “Surface correlated” Kr and Xe components “SUCOR” and “BEOC 12001” are a mixture of SW and SEP. The isotopic fractionation factors relating SW and SEP are close to the square of the mass ratios for all five noble gases. We infer that the measured Kr/Xe ratio in ilmenite is essentially identical to this ratio in the solar corpuscular radiation. 相似文献
320.
S.F. Rainer 《Estuarine, Coastal and Shelf Science》1982,15(4):423-441
The soft-bottom fauna of Gunnamatta Bay, Port Hacking, N.S.W., was sampled to estimate the abundance, trophic structure and net production of the macrobenthos. The samples were classified into groups from spatially distinct strata, the groups differing in species abundance and diversity and in the identity of the dominant species. The composition and community structure of the fauna was generally similar to that in other sheltered embayments on the southeastern coast of Australia. Estimated production values were low for an estuary, ranging from 10 kJ m?2 year?1 in an intertidal stratum of well sorted sand to 210–450 kJ m?2 year?1 in shallow subtidal strata with an admixture of silt. Estimated net production over all strata was 160 kJ m?2 year?1. Polychaetes dominated production, providing 45% of the total; crustaceans provided 20%, and molluscs and echinoderms 12% each. Detritus-feeders were dominant in most strata: the bivalve Theora fragilis, the polychaetes Australonereis ehlersi and Notomastus torquatus, and the urchin Echinocardium cordatum were major contributors to overall biomass and to net production. Substantial biomass and net production was also contributed by the suspension-feeding bivalve Corbula vicaria and a carnivorous crab Ceratoplax cf. glaberrimus. Overall, detritus-feeders contributed 61% of estimated net production, carnivores 32% and suspension-feeders 7%. Production estimated for carnivores was higher than could be supported by the non-carnivore populations, suggesting that some of the species considered to be carnivores have additional feeding modes. Excessive harvesting of bivalves by humans is suggested as the main reason for the low biomass of, and therefore low production by, suspension feeders. 相似文献