Age and evolution of scheelite-hosting rocks in the Felbertal deposit (Eastern Alps): U-Pb geochronology of zircon and titanite     

Roland Eichhorn  Urs Schärer  Rudolf Höll 《Contributions to Mineralogy and Petrology》1995,119(4):377-386

U-Pb isotope analyses of zircon and titanite extracted from different rocks of the Felbertal scheelite deposit yield the following information: (1) An age of 593±22 Ma (2) is obtained for zircon crystallization in the scheelite-bearing matrix of an eruption breccia in the western ore field. (2) Discordant zircons from an elongated, up to 8 m thick scheelite-rich quartzite body in the eastern ore field give an upper intercept age of 544±5 Ma. This quartzite contains a laminated, fine-grained scheelite mineralization. (3) Zircons from a small granitoid intrusion of the western ore field reveal an age of 336±16 Ma, and concordant titanites document an age of 282±2 Ma for Variscan amphibolite facies metamorphism. Both events, granitoid intrusion and later metamorphism caused ore re-mobilization, including the formation of yellowish fluorescent (molybdo-) scheelite porphyroblasts. (4) For a narrow lamprop-1hyric dike in the western ore field, a concordant titanite age of 283±7 Ma is obtained. This age is identical with the titanites from the amphibolite facies metamorphic intrusion. Tiny scheelite grains were tapped by the dike from pre-existing scheelite mineralizations in the truncated host rocks. (5) Alpine metamorphism at 31±4 Ma did not exceed lowermost amphibolite facies conditions, and it caused scheelite re-mobilization on a minor scale only, producing bluish fluorescent porphyroblasts in quartz veinlets and veins, as well as bluish fluorescent scheelite rims around older scheelite grains. Moreover, crosscutting Alpine fissure fillings show bluish fluorescent, inclusion-free scheelite. (6) The preservation of Variscan titanites, the absence of Alpine titanite growth, and the large degree of Variscan scheelite re-mobilization demonstrate that amphibolite facies metamorphism in the Felbertal area has a Variscan age. This result clearly documents Variscan tectono-metamorphism to be the dominant event, instead of the hitherto surmised Alpine metamorphism. This multi-stage evolution of the Felbertal ore bodies corroborates the view that tungsten deposits are conditioned by several succeeding thermal events, leading to a series of stages that ultimately produce high-grade scheelite concentrations. These high-grade ores predominately occur along shear zones of different age, accompanied by the formation of large volumes of low-grade scheelite mineralizations along host rock foliations and quartz veinlets and veins.  相似文献   

III. Bücher- und Zeitschriftenschau     

Bubnoff  Wilckens  Otto Wilckens  W. Obrutschew  Max Richter  R. Stickel  Rudolf Leutelt  Leuchs  Hans Frebold  W. Salomon-Calvi 《International Journal of Earth Sciences》1931,22(3-4):241-271

Ohne Zusammenfassung  相似文献   

Bücher- und Zeitschriftenschau     

Chudoba  Rudolf Leutelt  Wilckens 《International Journal of Earth Sciences》1929,20(6):458-461

  相似文献   

Bücher- und Zeitschriftenschau     

Leuchs  W. E. Schmidt  Bubnoff  H. Cl  Wilckens  W. Salomon  Donath  Wetzel  R. Stickel  Rudolf Leutelt 《International Journal of Earth Sciences》1930,21(5):314-338

  相似文献   

IV. Bücher- und Zeitschriftenschau     

Rudolf Hundt 《International Journal of Earth Sciences》1918,9(1-2):60-61

Ohne Zusammenfassung  相似文献   

Ferdinand von Wolff     

Dr. Rudolf Gaedeke 《Bulletin of Volcanology》1953,14(1):185-197

  相似文献   

Eine Methode zur Bestimmungdes wahren Winkelsder optischen Achsen und des mittleren Hauptbrechungsquotienten zweiachsiger Minerale im Dünnschliff     

Prof. Dr. Rudolf Mosebach 《Contributions to Mineralogy and Petrology》1951,2(5):432-436

Zusammenfassung Eine früher mitgeteilte Bestimmungsmethode des wahren Winkels der optischen Achsen und des mittleren Hauptbrechungsquotienten /ß mit Hilfe von Drehtischmessungen am Dünnschliff wird auf ihre Brauchbarkeit an Mineralien der Olivingruppe praktisch erprobt. Für senkrechten der nahezu senkrechten Austritt der Mittellinien werden einfache Berechnungsformeln abgeleitet und ihr Anwendungsbereich geprüft. An Olivinen verschiedener Herkunft wird der Fayalitgehalt optisch ermittelt und mit dem Ergebnis der quantitativen chemischen Analyse verglichen.Die Anwendbarkeit der Methode für ähnliche Bestimmungen an anderen, optisch zweiachsigen Mineralgruppen wird erwogen und in Ergänzung einer Methode von BuRRI besonders für rhombische Pyroxene vorgeschlagen.  相似文献   

Die Bestimmung des optischen Schwerpunktes von Glühlicht-Filter-Kombinationen     

Prof. Dr. Rudolf Mosebach 《Contributions to Mineralogy and Petrology》1951,2(5):437-442

Zusammenfassung Ein Verfahren zur mikroskopischen Bestimmung des optischen Schwerpunktes von Glühlicht-Filter-Kombinationen mit Hilfe von Drehkompensatoren wird entwickelt und praktisch erprobt. Bei genügend engem spektralen Durchlässig-keitsbereich (z. B. Lifa-Filter Nr. 215 rot und Nr. 391 blau) ist die Bestimmung der Schwerpunktswellenlänge () bis auf Bruchteile von m möglich. Das Verfahren kann prinzipiell auf alle Lichtquellen ausgedehnt werden; deren Wellenlängen sich in genügend engen Spektralbereichen halten. Erforderlich ist lediglich die genaue Kenntnis der Kompensatorkonstanten für Na-Licht, welche am besten durch Eichung mit einer Na-Dampflampe bestimmt wird.  相似文献   

Ecology of Nematodes in the Mediterranean Seagrass Posidonia oceanica (L.) Delile 1. General Part and Faunistics of the Nematode Community     

Rudolf Novak 《Marine Ecology》1989,10(4):335-363

Abstract. The nematode fauna of the phytal region of a stand of the Mediterranean seagrass Posidonia oceanica (L.) Delile was studied in a shallow subtidal location (5 m) at the island of Ischia (Gulf of Naples, Italy). During a one year's growth-cycle of the seagrass, abundance and faunal composition of the nematode community were investigated in a stratified sampling survey. Ninety seven species of nematodes were found. Nematode density and biomass ranged from 1.3 · 10⁵ indiv. · m^-2 (0.02g dwt · m^-2) in winter to 5.5 · 10⁵ indiv. · m^-2 (0.08 g dwt · m^-2) in early autumn. Density and biomass of nematodes were much lower and showed more marked seasonal fluctuations in the leaf strata than in the stem stratum of the seagrass. Diversity and seasonal homogeneity (expressed with Riedl 's index) were much lower in the two leaf strata (25–36 species, 29.6 ho%) than in the stem stratum (60–70 species, 42.5 ho%). The nematode community of the leaf stratum can be characterized as a Chromadora nudicapitata – Monhystrella sp. –Symplocostoma tenuicolle– community and is clearly set off from the stem stratum community (9.2% Riedl 's ho%), which is characterized as a Molgolaimus sp. 1 –Epsilonema sp. 1 –Chromadora nudicapitata– community. In the seasonal succession, the leaf stratum fauna shifts from a chromadorid-dominated community (from winter to summer) to a monhysterid-dominated community in early autumn. The stem stratum fauna shifts from a epsilonematid-dominated fauna in winter to a molgolaimid-dominated fauna in summer and early autumn. The distribution of nematode size classes showed a clear selection toward small animals (< 1 mm lenght), although marked seasonal fluctuations in size class distribution were observed. A modified approach for describing the trophic structure of the nematode fauna is presented. The observed abundance patterns and changes of community composition are discussed in relation to the development of habitat complexity and in relation to trophic conditions in the scagrass stand according to the seasonal growth rhythm of the plants and their aufwuchs-community.  相似文献   

The surge motion of a circular cylinder containing a concentric cylindrical hole in finite depth     

M. Ilki ik  K. Kafali 《Ocean Engineering》1986,13(4)

This paper deals with hydrodynamic forces of a single semisubmerged circular cylinder containing a concentric cylindrical hole constrained to move in a water domain of finite depth. The fluid domain is divided into inner and outer regions. The Laplace equations governing velocity potentials for the three regions are solved by separation of variables and expressed in terms of eigenfunctions of the resulting equations which satisfy appropriate boundary conditions. Continuity of pressure and velocity at the interface of the regions provides the necessary equations from which the velocity potentials, pressures and forces are obtained. Numerical results are plotted for added mass and damping coefficients for different draft-to-depth and radius-to-depth values and for various wave amplitudes.  相似文献