Island und die Frage der Kontinentalverschiebungen     

F. Bernauer 《International Journal of Earth Sciences》1939,30(3):357-358

Ohne Zusammenfassung  相似文献   

Mathiasite-loveringite and priderite in mantle xenoliths from the Alto Paranaíba Igneous Province,Brazil: genesis and constraints on mantle metasomatism     

Vidyã V. Almeida  Valdecir de A. Janasi  Darcy P. Svisero  Felix Nannini 《Central European Journal of Geosciences》2014,6(4):614-632

Alkali-bearing Ti oxides were identified in mantle xenoliths enclosed in kimberlite-like rocks from Limeira 1 alkaline intrusion from the Alto Paranaíba Igneous Province, southeastern Brazil. The metasomatic mineral assemblages include mathiasite-loveringite and priderite associated with clinopyroxene, phlogopite, ilmenite and rutile. Mathiasite-loveringite (55–60 wt.% TiO₂; 5.2–6.7 wt.% ZrO₂) occurs in peridotite xenoliths rimming chromite (～50 wt.% Cr₂O₃) and subordinate ilmenite (12–13.4 wt.% MgO) in double reaction rim coronas. Priderite (Ba/(K+Ba)< 0.05) occurs in phlogopite-rich xenoliths as lamellae within Mg-ilmenite (8.4–9.8 wt.% MgO) or as intergrowths in rutile crystals that may be included in sagenitic phlogopite. Mathiasite-loveringite was formed by reaction of peridotite primary minerals with alkaline melts. The priderite was formed by reaction of peridotite minerals with ultrapotassic melts. Disequilibrium textures and chemical zoning of associated minerals suggest that the metasomatic reactions responsible for the formation of the alkali-bearing Ti oxides took place shortly prior the entrainment of the xenoliths in the host magma, and is not connected to old (Proterozoic) mantle enrichment events.  相似文献   

Ergebnisse neuer Spezialforschungen in den deutschen Alpen     

F. Felix Hahn 《International Journal of Earth Sciences》1914,5(2):112-145

Ohne Zusammenfassung  相似文献   

SKA studies of atomic gas in the interstellar medium of the Milky Way     

John M. Dickey  N.M. McClure-Griffiths  Felix J. Lockman 《New Astronomy Reviews》2004,48(11-12):1311

The λ21-cm line is an excellent tracer of the neutral interstellar medium (ISM). Atomic hydrogen (HI) is found in a variety of environments, from dense clouds to the diffuse galactic halo, and its filling factor is often high, so structures with sizes over a wide range of scales can be mapped with this line. Galactic HI surveys show small scale structure that is consistent with a spectrum of interstellar turbulence similar to what is measured in the ionized component of the ISM. But our sampling of the spectrum of this turbulence is limited to a few size ranges, based on the sensitivities of existing telescopes for emission and absorption studies. The Square Kilometer Array (SKA) will provide the sensitivity and resolution to give continuous coverage of the turbulence spectrum from hundreds of parsecs to a few tens of Astronomical Units. By showing us the full spectrum of interstellar turbulence in the neutral medium, the physical processes driving hydrodynamic and magneto-hydrodynamic instabilities will be illuminated. Ultimately the turbulence governs the passage of the gas from the warm phases of the medium to the cold phases where gravitational collapse can initiate star formation. The SKA is needed to fill in this missing link in the cycle of star formation and chemical enrichment that drives the evolution of galaxies. In the Milky Way halo, SKA mapping of HI high velocity clouds will trace the structure and motion of both the warm phase gas and the hot medium. The interaction between these two phases of halo gas is a great unsolved problem in Galactic astrophysics.  相似文献   

Semi-analytic simulations of galactic winds: volume filling factor, ejection of metals and parameter study     

Serena Bertone †  Felix Stoehr  Simon D. M. White 《Monthly notices of the Royal Astronomical Society》2005,359(4):1201-1216

We present a semi-analytic treatment of galactic winds within high-resolution, large-scale cosmological N -body simulations of a Λ cold dark matter (ΛCDM) universe. The evolution of winds is investigated by following the expansion of supernova-driven superbubbles around the several hundred thousand galaxies that form in an approximately spherical region of space with diameter 52  h ⁻¹ Mpc and mean density close to the mean density of the universe. We focus our attention on the impact of winds on the diffuse intergalactic medium. Initial conditions for mass loss at the base of winds are taken from Shu, Mo & Mao. Results are presented for the volume filling factor and the mass fraction of the intergalactic medium (IGM) affected by winds, and their dependence on the model parameters is carefully investigated. The mass-loading efficiency of bubbles is a key factor to determine the evolution of winds and their global impact on the IGM: the higher the mass loading, the later the IGM is enriched with metals. Galaxies with 10⁹ < M _★ < 10¹⁰ M_⊙ are responsible for most of the metals ejected into the IGM at   z = 3  , while galaxies with   M _★ < 10⁹ M_⊙   give a non-negligible contribution only at higher redshifts, when larger galaxies have not yet assembled. We find a higher mean IGM metallicity than Lyα forest observations suggest, and we argue that the discrepancy may be explained by the high temperatures of a large fraction of the metals in winds, which may not leave detectable imprints in absorption in the Lyα forest.  相似文献   

An analytic method to determine future close approaches between satellites   总被引：6，自引：0，他引：6  

Felix R. Hoots  Linda L. Crawford  Ronald L. Roehrich 《Celestial Mechanics and Dynamical Astronomy》1984,33(2):143-158

The calculation of the times of future close approaches between pairs of satellites has been formulated using analytical techniques. The resulting analytical equations are solved using numerical iterative techniques similar to solving Kepler's equation. A solution is obtained in a very efficient manner by use of a series of prefilters which eliminate many cases from further consideration. The method is valid for all values of eccentricities less than one and all relative geometries between the two orbits. This approach produces results in a very efficient and reliable manner.  相似文献   

The delesse relation in a concentrically zoned sphere. I. The section-number bias     

Felix Chayes 《Mathematical Geology》1989,21(3):319-329

Zonal areas of a randomly chosen section through a concentrically zoned sphere yield an estimate of the (volumetric) amount of the outer zone which is subject to a large positive bias that decreases rapidly with increase in the number of sections on which the estimate is based. It will not exceed 3% of the amount present if an analysis is based on as many as 8 sections and will be less than 1% if 32 sections are used.  相似文献   

Eocene age of eclogite metamorphism in Pakistan Himalaya: implications for India-Eurasia collision     

Sonia Tonarini  Igor M. Villa  Felix Oberli  Martin Meier  David A. Spencer  Ugo Pognante  John G. Ramsay 《地学学报》1993,5(1):13-20

A geochronological investigation of two rocks with an eclogitic assemblage (omphacite-garnet-quartz-rutile) from the High Himalaya using the Sm/Nd, Rb/Sr, U/Pb and Ar/Ar methods is presented here. The first three methods outline a cooling history from the time of peak metamorphism at 49±6 Ma recorded by Sm/Nd in garnet-clinopyroxene to the closure of Rb/Sr in phengite at 43±1 Ma and U/Pb in rutile at 39–40 Ma. The Sm/Nd isotopic system was fully equilibrated during eclogitization and has not been disturbed since; its mineral ages may date the peak metamorphic conditions (650±50°C at 13–18 kbar: Pognante and Spencer, 1991). The Ar/Ar data reveal the presence of substantial amounts of excess ⁴⁰Ar in hornblende, and yield a statistically acceptable but geologically meaningless phengite plateau age of 81.4±0.2 Ma, inconsistent with Sm/Nd, Rb/Sr and U/Pb. This questions the use of such a chronometer for the dating of high-pressure assemblages. The results imply a Late Palaeocene or Early Eocene subduction of the northern Indian plate margin in NW Himalaya. The fact that eclogites are restricted to NW Himalaya may be the result of a peculiar p-T-t path associated with a high convergence rate during the first indentation, in contrast to the later and slow subduction in Central and Eastern Himalaya.  相似文献   

Will climate change exacerbate water stress in Central Asia?   总被引：3，自引：0，他引：3  

Tobias Siegfried  Thomas Bernauer  Renaud Guiennet  Scott Sellars  Andrew W. Robertson  Justin Mankin  Peter Bauer-Gottwein  Andrey Yakovlev 《Climatic change》2012,112(3-4):881-899

Millions of people in the geopolitically important region of Central Asia depend on water from snow- and glacier-melt driven international rivers, most of all the Syr Darya and Amu Darya. The riparian countries of these rivers have experienced recurring water allocation conflicts ever since the Soviet Union collapsed. Will climate change exacerbate water stress and thus conflicts? We have developed a coupled climate, land-ice and rainfall-runoff model for the Syr Darya to quantify impacts and show that climatic changes are likely to have consequences on runoff seasonality due to earlier snow-melt. This will increase water stress in unregulated catchments because less water will be available for irrigation in the summer months. Threats from geohazards, above all glacier lake outbursts, are likely to increase as well. The area at highest risk is the densely populated, agriculturally productive, and politically unstable Fergana Valley. Targeted infrastructural developments will be required in the region. If the current mismanagement of water and energy resources can be replaced with more effective resource allocation mechanisms through the strengthening of transboundary institutions, Central Asia will be able to successfully address these future climate-related challenges.  相似文献   

Classical Calculations of Scattering Signatures from a Gravitational Singularity or the Scattering and Absorption Cross-Sections of a Black Hole     

Felix C. Difilippo 《Journal of Astrophysics and Astronomy》2012,33(3):311-347

Within the context of general relativity theory we calculate, analytically, scattering signatures around a gravitational singularity: angular and time distributions of scattered massive objects and photons and the time and space modulation of Doppler effects. Additionally, the scattering and absorption cross sections for the gravitational interactions are calculated. The results of numerical simulations of the trajectories are compared with the analytical results.  相似文献