Deformation und Umwandlung von Plagioklas durch Stoßwellen in den Gesteinen des Nördlinger Ries     

Dieter Stöffler 《Contributions to Mineralogy and Petrology》1967,16(1):51-83

Plagioclase from fragments of crystalline basement rocks in breccias found in the area of the Nördlinger Ries crater displays characteristic plastic deformation and phase transition phenomena due to shock metamorphism at different pressures in the range of 100 to 1000 kilobars.These phenomena are discussed in the scope of a progressive impact metamorphism the degree of metamorphism reflecting a radial gradient of pressure and temperature diminishing outward from the point of meteorite impact.Within the lowest pressure range of about 100 to 300 kilobars (shock stage I) strong fracturing and plastic deformation such as bending of crystals, deformation bands and planar features (lamellae of lowered refractive index and of lowered or no birefringence) are to be found. The lamellae which are mostly isotropic, are interpreted as slip bands the glide planes of which are low indices planes of the plagioclase lattice such as (001), (010), (100), (1¯20), (130) and others. These slip bands are unknown from feldspar formed by normal processes within the earth's crust. Plagioclase of such a stage of deformation shows an unusual strong decrease of refraction and birefringence. Its optical properties are those of a highly disordered plagioclase. It may be called diaplectic plagioclase.Total isotropization of plagioclase is a typical feature of the pressure range from 300 to 500 kilobars (shock stage II). This glass which is called diaplectic glass differs strongly from the normal glass in physical properties and structural state. It is formed by a kind of solid state transformation without actual melting.Shock pressures in the order of 500 to 650 kilobars (shock stage III) are able to cause selective melting of plagioclase grains in a crystalline rock. Normal glasses with vesicles and streaks are formed by this process.Within the pressure range of about 650 to 1000 kilobars (shock stage IV) residual temperatures are so high that total melting of rocks occurs. Plagioclase melts are mixed inhomogenously with other silicate melts forming rock melts which can be found in suevite as flat glassy bombs. Vaporization of silicates must be expected in the upper pressure range of this shock stage.Statistical universal stage measurements on the fabric of plagioclase support theoretical considerations after which the deformation pattern of a single crystal should depend on the fabric relations to the surrounding minerals and on their physical properties. Strongly inhomogenous deformation of plagioclase minerals within the microscopic rock scale was observed because polycrystalline rocks are disorganizing a unique shock front by interaction of wave fronts at interfaces and free surfaces and perhaps by multiwave shocks. Directions of compressive and tensile stresses on a mineral are therefore changing from grain to grain.  相似文献   

A linear solution of the equations of motion of an earth-orbiting satellite based on a Lie-series     

Dieter J. Lelgemann 《Celestial Mechanics and Dynamical Astronomy》1983,30(3):309-321

Using Hill's variables, an analytical solution of a canonical system of six differential equations describing the motion of a satellite in the gravitational field of the earth is derived. The gravity field, expanded into spherical harmonics, has to be expressed as a function of the Hill variables. The intermediary is chosen to include the main secular terms. The first order solution retains the highly practical formal structure of Kaula's linear solution, but is valid for circular orbits and provides of course a spectral decomposition of radius vector and radial velocity. The resulting eccentricity functions are much simpler than the Hansen functions, since a series evaluation of the Kepler equation is avoided. The present solution may be extended to higher order solutions by Hori's perturbation method.  相似文献   

XENON,OSMIUM, AND LEAD FORMED IN O-SHELLS AND C-SHELLS OF MASSIVE STARS     

Dieter Heymann  Marlene Dziczkaniec 《Meteoritics & planetary science》1980,15(1):1-14

In this paper we show that the explosive products from O-shells of massive stars which contain ¹²⁴Xe with large overproduction factors do not contain any of the naturally occurring isotopes of Os and Pb. We show further that the explosive products from C-shells (explosive carbon burning) do contain Os and Pb along with Xe which is strongly enriched in r-Xe of anomalous isotopic composition. The composition of Os in this matter is probably s-like rather than r-like. Pb in this matter is enriched in ²⁰⁸Pb. The results and arguments of this paper have implications for studies of isotopic compositions of Xe, Os, and Pb in residues of the Allende and other carbonaceous chondrites.  相似文献   

Chemical Mechanism Development: Laboratory Studies and Model Applications     

Harald Geiger  Ian Barnes  Karl H. Becker  Birger Bohn  Theo Brauers  Birgit Donner  Hans-Peter Dorn  Manfred Elend  Carlos M. Freitas Dinis  Dirk Grossmann  Heinz Hass  Holger Hein  Axel Hoffmann  Lars Hoppe  Frank Hülsemann  Dieter Kley  Björn Klotz  Hans G. Libuda  Tobias Maurer  Djuro Mihelcic  Geert K. Moortgat  Romeo Olariu  Peter Neeb  Dirk Poppe  Lars Ruppert  Claudia G. Sauer  Oleg Shestakov  Holger Somnitz  William R. Stockwell  Lars P. Thüner  Andreas Wahner  Peter Wiesen  Friedhelm Zabel  Reinhard Zellner  Cornelius Zetzsch 《Journal of Atmospheric Chemistry》2002,42(1):323-357

Within the German Tropospheric Research Programme (TFS) numerous kinetic and mechanistic studies on the tropospheric reaction/degradation of the following reactants were carried out: oxygenated VOC, aromatic VOC, biogenic VOC, short-lived intermediates, such as alkoxy and alkylperoxy radicals.At the conception of the projects these selected groups were classes of VOC or intermediates for which the atmospheric oxidation mechanisms were either poorly characterised or totally unknown. The motivation for these studies was the attainment of significant improvements in our understanding of the atmospheric chemical oxidation processes of these compounds, particularly with respect to their involvement in photooxidant formation in the troposphere. In the present paper the types of experimental investigations performed and the results obtained within the various projects are briefly summarised. The major achievements are highlighted and discussed in terms of their contribution to improving our understanding of the chemical processes controlling photosmog formation in the troposphere.  相似文献   

Focal Mechanisms and Stress Field in The Region Vogtland/Western Bohemia     

Wirth  Wolfgang  Plenefisch  Thomas  Klinge  Klaus  Stammler  Klaus  Seidl  Dieter 《Studia Geophysica et Geodaetica》2000,44(2):126-141

We calculated focal mechanisms for 30 of the strongest events (1.5 M _L 3.3) in distinct subregions of Vogtland/Western Bohemia between 1990 and 1998. Our investigations are concerned with events of the swarms near Bad Elster (1991), Haingrün (1991), Nový Kostel (1994 and 1997) and Zwickau (1998), two events from a group of earthquakes near Klingenthal (1997) and eight single events. Seismograms were provided by the digital station networks of the Geophysical Observatory of the University of Munich, the Technical University of Freiberg, the Academy of Sciences of the Czech Republic in Prague, the Masaryk University in Brno and some nearby stations of the German Regional Seismic Network (GRSN). To calculate focal mechanisms two inversion methods were applied. The inferred focal mechanisms do not show a simple, uniform pattern of seismic dislocation. All possible dislocation types – strike-slip, normal and thrust faulting - are represented. The prevailing mechanisms are normal and strike-slip faulting. Considerable differences in the fault plane solutions are noted for the individual subregions as well as in some cases among the individual events of a single swarm. For the Nový Kostel area we succeeded to resolve a change in the orientations of the nodal planes for the two successive swarms of December 1994 and January 1997. Besides this we also observe a change in the mechanisms, namely from strike-slip and normal faulting (December 1994) to strike-slip and thrust faulting (January 1997). Based on the inferred focal mechanisms the stress field was estimated. It turned out, that the dominating stress field in the region Vogtland/Western Bohemia does not substantially differ from the known stress field of West and Central Europe, being characterized by a SE-NW direction of the maximum compressive horizontal stress. We conclude that the seismicity in the Vogtland/Western Bohemia region is not predominantly caused by an independent local stress field, but rather controlled by the dominating stress regime in Central Europe.  相似文献   

Spatial distribution and bonding forms of heavy metals in sediments along the middle course of the River Elbe (km 287ċ390)     

Andrea van der Veen  Corinna Ahlers  Dieter W. Zachmann  Kurt Friese 《洁净——土壤、空气、水》2006,34(3):214-222

Sediments of eight groyne fields along the middle course of the River Elbe (river km 287?390) were geochemically studied. The 78 sediment samples were analysed for pH and grain size distribution. The grain size fraction < 2 μm was used for mineralogical and chemical analysis: semiquantitative clay mineral analysis; total element content (Al, Ca, Fe, K, Mn, Cd, Cr, Cu, Ni, Pb, Zn), total inorganic and organic C, and bonding form fractionation with a six‐step sequential chemical extraction. The latter was performed on selected samples (n = 32). The sediments along the Elbe's course are still contaminated with heavy metals far above the local geogenic background level. An enrichment factor of more than 15 was calculated for zinc. Cr and Ni are the elements with the lowest enrichment. The bonding form analysis of selected heavy metals shows a dominance of relatively immobile bonding forms, e. g. the moderately reducible and the residual fraction, which implies a relative low mobility potential. Only Zn poses a higher potential threat to the environment, since it has a higher percentage of the first three extracted phases: adsorbed, carbonate, and easily reducible fraction.  相似文献   

Field Signatures of the SE-Asian Mega-Tsunami along the West Coast of Thailand Compared to Holocene Paleo-Tsunami from the Atlantic Region     

Dieter Kelletat  Sander R. Scheffers  Anja Scheffers 《Pure and Applied Geophysics》2007,164(2-3):413-431

The Andaman-Sumatra Tsunami of Dec. 26, 2004, was by far the largest tsunami catastrophe in human history. An earthquake of 9 to 9.3 on the Richter scale, the extension of waves over more than 5000 km of ocean and run-ups up to 35 m are its key features. These characteristics suggest significant changes in coastal morphology and high sediment transport rates. A field survey along the west coast of Thailand (Phuket Island, Khao Lak region including some Similan Islands, Nang Pha mangrove areas and Phi Phi Don Islands) seven to nine weeks after the tsunami, however, discovered only small changes in coastal morphology and a limited amount of dislocated sediments, restricted to the lower meters of the tsunami waves. This is in striking contrast to many paleo-tsunami's events of the Atlantic region. Explanations for this discrepancy are sought in: a. Mechanics of the earthquake. A rather slow shock impulse on the water masses over the very long earthquake zone, b. Shallow water in the earthquake zone, and c. Bathymetry of the foreshore zone at the impacted sites. Shallow water west of Thailand has diminished wave energy significantly. The differences in geomorphological and sedimentological signatures of this tsunami compared with many paleo-tsunami worldwide makes it unsuitable to be used as a model for old and future tsunami imprints by an event of this extreme energy and extension.  相似文献   

Isoseismals of the strongest Friuli aftershocks of September 1976     

Vít Kárník  Dana Procházková  Zdeňka Schenková  Julius Drimmel  Dieter Mayer-Rosa  Dragutin Cvijanovic  Vladimir Kuk  Andelka Miloševič  Francesco Giorgetti  Reviewer J. Janský 《Studia Geophysica et Geodaetica》1978,22(4):411-414

Summary Isoseismal maps of the three strongest Friuli aftershocks of September 1976 were compiled using the contributions from European countries within the shaken area. The characteristic features of the macroseismic fields are discussed.  相似文献   

The thermal circulation of the Central Mexican Meseta region within influence of the trade winds     

Prof. Dr. Wilhelm Lauer  Dr. Dieter Klaus 《Theoretical and Applied Climatology》1975,23(4):343-366

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Mitteilungen     

Dr. Dieter Stadler  Karl Schomaker 《Ocean Dynamics》1975,28(3):117-120

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