Neue Ergebnisse zur Tektonik der Allgäuer und Vilser Alpen

Zusammenfassung Eine Neuuntersuchung der Tektonik in den Vilser Alpen und im Hochvogelgebiet, wo die Frage seit langer Zeit diskutiert wird, ob dort die Allgäu- und Lechtal-Decke getrennte Einheiten bilden, oder stratigraphisch untrennbar zusammenhängen, erbrachte eine eindeutige Entscheidung für den Deckenbau. Der Verlauf der Deckengrenze konnte zwischen Hochvogel und Hohenschwangauer Alpen präzisiert werden. Der interne Falten- und Schuppenbau der Lechtal-Decke hat nirgends zur Bildung von tektonisch tieferen Teildekken geführt, die internen Verschuppungen besitzen nur ein geringes Ausmaß.

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A new investigation of the tectonics in the Vilser Alps and in the Mt. Hochvogel area where since a long time a discussion was going on if the thrust sheets of Allgäu and Lechtal-Decke are separate units or connected by stratigraphic sequences, a definite decision could be made in favour of the nappe structure in this part of the Northern Calcareous Alps. The internal structure of the Lechtal-Decke thrust sheet is characterized by local imbricate structure which originate from sheared folds.

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Résumé On a dicuté depuis longtemps dans les Vilser Alpen et dans la région du Mont Hochvogel le problème, si les nappes de Allgäu et Lechtal-Decke sont des unités separées ou qu'ils forment une partie inséparable par des séquences stratigraphiques. Une nouvelle examen de la tectonique a affirmé la structure de nappes dans cette région des Alpes Calcaires du Nord. La structure intérieure de la nappe de Lechtal-Decke est caracterisée par une structure écaillée locale, qui se developpe de plis cisaillés.

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A note on the performance of the multiply-upstream semi-Lagrangian advection schemes for one-dimensional nonlinear momentum conservation equation

Summary Two-time-level multiply-upstream semi-Lagrangian schemes were examined in the case of the self-advecting, one-dimensional nonlinear momentum conservation equation. The shock formation process was analyzed. It is pointed out that the shocks cannot be created in the truncated systems satisfying the Pudykiewicz, Benoit and Staniforth criterion.The numerical integrations were restricted to 12 h. It was shown that, at least in the sub-CFL range, increased complexity of the scheme can compensate reduced horizontal resolution. A considerable sensitivity of the schemes with respect to the time step was detected. In the super-CFL mode, several windows on various time scales were found within which the Pudykiewicz, Benoit and Staniforth criterion was satisfied. The time step of 1.44 times the maximum time step allowed by the CFL criterion was used in the semi-Lagrangian runs.The super-CFL, semi-Lagrangian solutions were diverging progressively from the sub-CFL ones as the forecasts advanced. This was also reflected in the energy spectra.Unacceptably large energy losses were encountered in the super-CFL, semi-Lagrangian runs. Most of these losses could be explained by the reduced mean wind speed, i.e., the amplitude of the zero wavenumber wave. At the same time, the energy content in the shorter waves increased. In a more complex model, such a situation would resemble a loss of zonal, and an increase of transient eddy kinetic energy.A trajectory error measure was defined as the maximum absolute value of the distance between the actual arriving point of the particle originating at the estimated departure point, and the grid point assumed to be the arrival point in the semi-Lagrangian procedure. In contrast to the sub-CFL regime, this measure could reach a considerable fraction of the grid distance in the computations with the super-CFL time steps.In the physical system considered, the trajectories are determined only by the velocities at the departure points. With the semi-Lagrangian schemes the distances traveled by the particles are estimated on the basis of the velocities at the points downstream with respect to the departure points. Thus, unless the solution is smooth (in space and time) on the scales of the extrapolation distances/times, the upstream extrapolation does not promise the convergence of the solution.With 16 Figures     

Cornetite: Modulated densely-packed Cu2+ oxysalt

Summary The crystal structure of cornetite, Cu₃(PO₄)(OH)₃, orthorhombic, a = 10.854(1), b = 14.053(3), c = 7.086(2), Å, V = 1080.8(3) ų, Z = 8, space group Pbca, has been refined to an R-index of 3.9% for 1231 observed reflections (I > 3I), measured with MoK X-radiation on an automated four-circle diffractometer. The structure consists of edge sharing zig-zag chains of distorted octahedra, cross-linked by edge-sharing octahedral dimers into complex octahedral layers. Adjacent layers are corner-linked together by neighbouring octahedra and PO₄ tetrahedra into a densely-packed heteropolyhedral framework, in which the phosphate tetrahedra share edges with the octahedral dimers. The polyhedral layers exhibit a commensurate modulation that results from the interaction between local relaxation of Jahn-Teller distorted octahedra and the long-range requirements of translational periodicity.

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Cornetit: Ein moduliertes, dicht gepacktes Oxosalz des zweiwertigen Kupfers

Zusammenfassung Die Kristallstruktur des Cornetits, Cu₃(PO4)(OH)3, orthorhombisch, a = 10,854(1), b = 14,053(3), c = 7,086(2,) Å, V = 1080,8(3) ų, Z = 8, Raumgruppe Pbca, wurde mit 1231 beobachteten Röntgenreflexen (I > 3I), die mit MoK-Strahlung auf einem automatischen Vierkreis-Diffraktometer gesammelt worden waren, auf einen R-Wert von 3,9% verfeinert. Die Struktur besteht aus kantenverknüpften Zickzack-Ketten verzerrter Oktaeder, die über kantenverknüfte Oktaeder-Dimere zu komplizierten Oktaederschichten verbunden sind. Benachbarte Schichten sind über Ecken durch benachbarte Oktaeder und PO₄-Tetraeder zu einem dichtgepackten, heteropolyedrischen Gerüst verknüpft, in welchem die Phosphattetraeder mit den Oktaeder-Dimeren Kanten gemeinsam haben. Die Polyederschichten zeigen eine kommensurable Modulierung, die aus der Wechselwirkung zwischen der lokalen Relaxation von Jahn-Teller-verzerrten Oktaedern und den Forderungen der translatorischen Periodizität über größere Entfernungen resultiert.

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With 5 Figures     

Some basic notions in geographical synthesis

Modern geography is based on ecological thinking. In this paper some geoecological notions are discussed: the scales and levels regarding spatial magnitude and complexity, the “hierarchy” of landscape units and espcially the scale of time and the concept of the supper-imposing “stamps”. This last mentioned concept is very important in relation to the problem regarding regionalization and its possibilities. Three “stamps” are recognized: 1. the substrate, 2. the climatic conditions, 3. the human (noötic) influence. Holistic regionalization in which all elements (including the human influences) are telling to full advantage, is unsatisfactory.     

Rb-Sr whole-rock dating of late diagenetic to anchimetamorphic,palaeozoic sediments in southern France (Montagne Noire)

Rb-Sr whole-rock and mineral analyses are reported from Early Paleozoic sediments of the southern rim of the French Central Massif (Montagne Noire). The sediments—mainly pelites, silt- and sandstones—can be separated into three different zones (A, B, and C) according to their varying degrees of deformation and transformation, which took place during the Hercynian (= Variscan) orogeny (Carboniferous). For the least deformed, folded but not schistose, fossiliferous Lower Ordovician sediments (zone A), a scatter of the data points resulted, at least partly due to the varying amount of detrital muscovites, which did not equilibrate their Sr isotopes with those of the clay minerals. Fossiliferous Middle Cambrian sediments (zone B), however, are colinear in an isochron plot. The rocks are also folded, and show a beginning schistosity in the pelitic layers. The age of 333±16 m.y. therefore does not correspond to the time of sedimentation, as one would expect from most of the interpretations given in the literature. It is, however, in close agreement with the stratigraphically known time of folding and anchimetamorphism. The same result, within analytical error, of 326±17 m.y. was obtained for Lower Ordovician sediments (zone C), which show a schistosity not only in the pelites but also in some psammitic layers. As for the sediments of zone B, this result indicates open whole-rock systems for Rb and/or Sr during folding and anchimetamorphism. Minerals extracted from psammites of zones B and C gave the following results: albite coincides with the isochrons; detrital muscovites do not coincide and yield ages of about 650 m.y. (Cadomian orogeny) for both zone B and C sediments; detrital chlorites from zone B sediments seem to be only partly reset by anchimetamorphism and therefore plot closer to the whole-rock isochron. From this it must be concluded that an increasing amount of these detrital micas could significantly shift the position of the total-rock points, as might be the case for zone A sediments. From the whole-rock results of zone B and C sediments and the mineralogical and petrological changes during diagenesis and anchimetamorphism we conclude that many of the isochrons obtained from stratigraphically uncontrollable Precambrian sediments should be reinterpreted in favour of metamorphic and not sedimentary ages, especially if the metamorphism reached greenschist facies conditions. Devonian and Cambrian limestones intercalated between the pelites, silstones and sandstones contain Sr of a variable and slightly radiogenic isotopic composition in contrast to the expected ancient sea water Sr. This fact is interpreted again in favour of open whole-rock systems during the postdepositional history of the rock, rather than primary scatter of ancient, radiogenic sea water Sr.     

Ground-Water Protection Zones

In many areas, the water demand of households, industries and farms is satisfied by ground water. Because of many human activities ground-water quality decreases, it is necessary to protect it. The quantity of pollutants entering the aquifers can be minimized by technical and legal measures. But it seems to be almost impossible to solve the problem regionally or nationwide. The delineation of protection zones around existing or planned wells is a more effective way. The intake area of wells or well fields have to be protected by legal measures against all activities which may affect ground-water quality. Regarding the migration of viruses and bacteria, it is well known that these biological pollutants have a distinct limited lifetime in aquifers, which is for West Germany estimated at 50 days. Because during this limited time they can move with the ground water, transfer diseases, and cause epidemics, certain zones around wells must be kept free from activities which may introduce bacteria into the subsurface systems. These zones are generally smaller than the catchments. For the determination of the zones, careful studies and calculations of the distance-velocity of ground water are necessary. Primary methods are the use of tracers and simple calculations. Examples are given for calculating the distance to the 50-day line, based on West German experience.