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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Meeresoptische Messungen während schwerer Stürme auf der Forschungsplattform “Nordsee” vom 14. November bis zum 8. Dezember 1980

Ocean Dynamics - Meeresoptische Messungen auf der Forschungsplattform “Nordsee” haben gezeigt, daß dort während schwerer Stürme, hauptsächlich durch den Einfluß...     

Impacts of Present and Future Climate Change and Climate Variability on Agriculture in the Temperate Regions: North America

The potential impact of climate variability and climate change on agricultural production in the United States and Canada varies generally by latitude. Largest reductions are projected in southern crop areas due to increased temperatures and reduced water availability. A longer growing season and projected increases in CO₂ may enhance crop yields in northern growing areas. Major factors in these scenarios analyzes are increased drought tendencies and more extreme weather events, both of which are detrimental to agriculture. Increasing competition for water between agriculture and non-agricultural users also focuses attention on water management issues. Agriculture also has impact on the greenhouse gas balance. Forests and soils are natural sinks for CO₂. Removal of forests and changes in land use, associated with the conversion from rural to urban domains, alters these natural sinks. Agricultural livestock and rice cultivation are leading contributors to methane emission into the atmosphere. The application of fertilizers is also a significant contributor to nitrous oxide emission into the atmosphere. Thus, efficient management strategies in agriculture can play an important role in managing the sources and sinks of greenhouse gases. Forest and land management can be effective tools in mitigating the greenhouse effect.     

Leakage below dam sites in limestone terrains by enhanced karstification: a modeling approach

Unnaturally high hydraulic gradients below dam sites enhance dissolutional widening of fractures in limestone. A model is presented which suggests that under unfavorable conditions, leakage rates could become unbearably high during the lifetime of the dam. At the beginning when water is impounded, leakage rates are low and increase slowly. A positive feedback loop, however, causes a sudden dramatic increase of leakage within a few years. Deep grouting becomes necessary to prevent such failures. Inefficiencies in grouting may leave some open fractures in the grouting curtain. These fractures widen faster than pathways below the grouting curtain, and reduce the effect of the grouted region located below. Therefore, open fractures act in a similar way as reduction of the grouting depth.     

Ophiolites of the Eastern Peninsulas zone (Eastern Kamchatka): Age, composition, and geodynamic diversity

Abstract   The geological, geochemical and mineralogical data of dismembered ophiolites of various ages and genesis occurring in accretionary piles of the Eastern Peninsulas of Kamchatka enables us to discriminate three ophiolite complexes: (i) Aptian–Cenomanian complex: a fragment of ancient oceanic crust, composed of tholeiite basalts, pelagic sediments, and gabbroic rocks, presently occurring in a single tectonic slices (Afrika complex) and in olistoplaques in Pikezh complex of the Kamchatsky Mys Peninsula and probably in the mélange of the Kronotsky Peninsula; (ii) Upper Cretaceous complex, composed of highly depleted peridotite, gabbro and plagiogranite, associated with island arc tholeiite, boninite, and high-alumina tholeiitic basalt of supra-subduction origin; and (iii) Paleocene–Early Eocene complex of intra-island arc or back-arc origin, composed of gabbros, dolerites (sheeted dykes) and basalts produced from oceanic tholeiite melts, and back-arc basin-like dolerites. Formation of the various ophiolite complexes is related to the Kronotskaya intra-oceanic volcanic arc evolution. The first ophiolite complex is a fragment of ancient Aptian–Cenomanian oceanic crust on which the Kronotskaya arc originated. Ophiolites of the supra-subduction zone affinity were formed as a result of repeated partial melting of peridotites in the mantle wedge up to the subduction zone. This is accompanied by production of tholeiite basalts and boninites in the Kamchatsky Mys segment and plagioclase-bearing tholeiites in the Kronotsky segment of the Kronotskaya paleoarc. The ophiolite complex with intra-arc and mid-oceanic ridge basalt geochemical characteristics was formed in an extension regime during the last stage of Kronotskaya volcanic arc evolution.     

Normal Point Algorithm For Reduction Of Two Colour Slr Observations

Two colour laser ranging to artificial satellites is an attractivetechnique, which is capable to provide refraction corrected ranges without the need of an atmospheric model by measuring the dispersive delay of laser pulses of different wavelength. Although the required accuracy of the detection scheme is stringent, the technique has matured so far, that routine two colour observationsbecame feasible.The present paper describes a normal point procedure reducing two colour laser range observations with respect to the dispersive delay,exploiting the knowledge of satellite response signatures in conjunction with detector characteristics and the appropriate center of mass correction models.Moreover the dispersion model of the atmosphere is briefly reviewed, paying attention to the wavelength domains provided by modern twocolour ranging lasers, e.g., the Ti:SAP laser.Preliminary data is presented and compared to both, normal point data reduced with a standard procedure and zenith path equivalent meteorological parameters.     

Adjustment of a Formulated Sediment for Sediment Testing with Caenorhabditis elegans (Nematoda)

The OECD soil, which is standardised for use in the sediment toxicity with the midge Chironomus riparius revealed inhibition of the nematode Caenorhabditis elegans in body growth length and egg production of 41.0% and 84%, respectively. 18 formulated sediments were tested to optimise the sediment composition for growth and reproduction of C. elegans. Their components were chosen to simulate native sediments, whereby different quantities and different clay minerals were tested. The mixture that we found to be optimal in our experiments consisted of 5% sphagnum peat, 70% calcitic sand, 0.5% dolomite limestone, 4.5% iron(III) oxide, and a clay combination of 1.5% chlorite and 18.5% aluminium(III) oxide. When applying this mixture to C. riparius, the new formulated sediment improved also growth in comparison to the OECD sediment.