ALBERT

Beschreibung: Abstract: A new experimental technique for the study of deformation processes in rocks in transmitted light under the microscope uses a modified sapphire anvil cell in which one of the sapphire anvils can be rotated and thus permit the deformation of a thin solid sample disc. The deformation can be observed during the experiment through the anvils using a polarizing microscope stage. The technique is applicable up to 450 Celsius degree and up to 2 GPa confining pressure in the central part of the sample.

Beschreibung: Single zircons from two orthogneiss complexes, the 'Grey Gneiss' and 'Red Gneiss', the lowermost tectonic units in the Erzgebirge, were dated. The zircon ages document a distinct late Proterozoic phase of granitoid magmatism, similar in age to granitoids in the Lusatian block farther north-east. However, Palaeozoic deformation as well as medium pressure metamorphism (approx 8 kbar/600-650 degrees C) are identifical in both gneiss units and distinguish these rocks from the Lusatian granitoids. They grey and red gneisses were overthrust by units with abundant high-pressure relicts and a contrasting P-T evolution. -from Authors

Beschreibung: Sets of seismological, geological and geophysical maps have been developed or compiled for the E part of the W European platform. The area under study includes the GDR, SW Poland, and N Czechoslovakia. The maps mentioned are presented and briefly discussed with regard to their suitability for a seismogenetic analysis. A first seismotectonic interpretation is made as a rough lineation of seismoactive zones based on the seismological as well as non-seismological data.-from Authors

Beschreibung: Additional keywords: cryptogrammic plants, algae, lichen flora, ionosphere observations, geomagnetic observations, atmospheric observations, references, maps, tables, kontinentale Eisbedeckung, Satellitenbeobachtungen der Meereisbedeckung, Hydrologie, Biologie, kryptogame Pflanzen, Algen, Flechten, Flora, Ionosphaeren-Beobachtungen, geomagnetische Beobachtungen, atmosphaerische Beobachtungen, Literatur, Karten, Tabellen

Beschreibung: The high spatial resolution of the multispectral channels (13.5m x 13.5m), the nadir panchromatic channel (4.5m x 4.5m) and their combination offers significant improvements for geoscientific applications. Common multispectral classification schemes however hardly benefit from the improved spatial resolution. Many objects can be better separated by their individual shape characteristics and not by the spectral information of a single pixel. Therefore a modular classification scheme was developed, which uses spectral as well as shape features. This technic was applied to a landcover classification on two different test sites. First applications show significantly improved results for certain object classes, which have a typical shape, like e.g. trees, houses, roads, and rivers. The common use of this technique is still restricted by the shape extraction.

Beschreibung: Additional keywords: cloudiness, isotope variations, allgemeine Bedingungen, lokale Bedingungen, Oasenklima, Makroklima, Klimavariationen, Sonnenstrahlung, Lufttemperatur, Windrichtung, Windgeschwindigkeit, Niederschlag, Feuchtigkeit, Bewoelkung, Isotopenvariationen

Beschreibung: This investigation is focused on the feasibility to conduct population statistics in developing countries, based on remote sensing data and consecutive field examination. Hereby, the average number of inhabitants per house unit (plot) is evaluated in field. These values are projected by numbers of plots evaluated on aerial photographs/maps and MOMS-02 spaceborne data to an estimated population number of areas formed by homogeneous types of houses (characterized by a size of 6 m x 3 m and up to 15 m x 7 m). Usually, this kind of RS-information is only provided by photographic systems e.g. aerial photographs, KVR-1000. A resolution of 10 m x 10 m like SPOT-HRV is still insufficient to this problem. The high resolution of MOMS-02 panchromatic data (4,5 m x 4,5 m) however, allows to distinguish clearly the single plots in high density sub-urban areas. Based on this information, population numbers are calculated for training and test are as of different but homogeneous housing units. Data are then compared to census data and evaluations using aerial photographs/maps. The results show that MOMS-02 panchromatic data in connection with the developed methodology can be used for this purpose as only minor deviations occur.

Beschreibung: For the German MOMS-02 sensor new wavebands have been designed for multispectral coverage in the visible and near infrared range and for panchromatic/stereoscopic recording. Data acquired during the STS-55/D2 have been investigated with regard to their technical performance and spectral significance to validate the design of bands derived from theoretical considerations and modelling. To meet the objective, raw data have been pre-processed and coefficients for absolute calibration are provided. Image distortions could be identified and related to electronic malfunctions and/or to lack of power, shielding and thermal influences. With some limitations, calculated results for radiometry, entropy, SNR and LSF performances are comparable to operational sensors. Results of variance/covariance analyses indicate a 10-15% improved spectral decorrelation for MOMS-02 bands as compared to those of operational sensors with broader band design and thus confirm the new arrangement of the band centers and widths. The extension of the panchromatic band pass to longer wavelengths has proven to be well suited to clearly resolve vegetated areas and rock/soil surfaces.

Beschreibung: The coincidence of a low velocity zone in a depth of 8-17 km, an estimated temperature of 250°C in the upper crust, relatively high recent lateral compression and relatively high shear strain in an area of the S part of the GDR (Vogtland region) may be favourable for the occurrence of small earthquakes. Further possible prerequisites for the causes of earthquakes have been taken into consideration.-Authors

Beschreibung: Slab breakoff is the buoyancy-drivend etachment of subducted oceanic lithosphere from the light continental lithosphere that follows it during continental collision.In a recent paper Davies and von Blanckenburg [1994] have assessed the physical conditions leading to breakoff by quantitative thermomechanical Modeling and have predicted various consequences in the evolution of mountain belts. Breakoff will lead to heating of the overriding lithospheric mantle by upwelling asthenosphere, melting of its enriched layers, and thus to bimodal magmatism. Breakoff will also lead to thermal weakening of the subducted crustall ithosphere, thereby allowing buoyant rise of released crustal slices from mantle depths. In this paper we present a test of this model in the Tertiary evolution of the European Alps. In the Alps, both basaltic and granitoid magmatism occur between 42 and 25 Ma, following the closure of oceanic basins by subduction and continental collision. The granitoids are now well established to result from mixing of basalt with assimilated continental crust. To identify the tectonically crucial origin of the partial mantle melts, we have compiled all published geochemical and isotopic data of numerous mafic dykes occurring throughout the whole Alpine arc. Their trace element and isotopic composition suggests that they have been formed by low-degree melting of the mechanically stable lithospheric mantle. We see no evidence for melting of asthenospheric mantle. It was thus not decompressed to depths shallower than 50 km. Once initiated, rapid lateral migration of slab breakoff will result in a linear trace of magmatism in locally thermal weakened crust. This explains why all Alpine magmatic rocks intruded almost synchronously along a strike-slip fault, the Periadriatic Lineament. A compilation of ages from Penninic high-pressure rocks subducted to depths of up to 100 km shows that subduction took place at circa 55-40 Ma, followed by uplift at 40-35 Ma. From the short time interval between their uplift and the onset of magmatism we infer that both processes have been induced by the breakoff. The slab breakoff model fulfills its predictions in the case of the Alps and therefore supports the assumptions made in the theoretical model on a geological basis. We believe that the characteristic association of magmatic activity with the return of high-pressure rocks to the surface allows the identification of this process in the Earth's mountain belts.