243 resultados para alpine

em Publishing Network for Geoscientific


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The objective of this study is the production of an Alpine Permafrost Index Map (APIM) covering the entire European Alps. A unified statistical model that is based on Alpine-wide permafrost observations is used for debris and bedrock surfaces across the entire Alps. The explanatory variables of the model are mean annual air temperatures, potential incoming solar radiation and precipitation. Offset terms were applied to make model predictions for topographic and geomorphic conditions that differ from the terrain features used for model fitting. These offsets are based on literature review and involve some degree of subjective choice during model building. The assessment of the APIM is challenging because limited independent test data are available for comparison and these observations represent point information in a spatially highly variable topography. The APIM provides an index that describes the spatial distribution of permafrost and comes together with an interpretation key that helps to assess map uncertainties and to relate map contents to their actual expression in terrain. The map can be used as a first resource to estimate permafrost conditions at any given location in the European Alps in a variety of contexts such as research and spatial planning. Results show that Switzerland likely is the country with the largest permafrost area in the Alps, followed by Italy, Austria, France and Germany. Slovenia and Liechtenstein may have marginal permafrost areas. In all countries the permafrost area is expected to be larger than the glacier-covered area.

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Early- and Middle-Miocene sediments of the North Alpine Foreland Basin (NAFB) in Southern Germany contain one of the world richest regional records of silicified wood. Here we analyze over 1,000 identifiable samples, belonging to 80 wood anatomical taxa from 61 stratigraphically well-dated localities using principally the Coexistence Approach. The samples investigated originate from fluvial sediments representing periods of intensified surface runoff in the NAFB and therefore represent and provide information pertaining to the wet end-member of the fluctuating climate system. The dry end of the climate system is represented in the profiles either by hiatuses or palaeosoils. The dataset is split into four xylofloras: (I) the Ortenburg xyloflora (Late Ottnangian; ~17.5 to 17.3 Ma) originating from a paratropical evergreen Carapoxylon (Xylocarpus) forest; (II) the Southern Franconian Alb xyloflora (Late Karpatian; 17.0 to ~16.3 Ma) originating from a subtropical semideciduous limestone forest; (III) the upper Older Series xyloflora (Early Badenian; ~16.3 to ~15.3 Ma) originating from a subtropical oak-laurel forest; and (IV) the upper Middle Series xyloflora (Middle Badenian; 14.3 to ~13.8 Ma) originating from a subtropical dry deciduous forest.

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In the frame of the transnational ALPS-GPSQUAKENET project, a component of the Alpine Space Programme of the European Community Initiative Programme (CIP) INTERREG III B, the Deutsches Geodätisches Forschungsinstitut (DGFI) in Munich, Germany, installed in 2005 five continuously operating permanent GPS stations located along the northern Alps boundary in Bavaria. The main objective of the ALPS-GPSQUAKENET project was to build-up a high-performance transnational space geodetic network of Global Positioning System (GPS) receivers in the Alpine region (the so-called Geodetic Alpine Integrated Network, GAIN). Data from this network allows for studying crustal deformations in near real-time to monitor Earthquake hazard and improve natural disaster prevention. The five GPS stations operatied by DGFI are mounted on concrete pillars attached to solid rock. The names of the stations are (from west to east) Hochgrat (HGRA), Breitenberg (BREI), Fahrenberg (FAHR), Hochries (HRIE) and Wartsteinkopf (WART). The provided data series start from October 7, 2005. Data are stored with a temporal spacing of 15 seconds in daily RINEX files.

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Expanding visitation to Polar regions combined with climate warming increases the potential for alien species introduction and establishment. We quantified vascular plant propagule pressure associated with different groups of travelers to the high-Arctic archipelago of Svalbard, and evaluated the potential of introduced seeds to germinate under the most favorable average Svalbard soil temperature (10°C). We sampled the footwear of 259 travelers arriving by air to Svalbard during the summer of 2008, recording 1,019 seeds: a mean of 3.9 (±0.8) seeds per traveler. Assuming the seed influx is representative for the whole year, we estimate a yearly seed load of around 270,000 by this vector alone. Seeds of 53 species were identified from 17 families, with Poaceae having both highest diversity and number of seeds. Eight of the families identified are among those most invasive worldwide, while the majority of the species identified were non-native to Svalbard. The number of seeds was highest on footwear that had been used in forested and alpine areas in the 3 months prior to traveling to Svalbard, and increased with the amount of soil affixed to footwear. In total, 26% of the collected seeds germinated under simulated Svalbard conditions. Our results demonstrate high propagule transport through aviation to highly visited cold-climate regions and isolated islands is occurring. Alien species establishment is expected to increase with climate change, particularly in high latitude regions, making the need for regional management considerations a priority.

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Analyses of rock clasts and of heavy minerals in upper Miocene coarse detrital units drilled along the East Sardinia passive-type continental margin (Sites 654, 653, 652, and 656) reveal that the stretched basement contains quite complex rock suites. Taking also into account previous sampling data, in moving from west to east across the margin, the nature of the basement changes drastically. To the west there are mostly Hercynian basement rocks with their cover, referable to the alpine foreland of the Corsica-Sardinia block. To the east, along the lower margin, where crustal thinning is quite severe, the basement contains rock suites referable to a pre-upper Tortonian orogenized zone with units constituting parts of the Alpine and Apenninic chains (presumably with thickened continental crust prior to stretching). Largest thinning and ocean forming occurred then, in a rather short time, mostly at the expense of unstable crust just thickened by orogenetic/tectogenetic processes.