Institut für Geographie und Geoökologie
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The Alborz range of N Iran provides key information on the spatiotemporal evolution and characteristics of the Arabia-Eurasia continental collision zone. The southwestern Alborz range constitutes a transpressional duplex, which accommodates oblique shortening between Central Iran and the South Caspian Basin. The duplex comprises NW-striking frontal ramps that are kinematically linked to inherited E-W-striking, right-stepping lateral to obliquely oriented ramps. New zircon and apatite (U-Th)/He data provide a high-resolution framework to unravel the evolution of collisional tectonics in this region. Our data record two pulses of fast cooling associated with SW-directed thrusting across the frontal ramps at similar to 18-14 and 9.5-7.5 Ma, resulting in the tectonic repetition of a fossil zircon partial retention zone and a cooling pattern with a half U-shaped geometry. Uniform cooling ages of similar to 7-6 Ma along the southernmost E-W striking oblique ramp and across its associated NW-striking frontal ramps suggests that the ramp was reactivated as a master throughgoing, N-dipping thrust. We interpret this major change in fault kinematics and deformation style to be related to a change in the shortening direction from NE to N/NNE. The reduction in the obliquity of thrusting may indicate the termination of strike-slip faulting (and possibly thrusting) across the Iranian Plateau, which could have been triggered by an increase in elevation. Furthermore, we suggest that similar to 7-6-m.y.-old S-directed thrusting predated inception of the westward motion of the South Caspian Basin. Citation: Ballato, P., D. F. Stockli, M. R. Ghassemi, A. Landgraf, M. R. Strecker, J. Hassanzadeh, A. Friedrich, and S. H. Tabatabaei (2012), Accommodation of transpressional strain in the Arabia-Eurasia collision zone: new constraints from (U-Th)/He thermochronology in the Alborz mountains.
Landschaften im Wandel : Auswirkungen der globalen Erwärmung auf das Uvs-Nuur-Becken (NW-Mongolei)
(2004)
Ausgehend von einer floristisch-vegetationskundlichen sowie faunistischen Bestandsaufnahme wurde im Planungsgebiet für den Ausbau des Flughafens Schönefeld 1995/96 der ökologische Wert der dort kartierten Biotope als Pflanzenstandort und als Lebensstätte der erhobenen Tierarten beurteilt. Diese Bewertung galt zunächst dem Biotoptyp. Die dafür relevanten Merkmale seiner Ausstattung wurden einzeln und unabhängig voneinander beurteilt. Die Gesamtbeurteilung des typbezogenen Biotopwertes erfolgte auf der Grundlage bedeutender Einzelparameter. Eine Mittelwertbildung wurde nicht vorgenommen. Dagegen wurde die typbezogene Bewertung hinsichtlich der konkreten Ausprägung jeder Kartiereinheit überprüft und gegebenenfalls korrigiert. Hierbei wurden die Ergebnisse unter Berücksichtigung der vorhandenen und beabsichtigten Schutzgebietsausweisungen für den Einzelfall verbal-argumentativ erläutert.
Entwicklung und Gestaltung von Erholungsgebieten in Bergbaufolgelandschaften der Niederlausitz
(1999)
Inhaltliche Schwerpunkte: Erfassung und Bewertung der landschaftlichen Ausstattung, Erkundung landschaftsprägender Prozesse in ihrer raum-zeitlichen Dimension Aktuelle Präferenzen, Nachfrage und Angebot bei Erholung und Tourismus im Umfeld der Sanierungsgebiete, Bestimmung von spezifischen Nutzergruppen im Tourismus- und Freizeitbereich Überlegungen zu einem variablen, informellen Planungsrahmen, der Inhalte der formellen Sanierungspläne umsetzungsfähig macht Aufstellen von Szenarien für die sich entwickelnde Nutzungslandschaft
Soils play a crucial role in biogeochemical cycles as spatially distributed sources and sinks of nutrients. Any spatial patterns depend on soil forming processes, our understanding of which is still limited, especially in regards to tropical rainforests. The objective of our study was to investigate the effects of landscape properties, with an emphasis on the geometry of the land surface, on the spatial heterogeneity of soil chemical properties, and to test the suitability of soil-landscape modeling as an appropriate technique to predict the spatial variability of exchangeable K and Mg in a humid tropical forest in Panama. We used a design-based, stratified sampling scheme to collect soil samples at 108 sites on Barro Colorado Island, Panama. Stratifying variables are lithology, vegetation and topography. Topographic variables were generated from high-resolution digital elevation models with a grid size of 5 m. We took samples from five depths down to I m, and analyzed for total and exchangeable K and Mg. We used simple explorative data analysis techniques to elucidate the importance of lithology for soil total and exchangeable K and Mg. Classification and Regression Trees (CART) were adopted to investigate importance of topography, lithology and vegetation for the spatial distribution of exchangeable K and Mg and with the intention to develop models that regionalize the point observations using digital terrain data as explanatory variables. Our results suggest that topography and vegetation do not control the spatial distribution of the selected soil chemical properties at a landscape scale and lithology is important to some degree. Exchangeable K is distributed equally across the study area indicating that other than landscape processes, e.g. biogeochemical processes, are responsible for its spatial distribution. Lithology contributes to the spatial variation of exchangeable Mg but controlling variables could not be detected. The spatial variation of soil total K and Mg is mainly influenced by lithology.
One of the mechanisms for sudden particle release is a decrease in groundwater salt concentration to below the critical salt concentration (CSC), where repulsion forces between fine particles and matrix surfaces exceed binding forces. In this paper, an attempt was made to determine the CSC with both batch and column experiments. Two types of sediments were tested: (a) homogeneous quartz sand and (b) mineralogically heterogeneous sediment, taken from the Hanford formation in southeast Washington. Stepwise decreasing concentrations of NaNO3 solution were applied until fine particles were released from the sediments and the CSC was determined. Two methods were used to minimize the interference of particle release due to physical forces (shear stress) in the batch experiments: (a) postexperimental correction for mechanical effects, and (b) minimization of shear stress on the sediments during the experiment. CSCs from batch experiments were compared to those obtained from column experiments. It was found that both the amount of particles released and the CSC were an order of magnitude higher for the Hanford sediment than for the Sand. Moreover, particle detachment above the CSC was observed for the Hanford sediment. This suggests that the concept of sharp CSCs could be problematic in natural heterogeneous sediments where fine particles may mobilize at salt concentrations significantly above the CSC, thus unexpectedly enhancing colloid-facilitated transport of contaminants. (C) 2004 Elsevier B.V. All rights reserved