Thrust sequence and syntectonic sedimentation in a piggy-back basin: the Oligo-Aquitanian Mula–Pliego Basin (Internal Betic Zone, SE Spain)
The Oligo-Aquitanian deposits of the Mula–Pliego basin consist of a marine carbonate platform assemblage (bottom), transitioning into a turbidite wedge (top). This evolution was controlled by tectonics in a piggy-back basin by means of three main mechanisms: first, a flexural tectonic event created the basin; later on, blind-fault-propagation folds deformed it progressively from south to north; finally a tectonic event destroyed the basin. To cite this article: M. Martin-Martin, A. Martin-Algarra, C. R. Geoscience 334 (2002) 363–370.
Realms of Subsidence
Abstract In this review, three major basin families are differentiated: 1. Basins on rigid lithosphere and not associated with the formation of megasutures. These include rifts, Atlantic-type margins, and cratonic basins. 2. Perisutural basins on rigid lithosphere and associated with the formation of megasutures (e.g., compressional zones that encompass all deformational, igneous, and metamorphic products of a large orogenic cycle). Deep-sea trenches are perisutural basins associated with Benioff or B-subduction zones. Foredeeps are perisutural basins that are associated with and adjacent to Ampferer or A-subduction zones (e.g., zones where limited amounts of continental lithosphere are subducted). 3. Episutural basins within a megasuture. These include forearc basins, backarc basins, and basins that are related to the superposition of megashear systems on megasutures. Basins on rigid lithosphere and certain episutural basins (such as backarc basins) are frequently initiated by thermally controlled rifting processes. Whether the thermal events lead to lithospheric uplift and attenuation, or whether they are themselves the consequence of lithospheric stretching remains to be evaluated for each basin class. Subsidence in these basins may be further modified by sediment loading, subcrustal flow, and density changes in the lower crust and mantle. Perisutural basins of the deep-sea trench and foredeep type are probably due to lithospheric bending modified by loading with thrust sheets and folds associated with mountain-building processes, and by filling with sediments derived from the adjacent mountains.
Frequency distributions of the mixing height over an urban area from SODAR data
The height of the mixing-layer (MLH) is an important parameter in the assessment of the dilution of primarily emitted or secondarily formed air pollutants in the atmospheric boundary-layer. A continuous measurement of MLH is possible only by remote sensing. Here, 17 months of SODAR data have been analysed automatically to derive the MLH over the city of Hannover in Northern Germany. In contrast to earlier studies the MLH has been determined from vertical profiles of the acoustic backscatter intensity and from the variance of the vertical velocity component. The results are presented in form of monthly frequency distributions and mean daily courses of MLH. These statistical evaluations of MLH show a clear annual course and interannual variability. The study shows the possibility to derive meaningful climatological information from long-term SODAR measurements for air quality issues.