Brittle deformation in the inner NW Alps: from early orogen-parallel extrusion to late orogen-perpendicular collapse

Internal parts of the Alps have undergone widespread extensional deformation in the course of their Neogene exhumation history. Palaeostress inversion methods are used to map the prevailing stress fields and their evolution through time. Here we present new data from 100 sites with a total of about 2000 faults/striae couples, covering a large portion of the inner north‐western Alps. Palaeostress tensors are mostly extensional, although one‐third of them are transcurrent. The dominant direction of minimum horizontal stress axes (σ3) is in an orogen‐parallel (N30° to N70°) orientation around the bend of the north‐west alpine arc. A comparison between this older (Neogene, post‐metamorphic) stress field with the current stress and strain field determined from seismotectonics and geodesy indicates a change in deformation mode from early orogen‐parallel extrusion to a late and ongoing orogen‐perpendicular spreading.     

Nye kandidater udgået fra Københavns Universitets Geografiske Institut

Danish Journal of Geography: 71–82, 1995.

This paper presents two mega events as tools in the strategic planning of the Copenhagen area. Due to growing inter-metropolitan competition, increasingly offensive and complex means are applied. This demands strong leadership, stable longterm planning and willingness to accept the costs in order to reach the objectives. Marketing versus strategic planning is discussed. The general position of Copenhagen in the European urban system gives perspective to a potential change on the South Scandinavian urban scene. New instruments of strategic planning in Greater Copenhagen are introduced. The competitive level of Copenhagen is analyzed in relation to Stockholm, Berlin and Hamburg. Two examples of mega events are discussed that represent typical elements in urban competition: cultural events and infrastructure improvements. 1) Copenhagen as ‘The cultural City of Europe’ in 1996 represents a temporary mega event. 2) The planned bridge between Copenhagen and the south Swedish city of Malmö, combined with Swedish entrance into EU, opens up for development of the first cross-national integrated large-city region outside the European centre. This is an example of a mega event which will alter the scene permanently. Both events are important issues used in developing a growth strategy for Greater Copenhagen. But neither the cultural city nor the bridge may by themselves guarantee any advantages. It depends upon the ability of local actors to develop and promote the quality of their city. The paper represents a continuation and elaboration on earlier papers, see Matthiessen (1990, 1992) and Andersen &; Jørgensen (1994).     

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Climatic significance of seasonal trace element and stable isotope variations in a modern freshwater tufa

We present a continuous ∼14-yr-long (1985 to 1999) high-resolution record of trace element (Mg, Sr, Ba, U) and stable isotope (δ¹³C, δ¹⁸O) variations in a modern freshwater tufa from northwestern Queensland, Australia. By utilizing the temperature dependence of the δ¹⁸O signal, an accurate chronology was developed for the sampled profile, which allowed a comparison of the chemical records with hydrological and meteorological observations. As a consequence, it was possible to constrain the relevant geochemical processes relating climate variables, such as temperature and precipitation, to their chemical proxies in the tufa record. Temperatures calculated from the Mg concentrations of the tufa samples provide close approximations of average annual water temperature variations. Furthermore, we demonstrate that temporal changes in (Mg/Ca)_water can be estimated using an empirically derived equation relating (Mg/Ca)_water to the (Sr/Ba) ratio measured in the tufa samples. By means of this relationship, it is theoretically possible to determine the (Mg/Ca) ratio of paleowaters, and hence to derive reliable estimates of former water temperatures from the Mg concentrations of fossil tufas from the study area. Sympathetic variations in Sr, Ba, and δ¹³C along the sampled profile record changes in water chemistry, which are most probably caused by variable amounts of calcite precipitation within the vadose zone of the karst aquifer. This process is thought to be markedly subdued whenever the amount of wet-season precipitation exceeds a given threshold. Accordingly, distinct minima in Sr, Ba, and δ¹³C are interpreted to reflect years with above-average rainfall. The pronounced seasonal and annual variability of the U concentration along the profile is thought to primarily record changes in the U flux from the soil to the water table. We suggest that during intensive rain events U is transported to the phreatic zone by complexing organic colloids, giving rise to conspicuous U maxima in the tufa after above-average wet seasons. This study demonstrates the potential of freshwater tufas to provide valuable information on seasonal temperature and rainfall variations. If tufa deposits turn out to be reasonably resistant to secondary processes, combined investigation of speleothems and tufas from the same area could become a promising approach in future research. While speleothems offer continuous records of long-term paleoenvironmental changes, tufas could provide high-resolution time windows into selected periods of the past.     

Reasons for Spatial Microdistributions of Foraminifers in an Intertidal Pool (Northern Adriatic Sea)

Abstract. The spatial microdistribution of foraminifers was tested by the method of quadratic samplings on 2 sample grids in an intertidal pool of the northernmost Adriatic sea. Abundant species of foraminifers exhibit patchy distributions throughout; the distribution-patterns of some species correspond nearly completely. Using statistical methods (regression- and correlation-analyses) correlations to abiotic and biotic factors (water depth, exposure rate, seagrass, benthonic algae) were ascertained. The significant correlations of the foraminiferal frequencies to blue-green algae and/or diatoms enable an interpretation of these connexions as food dependences. Several foraminiferal species seem to have specific diets.