Castiglione (Oletta,Corsica): relationships between phenomena of calcification and tectonic fossiliferous fracture dating

Abstract

Six cavities have been discovered in the Oletta massif. The massif, today constitued of Schistes lustrés with several metres of calcareous layers above them, has undergone intense fracturing. The networks of cavities are organised along north-south and subequatorial directions, and form a narrow bayonnet-network. All the elements in the galleries appear to be karstic: stalagmites, stalactites and calcitic deposits along the walls; but no trace of dissolution or excavation was found. Thus, the origin of the galleries is only tectonic, while the calcitic deposits result from the dissolution of the old, thick calcareous layers above, which are no longer present. The thickness and the volume of the calcitic deposits, which is variable depending on the galleries, indicates the chronology of the different tectonic periods which have fractured the massif. Five tectonic and successsive events have been detected. Calcitic datings confirm the timing of successional fracturing, indicating also the variable age of the fossiliferous Middle Pleistocene deposits found in these cavities. © 1999 Éditions scientifiques et médicales Elsevier SAS     

Diet of fishes in a detritus-based sandy lowland brook

To assess the trophic relationships of consumers in a sandy lowland brook (Ladberger Mühlenbach, Northrhine-Westphalia, Germany) the fish as well as the benthic communities were sampled monthly over half a year. Analysis of stomach contents of the fishes revealed two different feeding types: detritivores (including only Cyprinidae; foremost roach, Rutilus rutilus and Prussian carp, Carassius auratus gibelio) and benthivores (mostly stone loach, Barbatula barbatula and three-spined stickleback, Gasterosteus aculeatus). The detritivores mainly foraged on detritus, but also benthic invertebrates were found in their stomachs. This latter prey (especially some Trichoptera and Coleoptera, which were selected with a high preference) is strongly associated to hard substrates, only present in the brook as coarse detritus. Benthivore fishes only foraged on benthic invertebrates, mostly Gammaridae and Chironomidae, which were the most dominant elements of the macrozoobenthos. Niche overlap between these two foraging groups was very low, while the within-group overlap was rather high. As food could not be shown to be a limiting factor, a direct competition for food between most of these species in this brook seems most unlikely.     

Combined object-based classification and manual interpretation–synergies for a quantitative assessment of parcels and biotopes

Recent technical advances in remote sensing data capture and spatial resolution lead to a widening gap between increasing data availability on the one hand and insufficient methodology for semi-automated image data processing and interpretation on the other hand. At the interface of GIS and remote sensing, object-based image analysis methodologies are one possible approach to close this gap. With this, methods from either side are integrated to use both the capabilities of information extraction from image data and the power to perform spatial analysis on derived polygon data. However, dealing with image objects from various sources and in different scales implies combining data with inconsistent boundaries. A landscape interpretation support tool (LIST) is introduced which seeks to investigate and quantify spatial relationships among image objects stemming from different sources by using the concept of spatial coincidence. Moreover, considering different categories of object fate, LIST enables a change categorization for each polygon of a time series of classifications. The application of LIST is illustrated by two case-studies, using Landsat TM and ETM as well as CIR aerial photographs: the first showing how the tool is used to perform object quantification and change analysis; the latter demonstrating how superior aggregation capabilities of the human brain can be combined with the fine spatial segmentation and classification. Possible fields of application are identified and limitations of the approach are discussed.     

Landscape care paradoxes: Swedish landscape care arrangements in a European context

Contemporary European agriculture has a number of additional aims beside of food production, such as safeguarding environmental services and conservation values. Substantial efforts at official levels are aimed towards sustainable development but also towards maintaining values of what may be termed vanishing landscapes. Selected areas and landscape features are set aside for protection or restoration. Individual efforts of this type have a long history in Sweden, and the issue has recently received increased attention, primarily due to more ambitious government goals concerning biodiversity conservation and Sweden’s ratification of the European Landscape Convention. This has resulted in an increased scientific and official interest in vanishing values in the rural landscape, where parts of Eastern Europe, such as the Maramures district in Romania, have been used as model examples of land use regimes which in the past was common in Sweden. In this context, the dilemma of romanticizing peasants’ use of land is highlighted and discussed more than has hitherto been done. This paper sheds light on some paradoxes inherent in official policies in relation to land use practices concerning the management of rural landscapes in Sweden, and relates the Swedish situation to a contrasting example of landscape practice in Romania. We discuss the concept of landscape care in relation to the construction and perception of landscape values and valuable landscapes through the lenses of rural realities and official policies. When Swedish authorities engage in the promotion of landscape care, they tend to work with slices of land, specific predefined values and individual farmers, and they often disregard the need to treat the landscape as a socio-ecological complex dynamic in space and time. We discuss how environmental policy generally could be improved through the adoption of a more inclusive and flexible approach towards aiding the different aims inherent in multifunctional rural landscapes.     

Ecological consequences of land use change: Forest structure and regeneration across the forest-grassland ecotone in mountain pastures in Nepal

The ecotone, the spatial transition zone between two vegetation communities, is claimed to have more species than the adjoining communities. However, empirical studies do not always confirm higher richness at the ecotone. The ecotone position and structure are dynamic over time and space and it is driven by the changes in climate, land use or their interaction. In this context, we assessed the forest- grassland ecotone of temperate mountains in central Nepal by i） comparing species composition and richness across the ecotone, ii） analyzing if the forestgrassland ecotone is shifting towards the grassland center by colonizing them with trees, and iii） discussing the consequence of changed disturbance regime in the dynamics of this ecotone and the surrounding grasslands. We analyzed vegetation data sampled from belt transects laid across the forest- grassland ecotone in semi-natural grassland patches. Vegetation data consisting of species richness and composition, and size structure and regeneration of the two most dominant tree species, namely Rhododendron arboreum and Abies spectabilis, from the transects, were used to analyze the trend of the forest-grassland ecotone. Forest and grasslands were different in terms of floristic composition and diversity. Vascular plant speciesrichness linearly increased while moving from forest interior to grassland center. Spatial pattern of tree size structure and regeneration infers that forest boundary is advancing towards the grasslands at the expense of the grassland area, and tree establishment in the grasslands is part of a suceessional process. Temporally, tree establishment in grasslands started following the gradual decline in disturbance. We argue that local processes in terms of changed land use may best explain the phenomenon of ecotone shift and consequent forest expansion in these grasslands. We underpin the need for further research on the mechanism, rate and spatial extent of ecotone shift by using advaneed tools to understand the process indepth.     

Kaolinitic meniscus bridges as an indicator of early diagenesis in Nubian sandstones, Sinai, Egypt

Characteristic meniscus geometries formed by kaolinitic infiltration are observed in Nubian sandstones collected on the western coast of the Sinai Peninsula (Egypt). Based on petrographic and scanning electron microscope (SEM) observations, the kaolinite forming the menisci consists of mixed-size discrete platelets that gather into the corners around the framework grain-to-grain contacts. Specifically, the internal fabric of menisci indicates a general organizing trend from (1) the centre, where the platelets coat the framework grains; (2) to the peripheral zone, where they are oriented tangentially to grain surfaces; (3) to the pore linings with curvatures that are consistent with theoretical considerations of air–water interfaces. This typical arrangement suggests a detrital origin of kaolinite platelets by mechanical infiltration into sediments lying above the tablewater, in vadose conditions. This type of clay cementation occurring during early diagenesis can prevent (delay) deep burial diagenetic processes and therefore preserve excellent reservoir properties.     

Determination of Rare Earth Elements, Y, Th, Zr, Hf, Nb and Ta in Geological Reference Materials G-2, G-3, SCo-1 and WGB-1 by Sodium Peroxide Sintering and Inductively Coupled Plasma-Mass Spectrometry

Data are reported for rare earth elements (REE), Y, Th, Zr, Hf, Nb and Ta in four geological reference materials using sodium peroxide (Na₂O₂) sintering and inductively coupled plasma-mass spectrometry. The described procedure was used by students during their thesis work. A compilation of their reference material data acquired over one year of laboratory work demonstrates the ease and reliability of the method and the high reproducibility of the analytical results. Relative standard deviations of up to thirty six measurements of one reference material were lower than 5% for Y and the REE. Reproduciblities of Zr, Hf, Nb, Ta and Th were higher at between 5% and 10%, and can be attributed to the inhomogeneous distribution of zircon and other trace mineral phases and uncorrected drift effects. The concentration data are compared to reference and literature values and demonstrate that the procedure is also accurate. New data on G-3 show some systematic deviations from G-2, which are statistically significant.     

Gendered labour arrangements in Switzerland: Structures, cultures, meanings: statistical evidence and biographical narratives

In this paper we explore the role of culture in the reproduction of gendered labour arrangements. Using Switzerland as an example, we first analyse statistical data on paid and unpaid labour. We look at differences between women and men, but also between different types of regions. Patterns emerge to support our hypothesis that beyond structures of economic opportunity, economic cycles and welfare state provisions, local (gender) culture might explain some of the particularities of gendered labour arrangements. The argument is reinforced by data on regional voting patterns in a recent referendum on the issue of maternity leave. In the second part, we further explore these issues by looking at a particular place and re-telling work-life-stories that show how two women navigate between different working culture environments in accordance with their life-cycle needs and individual ideas and values. Finally, we discuss issues of scale and methodology and reflect on the significance of varying local working environments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Morphological and ecological parallels between sublittoral and abyssal foraminiferal species in the NE Atlantic: a comparison of Stainforthia fusiformis and Stainforthia sp.

Dead specimens of a minute fusiform rotaliid foraminifer are common in the 28–63 μm fraction of multiple corer samples from a 4850 m-deep site on the Porcupine Abyssal Plain (PAP). Their test morphology is remarkably similar to small specimens of Stainforthia fusiformis (Williamson, 1858), a species which is well known from coastal settings (intertidal to outer shelf) around NW Europe and North America. A detailed comparison of the PAP form with typical individuals of S. fusiformis from Norwegian waters (55–203 m depth), however, reveals slight but consistent morphological differences. The PAP specimens are smaller (test length 40–140 μm) than those from Norway (test length 80–380 μm), the chambers tend to be rather less elongate, the density of pores in the test wall is much lower, and there are differences in apertural features. We therefore conclude that the diminutive abyssal form is a distinct species, here referred to as Stainforthia sp. This interpretation is consistent with increasing evidence for genetic differentiation in deep-sea organisms, particularly along bathymetric gradients. Stainforthia sp. was previously illustrated by Pawlowski as Fursenkoina sp. and appears to be widespread and abundant in the abyssal North Atlantic (>4000 m depth). Stainforthia fusiformis, on the other hand, is most abundant in continental shelf and coastal settings. It extends onto the continental slope in the North Atlantic but has not been reported reliably from depths greater than about 2500 m.We suggest that the striking morphological convergence between these two species reflects the adoption of similar ecological strategies in widely separated habitats. Both are enrichment opportunists, a life-style which may explain the rather broad bathymetric range of Stainforthia fusiformis. This is a dominant species in organically-enriched and sometimes extremely oxygen-depleted environments on the continental shelf, and is a rapid coloniser of formerly azoic habitats. Live specimens of the abyssal form are typically found embedded within phytodetrital aggregates (organic material derived from primary production in the euphotic zone). It is presumably the availability of these organic-rich microhabitats, which enables this species to survive in the otherwise oligotrophic deep sea.