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showing 10 items of 4660 documents
Diagenesis of speleothems and its effect on the accuracy of 230 Th/U-ages
2014
Abstract Speleothems can be precisely dated by U-series disequilibrium methods. One basic assumption of the 230Th/U-dating method is that the system remains closed and U and Th isotopes are neither lost nor added after deposition. For stalagmites, this requirement is usually fulfilled due to their protected environment in caves. However, undersaturated drip water may lead to diagenesis of speleothem CaCO3 and altered 230Th/U-ages. Here we present a detailed petrographic investigation using thin sections and 230Th/U-ages of a stalagmite from the Riesenberghohle, northern Germany, which grew during Marine Isotope Stages 5e, c and a. The occurrence of a mosaic fabric in large parts of the stal…
Geochemical characterisation of the alkaline and hyperalkaline groundwater in the Othrys Ophiolite Massif, central Greece
2021
The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to the westernmost of them. In the current study, 33 water samples from cold hyperalkaline and hypothermal (T < 40°C) alkaline springs and 30 gas samples (either dissolved or free) were collected at 17 different sites in and around this wide ophiolite outcrop, aiming to determine the origin of fluids and evidence gas-water-rock interaction processes taking place in the area. Water samples were analysed for their chemical (major ions and trace elements) and isotope (d18O-H2O, d2H-H2O) composition. They can be subdivided into alkaline (pH <11) of both Mg-Ca…
The identity and geographical distribution of Jacobaea vulgaris subsp. gotlandica , supposedly endemic to Gotland and Öland (Sweden)-the importance o…
2009
The identity of Jacobaea vulgaris Gaertn. subsp. gotlandica (Neum.) B. Nord., hitherto considered an endemic to the Swedish islands Oland and Gotland, was investigated using nrITS and trnT-trnL intergenic spacer sequences and a broad sample of species and accessions particularly of J. vulgaris. We found that J. vulgaris subsp. gotlandica is a distinct evolutionary lineage more widespread in Europe than previously thought and may be a southeastern European steppe floristic element with outliers on the large Baltic islands. Our entirely unexpected findings underline the need of multiple intraspecific sampling in species-level phylogenetic studies.
The societal contexts for sound and music computing: Research, education, industry, and socio-culture
2007
Abstract The paper addresses the various contexts that determine the societal framework for research in the field of sound and music computing. Four of these contexts are identified, namely, the research context, the educational context, the industrial context and the socio-cultural context. For each context, the major trends are analysed and summarized as short statements, thus providing a background in which the state-of-the-art and the challenges of sound and music research can be situated.
A new subspecies of Rosmarinus officinalis (Lamiaceae) from the eastern sector of the Iberian Peninsula
2014
Rosmarinus officinalis subsp. valentinus (Lamiaceae) is described as a new subspecies in the flora of the Iberian Peninsula. The diagnostic characters for the subsp. valentinus include several morphological differences, mainly based on a distinctly prostrate habit, a reduced leaf size, smaller calyx and corolla, and white flower. A comparative table with diagnostic morphological features to distinguish among the three subspecies of the R. officinalis is provided. Habitat, ecology, greenhouse cultivation and phenolic profile are also considered.
Response of macrophyte communities and status metrics to natural gradients and land use in boreal lakes
2012
Abstract We studied the relations of aquatic macrophyte communities, ecological quality metrics and water quality to lake characteristics and to land use defined at multiple spatial scales (three lake marginal zones (LMZs) of contrasting width and the whole topographic catchment) in 110 boreal lakes in Finland using ordination and generalised additive modelling. Variation in macrophyte community composition of our lakes was related to water quality, land use, latitude and lake morphology. Relationships of macrophyte status metrics – the proportion of type-specific species (TT50), Percent Model Affinity (PMA) and Trophic Index (TI) – to land use were scale dependent. The proportion of agricu…
Erosion and stabilisation sequences in relation to base level changes in the El Cautivo badlands, SE Spain
2008
Abstract The complex multiple-age badlands at El Cautivo are cut in upper Miocene marls of the uplifted and dissected Tabernas Basin, Almeria, in semi-arid SE Spain. Previous work identified six episodes of erosion and subsequent stabilisation, with ages ranging from the late Pleistocene to the present day. This paper uses newly-acquired digital elevation models, orthorectified aerial photographs, and field survey data to illustrate the development sequence of a series of gullies which drain into the Rambla de Tabernas. Changing drainage directions and phases of incision and stabilisation are related to the filling and subsequent dissection of the Tabernas lower lake sediments, differential…
Discussion on 'Estimating depth-averaged velocities in rough channels'
2002
In this short communication the four estimate criteria of the depth-averaged local velocity proposed by Byrd et al. (Earth Surface Processes and Landforms, 2000, Vol. 25, pp. 167-173) are compared both with the three-point method of Bathurst and with the average velocity obtained by integrating the velocity profile (FPa2) suggested by Ferro and Pecoraro (Water Resources Research, 2000, vol. 36, pp. 2761-2770). The comparison was carried out using 84 velocity profiles measured by an acoustic Doppler velocimeter in a rectangular flume with a gravel bed. Copyright © 2002 John Wiley and Sons, Ltd.
Drumlins and related glaciogenic landforms of the Madliena Tilted plain, Central Latvian Lowland
2012
This paper presents new results on the morphometry and spatial distribution of the glaciogenic landforms and ice flow directions in the Madliena Tilted Plain that occupies the eastern part of the Central Latvian Lowland. Landforms were investigated by using topographic maps at scales of 1:25 000 and 1:10 000. There were identified and mapped 1461 glaciogenic landforms such as drumlins, end moraine ridges, eskers, ribbed moraines, marginal ridges, lateral shear margin moraines and recessional formations. Particular attention is given to the morphometry, spatial distribution, and the internal structure of drumlins. Glacial landscape of the study area was formed by the Zemgale ice lobe in cour…
Deglaciation history of Latvia
2004
This chapter discusses the deglaciation history of Latvia. The earliest deglaciation schemes of Latvia were based entirely on morphological features. The spatial distribution of glacial landforms, with crests transverse to glacier movement combined with radiocarbon dates and biostratigraphical evidence, have provided the principal data for the reconstruction of the deglaciation process from the mid-1960s until the present. A deglaciation history should be based on multiple criteria. Attention should be paid to the identification of ice-marginal formations, and complex studies are also needed, including the investigation of the spatial distribution and internal composition of subglacial land…