Search results for "Structural basin"
showing 10 items of 292 documents
Monitoring and predicting sediment yield in a small Sicilian basin
2001
Identifying areas of a basin that are most sensitive to erosion have stimulated the study of within–basin variability of the sediment–delivery processes and the use of spatially distributed models. To verify the reliability of a sediment–delivery distributed model applicable at the morphological unit scale (i.e., the area of clearly defined aspect, length, and steepness), experiments were carried out at mean annual and event scales in a small Sicilian basin. A Geographical Information System is briefly presented into which the measurements carried out at the basin outlet (runoff, sediment yield, etc.) and other point and areal information (soil erodibility, digital terrain model, etc.) were…
Assessing soil erosion in a small Sicilian basin by caesium-137 measurements and a simplified mass balance model
2000
Abstract The caesium-137 technique affords both an alternative to conventional measurement methods and an effective quantitative estimate of soil redistribution at the basin scale. Among the available calibration relationships which link the degree of increase or depletion of the 137Cs activity relative to the baseline 137Cs input and sediment yield, the mass balance approach has received increased application for its physical basis. First, the applicability of the refined simplified point-based mass balance (RSPMB) model of Zhang et al. (1999) at the scale of the morphological unit is proposed herein. The 137Cs spatial distribution measured in a small Sicilian basin and the spatial distrib…
Characterisation of submarine groundwater discharge offshore south-eastern Sicily
2005
A complex approach in characterisation of submarine groundwater discharge (SGD) off south-eastern Sicily comprising applications of radioactive and non-radioactive tracers, direct seepage measurements, geophysical surveys and a numerical modelling is presented. SGD fluxes in the Donnalucata boat basin were estimated by direct seepage measurements to be from 4 to 12Ls(-1), which are comparable with the total SGD flux in the basin of 17Ls(-1) obtained from radon measurements. The integrated SGD flux over the Donnalucata coast estimated on the basis of Ra isotopes was around 60m(3)s(-1) per km of the coast. Spatial variations of SGD were observed in the Donnalucata boat basin, the average (222…
δ pattern of dissolved inorganic carbon in a small granitic catchment: the Strengbach case study (Vosges mountains, France)
1999
Abstract The transfers and origins of dissolved inorganic carbon (DIC) were studied for a year in a soil–spring–stream system in the Strengbach catchment, Vosges mountains, France. This 80 ha experimental research basin is located on the eastern side of the mountains, at an altitude ranging from 883 to 1146 m.a.s.l. and is mainly covered by spruce (80%). Brown acid and podzolic soils developed on a granitic basement, and, as a result, the DIC originates solely from CO2 generated by oxidation of soil organic matter. The ( δ 13 C DIC ) in catchment waters is highly variable, from about −22‰ in the springs and piezometers to about −12‰ in the stream at the outlet of the catchment. In the sprin…
Regional flow duration curves for ungauged sites in Sicily
2011
Abstract. Flow duration curves are simple and powerful tools to deal with many hydrological and environmental problems related to water quality assessment, water-use assessment and water allocation. Unfortunately the scarcity of streamflow data enables the use of these instruments only for gauged basins. A regional model is developed here for estimating flow duration curves at ungauged basins in Sicily, Italy. Due to the complex ephemeral behaviour of the examined region, this study distinguishes dry periods, when flows are zero, from wet periods using a three parameters power law to describe the frequency distribution of flows. A large dataset of streamflows has been analysed and the param…
Late Turonian climate variability in the Bohemian Cretaceous Basin – A sclerochronological study of Inoceramus hercules shells from the Úpohlavy quar…
2020
Abstract The δ18O record of well-preserved shells of the inoceramid Inoceramus hercules from the Upohlavy working quarry (Czech Republic) provides an insight into the climate variability in the late Turonian benthic environment of the Bohemian Cretaceous Basin. Similar to modern bivalves, this inoceramid species built its shell near equilibrium with the oxygen isotope value of the ambient water. Due to the nearly year-round shell growth, sequentially sampled δ18O values allowed to estimate the narrowest sub-annual temperatures fluctuations that prevailed during lifetime of the organisms. In accordance with previous studies, reconstructed temperatures suggest colder water conditions (19.0 ± …
First xiphosuran traceway in the middle Muschelkalk facies (Middle Triassic) of the Catalan Basin (NE Iberian Peninsula)
2021
In the last decade, the first ichnoassamblages from the middle Muschelkalk facies (upper Anisian-middle Ladinian) of the Catalan Basin (NE Iberian Peninsula) have been discovered. Herein, the first xiphosuran trace fossils are described from the locality of Penya Rubí, a newly discovered ichnosite from the Catalan Basin. The finding opens a window into peri-Tethys ecosystems with coastal influence. The traceway is referred to the ichnogenus Kouphichnium, a locomotion trace attributed to xiphosurans. The traceway preserves telson grooves and different imprint morphologies from the various appendages. The traceway pattern and arrangement of the different traces suggest a crawling locomotion s…
L'évolution paléoenvironnementale des faunes de poissons du Crétacé supérieur du bassin du Tafilalt et des régions avoisinantes (Sud-Est du Maroc) : …
2001
Abstract A critical revision of published data along with new field data allow to draw up the succession of the fish faunas from the Lower Cenomanian to the Lower Turonian in the Tafilalt basin and surrounding areas (southeast Morocco). The analysis of these faunas shows changes from freshwater to marine palaeoenvironments. The palaeogeographic distribution of some taxa is discussed. It shows that the crossing of strictly freshwater organisms between Africa and South America was likely impossible at the time of the formation of the deposits resting around the Tafilalt basin and named ‘Kem Kem beds’. The Cenomano-Turonian transgression reached the Erfoud–Errachidia carbonate platform from th…
Distribution of Albian clastic deposits in the Benguela basin (Angola): evidence of a Benguela palaeocurrent?
2009
Abstract The Albian clastic Tuenza Formation of the Benguela basin (south Angola) is described and its geographic distribution analysed in detail. From these observations, the existence of an Albian “PalaeoBenguela current” is proposed. This would imply that a marine longshore current reworked the sand transported by palaeorivers and settled it northward along the coast of the young Atlantic Ocean (during the Albian). A parallel between Albian clastic deposits and the modern sediments deposited by the Benguela current is drawn, focusing on the striking resemblance between the two currents, i.e. the actual Benguela current and the Albian marine current, and the associated sedimentary bodies.
Establishing a high-resolution surface sediment chronology with multiple dating methods – Testing 137Cs determination with Nurmijärvi clastic-biogeni…
2017
Abstract The uppermost 50 cm of sediments from the 23 m deep lacustrine basin of Nurmijarvi, a lake in south-central Finland, are composed of the clastic-biogenic type of varves. We use multiple dating methods to render a sediment chronology that is as precise and accurate as possible for future paleoenvironmental research on this high-fidelity sedimentary archive. The 250-year-long varve chronology contains a chronological error of ±2%, as estimated based on repeated varve counts. The varve-based chronology was verified with the vertical distribution of 137Cs by comparing variations in the paleomagnetic relative declination of the surface sediments with instrumental observations and a calc…