Search results for "Luvia"
showing 10 items of 223 documents
Il risarcimento del danno ambientale da inquinamento: modelli di analisi geochimica valutazione monetaria di un eco-socio-sistema fluviale in Sicilia.
2014
Utilisation des minéraux lourds comme indicateurs de paléoplacers alluvionnaires diamantifères en République centrafricaine (RCA). Use of heavy miner…
2001
International audience; Le diamant est la première ressource minérale de la République Centrafricaine (RCA). Exclusivement exploité par plusieurs sociétés minières avant 1960, il l'est maintenant de façon artisanale. Avec une production annuelle d'envi-ron 500 000 carats (1 carat = 0,2 g), la RCA est le dixième producteur de diamant (en valeur) dans le monde. Les diamants gemmes (pierres de joaillerie, taillables) représentent 70 à 75 % de la production. Deux principales zones diamantifères présentant une relation spatiale évidente existent en RCA : la Formation de Mouka-Ouadda à l'Est et celle de Carnot à l'Ouest. Ces formations, représentant les 'roches magasins' du diamant, constituent a…
Les relations entre les sociétés et le fleuve Loire depuis le Moyen-Âge
2008
L'objectif de cet article est la compréhension des inter-relations entre un système fluvial – la Loire – et les sociétés riveraines. Souvent qualifiée de « dernier fleuve sauvage d'Europe » et réputée pour son patrimoine historique et écologique, la Loire a cependant subi depuis des siècles des interventions et aménagements variés. Les recherches interdisciplinaires récentes mettent en évidence l'importance des actions anthropiques sur le fonctionnement hydro-morphodynamique et écologique du fleuve depuis le Moyen-Âge. Les formes fluviales et les paysages actuels expriment des réajustements du fleuve à l'évolution de facteurs hydro-climatiques et socio-économiques qui jouent sur des pas de …
Elemental contamination of an open-pit mining area in the Peruvian Andes
2014
New technologies and higher prices of raw materials have promoted the expansion of mining activity throughout the world; if not properly regulated, this activity can lead to contamination of the local and regional environ- ment. The city of Cerro de Pasco is located close to a large open-pit mine and in recent years, several reports have pro- vided evidence of environmental contamination and related health problems. The aim of this paper is to evaluate the contamination in fluvial water, sediments and biological fluids from this area. The collective results show elevated metal and metalloid concentrations in rivers and sediments, especially in the areas downstream of the mine. For instance,…
Predicting the equilibrium bed slope in natural streams using a stochastic model for incipient sediment motion
2011
Upper Miocene siliciclastic depositional systems in the central-eastern Sicily basins
2014
Geophysical investigations in the Flumendosa River Delta, Sardinia (Italy) — Seismic reflection imaging
2006
A geophysical investigation that included seismic-reflection surveying and time-domain electromagnetics (EM) was carried out in the Flumendosa River Delta plain in southeastern Sardinia, Italy. The objective was to improve knowledge of geologic and hydrogeologic controls on a highly productive aquifer hosted in thick Quaternary deposits and known to be affected by an extensive saltwater intrusion. The seismic reflection survey, whose results are reported here, aimed to image the Paleozoic bedrock topography and to obtain detailed structural and stratigraphic information on the sequence of largely fluvial sediments extending from the surface down to bedrock. The survey consisted of two inli…
Late Quaternary slip rates for the southern Elsinore fault in the Coyote Mountains, southern California from analysis of alluvial fan landforms and c…
2019
Abstract Offset alluvial fans along the Elsinore fault in the south-central Coyote Mountains were studied to resolve an average late Quaternary slip rate for this major western strand of the San Andreas fault system in southern California. Alluvial fans and their offsets were mapped using high-resolution DEMs combined with field observations of fan-surface morphology and the character of the soils developed in each fan remnant. Clast assemblage data was used to determine the source of each alluvial fan upstream of the fault, and U-series dating of pedogenic carbonate was used to estimate minimum ages of the alluvial fan surfaces. Forty U-Th dates on pedogenic carbonate confirm the utility o…
Stratigraphy of the Neoproterozoic Damara Sequence in northwest Namibia: Slope to basin sub-marine mass-transport deposits and olistolith fields
2016
Abstract The Neoproterozoic Damara Sequence (>1000 m thick) is composed of siliciclastic and carbonate rocks that crop out in the Damara Belt, Namibia. In Damaraland (including the Vrede, Bethanis, Austerlitz and Toekoms farms), these rocks were deformed and metamorphosed under greenschist facies (biotite zone) conditions during the Damara Orogeny. The stratigraphy and paleoenvironments of the Damara Sequence rocks are debated by the scientific community. We use field data, including detailed 1:25,000 geological mapping, elaboration of stratigraphic profiles and observation of preserved primary structures, textures and composition, to identify lithofacies and lithofacies associations, and t…
Modeling of wind gap formation and development of sedimentary basins during fold growth: application to the Zagros Fold Belt, Iran
2016
Mountain building and landscape evolution are controlled by interactions between river dynamics and tectonic forces. Such interactions have been extensively studied, however a quantitative evaluation of tectonic/geomorphic feedbacks, which is imperative for understanding sediments routing within orogens and fold-and-thrust belts, remains to be undertaken. Here, we employ numerical simulations to assess the conditions of uplift and river incision necessary to deflect an antecedent drainage network during the growth of one, or several, folds. We propose that a partitioning of the river network into internal (endorheic) and longitudinal drainage arises as a result of lithological differences w…