DEGEO - Departamento de Geologia

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8

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2006 - 20072

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Autor: search.filters.author.Braucher, RégisAssunto: search.filters.subject.Quadrilátero Ferrífero

Resultados da Pesquisa

Agora exibindo 1 - 2 de 2
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    Study of the erosion rates in the upper Maracujá Basin (Quadrilátero Ferrífero/MG, Brazil) by the in situ produced cosmogenic 10Be method.
    (2007) Salgado, André Augusto Rodrigues; Varajão, César Augusto Chicarino; Colin, Fabrice; Braucher, Régis; Varajão, Angélica Fortes Drummond Chicarino; Nalini Júnior, Hermínio Arias
    The present work quantifies the erosive processes in the two main substrates (schists–phyllites and granites–gneisses) of the upper Maracujá Basin in the Quadrilátero Ferrífero/MG, Brazil, a region of semi-humid tropical climate. Two measuring methods of concentration were used: (i) in situ produced 10Be in quartz veins (surface erosion rates) and (ii) 10Be in fluvial sediments (basin erosion rates). The results confirm that (i) erosion tends to be more aggressive close to the headwaters than in the lower parts of the basin and (ii) the region is now affected by dissection.
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    Denudation rates of the Quadrilátero Ferrífero (Minas Gerais, Brazil) : preliminary results from measurements of solute fluxes in rivers and in situ-produced cosmogenic 10Be.
    (2006) Salgado, André Augusto Rodrigues; Braucher, Régis; Colin, Fabrice; Nalini Júnior, Hermínio Arias; Varajão, Angélica Fortes Drummond Chicarino; Varajão, César Augusto Chicarino
    This paper investigates the denudation rates in the Quadrila´tero Ferrı´fero, Minas Gerais State (Brazil). The aim is to compare chemical weathering rates from measurements of solute fluxes in rivers and long-term mean erosion rates deduced from in situproduced cosmogenic 10Be concentrations measured in fluvial sediments. Both water samples and sediments were collected in fifteen stations (checkpoints) located in four hydrographic basins with low anthropogenic perturbations. Depending of the type of substratum, three degrees of chemical denudation rates from water samples are observed: (i) high rates in marbles; (ii) medium rates in schists, phyllites, granites, gneisses and migmatites; (iii) low rates in quartzites and itabirites. Preliminary results of long-term erosion rates deduced from in situ-produced 10Be are comparable with those of chemical rates.