Navegando por Assunto "Solos - Carajás, Serra dos (PA)"

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Acesso aberto (Open Access)
Evolução recente da cobertura de alteração no platô N1-Serra dos Carajás.
(Universidade Federal do Pará, 1995-04-26) MAURITY, Clovis Wagner; KOTSCHOUBEY, Basile; http://lattes.cnpq.br/0096549701457340
Acesso aberto (Open Access)
Tratamento estatístico de dados geoquímicos e sua aplicação ao mapeamento geológico e definição de anomalias geoquímicas no alvo 2 - corpo 4 - Província Mineral de Carajás
(Universidade Federal do Pará, 1982-12-29) MOURA, Candido Augusto Veloso; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
A geochemical soil survey was .carried out in the Alvo 2 - Corpo 4 area of t.he Província Mineral de Carajás (Carajas Mineral Province), Pará, Brazil. Sample elements were collected and analyzed in order to determine, for each one of them, the degree of concentration of the following chemical elements: iron, aluminum, magnesium, manganese, titanium, cobalt, nickel, vanadium, copper, and zinc. Thereafter, multivariate statistical techniques were employed to process the data, that are known as cluster analysis and discriminant analysis. The former algorithm was applied in order to classify the elements of the soil sample into geochemically homogeneous groups that could be correlated with underlying lithologies. A discriminant analysis was then per formed to statiscally evaluate the distinctiveness of groups arrived at, and at the same-time to define those chemical elements which were most determinant throughoot the discriminatory process. Cluster analysis classified the soil sample elements into eight homogeneou groups that are perfectly correlated with underlying rocks. Discriminant analysis showed that results of the cluster are good, and only titanium and zinc do not play an important role in discriminating the groups arrived at. The results obtained show that the multivariate statistical processing of geochemical soil data can be used successfully as a useful tool when mapping the geology of tropical areas. Finally, an examination of Pearson correlation coefficients, scatter diagrams and residuals from regression analysis, allowed to explore the possible effect of hydrous iron and manganese oxides and of clay minerals (extra-mineralization factors), in producing the copper and zinc anomalies revealed by the geochemical soil survey, originally. Concentrations of hydrous iron and manganese ox ides and of clay minerals were correlated with concentrations of iron, manganese and aluminum in the soil. The Pearson correlation coefficients and the scatter diagrams of copper, and then of zinc, with iron manganese and aluminum, as well as the reduced major axis regression line of copper on iron, indicated that high, grades of copper and zinc found in the soil sample of Alvo 2 - Corpo 4 are not affected by the extra-mineralization factors considered. Therefore, it is conclude that it is the sulphide mineralization present in the study area that can be held responsible for those high concentrations of copper and zinc.