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ASSINATURA ISOTÓPICA Sm-Nd DE SEDIMENTOS EM SUSPENSÃO: IMPLICAÇÕES NA CARACTERIZAÇÃO DA PROVENIÊNCIA DOS SEDIMENTOS DO RIO PARAÍBA DO SUL - SP

2007; Sociedade Brasileira de Geologia; Volume: 35; Issue: 4 Linguagem: Inglês

10.5327/rbg.v35i4.1192

2317-4889

Henrique Llacer Roig, Augusto Pinheiro De Moraes Rego, Elton Luiz Dantas, Paulo Roberto Meneses, Detlef Hans Gert Walde, Simone M. Lc Goia,

Geological and Geochemical Analysis

In order to identify the soure area for the sediments in suspension that contribute to the Funil RJ reservoir, Sm-Nd isotopic Sm-Nd signatures indicates the homogenization of the sediments. Despite this homogeneity, a variation in the space distribution of the Sm-Nd isotopic characteristics is noticed among the sub-basins. This is due to differences in the isotopic signatures of the source rocks and to the variation in the occurence area of each lithology in each sub-basin. The Guaratingueta and Piquete sub-basin show the highest T DM (2.11 e 2.13,Ga respectively) due to the erosion of the Mantiqueira Complex( average T DM 2.9 Ga) and of the Andrelândia Group ( T DM 2,1 Ga) lithologies. The sub-basin Buquira ( T DM 1.76 Ga) and Matos ( T DM 1.78 Ga) are influenced by Complexo Embu.s biotite gneiss (1.56 . 1.67 Ga). Embu.s Complex paragnaiss ( T DM 1.94 Ga) cover 77% of the area of the Uma sub-basin, whose T DM 1.96 Ga. The Paratei ( T DM 1.85 Ga) and divisa ( T DM 1.859 Ga) sub-basin have as their principal source, the sedimentary rocks of the Thaubate Basin ( T DM 1.9 Ga). The mass balance obtained from _ Nd(0) and T DM shows a good correlation between the discharge on the suspended sediments and the estimated average of the existent rocks in each sub-basin. The average values of R sed-rock are 1.08 ( _ Nd(0) ) and 1.02 ( T DM ) suggesting, for the analyzed period, the existence of a steady-state dynamic balance between the weathering and erosion;transportation processes in region of the Paraiba do Sul river basin.