GEOQUÍMICA ISOTÓPICA EM VULCÂNICAS ÁCIDAS DA BACIA DO PARANÁ, E IMPLICAÇÕES GENÉTICAS ASSOCIADAS

M. S. M. MANTOVANI, U. G. CORDANI, A. ROISENBERG

Resumo


Three samples representatives of the acidic volcanism ot the Paraná Basin, collected in lhe States of PR, SC and RS, were dated by Rb-Sr and K-Ar methods. Cbemical analysis classify the three occurrences as belonging to the group enriched in phosphorus, titanium and LIL elements (HPT), oompared to the other (LPT) defined for the Paraná Basin. Mineral isochrons show the cogeneticity of the components, and the resultant Rb-Sr age is systematically higher than the value obtained by K~Ar method in the plagioclase phenocrysts. Sr initial ratio indicates a common source for the three occurrences.

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