A SÉRIE MARICÁ E SUA POSIÇÃO NA COLUNA GEOLÓGICA DO ESTADO DO RIO GRANDE DO SUL(*)

ALCEU FÁBIO BARBOSA

Resumo


In this paper the Author deals with some features of the Maricá series, which occurence area is limited to the Lavras County State of Rio Grande do Sul, Brazil. The main scope of this paper is to bring to light a discussion on the State of Rio Grande do Sul geological column, recently modified by, BEURLEN and assistants. The author's first step was a general picture of the local geology with special reference to the area under discussion, in accordance with the geological column proposed by LEINZ and cooperators in 1941. Great emphasis is done in this study to the Maricá series not only to its tectonic framework but also to its relationships to the Camaquã series, and specially to its chronological position to the Carboniferous and volcanic eruptions of quartz-porphyry, andesite and basalt. In the field the Maricá series bears evidence to have a general and extensive unconformity under the Itararé series, which is witnessed in many outcrops as it is seen in Budó, for instance. On the other hand there is a quite different tectonic style between the Maricá sediments and the fossiliferous Carboniferous ones, as it may be seen in Cerro Formoso. The author leads the discussion to the conclusion that the Maricá series, the Camaquã series, and the andesites and quartzporphyries must not be aged together with the fossiliferous upper sediments of the Itararé series, in the Carboniferous times, because they are positively olders in the geological column, what stands off from BEURLEN'S ideas. Finally the Author concludes that local geological column set by LEINZ and cooperators must be keep on, and for geological mapping special care must be carried in order to appart the Carboniferous sediments from the inferior Marica series.

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