CONTRIBUIÇÃO À GEOLOGIA DO PRÉ-CAMBRIANO DA PORÇÃO CENTRAL DE GOIÁS

ONILDO JOÃO MARINI, REINHARDT ADOLFO FUCK, MARCEL AUGUSTE DARDENNE, ÁLVARO DE FARIA

Resumo


Several units of Precambrian rocks have been recognized in Central Goiás. An older group is represented by the Alpine type basic-ultrabasic rocks qf the Cana Brava massif and the granodioritic gneisses of Trombas and Montividiu. These rocks are thought to be Archean. The paragneisses of the Cachoeira das Éguas Formation, the micaschists, the quartzites and the calcschists of the Serra da Mesa Group, as well as the granitic ortogneisses of Serra da Mesa, Serra do Encosto and Serra Dourada, are preliminarily assigned to the Middle Precambrian. The Serra da Mesa Group and the Serra Dourada granite are cut through by several pegmatitic granites of unknown age. The youngest unit is represented by the Paraopeba Formation of the Upper Precambrian Bambuí Group. It comprises phyllite, quartzite and small lenses of calcitic and dolomitic marbles. The major structural features are formed by the Cana Brava massif - a westward basculated overthrusted block - and the braquianticlines of the Serra Dourada, Serra do Encosto and Serra da Mesa. Other important features are the nearly North-South overthrusts near Trombas and between Serra Dourada and Cana Brava.


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