Revision on the lithostratigraphy of the São Roque/Serra do Itaberaba Belt - state of São Paulo

Abstract

A great number of publications on the geology of the São Roque/Serra do Itaberaba Belt (São Paulo State, Brazil) introduce and use diverse lithostratigraphic denominations, creating difficulties to a clear understanding of the geological evolution and lithostratigraphy of the metamorphic belt. This paper seeks an organization of the various nomenclatures and litostratigraphic suggestions for the Belt. A review of theessential publications about the subject is made, including those where the first litostratigraphic denominations were cited. After acomparative and critical analysis of the bibliography and, taking as a basis the geologic map 1:25.000 of the Itaberaba and Pedra Branca inountains, a sepatation of the supracrustal mcks which constitute the Belt in two major litostratigraphic units is proposed: Serra do Itaberaba Group and São Roque Group. The Serra do Itaberaba Group is subdivided into the Morro da Pedra Preta, Nhanguçu and Pirucaia formations. The Morro da Pedra Preta Fotmation is a volcano-sedimentary sequence, and is basal to the Nhanguçu, mainly composed by andalusite-bearing and manganesiferous metapelites, with some smalllenses of carbonatic and calc-silicatic rocks. The Pirucaia Formation is predominantly quariizitic and probably represents lhe lithoracies deposited in the margins of the two other formations, partieularly oft he Nhanguçu Formation. In the São Roque Group the following formations can be recognized: Piragibu, composed by metapelites with few lenses of metaconglomerates and metavolcanics; Pirapora do Bom Jesus, essentialy volcanic/volcaniclastic, with bioherms and calc-phyllites; Estrada dos Romeiros, with rhythmic metapelites and metarenites and, finally, the metarenitic arcosean . Boturuna Formation. The Piragibu Formation is basal in the area of the Itaberaba, Pedra Branca and Morro Doce Mountains. In the Pirapora Synclinorium, the homonymic formation is basal to the Estrada dos Romeiros Formation, which corresponds to the more distal facies of the Piragibu Formation, covered by the Boturuna Formation.