Estratigrafia do Grupo Bambuí na Serra da Saudade e geologia do depósito fosfático de Cedro do Abaeté, Minas Gerais

Abstract

This work focalizes the Bambuí Group in the Serra da Saudade, including lithostratigraphical units description, geological map, and cross sections drawing. The lithofacies of the Serra da Saudade Formation were described: (1) pelitic-psamitic rhythmites; (2) sandstone with hummocky cross estratification; (3) green glauconitic rhythmite; (4) phosphatic rhythmite; (5) reworked carbonates (calcirudites and calcarenites). The pelitic-sandy sediments of Serra da Saudade Formation were deposited on a platform lying at a mean water depth periodically influenced by storm currents. The Serra da Saudade Formation terrigenous rocks show coarsening upward sequence, are immature sediments and were accumulated in a basin under the influence of collisional processes. The phosphatic rhythmite (phosphoarenite) is situated near Cedro do Abaeté city. It consists of phosphate intraclasts in a microcrystalline grained matrix (micrite), rich in fluorapatite, and addition to detrital quartz, feldspar, muscovite and other minerals.The phosphatization is a syn-diagenetic phase, but with important development of the wavelite by the supergene alteration.