Guabirotuba Formation
The Guabirotuba Formation is a late Middle Eocene geologic formation of the Curitiba Basin in Paraná, Brazil. The formation crops out in and around the city of Curitiba and comprises mudstones and sandstones deposited in a fluvial floodplain environment.
The thick formation has provided several fossil mammals, and indeterminate side-neck turtle fossils, and indeterminate terror bird fossils. A newly described species of Cingulata; Proeocoleophorus carlinii was also found in the formation.
Description
The Guabirotuba Formation was first described by and in 1962. The geologists named the formation after, a neighborhood of Curitiba, the capital of Paraná State. The formation is the lowermost sedimentary unit in the Curitiba Basin, a Cenozoic continental rift basin of southeastern Brazil, overlying Cambrian basement comprising gneisses, amphibolites and migmatites of the Atuba Complex and metasediments of the Açungui Group.Lithologies
The thick Guabirotuba Formation comprises a basal conglomerate, mudstones and sandstones, deposited in a fluvial floodplain environment.The sediments of the formation contain between 0.24 and 2.61% heavy minerals. Heavy mineral analysis on the very abundant zircons, abundant epidote, common tourmaline and kyanite and rare rutile has provided insight in the paleocurrents of the fluvial environment, with predominant flow directions towards the northwest and east-northeast.