A SEDIMENTAÇÃO DO GRUPO PASSA DOIS (EXCLUSIVE FORMAÇÃO IRATI): UM MODELO GEOMÓRFICO

Abstract

Regional investigation of the Passa Dois Group of the Paraná Basin, excluded Irati Formation using outcrop and subsurface data indicates three principal depositional systems: (1) a high destructive tide dominated delta system designated Serra do Espigão Delta System; (2) the Corumbatai tidal flat System developed in the northeastern of São Paulo State: and (3) the Serra Alta epeineritic shelf System. The Serra do Espigão Delta System is te dominant element in the Santa Catarina and Paraná States and comprises several deltas developed throughout the Upper Permian. Vertical sequence grades upward from Terezina prodelta muds through Serrinha delta front sands into fluvial sands and muds of the Morro Pelado delta plain. Such succession reflects regression and progradation of the system. Sediments were derived from South of Mato Grosso State carried by low gradient retilineous rivers. The deltas prograded from West to East over a shallow epicontinental sea opened at East in which was developed the muds of the extensive Serra Alta Shelf System. Prograding from north to south into the furthest end of the Serra Alta gulf a tidal flat was developed, behind of the Serra do Espigão deltas, supplied by longshore drift of sediments from the delta system. Principal features of the main depositional systems are shown in strike and dip stratigraphic sections and in isolith and distribution maps. These illustrate the relationship of the major systems and their constituent facies and also define the sedimentation geomorphic model of the Passa Dois Group.