The Paraguay Fold Belt in the Serra da Bodoquena and Miranda River Depression, Mato Grosso do Sul

Abstract

The Southern Paraguay Belt is a typical fold-and-thrust belt. Its geological evolution began with a continental riftingprocess, probably at the end of the Cryogenian, evolving into a restricted sea and an extensive marine transgression at theend of the Ediacaran. The fi nal collisional event occurred during the Lower Cambrian, with post-collisional magmatismduring the Upper Cambrian. The Corumbá Group is divided into fi ve formations (Cadiueus, Cerradinho, Bocaina, Tamengoand Guaicurus). The Puga Formation is correlated to the Cerradinho and Cadiueus formations. This stratigraphy can be seeneven in the most deformed parts located in central-eastern area. In the far west of the area, the Corumbá Group is depositedabove an unconformity in the Rio Apa cratonic block. The name Agachi Schists is suggested for the schists located at theeasternmost portion of the area. During the Ediacaran period, whereas, in the east part of the area, the Cuiabá Group wasaffected by deformation, metamorphism and arc-related granites, in the west part of the area, the Tamengo and Guaicurus formations were deposited, probably in a context of foreland basin. Up to three superimposed coaxial folding events are observedassociated with greenschist metamorphism and thrust faults, showing a westward tectonic vergence. WSW - ESE convergence vectorsindicate that the collision with the Rio Apa block was slightly oblique. Changes in metamorphism and structural style can be explainedby the westward migration of the deformational front. The main thrust faults coincide with important basin boundaries, suggesting thatthe listric faults of the rift stage were reactived by them.

Keywords

• Brasiliano
• Mobile belt
• Corumbá Group
• Cuiabá Group
• Neoproterozoic
• Ediacaran