Application of morphometry in neotectonic studies at the eastern edge of the Parana Basin, Santa Catarina State, Brazil

摘要

The neotectonic evolution of the eastern edge of the Parana Basin in the Santa Catarina State, Brazil was investigated using field data and detailed morphometric analysis along an east-west section. Analysis included generation of maps of isobase, hydraulic gradients, hypsometry, incision of drainage basins, drainage asymmetry and anomalous morphological features. All these maps generated results that agreed with field data and helped define recent faults in directions close to N-S and E-W, both probably reactivated faults of the Parana Basin and the basement. Geomorphological features identified in topographic maps, possibly related to neotectonism, have a close agreement with our observations in the field. The asymmetry of basins as analysed by the T-Index method proved to be compatible with the influence of a E-W compressive tectonic regime and showed a movement from W to E. Application of the hypsometric integral technique helped establish a correlation between the younger basins with structures trending N-S (± 30°). The N-S faults were related to a compressional stress field (SH_(max)) close to E-W and SH_(min) (stress minimum) around N-S, thereby establishing a tectonic context of structures developed in a transpressive regime. The compressional field was caused by the subduction of the Nazca tectonic plate below the South American plate, whereas the transcurrent component exploited pre-existent E-W structures when the Atlantic Ocean was opening.