Absolute luminescence dating of the Alto Rio Paraná Allogroup - São Paulo, Paraná and Mato Grosso do Sul

Abstract

The Alto Rio Paraná Allogroup is a Quaternary stratigraphic unit of the Upper Paraná River Hydrographic Basin (São Paulo, Paraná and Mato Grosso do Sul), constituted by the Paranavaí Alloformation (colluvial deposits) and the Paraná Alloformation (alluvial deposits). These deposits have been dated by Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) methods, which indicated absolute depositional ages between 6,200±750 and 980,000±100,000 years B.P. for the Paranavaí Alloformation, and 14,000±2,000 and 240,000±30,000 years B.P. for the Paraná Alloformation. These ages show that the Upper Paraná River was active during the last million years in modeling relief by both constructive (terraces) and destructive (dissection) processes. These events are probably related to palaeoclimatic changes and/or neotectonic activities, which gave rise to base level fluctuations and, consequently, transformations of topographic relief.