Provável significado geológico de idades LOE (luminescência opticamente estimulada) da formação Itaquaquecetuba, SP

Abstract

The Itaquaquecetuba Formation can be considered as relatively well-known from a paleontological viewpoint. Its fossil content, which is very rich and represented by plants (tree trunks, seeds and leaves) and palynomorphs, has been studied in detail, allowing several authors to suggest different ages and depositional conditions for this unit in terms of paleoclimate and paleoenvironment. At the present state of knowledge, the age assumed of this formation is Paleogene (upper Eocene to lower Oligocene) or Neogene (Miocene), although controversies still remain about the depositional paleoclimate and paleoenvironment. More recently, OSL (Optically Stimulated Luminescence) depositional ages between 47,000 ± 6,000 and 89,000 ± 12,000 years were obtained from samples of sands from the Itaquareia sand pit located in the city of Itaquaquecetuba (São Paulo state). These ages correspond to the Pleistocene (Quaternary) and are correlatable with the time of the Wisconsin Glaciation in North America. Considering these new data and some stratigraphic aspects which were unknown before this study, great part of the Itaquaquecetuba Formation, which outcrops in the Itaquareia sand pit, is here interpreted as a Quaternary fuvial channel deposit.