Probable Geological Significance of the OSL (Optically Stimulated Luminescence) Ages of the Itaquaquecetuba Formation, SP

Abstract

The Itaquaquecetuba Formation can be considered as relatively well-known from a paleontological viewpoint. Itsfossil content, which is very rich and represented by plants (tree trunks, seeds and leaves) and palynomorphs, has beenstudied in detail, allowing several authors to suggest different ages and depositional conditions for this unit in terms ofpaleoclimate 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 depositionalpaleoclimate and paleoenvironment. More recently, OSL (Optically Stimulated Luminescence) depositional ages between47,000 ± 6,000 and 89,000 ± 12,000 years were obtained from samples of sands from the Itaquareia sand pit located in thecity of Itaquaquecetuba (São Paulo state). These ages correspond to the Pleistocene (Quaternary) and are correlatable withthe time of the Wisconsin Glaciation in North America. Considering these new data and some stratigraphic aspects whichwere unknown before this study, great part of the Itaquaquecetuba Formation, which outcrops in the Itaquareia sand pit, ishere interpreted as a Quaternary fluvial channel deposit.

Keywords

• Quaternary
• Paleogene
• Itaquaquecetuba Formation
• São Paulo basin
• OSL age
• Fluvial deposits