Paleomagnetic analysis of Rio Claro Formation

• Grant number: 17/09248-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2017
• End date: December 31, 2017
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Giancarlo Scardia
• Grantee: Giovana Oliveira Pimentel
• Host Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

The Rio Claro Formation is a Cenozoic unit deposited on Paleozoic sediments of the Paraná Basin. Located in the geomorphological province of Paulista Peripheral Depression, center-east of São Paulo state, the unit is composed of fluvial origin deposits delimited by topographic, lithologic and structural conditioners. Many authors proposed ages for the Rio Claro Fm. based on correlations with geomorphological and / or structural events that placed the unit in a time period that goes from the Miocene to Pleistocene. The definition of Rio Claro Fm age has scientific importance, because is essential to understand the evolution and configuration of the current landscape, the neotectonic and climatic processes. This unit exemplifies the general difficulty of dating continental deposits when there are no materials that can be dated by radiometric methods or guiding fossils. The great imprecision of Rio Claro Fm age opens two possible solutions based on paleomagnetism. If the age of 745 ka proposed by Ferreira & Caetano-Chang (2008), the only direct dating performed in the unit, is correct, Fm Rio Claro must cross the Brunhes-Matuyama boundary (780 ka) entering the Matuyama chron and perhaps crossing the Subchron Jaramillo (1.07-0.99 Ma). In the case of an older age, the strategy will be to define the Rio Claro Fm virtual geopaleomagnetic pole and compare it with the apparent polar wander path (APWp) of the South American plate (e.g., Besse & Courtillot, 2002). Briefly, the idea proposed here is to apply paleomagnetism to provide a chronological link to the Rio Claro Fm deposits. (AU)