Studies of provenance and volcanic ash fossil beds by the U-Pb (LA-ICP-MS) method in zircon of sedimentary rocks of the Irati Formation, Paraná Basin, São Mateus do Sul-PR

• Grant number: 23/12656-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2024
• End date: December 31, 2024
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Cláudia Regina Passarelli
• Grantee: Lucas Sant' Anna de Carvalho
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 15/03737-0 - The Rio de La Plata Craton and the Western Gondwana Assembly, AP.TEM

Abstract

The margins of the Paleozoic continents experienced several oogenesis episodes due to the collision of the tectonic plates that culminated in the assembly of the Supercontinent Pangea. The regions far from the margins experienced long periods of tectonic stability and large Paleozoic syneclyses were formed in Brazilian territory, among them the Paraná Basin.This project aims to study samples collected from the Irati Formation - Assistance Member of the Paraná Basin in the Petro Six Mine and in outcrop of BR-280, São Mateus city - PR. The Assistance Member of the Irati Formation outcrops in the mine and consisting mainly of shales, siltstones, interbedded with limestone and centimetric levels of volcanic ash. Additionally, in the outcrop of the Irati Formation on the BR-280 highway, tuff levels associated with Mesosaurid remains were sampled.The samples will be prepared aiming at the separation of detrital crystals, from the levels of shales and siltstones, from the volcanogenic zircon crystals from the levels of volcanic ash (Tolsteins).This CI work is related to the first stages of the isotopic analyses that will be performed: U-Pb and Hf analysis in zircon and stable isotopes. The layers of volcanic ash are currently attributed to the Choiyoi magmatism that occurred during the San Rafael Orogeny between the Permian and Lower Triassic. The U-Pb and Lu-Hf methods by the LA-ICP-MS (Laser Ablation - Inductively Coupled Plasma - Mass Spectrometer) technique will be used in volcanogenic zircon crystals present at the volcanic ash levels. The presence of ash levels, as it constitutes an important chronostratigraphic marker, will allow the correlation between layers inside and outside the sedimentary basin, as well as the calibration in the age of Mesosaurus fossils, unprecedented in this area.At carbonate beds, it is intended to perform analysis on C and O stable isotopes for paleoclimate studies in order to provide information on climate change in the Permian. This research, unprecedented in this important outcrop of the Irati Formation of the Paraná Basin, in addition to contributing to the understanding of the evolution of the Basin itself and characterization of the origin of the sediments, aims to offer subsidies to decipher the characteristics of its margins, in addition to the calibration of the age of Mesosaurus fossils.