40Ar/39Ar geochronology in feldspars and manganese oxides: Thermochronological reconstruction and relief evolution in Southern Brasília Orogen

• Grant number: 24/01341-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: December 01, 2024
• End date: July 31, 2027
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Fabiano Tomazini da Conceição
• Grantee: Davi Diorio Parrotti
• Host Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

Termochronology is a study based on thermal evolution history of rocks using the thermal history of minerals. Thereby, the cooling history of geologic frameworks denudacional processes can be obtained. Additionally, the 40Ar/39Ar geochronology of weathering allows to determine the ages at which fresh rocks reach Earth's surface, as well as to clarify the paleoclimatic conditions and evolution of relief in the region to be studied. The Southeast Brazilian Orogen (SOB) comprises an Ediacaran orogenic belt created during the collision between the Magmatic Arc of the Paranapanema Craton and the Passive Margin of the São Francisco Craton. Associated with the crystalline basement in SOB, there are several supergene manganese deposits, which were produced from the Chemical weathering of gondites of the Itapira Group. This research aims to use 40Ar/39Ar geochronology in K-feldspars and manganese oxides for thermochronological reconstruction and relief evolution in SOB. For this will be dated crystals of K-feldspar, to obtain its crystallization age, alongside to using multidomain diffusion modeling of Ar isotope data acquired during 40Ar/39Ar dating to trace the cooling history of the crystalline basement rocks in SOB. The 40Ar/39Ar ages of the Mn supergene minerals will allow to understand the weathering historic, paleoclimatic conditions and landscape evolution in the SOB. Thus, the combination of thermochronological methods applied to crustal rocks and weathering dating will allow an advance in the knowledge of the evolution of SOB and the geodynamic processes associated with this region.