Dating deformational processes in the middle to upper continental crust: A multi-method geochronological investigation in the Southern Brasília Orogen

• Grant number: 23/17675-2
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2024
• End date: September 30, 2027
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Caue Rodrigues Cioffi
• Grantee: Armando Lucas Souza de Oliveira
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The role of deformational processes on the crustal evolution of orogenic regions is often poorly-constrained, especially on what concerns their geochronological record. In the middle to upper continental crust, recrystallization, neocrystallization, and fluid flow may occur below the closure temperatures of important isotopic systems (e.g., Rb-Sr, 40Ar-39Ar), hence potentially influencing on the isotopic exchanges. In this sense, the challenge of dating deformation-related processes can be overcome by combining in situ geochronological methods to meticulous microstructural analysis. The evolution of the Southern Brasília Orogen, SE Brazil, records the Neoproterozoic collision between the São Francisco and Paranapanema paleocontinents. A myriad of geochronological studies has contributed to assess geological processes related to the main orogenic stages, although the late orogenic story remains poorly addressed. The main goal of this research project is to constrain ages and duration of deformational processes that took place during the tectonic evolution of the Southern Brasília Orogen. A multi-method approach is proposed, supported by in situ Rb-Sr dating of micas (LA-ICP-MS/MS) coupled to compositional and microtextural observations (EPMA/WDS, high-spatial resolution EBSD) and complemented by U-Pb apatite and rutile geochronology. This project has the potential to shed light on relevant issues of the modern geochronology, such as the effects of deformational processes on the isotopic evolution of common geochronological systems (e.g., 40Ar-39Ar and Rb-Sr).

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

AIRES, FELIPE DA SILVA; DOS SANTOS, LUCILENE; DE MORAES, RENATO; DE OLIVEIRA, ARMANDO LUCAS SOUZA; GILIO, MATTIA; PESTILHO, ANDRE LUIZ SILVA; DOS SANTOS, FELIPE HOLANDA; CRUZ, CARLOS EDUARDO MACIEL. Using elastic geobarometry to unveil subduction-collision and rapid exhumation in the West Gondwana Orogen: Application to high-T/HP rocks in the NW part of the Borborema Province, NE Brazil. LITHOS, v. 494, p. 11-pg., 2024-12-21. (23/17675-2, 23/07347-8)