Geometry, deformation and thermokinematic history of Itapirapuã Shear zone, Ribeira belt, Brazil

• Grant number: 24/15682-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2025
• End date: December 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Ginaldo Ademar da Cruz Campanha
• Grantee: Arthur Rodrigues da Silva
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 23/16838-5 - Comparative tectonic analysis of fold-and-thrust belts, AP.R
• Associated scholarship(s): 25/07592-8 - Constraining the kinematic and the chronological evolution of Itapirapuã Shear Zone through electron backscatter diffraction (EBSD) and in situ mica Rb-Sr geochronology, BE.EP.IC

Abstract

The southern Ribeira Belt is the result of an oblique collision between the São Francisco,Paranapanema and Luís Alves cratons, with the participation of microplates andallochthonous terrains remobilized during the Brasiliano-Pan-African cycle. This processresulted in a series of juxtaposed domains limited by shear zones that accumulatedappreciable horizontal displacements, some of which can represent possible continentalsutures. The Itapirapuã shear zone is one of the most important in this context, separatingtwo lithostratigraphic units of contrasting geochronological ages: the Água Clara Formation(1590-1470 Ma) and the Itaiacoca Group (650-610 Ma), and has not yet been studied interms of its thermokinematic evolution. This work aims to investigate thermobarometricand kinematic of mylonitic fabrics associated with the Itapirapuã shear zone,reconstructing their thermokinematic history and the P-T conditions of deformation,through petrographic and microstructural analysis, mineral chemistry, thermobarometry,crystallographic fabric analysis (EBSD) and thermodynamic modeling. The application ofthese tools is unprecedented for the proposed study area and can contribute to theunderstanding of the deformation processes operative during the collisional event.