Magmatism, tectonic reworking and partial melting of ferroan granites in the Campo do Meio Shear Belt, Brazil: Timescales from zircon, titanite, and garnet petrochronology.

• Grant number: 25/06053-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Renato de Moraes
• Grantee: Edinson Yesid Bonilla Celis
• Supervisor: Horst Marschall
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Goethe University Frankfurt, Germany
• Associated to the scholarship: 23/14579-2 - P-T-t-d paths of migmatites in the Campo Gerais Shear Zone, MG, Brazil, BP.DD

Abstract

The Campo do Meio Shear Belt limits the northern portion of the Socorro-Guaxupé Nappe, which is part of the Southernmost Brasília Orogen, and at its base, migmatites with ferroan granite protoliths are exposed. Although ferroan granites are commonly found in the Proterozoic era, studies on the effects of tectonic reworking and partial melting in collisional orogens of these rocks-leading to the formation of migmatites-remain scarce. As part of this doctoral research, an integrated approach-including fieldwork, petrography, whole-rock and mineral chemistry, and phase diagram modelling-has enabled the characterization of these rocks. Two distinct units have been identified: the Areado Granite-Migmatite unit in the south and the São Pedro da União Migmatite unit in the north, both composed of hornblende bearing migmatites and ferroan granites. Nevertheless, due to the absence of geochronological data, the origin and tectonic evolution of these units remain unclear. This project aims to constrain the timescale of the magmatic crystallization of the ferroan granites, as well as their subsequent history of metamorphism, partial melting, and melt crystallization. To achieve this, an integrate approach will be applied, involving petrochronology (U-Pb and trace elements) in zircon, titanite, and garnet, coupled with Lu-Hf isotope in zircon, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The analysis will be conducted at the Frankfurt Isotope and Element Research Center (FIERCE) at Goethe Universität Frankfurt am Main (Germany), under the supervision of Dr. Horst Marschall and Dr. Axel Gerges, both experts in isotope geochemistry in metamorphic rocks. The geochronological data will then be matched with thermodynamic modelling and textural analyses. We expect to establish the magmatic history of the protolith in the Paleoproterozoic, as well as the tectonic reworking and partial melting in the Neoproterozoic during the western Gondwana assembly.