ELASTIC GEOTHERMOBAROMETRY, PETROCHRONOLOGY, AND THERMODYNAMIC MODELING AND THEIR RELATIONSHIPS WITH UHT AND UHP ROCKS FROM THE SOCORRO-GUAXUPÉ AND TRÊS PONTAS-VARGINHA NAPPES: INVESTIGATING MELTING PROCESSES AND THEIR GEODYNAMIC IMPLICATIONS

• Grant number: 24/19551-1
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: May 01, 2025
• End date: April 30, 2028
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Renato de Moraes
• Grantee: Felipe da Silva Aires
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

During extreme tectonic episodes, such as subduction and continental collision, crustal rocks aresubjected not only to metamorphic reactions but also to partial melting reactions (anatexis),particularly in the lower continental crust. These physicochemical transformations result in theformation of (U)HP and/or (U)HT metamorphic rocks on one hand, and the production of igneousrocks on the other. Partial melting of crustal rocks under extreme metamorphic conditionssignificantly influences the physical and chemical properties of the continental crust. It is widelysuggested that the anatexis process under such metamorphic conditions occurs during theexhumation or subduction stages. To define such a stage, detailed petrochronological,geochemical, geothermobarometric, and thermodynamic studies are necessary. Conventionalgeothermobarometry and thermodynamic modeling are well-established methods that rely on thechemical equilibrium between coexisting mineral phases to calculate pressure and temperatureconditions. However, their applications in high-grade metamorphic terrains can be challenged dueto mineral reequilibration during the exhumation stage, which may lead to the loss of the previousmetamorphic record. The reliability of these methods can be tested through elasticgeothermobarometry, which offers a complementary approach to constrain pressure andtemperature conditions, as it is a physical method independent of chemical equilibrium amongphases. A detailed study of the relationship between UHT and (U)HP metamorphism in theSocorro-Guaxupé and Três Pontas-Varginha nappes may reveal crucial geodynamic andpetrological information for understanding deep crustal metamorphism and the tectonic evolutionof the Brasília Orogen.