"Tracing the onset and evolution of plate tectonics with rutile".
The earth is the only planet in the Solar System that is characterized by an active plate tectonic regime, that is responsible for cyclic supercontinent formation and played a major role in the atmosphere oxygenation, the addition of nutrients to the ocean and produced resources that supported the biosphere. There is still no consensus about the age that plate tectonics was fully operational in the geological community, generating discussions if it was fully operational in the Archean or if it only developed in the Paleoproterozoic. To constrains the earliest plate tectonic regime, the metamorphic record is widely used to interpret the age and conditions of the early plate tectonic regime, since the hallmark of modern plate tectonics resides in the paired, high and low T/P metamorphic conditions. To address the issue of when plate tectonics was fully operational, this project aims to analyze rutile, a Ti phase stable in high/ultra-high pressures that form during subduction and deep-crustal metamorphism. Rutile is being recently used as a new proxy to track the existence of low T/P and paired metamorphism as it has the potential to constrain its crystallization temperature (Zr-in-rutile thermometer) and U-Pb ages of individual rutile grains. Considering this discussion, this research project aims to find whether there is any change in the T/P distribution of rutile from the Archean (Superior Province, Ontario and Quebec, Canada) to the Paleoproterozoic (São Francisco Craton, Brazil and West African Craton, Man Shield, Ghana, Africa), to identify the earliest evidence of modern plate tectonic regime through geochemical and U-Pb geochronology of rutile.
Funded by São Paulo Research Foundation (FAPESP) - grant number 2022/06156-1.
People involved:
- Prof. Dr. George Luiz Luvizotto, São Paulo State University (UNESP).
- Prof. Dr. Fabrício de Andrade Caxito, Federal University of Minas Gerais (UFMG).
- Prof. Dr. Alex Joaquim Choupina Andrade Silva, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM).
- Prof. Dr. Claudio Riccomini, University of São Paulo (USP).
- Prof. Dr. Renato de Moraes, University of São Paulo (USP).
- Prof. Dr. Christopher Spencer, Queen's University, Canada.
Main methods:
- U-Pb dating of rutile (LA-ICP-MS);
- Systematic rutile trace element analysis (Electron Probe Microanalyzer - EPMA).