Identification of included phases in zircon and rutile from eclogitic rocks from Passos nappe (Brazilian belt - MG)

• Grant number: 19/20667-6
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): February 01, 2020
• Effective date (End): January 31, 2022
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal researcher: George Luiz Luvizotto
• Grantee: Lorenzo Tebaldi Capelane
• Home Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

Occurrences of basic rocks containing garnet an clinopyroxene in the São Sebastião do Paraíso region date back from the pioneer work of Hoppe et al. (1985). Such rocks have typical textures that indicate post Pressure-peak reequilibration (clinopyroxene and plagioclase symplectite and coronas of plagioclase and hornblende surrounding garnet). Therefore, determination of peak metamorphic condition cannot be performed using rock forming minerals, since their chemical composition has changed. The interpretation that the garnet and clinopyroxene rocks represent former eclogite is, therefore, only based in metamorphic textures and relicts of mineral crystalized during peak conditions. As an independent approach, this project aims to investigate occurrences of high and ultra high pressure mineral phases as inclusions in zircon and rutile. The occurrence of, for example, coesite, would indicate that the studied rocks were formed under a subduction setting. The work will be carried out using detailed techniques such as: Scanning Electron Microscopy, Energy Dispersive Spectroscopy and Raman Spectroscopy. Results will foment discussions on the geological setting under which the rocks were formed and the implications on the evolution of the Brasilia Belt.