Thermo-kinematic evolution of the Anta Gorda anticlinorium basement and metasedime...
| Grant number: | 15/05230-0 |
| Support type: | Regular Research Grants |
| Duration: | October 01, 2015 - December 31, 2017 |
| Field of knowledge: | Physical Sciences and Mathematics - Geosciences |
| Principal Investigator: | George Luiz Luvizotto |
| Grantee: | George Luiz Luvizotto |
| Home Institution: | Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil |
| Assoc. researchers: | Andreas Kronz ; Caio Arthur Santos ; Daniel Francoso de Godoy ; Edson Ricardo Maia Ferraz ; Luiz Sérgio Amarante Simões ; Rafael Vieira Ribeiro ; Regiane Andrade Fumes ; Renato de Moraes ; Thomas Zack |
Abstract
The present work focuses on the metamorphic characterization of high pressure metapelitic rocks from two localities in Southern Minas Gerais State. The study rocks record metamorphic processes and deformation that took place in the Neoproterozoic, during the Brasiliano Orogeny. They belong to the Brasilia Belt (Passos / São Sebastião do Paraíso Region - SSP) and Ribeira Belt (Luminárias Region - LM). Rocks from SSP have the mineral assemblage Grt+KFs+Ky+Rt and show abundant layers of KFs+Qtz, indicating partial melting at high-pressure granulite facies (corroborated by retroeclogite occurrences). Phylites and schists from LM fall in the field of high Al pelites. These rocks show mineral assemblages that differ from those of pelites from the classic barrovian series, since Bt is not crystalized under greenschist and amphibolite facies. Highest grade rocks from LM have the mineral assemblage Grt+St+Ky, which is indicative ob amphibolite facies (Ky zone). Metamorphic studies have previously been carried out in both areas. However, they did not include modern techniques like, pseudosection, and trace-element geothermobarometers, such as Zr-in-Rutile and Ti-in-Quartz. The aim of the present study is to calculate peak P-T conditions for these rocks, as well as U-Th-PbT monazite ages. Together with petrographic and field observation, the data will be used to construct P-T-t-d paths for the study rocks. The new data will favor discussion about the interference zone between Brasilia and Ribeira belts, shedding light into the formation of southern São Francisco Craton region. The project also aims to develop and implement trace element analyses in the EPMA laboratory at Unesp - Rio Claro, where it has recently been installed a JEOL JXA 8230. Protocols will include trace element analyses in Rt (V, Cr, Fe, Zr, Nb, Sn, Sb, Hf, Ta, e W), Ti in Qtz, as well as U-Th-PbT monazite dating. (AU)