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Metamorphic, partial melting and deformation studies in high-pressure metapelitic rocks


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)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
FUMES, REGIANE ANDRADE; LUVIZOTTO, GEORGE LUIZ; MORAES, RENATO; LANARI, PIERRE; VALERIANO, CLAUDIO DE MORISSON; ZACK, THOMAS; CADDICK, MARK J.; SIMOES, LUIZ SERGIO AMARANTE. etrochronology of high-pressure granulite facies rocks from Southern Brasilia Orogen, SE Brazil: Combining quantitative compositional mapping, single-element thermometry and geochronolog. JOURNAL OF METAMORPHIC GEOLOGY, v. 40, n. 3, . (15/05230-0, 16/22627-3)
SANTOS, CAIO A.; LUVIZOTTO, GEORGE L.; MORAES, RENATO; FUMES, REGIANE A.; ZACK, THOMAS. Metamorphism of retroeclogites from the Passos Nappe, Southern Brasilia Orogen. Journal of South American Earth Sciences, v. 112, n. 2, . (16/22627-3, 15/05230-0, 13/04007-0)

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