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Title: Thermobarometry and electron-microprobe Th-U-Pb monazite dating in garnet metapelites from the Capelinha Formation, Araçuaí Orogen, Brazil.
Authors: Queiroga, Gláucia Nascimento
Schulz, Bernhard
Martins, Maximiliano de Souza
Castro, Marco Paulo de
Soares, Antônio Carlos Pedrosa
Evangelista, Hanna Jordt
Silva, Ana Lúcia da
Keywords: Capelinha formation
Garnet metapelites
Geothermo barometry
Electron microprobe Th U Pb dating
Issue Date: 2016
Citation: QUEIROGA, G. N. et al. Thermobarometry and electron-microprobe Th-U-Pb monazite dating in garnet metapelites from the Capelinha Formation, Araçuaí Orogen, Brazil. REM. Revista Escola de Minas, v. 69, p. 33-44, 2016. Disponível em: <>. Acesso em: 11 jul. 2016.
Abstract: The Capelinha Formation (Macaúbas Group) consists of a lower quartzitic unit with metamafic intercalations and an upper metapelitic sequence. It occurs in a complex tectono-metamorphic sector of the Araçuaí orogen, where post-collisional collapse-related structures superimposed collisional structures. The garnet-bearing assemblages started crystallization in the collisional deformation stage that formed the main regional foliation around 570 Ma. Garnet porphyroblasts display a well-developed growth zonation of Fe-Mg-Ca-Mn and show, from core to rim, increasing almandine and pyrope contents in contrast with decreasing grossular and spessartine contents. Mineral relations and microstructures provide criteria for local equilibria and a structurally controlled application of geothermobarometers based on cation ex¬change and net transfer reactions. The P-T values calculated from cores to rims of gar¬nets, aligned along clockwise trends, resulted in increasing temperatures (from 500 ºC up to 620 ºC) under decompression conditions (from 8.0 kbar to 4.5 kbar). The Th-U-Pb dating of homogeneous monazites by electron microprobe revealed a recrystalliza¬tion period at around 490 – 480 Ma. These ages can be related to the tectono-thermal event associated with the gravitational collapse, constraining the youngest time limit for metamorphic processes in the Araçuaí orogen.
ISSN: 1807-0353
metadata.dc.rights.license: A Revista Escola de Minas - REM - autoriza o depósito de cópia de artigos dos professores e alunos da UFOP no Repositório Institucional da UFOP. Licença concedida mediante preenchimento de formulário online em: 12 set. 2013.
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