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Mineralogia e petrologia dos granitos variscos sin-D3 da região de Santa Comba de Rossas, norte de Portugal
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Abstract(s)
SUMMARY: In the Santa Comba de Rossas - Paredes area, a granitic complex (G1-G3) was emplaced during the syn-kinematic stages of the Variscan Orogeny, at 317.9 ± 8.7 Ma, as determined by whole rock Rb-Sr dating. The complex intruded Silurian metasediments, from the Parauthocthonous Domain of Galicia – Trás-os-Montes Zone, in a NW-SE trending antiform formed during the D1 and D3 deformation phases, but was itself affected by ductile and brittle deformation. Geochemical and isotopic characteristics suggest that the biotite > muscovite granite G1 and the biotite ≈ muscovite granite G2 correspond to distinct pulses of magma formed by partial melting of metasedimentary materials that subsequently evolved by fractional crystallization. This process was responsible for the increase in Sn content in those granites and, most probably, for the occurrence of the exocontact muscovite granite G3, which is the richest in Sn (77 ppm), due to a higher degree of fractional
crystallization.
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Resumo alargado
Keywords
S-type granites Rb-Sr dating Fractional crystallization Tin Granitos do tipo S Datação Rb-Sr Cristalização fraccionada Estanho Portugal (Norte)
Citation
Teixeira, R.J.S.; Gomes, M. Elisa Preto; Silva, Paulo Bravo; Meireles, Carlos (2023) - Mineralogia e petrologia dos granitos variscos sin-D3 da região de Santa Comba de Rossas, norte de Portugal. In: Lopes, F. C., Dinis, P. A., Duarte, L. V. e Cunha, P. P. (Coords.). XI Congresso Nacional de Geologia: Geociências e Desafios Globais. Livro de Resumos. Coimbra, 16- 20 julho de 2023, Departamento de Ciências da Terra da Universidade de Coimbra (eds.), p. 43-44. ISBN: 978-989-98914-8-7
Publisher
Departamento de Ciências da Terra da Universidade de Coimbra