Insights on the origin of the Graciosa A-type granites and syenites (Southern Brazil) from zircon U-Pb geochronology, chemistry, and Hf and O isotope compositions

Autor(es)

Jobim Vilalva, Frederico Castro ^[1] ; Simonetti, Antonio ^[2] ; Farias Vlach, Silvio Roberto ^[3]

Afiliação do(s) autor(es)

^[1] Univ Fed Rio Grande do Norte, Ctr Ciencias Exatas & Terra, Dept Geol, BR-59078970 Natal, RN - Brazil

^[2] Univ Notre Dame, Dept Civil & Environm Engn & Earth Sci, Notre Dame, IN 46556 - USA

^[3] Univ Sao Paulo, Inst Geociencias, Dept Mineral & Geotecton, BR-05508080 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: LITHOS; v. 340, p. 20-33, SEP 2019.
• Citações Web of Science: 1

Resumo

The Neoproterozoic, post-collisional, Graciosa Province (southern Brazil) comprises several A-type intrusions and related volcanics of alkaline and subalkaline (or aluminous) petrographic associations. U-Pb age determinations, trace element, and Hf and O isotopic compositions were obtained for zircons from six distinct A-type granitic and syenitic plutons from both alkaline and subalkaline associations from the province. Geochronological results indicate that their emplacement, petrogenetic evolution and crystallization spanned over a similar to 9 million years interval, with peak magmatism at similar to 580 Ma. Plutons were emplaced in a post-collisional extensional regime related to the geodynamic evolution of the south-southeastern part of the Gondwana supercontinent. Hf isotopic compositions are highly variable, with epsilon Hf(t) values between +1.4 to -31, whereas delta(18)0 signatures are mainly between +4.7 and +6.0 parts per thousand. These features, along with trace element signatures, especially for Hf, U, Nb, and rare-earth elements, suggest that generation of the Graciosa rocks occurred via partial melting of a lithospheric mantle previously metasomatized by slab-derived fluids, followed by variable degrees of crustal contamination at depth. (C) 2019 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 08/00562-0 - Interação manto-crosta e a geração e evolução do magmatismo pós-colisional de tipo-A: registros geoquímicos e isotópicos da Província Graciosa, S-SE do Brasil
• Beneficiário: Silvio Roberto Farias Vlach
• Modalidade de apoio: Auxílio à Pesquisa - Regular