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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Crystallization ages of the A-type magmatism of the Graciosa Province (Southern Brazil): Constraints from zircon U-Pb (ID-TIMS) dating of coeval K-rich gabbro-dioritic rocks

Texto completo
Autor(es):
Vlach, Silvio R. F. [1] ; Siga, Jr., Oswaldo [1] ; Harara, Ossama M. M. [1] ; Gualda, Guilherme A. R. [2] ; Basei, Miguel A. S. [1] ; Vilalva, Frederico C. J. [1]
Número total de Autores: 6
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil
[2] Vanderbilt Univ, Dept Earth & Environm Sci, Nashville, TN 37240 - USA
Número total de Afiliações: 2
Tipo de documento: Artigo Científico
Fonte: Journal of South American Earth Sciences; v. 32, n. 4, SI, p. 407-415, DEC 2011.
Citações Web of Science: 8
Resumo

Zircon U-Pb (ID-TIMS) ages for gabbro-dioritic rocks and for a monzogranite from the Graciosa Province of A-type granites and syenites, southern Brazil, are presented. Two gabbro-dioritic samples gave concordant ages (580 +/- 2, 583 +/- 3 Ma), while less precise upper intercept ages were obtained for another one (584 +/- 8 Ma) and the monzogranite (585 +/- 12 Ma). The best results indicate crystallization ages of the basic-intermediate magmas around 580-583 Ma. Micro-structural evidences and structural relationships between the mafic-intermediate rocks and the much more abundant granites and syenites demonstrate that magmas mingled and partially mixed with one another during emplacement and crystallization. Therefore, the results are representative of the overall magmatism. The extensional A-type magmatism occurred ca. 10-30 Ma after (1) emplacement and crystallization of the high-K calc-alkaline syn- to late-collisional batholiths, (2) peak regional metamorphism, and (3) final amalgamation of the Luis Alves, Curitiba, and Paranagua terrains. It is suggested that the whole magmatism occurred in a short time interval and there is no evidence of spatial or temporal migration of the magmatic foci. ID-TIMS zircon dating of coeval basic-intermediate rocks may yield better emplacement and crystallization ages than direct dating of granitic and syenitic rocks, which are more susceptible to inheritance and/or late- to post-magmatic disturbances. (C) 2011 Elsevier Ltd. 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
Linha de fomento: Auxílio à Pesquisa - Regular
Processo FAPESP: 05/58688-1 - A América do Sul no contexto dos supercontinentes: fusão e fissão
Beneficiário:Miguel Angelo Stipp Basei
Linha de fomento: Auxílio à Pesquisa - Temático