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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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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]
Total Authors: 6
[1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil
[2] Vanderbilt Univ, Dept Earth & Environm Sci, Nashville, TN 37240 - USA
Total Affiliations: 2
Document type: Journal article
Source: Journal of South American Earth Sciences; v. 32, n. 4, SI, p. 407-415, DEC 2011.
Web of Science Citations: 8

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)

FAPESP's process: 05/58688-1 - South America in the context of supercontinents: fusion and fission
Grantee:Miguel Angelo Stipp Basei
Support type: Research Projects - Thematic Grants
FAPESP's process: 08/00562-0 - Mantle-crust interaction and the genesis and evolution of the A-type: post-collisional magmatism: geochemical and isotopic records from the Graciosa Province, S-SE Brazil
Grantee:Silvio Roberto Farias Vlach
Support type: Regular Research Grants