Contemporaneous alkaline and tholeiitic magmatism in the Ponta Grossa Arch, Parana-Etendeka Magmatic Province: Constraints from U-Pb zircon/baddeleyite and Ar-40/Ar-39 phlogopite dating of the Jose Fernandes Gabbro and mafic dykes

Autor(es)

Almeida, Vidya V. ^{[1, 2]} ; Janasi, Valdecir A. ^[1] ; Heaman, Larry M. ^[3] ; Shaulis, Barry J. ^{[3, 4]} ; Hollanda, Maria Helena B. M. ^[1] ; Renne, Paul R. ^[5]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Geociencias, Dept Mineral & Geotecton, Sao Paulo - Brazil

^[2] Superintendencia Reg Sao Paulo Sureg SP, Geol Survey Brazil CPRM, Sao Paulo - Brazil

^[3] Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB - Canada

^[4] Lunar Planetary Inst, Houston, TX - USA

^[5] Berkeley Geochronol Ctr, Berkeley, CA - USA

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH; v. 355, n. SI, p. 55-65, APR 15 2018.
• Citações Web of Science: 6

Resumo

We report the first high-precision ID-TIMS U-Pb baddeleyite/zircon and Ar-40/Ar-39 step-heating phlogopite age data for diabase and lamprophyre dykes and a mafic intrusion (Jose Fernandes Gabbro) located within the Ponta Grossa Arch, Brazil, in order to constrain the temporal evolution between Early Cretaceous tholeiitic and alkaline magmatism of the Parana-Etendeka Magmatic Province. U-Pb dates from chemically abraded zircon data yielded the best estimate for the emplacement ages of a high Ti-P-Sr basaltic dyke (133.9 +/- 0.2 Ma), a dyke with basaltic andesite composition (133.4 +/- 02 Ma) and the Jose Fernandes Gabbro (134.5 +/- 0.1 Ma). A 40Ar/39Ar phlogopite step-heating age of 133.7 +/- 0.1 Ma from a lamprophyre dyke is identical within error to the U-Pb age of the diabase dykes, indicating that tholeiitic and alkaline magmatism were coeval in the Ponta Grossa Arch. Although nearly all analysed fractions are concordant and show low analytical uncertainties (+/- 0.3-0.9 Ma for baddeleyite; 0.1-0.4 Ma for zircon; 2 sigma), Pb loss is observed in all baddeleyite fractions and in some initial zircon fractions not submitted to the most extreme chemical abrasion treatment. The resulting age spread may reflect intense and continued magmatic activity in the Ponta Grossa Arch. (C) 2017 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 12/06082-6 - A província magmática Paraná-Etendeka no Brasil: relações temporais e petrológicas entre o magmatismo toleítico e alcalino e suas implicações geodinâmicas
• Beneficiário: Excelso Ruberti
• Linha de fomento: Auxílio à Pesquisa - Temático