Geochronology of mafic magmatism and hydrothermal alteration during early stages of South Atlantic opening

Autor(es)

Carvas, Karine Zuccolan ^[1] ; de Paula Vasconcelos, Paulo Marcos ^[2] ; Marques, Leila Soares ^[1] ; Ubide, Teresa ^[2] ; Carmo, Isabela de Oliveira ^[3] ; Babinski, Marly ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Queensland, Sch Earth & Environm Sci, Brisbane, Qld 4072 - Australia

^[3] PETROBRAS CENPES, BR-21941915 Rio De Janeiro, RJ - Brazil

^[4] Univ Sao Paulo, Inst Geociencias, BR-05422970 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: GEOCHIMICA ET COSMOCHIMICA ACTA; v. 314, p. 358-380, DEC 1 2021.
• Citações Web of Science: 0

Resumo

Ar-40/Ar-39 laser incremental-heating geochronology of whole-rock fragments and minerals from primitive subalkaline mafic dykes from the Cabo Frio Tectonic Domain, southeastern Brazil, reveals a complex combination of intrusive ages, apparent ages affected by excess argon, and ages that record late-stage hydrothermal alteration. Incremental-heating analysis of encapsulated magmatic amphibole-biotite clusters reveals a minimum intrusive age of 132.83 +/- 0.30 Ma. Sericitized plagioclase crystals show the percolation of K-rich fluids at similar to 106 Ma. Albitized plagioclase phenocrysts suggest the percolation of Na-rich fluids in the 60-30 Ma interval. Hydrothermal alteration events overlap in time with pulses of alkaline magmatism in the extending Brazilian crust, suggesting a link between magmatic activity and generation of fluid circulation cells along the margin and adjacent sedimentary basins. Evidence for pervasive hydrothermal re-setting of the K-Ar system in the Cabo Frio Tectonic Domain dykes suggests that young Ar-40/Ar-39 geochronology results obtained for mafic dykes here and elsewhere along the continental margins may not record multiple intrusive events, reflecting instead partial or total resetting of the K-Ar system by water-rock interaction during fluid circulation. (C) 2021 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 18/23650-4 - Proposta de período sanduíche no Argon Geochronology Laboratory da School of Earth and Environmental Sciences da University of Queensland (Austrália)
• Beneficiário: Karine Zuccolan Carvas
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 14/22948-9 - Caracterização geoquímica, isotópica e geocronológica dos diques toleíticos da costa do Sudeste do Brasil: implicações geodinâmicas
• Beneficiário: Karine Zuccolan Carvas
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• 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
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 17/18232-6 - Intrusões toleíticas do Cretáceo Superior e do Paleogeno da Região dos Lagos (RJ): inversão de dados termocronológicos 40Ar/39Ar e natureza das fontes mantélicas
• Beneficiário: Karine Zuccolan Carvas
• Modalidade de apoio: Bolsas no Brasil - Doutorado