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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.)

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

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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]
Total Authors: 6
[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
Total Affiliations: 4
Document type: Journal article
Source: GEOCHIMICA ET COSMOCHIMICA ACTA; v. 314, p. 358-380, DEC 1 2021.
Web of Science Citations: 0

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)

FAPESP's process: 18/23650-4 - Proposal for a research abroad period in the Argon Geochronology Laboratory of the School of Earth and Environmental Sciences of the University of Queensland (Australia)
Grantee:Karine Zuccolan Carvas
Support Opportunities: Scholarships abroad - Research Internship - Doctorate
FAPESP's process: 14/22948-9 - Geochemical, isotopic and geochronological characterization of tholeiitic dykes of the Southeastern Coast of Brazil: geodynamical implications
Grantee:Karine Zuccolan Carvas
Support Opportunities: Scholarships in Brazil - Master
FAPESP's process: 12/06082-6 - The Paraná-Etendeka magmatic province in Brazil: temporal and petrologic relationships between the tholeiitic and alkaline magmatism and geodynamic implications
Grantee:Excelso Ruberti
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 17/18232-6 - Late Cretaceous and Paleogene tholeiitic intrusions from Região dos Lagos (RJ): 40Ar/39Ar thermochronological data inversion and nature of mantle sources
Grantee:Karine Zuccolan Carvas
Support Opportunities: Scholarships in Brazil - Doctorate