Environmental magnetism evidence for longshore drift distribution of fe-bearing phases: An example from the Brazilian Southeastern Coastal Region

Vitor E.P. Silveira, Natália B. Dos Santos, Daniel R. Franco, Emanuele F. La Terra, Joshua M. Feinberg, R. B. Scorzelli, Magda B. Fontes, Luiz C. Bertolino, Joice Cagliari, Marcelo K. De Souza, Gelvam A. Hartmann

Research output: Contribution to journalArticlepeer-review

Abstract

The accumulation of heavy minerals along a part of the southeastern Brazilian coast (northern coast of Rio de Janeiro State, Brazil) provides insight into sedimentary provenance and transport by longshore drift. In particular, recent work has focused on heavy minerals as tracers to determine sedimentary sources and transport pathways, indicating a mineral distribution according to the northward and southward coastal transport cells. There is also evidence of heavy-mineral transport by the Parsíba do Sul River. However, research has not been done in this area on the opaque fraction (iron oxides and oxyhydroxides), which are good tracers for provenance and distribution processes. Here we intend to: 1) characterize the spatial variation of the magnetic properties of heavy-mineral contents throughout a coastal area of the Itabapoana and Parsíba do Sul River mouths (state of Rio de Janeiro), 2) evaluate the contribution of coastal dynamics on the mineral distribution along this coastal area, 3) provide contributions on the provenance of iron-bearing minerals. Results indicate that a bimodal pattern was observed for the magnetic remanence of magnetite and hematite near the Parsíba do Sul River. For the northernmost section, goethite exhibits a gradual increase in concentration towards the central part of the study area. Additionally, higher heavy-mineral content is observed at the northern coastal section, which may be related to coastal morphology, which is exposed to high-energy beach processes. It is possible to verify three sampling groups in accordance with their magnetic properties: 1) the ''southernmost'' and 2) the ''northernmost'' groups, suggesting a mineral provenance related to the Parsíba do Sul and Itabapoana rivers, respectively, as possible major sources, and 3) another at the intermediate section of the area, possibly linked to the erosion of the Barreiras Formation bluffs. Results also show a correspondence between the variability of magnetic parameters and the main directions of the coastal transport cells.

Original languageEnglish (US)
Pages (from-to)1133-1150
Number of pages18
JournalJournal of Sedimentary Research
Volume91
Issue number11
DOIs
StatePublished - 2021

Bibliographical note

Funding Information:
The authors are grateful to Dr. Marcia Ernesto, Giovanni Moreira, Plinio Jaqueto, Dr. Daniele Brandt, and Let?cia Dantas (Institute of Astronomy, Geophysics and Atmospheric Sciences, University of S?o Paulo, Brazil), Dr. Luigi Jovane and Muhammad Hassan (Institute of Oceanography, University of S?o Paulo, Brazil), Ronaldo Carvalho, Alcides Santos, Jonne Vidal, and Israeli Mathias (Observat ?rio Nacional, Brazil), Vitor Schwenck and Adauto Jos? da Silva (Centro de Tecnologia Mineral, Brazil) for technical assistance. This work was supported by Brazilian agencies CNPq (grants 131277/2017-0, 313253/ 2017-0, 306527/2017-0, 312737/2020-3, and 300962/2020-7) and FAPERJ (grants E-26/203.302/2017 and E-26/200.879/2017). While we conducted the present study, we were deeply saddened to learn of the passing of Dr. Jean- Marie Flexor, a pioneer and major contributor to research that paved the way to the findings of this paper. Like many others, we have greatly benefited from his support and sage mentorship. We honor his legacy by dedicating the present work to his memory.

Funding Information:
The authors are grateful to Dr. Marcia Ernesto, Giovanni Moreira, Plinio Jaqueto, Dr. Daniele Brandt, and Letícia Dantas (Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Brazil), Dr. Luigi Jovane and Muhammad Hassan (Institute of Oceanography, University of São Paulo, Brazil), Ronaldo Carvalho, Alcides Santos, Jonne Vidal, and Israeli Mathias (Observatório Nacional, Brazil), Vitor Schwenck and Adauto José da Silva (Centro de Tecnologia Mineral, Brazil) for technical assistance. This work was supported by Brazilian agencies CNPq (grants 131277/2017-0, 313253/ 2017-0, 306527/2017-0, 312737/2020-3, and 300962/2020-7) and FAPERJ (grants E-26/203.302/2017 and E-26/200.879/2017). While we conducted the present study, we were deeply saddened to learn of the passing of Dr. Jean- Marie Flexor, a pioneer and major contributor to research that paved the way to the findings of this paper. Like many others, we have greatly benefited from his support and sage mentorship. We honor his legacy by dedicating the present work to his memory.

Publisher Copyright:
Copyright © 2021, SEPM (Society for Sedimentary Geology).

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