On the radiometric significance of glauconies in studies of provenance: An example of the quaternary marine sequences of the Rio Grande Cone (Pelotas basin, southern Brazil)

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Autor(es): dc.contributorPontifical Catholic University of Rio Grande do Sul-Porto Alegre-
Autor(es): dc.contributorUniversidade Estadual Paulista (UNESP)-
Autor(es): dc.contributorLinaeus University-
Autor(es): dc.contributorFederal University of Rio Grande do Sul-
Autor(es): dc.contributorCidade Universitária-
Autor(es): dc.creatorMaraschin, Anderson José-
Autor(es): dc.creatorLuvizotto, George Luiz-
Autor(es): dc.creatorMedina Ketzer, João Marcelo-
Autor(es): dc.creatorMizusaki, Ana Maria-
Autor(es): dc.creatorFerreira de Menezes, Maria Rosilene-
Data de aceite: dc.date.accessioned2025-08-21T15:58:22Z-
Data de disponibilização: dc.date.available2025-08-21T15:58:22Z-
Data de envio: dc.date.issued2025-04-29-
Data de envio: dc.date.issued2024-08-01-
Fonte completa do material: dc.identifierhttp://dx.doi.org/10.1016/j.jsames.2024.104936-
Fonte completa do material: dc.identifierhttps://hdl.handle.net/11449/300460-
Fonte: dc.identifier.urihttp://educapes.capes.gov.br/handle/11449/300460-
Descrição: dc.descriptionThe sediments of the Pleistocene-Holocene marine sequences of the Rio Grande Cone (RGC) (offshore Pelotas Basin, southernmost Brazilian Margin) are dominantly composed by muddy facies with thin interspersed sandy layers containing abundant very fine-to coarse green grains, heavy minerals assemblage, shards and planktonic foraminifera. These components contribute for a better understanding of the RGC filling during the Pleistocene-Holocene. However, the aim of this work was focused in the radiometric dating of the green grains as tool for provenance studies in marine sedimentary sequences. Based on Electron Microprobe, Scanning Electron Microprobe, Transmission Electron Microprobe and optical analysis the green grains occur as: (01) yellowish-green grains with smooth surfaces, low K2O and moderate Fe2O3 contents, (02) pale green grains with surfaces slightly fractured with moderate K2O and Fe2O3 contents, and (03) dark green grains characterised by fractured (cracked) surfaces and high of K2O and Fe2O3 contents. These characteristics classified them as glauconitic minerals ranging from glauconitic smectite to glauconitic mica (glauconite) indicating the first (nascent) and intermediate (slightly-evolved and evolved) stages of the glauconitization process. K–Ar radiometric dating indicated ages from 33.2 ± 0.99 to 6.69 ± 0.54 Ma corresponding from Rupelian Stage (Oligocene) to Messinian Stage (Miocene) to these grains. Considering these glauconitic grains within a Quaternary sequence, an allochthonous (detrital) origin was attributed whose probable source areas were older sedimentary sequences exposed on the seafloor along fold-and-thrust belts related to the gravitational collapse of the RGC depocentre. After eroded the glauconitic minerals probably were distributed by countourite currents and deposited within the Quaternary deposits of the RGC.-
Descrição: dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)-
Descrição: dc.descriptionConsejo Nacional para Investigaciones Científicas y Tecnológicas-
Descrição: dc.descriptionEDS-
Descrição: dc.descriptionInstitute of Petroleum and Natural Resources Pontifical Catholic University of Rio Grande do Sul-Porto Alegre-
Descrição: dc.descriptionInstitute of Geosciences Universidade Estadual Paulista Júlio de Mesquita Filho-UNESP-Rio Claro, SP-
Descrição: dc.descriptionDepartment of Biology and Environmental Science Faculty of Health and Life Sciences Linaeus University, Hus Vita-
Descrição: dc.descriptionGeoscience Institute Federal University of Rio Grande do Sul, RS-
Descrição: dc.descriptionPetrobras Cidade Universitária, RJ-
Descrição: dc.descriptionInstitute of Geosciences Universidade Estadual Paulista Júlio de Mesquita Filho-UNESP-Rio Claro, SP-
Idioma: dc.languageen-
Relação: dc.relationJournal of South American Earth Sciences-
???dc.source???: dc.sourceScopus-
Palavras-chave: dc.subjectContourites-
Palavras-chave: dc.subjectGlauconitic minerals-
Palavras-chave: dc.subjectK–Ar radiometric dating-
Palavras-chave: dc.subjectPelotas basin-
Palavras-chave: dc.subjectRio grande cone-
Título: dc.titleOn the radiometric significance of glauconies in studies of provenance: An example of the quaternary marine sequences of the Rio Grande Cone (Pelotas basin, southern Brazil)-
Tipo de arquivo: dc.typelivro digital-
Aparece nas coleções:Repositório Institucional - Unesp

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