Taphonomy of Recent Bioclastic Deposits from the Southern Brazil Shelf: Stratigraphic Potential

Erthal, Fernando; Ritter, Matias do Nascimento

doi:10.1007/978-3-030-20625-3_1

Cited by 5 publications

(2 citation statements)

References 49 publications

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“…Although modern shells and remains of other organisms also occur on the concentrations, for simplicity we refer herein only to the fossil material. Those concentrations are regarded as lag deposits (Erthal and Ritter 2020), the fragmented and abraded state of the fossils indicate reworking and concentration on high-energy nearshore settings in the past (Figueiredo Jr. 1975; Lopes and Buchmann System III during the late Pleistocene, and System IV during the Holocene (Villwock and Tomazelli 1995;Lopes et al 2014a). These systems are the result of glacioeustatic oscillations that produced high-frequency depositional sequences integrating a falling stage systems tract (Rosa et al 2017).…”

Section: Submarine and Coastal Sitesmentioning

confidence: 99%

Fossiliferous sites of the southern coast of Rio Grande do Sul state, Brazil: geoheritage records of Quaternary sea-level, climate and environmental changes

Lopes,

Pereira,

Ritter

et al. 2024

JGSB

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The southern coastal plain of Rio Grande do Sul state hosts essential fossil records of both marine and terrestrial faunas that have provided invaluable information about the geological and environmental Quaternary history of southern Brazil. These fossils are found in surface and subsurface deposits on sites stretching from the continental shelf up to coastal lagoons inland. The sites on the shelf are time-averaged lag deposits formed of marine and terrestrial fossils exhumed and mixed together as a result of erosion of the original deposits by sea-level oscillations. Although lacking any precise stratigraphic context, the available numerical dates indicate Middle to late Pleistocene ages. Fossils removed from the shelf by waves today form large Konzentratt-Lagerstätten on the beach, called concheiros. The sites on continental areas occur in barrier-lagoon depositional systems, and include marine deposits formed under higher than present sea levels formed by Middle and late Pleistocene and Early-Middle Holocene marine transgressions. The fossiliferous sites with well-defined stratigraphic context encompass fluvial and aeolian (loess) deposits and paleosols associated with the Middle-late Pleistocene Santa Vitória Alloformation and Cordão Formation outcropping along Chuy Creek. Fossils of late Pleistocene terrestrial and Holocene marine organisms were collected from the bottom and marginal terraces of Mirim Lagoon. Although most sites are not directly under threat today, their wide distribution poses potential problems for protection. Current protection measures for the sites and associated fossils include requests by environmental agencies for preliminary surveys and fossil rescue programs prior to construction projects, and the proposal of a marine-coastal protected area is currently under consideration. Educational programs with schools and exhibits for the general public executed by the museums in the town of Santa Vitória do Palmar have contributed to public awareness about the importance of the regional paleontological heritage and have produced positive feedback and results that increased the number of known fossiliferous sites in the region thanks to communication by local people. These actions are essential to establish protection measures in case new developments emerge in the future that could threaten the sites and their fossils.

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Section: Submarine and Coastal Sitesmentioning

confidence: 99%

Fossiliferous sites of the southern coast of Rio Grande do Sul state, Brazil: geoheritage records of Quaternary sea-level, climate and environmental changes

Lopes,

Pereira,

Ritter

et al. 2024

JGSB

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“…Exemplos disso são Fornari et al (2012), Ritter et al (2013) e Porto- Barros et al (2017) que analisaram depósitos holocênicos de conchas na planície costeira do Rio Grande do Sul (Tramandaí), de Santa Catarina (Jaguaruna) e Rio de Janeiro (Região dos Lagos), respectivamente. Já em ambiente marinho plataformal, Erthal & Ritter (2020) aplicaram o estudo da tafonomia de depósitos bioclásticos recentes ao entendimento estratigráfico da plataforma continental do extremo sul brasileiro.…”

Section: Introductionunclassified

Análise tafonômica de concentrações bioclásticas geradas em modelagem física de um sistema de águas rasas dominado por ondas

2020

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Este estudo procurou detalhar os efeitos deposicionais das dinâmicas de concentração de conchas (retrabalhamento mecânico, winnowing e bypass dinâmico) governadas pelas ondulações. Parâmetros tafonômicos, incluindo orientação e posicionamento das conchas, empacotamento e o conteúdo percentual de matriz (em peso), foram analisados a partir de amostras rígidas e inconsolidadas dos depósitos modelados, bem como pelo imageamento do modelo físico. As orientações topo-base das conchas foram predominantemente concordantes em todo perfil simulado (>70%), porém com um percentual maior de bioclastos oblíquos e verticais nas amostras mais distais do modelo, associadas ao winnowing e ao bypass dinâmico. As orientações em planta mostraram tendências bimodais ou unimodais nos depósitos intermediários do perfil, associadas a dinâmica de retrabalhamento mecânico (na rebentação) e winnowing, e polimodais nas amostragens mais proximais e distais, associados ao retrabalhamento mecânico no espraiamento e bypass dinâmico, respectivamente. O posicionamento da concavidade dos bivalves foi majoritariamente para baixo ao longo da seção analisada. O empacotamento e percentual de matriz foi, respectivamente, denso e mais baixo (30%) no depósito gerado pelo winnowing, sendo os demais com empacotamento moderado ou disperso. A análise tafonômica empregada em concentrações bioclásticas (coquinas) geradas por modelagem física de ambiente costeiro dominado por onda pode ser utilizada para previsão de determinadas dinâmicas sedimentológicas de acumulação de conchas.

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Genesis of fossil concentrations in foreland basins: A case study of the middle Eocene Man Aike Formation, Magallanes Basin, Chilean Patagonia

Müller,

Horodyski,

Diemer Kochhann

et al. 2024

Evolving Earth

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Taphonomy of Recent Bioclastic Deposits from the Southern Brazil Shelf: Stratigraphic Potential

Cited by 5 publications

References 49 publications

Fossiliferous sites of the southern coast of Rio Grande do Sul state, Brazil: geoheritage records of Quaternary sea-level, climate and environmental changes

Fossiliferous sites of the southern coast of Rio Grande do Sul state, Brazil: geoheritage records of Quaternary sea-level, climate and environmental changes

Análise tafonômica de concentrações bioclásticas geradas em modelagem física de um sistema de águas rasas dominado por ondas

Genesis of fossil concentrations in foreland basins: A case study of the middle Eocene Man Aike Formation, Magallanes Basin, Chilean Patagonia

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