Sandy barrier overstepping and preservation linked to rapid sea level rise and geological setting

Cooper, J. Andrew G.; Green, Andrew N.; Meireles, Ricardo Piazza; Klein, Antonio H. F.; Souza, Jorge A. G.; Toldo, Elírio E.

doi:10.1016/j.margeo.2016.10.003

Cited by 52 publications

(24 citation statements)

References 42 publications

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“…Deposits were interpreted as barrier islands if the preserved shoreface was directly associated with estuarine, lagoon (Davies, 1978), or back barrier deposits, as per widelyused definitions (Oertel, 1985;Otvos, 2012). This designation includes examples of recently drowned barriers on the present day shelf (Mellett et al, 2012;Green et al, 2013Green et al, , 2018Salzmann al., 2013;Cooper et al, 2016Cooper et al, , 2018bPretorius et al, 2016;Brooke et al, 2017;Mellett and Plater, 2018).…”

Section: Database Developmentmentioning

confidence: 99%

Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics

2019

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Ancient barrier islands are poorly understood relative to other clastic depositional environments, despite being prominent features along modern coastlines and important for understanding transgressive shoreline deposits. A new dataset of ancient barrier island dimensions (n = 83 examples) addresses this knowledge gap with a quantitative analysis of barrier island sand body dimensions including thickness (vertical), length (shore-parallel direction), and width (shore-perpendicular direction). This dataset of barrier island deposits was compared to planform measurements made for modern islands (n = 274), to investigate possible scaling relationships and other aspects of modern to ancient linkages. These measurements are nuanced and challenging to perform, and first-pass comparisons show that modern barrier islands should not be used as direct analogs for ancient systems. Nevertheless, results emphasize key depositional and preservation processes, and the dimensional differences between deposits formed over geologic vs. modern time scales. Using the methods outlined herein, barrier island deposits appear to be 2-5x longer (p50 modern = 10.7 km; p50 ancient = 20.0 km), and 6-15x wider (p50 modern = 1.2 km; p50 ancient = 7.3 km) than modern barrier islands. We interpret the results to indicate that ancient barrier islands are time-transgressive deposits recording vertical amalgamation, and barrier island growth by lateral accretion, and progradation. When comparing single barrier islands, thickness measurements do not vary systemically between modern and ancient examples, suggesting that local accommodation dictates barrier island thickness as a preservation control. Gross length, width, and thickness measurements are too coarse for robust paleomorphodynamic calculations, therefore more detailed sub-environment analysis (e.g., upper shoreface delineation), with improved facies models, is required before rigorous quantifications can Mulhern et al. Barrier Island Dimensional Comparisons be generated. However, these initial comparisons do show scaling trends between length and width which could be leveraged, with caution, in the interim. As sea levels continue to rise, understanding barrier island motion and preservation will be central to predicting coastal change.

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Section: Database Developmentmentioning

confidence: 99%

Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics

2019

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“…10C; Snedden et al, 1999) and overstepped barrier islands ( Fig. 10D; Rodriguez et al, 1999;Cooper et al, 2016). Despite some similarities, such as sharp-based, prograding, well-sorted sandstones, existing shelf sand models do not easily explain those on the Lajas shelf.…”

Section: Previously Described Shelf Sand Bodiesmentioning

confidence: 99%

Hyperpycnal delivery of sand to the continental shelf: Insights from the Jurassic Lajas Formation, Neuquén Basin, Argentina

et al. 2018

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Hyperpycnal currents are river‐derived turbidity currents capable of transporting significant volumes of sediment from the shoreline onto the shelf and potentially further to deep ocean basins. However, their capacity to deposit sand bodies on the continental shelf is poorly understood. Shelf hyperpycnites remain an overlooked depositional element in source to sink systems, primarily due to their limited recognition in the rock record. Recent discoveries of modern shelf hyperpycnites, and previous work describing hyperpycnites deposited in slope or deep‐water settings, provide a valuable framework for understanding and recognizing shelf hyperpycnites in the rock record. This article describes well‐sorted lobate sand bodies on the continental shelf of the Neuquén Basin, Argentina, interpreted to have been deposited by hyperpycnal currents. These hyperpycnites of the Jurassic Lajas Formation are characterized by well‐sorted, medium‐grained, parallel‐laminated sandstones with hundreds of metre extensive, decimetre thick beds encased by organic‐rich, thinly laminated sandstone and siltstone. These deposits represent slightly obliquely‐migrating sand lobes fed by small rivers and deposited on the continental shelf. Hyperpycnites of the Lajas Formation highlight several unique characteristics of hyperpycnal deposits, including their distinctively thick horizontal laminae attributed to pulsing of the hyperpycnal currents, the extraction of coarse gravel due to low flow competence, and the extraction of mud due to lofting of light interstitial fluid. Recognition of shelf hyperpycnites in the Lajas Formation of the Neuquén Basin allows for a broader understanding of shelf processes and adds to the developing facies models of hyperpycnites. Recognizing and understanding the geometry and internal architecture of shelf hyperpycnites will improve current understanding of sediment transfer from rivers to deeper water, will improve palaeoenvironmental interpretations of sediment gravity‐flow deposits, and has implications for modelling potentially high‐quality hydrocarbon reservoirs.

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“…As estruturas das rochas, ilha e calhaus parece ser fortemente condicionadas pelos dois principais falhamentos e suas respectivas direções, como no caso do Saco da Bala e da Ilha Deserta, sendo que tais rochas são cortadas por diques de diabásio de granulação fi na e coloração escura (CHLUDINSKI, 2002). COOPER et al, (2016), por sua vez, afi rmam que a Baia de Tijucas passou por diferentes processos sedimentares evolutivos durante o Holoceno, até atingir sua confi guração geomorfológica atual, fato evidenciado pela diversidade de ecofácies identifi cadas em recente mapeamento sísmico ali conduzido.…”

Section: Rebiomar Do Arvoredounclassified

Caracterização Geomorfológica Do Relevo Submarino De Áreas Marinhas Protegidas Brasileiras Com Base Em Técnicas De Análise Espacial

Pereira

Bonetti

2018

Rev. Bras. Geomorfol.

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Resumo:O substrato marinho possui grande importância na atração e na agregação de vida, sendo o estabelecimento de habitats bênticos condicionado primariamente por suas características morfossedimentares. Este trabalho analisa o fundo marinho raso de três importantes Unidades de Conservação Marinho Costeiras do Brasil através dos estudos morfológicos das feições de relevo e das paleodrenagens e paleobacias hidrográfi cas que foram estabelecidas em condições pretéritas de exposição subaérea da plataforma continental. Os resultados, obtidos através de técnicas de análise espacial em Sistemas de Informações Geográfi cas (SIG), trazem informações inéditas sobre o relevo de fundo dessas áreas, como sua complexidade morfológica, que poderão ser usadas no manejo e na conservação dos recursos naturais marinhos brasileiros, seja por sua geodiversidade ou pela biodiversidade associada a essas feições. Abstract:The marine substrate has high importance in attracting and aggregating life, being the establishment of benthic habitats primarily conditioned by its morphosedimentary features. This paper analyses the shallow seabed of three important Marine Protected Areas in Brazil through morphological studies of their actual bottom features, paleo drainages and paleo watersheds that were established in past conditions of subaerial exposure of the inner continental shelf. The results obtained through spatial analysis techniques in Geographic Information Systems

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Sandy barrier overstepping and preservation linked to rapid sea level rise and geological setting

Cited by 52 publications

References 42 publications

Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics

Modern to Ancient Barrier Island Dimensional Comparisons: Implications for Analog Selection and Paleomorphodynamics

Hyperpycnal delivery of sand to the continental shelf: Insights from the Jurassic Lajas Formation, Neuquén Basin, Argentina

Caracterização Geomorfológica Do Relevo Submarino De Áreas Marinhas Protegidas Brasileiras Com Base Em Técnicas De Análise Espacial

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