Radiocarbon reservoir corrections on the Brazilian coast from pre-bomb marine shells

Alves, Eduardo Queiroz; Macario, Kita C. D.; Souza, Rosa Cristina Corrêa Luz de; Pimenta, Alexandre Dias; Douka, Katerina; Oliveira, Fernanda Midori de; Chanca, Ingrid; Ângulo, Rodolfo José

doi:10.1016/j.quageo.2015.05.006

Cited by 62 publications

(57 citation statements)

References 27 publications

(35 reference statements)

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“…More data on the MRE and on d 18 O derived temperatures from the Cabo Frio shellmounds and those from the nearby region are needed to confirm this hypothesis. Comparing past and present upwelling influence we found a slightly lower value of DR, but statistically similar to the modern value of 96 ± 48 14 C yr obtained by Alves et al (2015a). Again, further analyses are desirable in order to evaluate a possible variation in the upwelling influence over time, however, the results here obtained corroborate the presence of upwelling influences between 1600 and 1200 cal yr BP in this region of the Brazilian coast.…”

Section: Discussionsupporting

confidence: 85%

The Usiminas shellmound on the Cabo Frio Island: Marine reservoir effect in an upwelling region on the coast of Brazil

Macario

Alves

Chanca

et al. 2016

Quaternary Geochronology

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Section: Discussionsupporting

confidence: 85%

The Usiminas shellmound on the Cabo Frio Island: Marine reservoir effect in an upwelling region on the coast of Brazil

Macario

Alves

Chanca

et al. 2016

Quaternary Geochronology

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“…The samples for radiocarbon dating were chemically prepared and measured at the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF). Samples were calibrated through OxCal software (Bronk Ramsey, 2009) using the Marine13 curve and delta R 32 ± 44 (Alves et al, 2015). The terrestrial sample was calibrated using SHCal13 (Hogg et al, 2013).…”

Section: Methodsmentioning

confidence: 99%

Northeast Guanabara Bay and Coastal Plain Holocene Sedimentary Evolution (Brazil): A Contribution

et al. 2017

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Sedimentological and radiocarbon investigations are part of an ongoing research on the Bay-head delta of northeast Guanabara Bay, Rio de Janeiro State. Sediment accumulation indicates that the Holocene infill of the bay-head delta started around 8.2 kyr BP and was not in pace with the eustatic sea-level rise. Sediment accumulation was faster during the transgressive phase (0.56 cm.yr -1 ). However, during the regressive phase, progradation driven by baselevel fall was predominant over vertical sediment accumulation (0.02 cm.yr -1 ). Based on coring, three sedimentary units were defined: fluvial sands (U1), estuarine deposits (U2) and fluvial mud (U3).

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“…(Urey et al, 1951;Craig, 1957 Alves et al (2015). As alíquotas enviadas laboratório para datação representavam um todo da amostra, visto que era de extrema complexidade a separação dos tipos de cimento que as envolve.…”

Section: Petrografi a Isótopos Estáveis E Geocronologia Das Rochas Dunclassified

Petrography, Stable Isotops and Geochronology of Beachrocks from the Coastline of Rio de Janeiro State, SE Brazil

Malta

Castro

2018

Anuário IGEO UFRJ

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ResumoAs rochas de praia (beachrocks) marcam linhas de costa pretéritas e a constituição sedimentar de paleopraias. Em ambiente de micromarés definem com precisão a posição do nível médio do mar na ocasião do processo deposicional. No segmento central voltado para o quadrante sul do litoral do Estado do Rio de Janeiro foram identificadas diversas ocorrências de beachrocks entre a Ilha do Cabo Frio (Arraial do Cabo) e a Praia da Barra da Tijuca (Rio de Janeiro), entre a altitude de 1,5 m e a profundidade de -5,0 m. Nesse trabalho são apresentados novos dados petrográficos, isotópicos e geocronológicos envolvendo essas rochas. Foram identificadas em três categorias em relação ao ambiente de formação: (a) precipitação de calcita magnesiana decorrente de temperaturas elevadas da água do mar; (b) precipitação de calcita magnesiana a partir da mistura de água subterrânea com água do mar e (c) precipitação da calcita magnesiana da água capilar em sedimentos. Dados ao radiocarbono sugerem que os beachrocks foram litificados entre 11.940 -11.240 a 3130 -2860 cal anos AP. Este intervalo de tempo denota temperatura da água do mar mais elevada, favorecendo à precipitação da calcita magnesiana e a cimentação dos beachrocks. Palavras-chave: Petrografia de beachrocks; isótopos estáveis de δ 18 O e δ 13 C; cimentação e litificação em beachrocks; datações ao radiocarbono; variação do nível relativo do mar AbstractThe beachrocks mark a paleocoastline and its composition. In micro-tidal environments, they accurately define the position of the mean sea level at the time of the depositional process. In the central segment of Rio de Janeiro State shore, facing the south quadrant, were identified several occurrences of beachrocks between Cabo Frio Island (Arraial do Cabo) and Barra da Tijuca Beach (Rio de Janeiro), between the +1.5 m and depth of -5.0 m. In this study, new petrographic, isotopic and geochronological data were presented on these rocks. They were divided in three categories regarding the formation environment: (a) precipitation of magnesian calcite due to high seawater temperatures; (b) precipitation of magnesian calcite from the mixture of ground freshwater with seawater and (c) precipitation of magnesian calcite from capillary water in sediments. The radiocarbon data suggests that the beachrocks were lithified between 11,940 -11,240 to 3,130 -2,860 cal years BP. This time interval indicates a higher seawater temperature, favoring the precipitation of magnesian calcite and cementation of beachrocks.

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Radiocarbon reservoir corrections on the Brazilian coast from pre-bomb marine shells

Cited by 62 publications

References 27 publications

The Usiminas shellmound on the Cabo Frio Island: Marine reservoir effect in an upwelling region on the coast of Brazil

The Usiminas shellmound on the Cabo Frio Island: Marine reservoir effect in an upwelling region on the coast of Brazil

Northeast Guanabara Bay and Coastal Plain Holocene Sedimentary Evolution (Brazil): A Contribution

Petrography, Stable Isotops and Geochronology of Beachrocks from the Coastline of Rio de Janeiro State, SE Brazil

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