Paleoproductivity changes in the upwelling system of cabo frio (Rio de Janeiro State, SE - Brazil) during the last 4,000 years: evidence from geochemical signatures
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2004
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INTERNATIONAL SYMPOSIUM ENVIRONMENTAL GEOCHEMISTRY IN TROPICAL COUNTRIES, 4th
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Barium was first proposed as a proxy for paleoproductivity in sediments
of the equatorial Pacific, where high Ba concentrations were
correlated with organic carbon flux. Upwelling systems are
characterized by high pelagic productivity which may be observed in
bottom sediments. The coastal region of Cabo Frio in the Rio de
Janeiro State (~22°S) is a prominent site of seasonal upwelling.
Prevailing NE winds associated with bottorm topography enhance
upwelling of the colder and nutrient-rich South Atlantic Central Water
(SACW). A sediment core was collected in a mud bank in the area affected by the upwelling (water depth 115 m) and analyzed for U, Ba,
Sc through Neutron Activation analysis, S by an automatic CHNS
analyzer and the radiocarbon cronology was obtained by AMS. The
consistent pattern of Babiogenic records in Figure 1 suggest increase of
the Cabo Frio productivity during 2000 fi 3450 yr cal. BP. The absence of
sulphur enrichments and the decrease of uranium values supports that
sedimentation occured under oxygenated bottorm water condifions.
We infer that bottom water oxygen concentrations in the upwelling
Cabo Frio region were high enough to prevent extensive sulfate
reduction and the Ba remobilization. Consequentely our Babiogenic can
be used as a reliable paleoproductivity proxy.
Como referenciar
SILVA FILHO, E.V.; ALBUQUERQUE, A.L.S.; FIGUEIREDO, A.M.G.; ANDRADE, M.M.; SANTOS, I.R; SILVA, A.C.C.; TURCQ, B.; SIFEDDINE, A. Paleoproductivity changes in the upwelling system of cabo frio (Rio de Janeiro State, SE - Brazil) during the last 4,000 years: evidence from geochemical signatures. In: INTERNATIONAL SYMPOSIUM ENVIRONMENTAL GEOCHEMISTRY IN TROPICAL COUNTRIES, 4th, 25-29 Oct, 2004, Buzios, RJ. Abstract... p. 308-309. Disponível em: http://repositorio.ipen.br/handle/123456789/22554. Acesso em: 24 Mar 2026.
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