Contributions to South Atlantic paleoceanography in the last 25,000 years: evidence from calcareous nannofossils from northeastern brazilian slope / Nanofósseis calcários da margem continental nordeste do Brasil: uma contribuição à paleoceanografia do Atlântico Sul nos últimos 25.000 anos

AUTOR(ES)

Juliana Pereira de Quadros

DATA DE PUBLICAÇÃO

2007

RESUMO

This study focuses on changes in calcareous nannofossil assemblages as an evidence of paleoceanographic variability during the last 25,000 years in two deep sea piston cores from the northeastern Brazilian continental margin. To support reconstructing ancient marine environment others proxies have been applied along with the calcareous nannofossil analysis: 1) oxygen isotopic data from planktonic and benthic foraminiferstests; 2) temperature and nutrient indices; 3) paleoproductivity equation and 4) multivariate analysis. For the first time the temperature and nutrient indices were employed to Quaternary calcareous nannofossil from the South Atlantic Ocean. According to presented results major oceanographic features were stable in the last 25,000 years, although instable environmental conditions were recorded in the Last Glacial Maximum - Holocene boundary. During the Last Glacial Maximum the western tropical Atlantic seems to have experienced slight temperature changes and served as a heat and salt reservoir. Nutricline and thermocline depth variation was considered the most important response to climate changes largely related to Trade Winds strength oscillation.

ASSUNTO(S)

atlântico sul paleoceanography calcareous nannofossils paleoceanografia last glacial maximum - holocene. nanofósseis calcários Último máximo glacial-holoceno. south atlantic

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