Modern sedimentation in the Cabo Frio upwelling system, Southeastern Brazilian shelf

Anais da Academia Brasileira de Ciências

Michel M. De Mahiques¹  Marcia C. Bícego¹  Ilson C.a. Silveira¹  Silvia H.m. Sousa¹  Rafael A. Lourenço¹  Marina M. Fukumoto¹ 

[1] ,Universidade de São Paulo Instituto Oceanográfico Departamento de Oceanografia Física, Química e GeológicaSão Paulo SP ,Brasil

关键词: sedimentation;    alkenones;    bulk organic matter;    upwelling;    Brazil;    South Atlantic;    sedimentação;    alquenonas;    matéria orgânica total;    ressurgência;    Brasil;    Atlântico Sul;   

DOI  :  10.1590/S0001-37652005000300013

来源: SciELO

【 摘 要 】

The analyses of Uk'37 paleotemperatures and sedimentological parameters in box cores from the Cabo Frio upwelling zone, southeastern Brazil, were used to understand the modern sedimentation as well as to evaluate the role played by the upwelling process in the sedimentary patterns. Three box-cores located closer to the upwelling area show a general trend of cooling waters taking place in the last 700 years. Since the present upwelling is dependent on local and remote wind regime, a phase of dominating NE winds favors a more effective upward transport of the cold thermocline level South Atlantic CentralWater towards the coast. The intensification in the upwelling regime for the last ca. 700 years can be associated with the strengthening of the NE winds off the area and a possible increase of the Brazil Current mesoscale activity. Nevertheless, the lack of significant correlation of the paleotemperatures and most of sedimentological parameters indicate that upwelling is not the only sedimentation mechanism in the area. Also, the comparison of sedimentological parameters reveals that eventual temporal changes are superimposed by the geographical variability. Sedimentation rates vary from 0.26 mm.yr-1 to 0.66 mm.yr-1.

【 授权许可】

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