Control orbital de la dinámica de la surgencia de Perú durante los últimos 800 ka evidenciado por las asociaciones de Cocolitofóridos

Abstract

In order to analyze the surface water dynamics in the Peru upwelling system zone during the last 800 Ka, we studied the calcareous nannofossil content. The ODP site 1237 coccolith assemblage revealed two dominant taxa: «small» Gephyrocapsa and Florisphaera profunda. The «small» Gephyrocapsa abundance increased between 0,2 and 0,45 Ma allowing us to interpret a shallow nutricline consequent with a Trade wind intensification. Relative increases in the Florisphaera profunda abundance occurred between 0,86- 0,45 Ma and 0,20-0 Ma consistent with a deeper nutricline and weaker Trade winds. Spectral analyses in the Florisphaera profunda percentages show orbital frequences with peaks at 100, 41 and 23 Kys