Resumo

LAPRIDA, Cecilia et al. Condicionantes ambientales de comunidades de foraminíferos bentónicos durante el pleistoceno medio en el Atlántico sudoccidental. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.3, pp.356-368. ISSN 0004-4822.

The southern South Atlantic is crucial in the distribution of deep water masses towards other ocean basins. Given the role of the thermohaline circulation in the climatic system, insights into its variations during glacial/interglacial cycles is of great interest. Benthic foraminifera are used in paleoceanographic reconstructions, tracking changes in deep oceanic circulation by means of the distribution of indicator species associated with certain water masses. However, the relationship between benthic foraminifera and water masses is controversial. A sediment core drilled at the North Atlantic Deep Water-Circumpolar Deep Water limit was surveyed for benthic foraminifera in order to determine whether assemblages reflect patterns of deep watermasses distribution during a Middle Pleistocene glaciation event. The assemblages recovered comprised species indicative of both water types, with Circumpolar Deep Water-indicator species being slightly more abundant due to Uvigerina peregrina dominance. In spite of this, the low abundance of other Circumpolar Deep Water-indicator species such as Globocassidulina subglobosa coupled with the evenness in the relative abundance of North Atlantic Deep Water indicator-species preclude the interpretation of Uvigerina peregrina’s dominance in terms of a greater influence of Circumpolar Deep Water at the expense of North Atlantic Deep Water. The latter species, also an indicator of high organic matter fluxes, increases its relative abundance jointly with those of Globigerina bulloides, which suggests that surface productivity influenced deep benthic foraminifera assemblages in the Buenos Aires talus during Middle Pleistocene glaciations.

Palavras-chave : Benthic foraminifera; Glacial South Atlantic; Middle Pleistocene.

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