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Oliver Esper, Karin Zonneveld, Helmut Willems:
Reconstruction of Late Quaternary palaeoceanographic conditions in the South Atlantic Ocean based on calcareous dinoflagellate cysts
(Talk)

Despite the increasing interest in the S Atlantic Ocean as key area of the heat exchange between the Southern and Northern Hemispheres, information about its palaeoceanographic conditions during Late Quaternary glacial/interglacial cycles are not well understood. Here we attempt to increase this information by studying the calcareous dinoflagellate cysts and the shells of Thoracosphaera heimii (calcareous cysts) of six Late Quaternary S Atlantic Ocean cores. Generally, accumulation rates of calcareous cysts were increased during warmer periods due to higher cyst production. Extremely high accumulation rates in the transitions from glacials to interglacials (terminations) might be due to a combined effect of increased cyst production as the result of calm, oligotrophic conditions in the upper water-layers, and better preservation.

In contrast to the equatorial Atlantic Ocean, lower relative abundances of Sphaerodinella albatrosiana compared to Sphaerodinella tuberosa are observed in the Cape Basin. This may be the result of the relatively colder environmental conditions in this region compared to the equatorial Atlantic Ocean. S. tuberosa dominated the association during glacials and interglacials in the western tropical Atlantic Ocean. This might reflect decreased salinity in the upper water-layer.

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 [Division of Micropalaeontology] [Department of Geosciences] [Bremen University]

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