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Assessment of sea surface temperature changes in the Gulf of Cadiz during the last 30 ka: Implications for glacial changes in the regional hydrography
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Resumo(s)
New dinocyst analyses were conducted on
core MD99-2339 retrieved from the central Gulf of Cadiz.
Dinocyst and foraminiferal assemblages from this core are
combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the
last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas
and weaker upwelling cells during the Last Glacial Maximum (LGM) and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between the Gulf of Cadiz
and the NW Moroccan margin, and distinct species off Portugal, were observed during the cold climatic extremes that
punctuated the last 30 ka. This pattern has been linked to the
occurrence of a hydrological structure between SW Iberia
and Cadiz during the last glacial period, perhaps similar to
the modern Azores Front. This front was probably responsible locally for heterotrophic dinocysts found in the Gulf
of Cadiz during the last glacial period, even if this sector is
not conductive to upwelling phenomena by Ekman transport.
Regional reconstructions of paleo-sea-surface temperatures
(SSTs) using dinocyst and foraminiferal transfer functions,
as well as alkenones, are also discussed and depict coherent scenarios over the last 30 ka. Seasonal reconstructions
Correspondence to: A. Penaud
(aurelie.penaud@univ-brest.fr.)
of LGM SSTs obtained with this multi-proxy panel are discussed jointly with model outputs in order to contribute to
ongoing efforts in model-data comparison
Descrição
Palavras-chave
Dinocysts Gulf of Cadiz Planktonic foraminifera Micropaleontology Paleotemperature Last Glacial Maximum Abrupt climate change
Contexto Educativo
Citação
Editora
European Geosciences Union