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| Titel |
Late Quaternary environmental and oceanographical change in the Mozambique Channel (east Africa): a palynological approach |
| VerfasserIn |
Willemijn Quaijtaal, Francesca Sangiorgi, Timme Donders, Henk Brinkhuis, The INATEX Group |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046113
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| Zusammenfassung |
| The southwestern Indian Ocean is greatly influenced by the Agulhas Current. At Cape
Agulhas eddies - so-called Agulhas rings - occasionally flow into the Atlantic Ocean, instead
of retroflecting into the Agulhas Return Current. This process is called Agulhas leakage. A
strong 100-kyr periodicity, related to the glacial-interglacial cycles, has been found in fauna
characterizing Agulhas leakage water. Agulhas leakage might therefore play an important
role in the termination of glacials, because its waters are warmer and more saline and
may influence the entire Meridional Overturning Circulation (MOC). However,
interacting oceanographical processes between Indian and Atlantic Ocean are still poorly
understood.
The Indian-Atlantic Exchange in present and past climate (INATEX) project aims to
elucidate this process and its effects on different spatial and temporal scales. During the
INATEX-GEO cruise (March 2009) several piston cores were retrieved from the
Mozambique Channel, where the Agulhas current originates. Preliminary analyses indicated
that core PE304-80 (~1200 cm long, ~1300 m water depth) is particularly interesting, since
it shows the longest and most continuous record, covering the last ca. 50,000 years (Marine
Isotope Stages 1-3) and contains expanded Last Glacial Maximum and Holocene
records.
We have performed a preliminary marine palynological study on this core as part of a
large multi-proxy study, involving a.o. isotope and organic and inorganic geochemistry. Our
study represents the first marine, late Quaternary palynological record available from this
area. By coupling information derived from pollen and spores (remains of terrestrial
vegetation) and dinoflagellate cysts (remains of unicellular marine planktonic organisms)
deposited in the same sediments we are able to simultaneously reconstruct the changes in the
terrestrial and marine environment through time.
From the Last Glacial Maximum onwards lagoonal euryaline environments where
mangroves grew developed, whilst further deglaciation and subsequent sea level rise into the
Holocene created more oligotrophic open water conditions. Our information, together with
that from other proxies, will eventually unravel the environmental (e.g., temperature,
salinity, productivity) changes occurred during the last 50,000 years, improving our
understanding of the links between climate change and water exchange between the
Indian and Atlantic Ocean, likely important for the entire (global) ocean circulation. |
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