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| Titel |
New cores-top Mg/Ca calibration of multiple benthic foraminiferal species: Thermometry of the thermocline water in Tropical western Atlantic |
| VerfasserIn |
A. Tisserand, T. Dokken, V. Scao, F. Jorissen, C. Fontanier |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022561
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| Zusammenfassung |
| A cruise with the research vessel G.O. SARS was carried out from 07 to 20 December 2007
within the framework of the European Science Foundation (EuroMARC) project RETRO,
which aims to reconstruct changes within the thermocline in the tropics during periods of
reduced Meridional Overturning Circulation (MOC). As part of this strategy we need a best
possible calibration of methods to reproduce water mass properties, and part of
the goal of this cruise was to get a good representation of the thermocline area
present at the Brazilian Atlantic margin. The method used to map the thermocline
gradient in the western tropical Atlantic is to use the concept of Magnesium/Calcium
(Mg/Ca) on bottom water living foraminifera as a representation of temperature at
site. The Mg/Ca thermometry on deep-dwelling foraminifera calibrated vs. δ18O
measurements provides an estimate of depth of thermocline penetration in modern
climate. Knowing the function of modern representation of the thermocline defined by
Mg/Ca, we can use this concept to map thermocline deepening/shallowing in the
past.
The Mg/Ca ratios in benthic foraminiferal calcite are considered as the most commonly used
and a reliable paleo-proxy for reconstructing bottom-water temperatures. Mg/Ca ratios of
thermocline and deep-dwelling benthic foraminiferal species were determined on cores-top
samples from a depth transect from the western tropical Atlantic, spanning a depth range of
600 to 1000 m representing a temperature range of 6 to 4 |
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