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| Titel |
Employing δ44â40Ca ratios in foraminifera to simultaneously track sea surface regional temperatures (SST) and salinities (SSS) variations across Termination I |
| VerfasserIn |
Christian Horn, Anton Eisenhauer, Dirk Nürnberg |
| 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 |
250053095
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| Zusammenfassung |
| Previous studies of coupled Mg/Ca and δ18O time series measured at planktic foraminifera
across Termination I have shown that the planktonic Mg/Caforam signal leads the δ18Oforam
in tropical settings by several thousand years [1,2,3]. This implies that the tropical ocean
must have warmed before the melting of Northern Hemisphere. Latter observation
challenges the role of the North Atlantic as the driving force of glacial/interglacial
transitions emphasising the tropical ocean as an important area triggering global climate
changes.
In order to test this hypothesis a multi-proxy approach of coupled δ44-40Ca, Mg/Ca and
δ18O measurements on G.sacculifer was applied. The goal is to decouple global and regional
influences of SST, SSS and ice volume on the three proxie records. In order to extract
regional signals the study was performed on sediments along a south-north transect from the
Central Caribbean Sea (SO 164-03-4) via the Blake Outer Ridge (ODP 1058c) to high
northern latitudes.
Our findings indicate the presence of a phase shift in the timing of the glacial/interglacial
temperature transition in the Caribbean between the Mg/Ca and δ18O signals in the
order of ~3500 years in accordance with previous observations [2,3]. However, our
interpretation of the origin of the phase shift is different to earlier understandings since it´s
occurrence coincides with salinity variations reflecting a climatic driven change of the
evaporation/precipitation ratio at the site of the sediment core SO164-03-4. Latter variations
are most likely driven by a northward movement of the Inner Tropical Convergence Zone
(ITCZ). In contrast to the observations from the Caribbean no salinity driven phase shifts
between proxies exist in the sediments from North Atlantic. We interprete these
observation that all sediments located within the influence of the ITCZ show salinity
driven phase shifts across Termination I between δ18O and other temperature proxie
records.
[1] Lea et al.(2000) Science 289, 1719-1724
[2] Nürnberg et al. (2000) Paleoceanography 15 (1), 124-134
[3] Visser et al. (2003) Nature 421, 152-155 |
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