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| Titel |
A potential gradual buildup of Antarctic cryosphere in the Middle Eocene. |
| VerfasserIn |
P. K. Bijl, S. Schouten, H. Brinkhuis, A. Sluijs, G. Reichart, J. C. Zachos |
| 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 |
250024789
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| Zusammenfassung |
| Around the Eocene-Oligocene Boundary, large and permanent Antarctic ice sheets
developed, as a culmination of Eocene global climate cooling. However, uncertainties exist if
there were significant Antarctic continental ice prior to the Eocene- Oligocene boundary.
Traditionally, δ18O of benthic foraminifera, in combination with an independent temperature
proxy are used to gauge the extent of (Antarctic) ice volume in the Paleogene, but available
records are of short temporal range, low resolution, discontinuous and not well calibrated to
the International Time Scale. Here we generated a quasi continuous Paleogene sea surface
temperature (SST) record of the South Pacific by applying TEX86 paleothermometry to
sediments retrieved from the East Tasman Plateau (Ocean Drilling Project Leg 189, Site
1172, ~65ºS paleolatitude). Trends in South Pacific Paleogene SSTs remarkably mimic those
of the global stack record of Paleogene benthic foraminiferal δ18O, with values ranging
between ~34ºC during the Early Eocene Climatic Optimum (EECO) and ~21ºC in the
Paleocene and Middle and Late Eocene. Detailed comparison of the two records
shows an increasing ice volume effect on benthic δ18O from ~47 Ma onwards, ~14
Myrs prior to the Eocene-Oligocene glaciation. Comparisons of the East Tasman
Plateau Paleogene TEX86SSTs with coeval TEX86SSTs reconstructions from New
Zealand, Tanzania and the Arctic shows that equator-to-pole SST gradients were
remarkably low in the Early Eocene, and dramatically increased during the Middle
and Late Eocene, concurrently with the establishment of an Antarctic cryosphere. |
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