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| Titel |
Multiproxy record to constrain sea surface temperature cooling across the greenhouse-icehouse transition in the Gulf of Mexico |
| VerfasserIn |
Bridget Wade, Willemijn Quaijtaal, Stefan Schouten, Alexander Houben, Kenneth Miller, Yair Rosenthal, Miriam Katz, Henk Brinkhuis |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036313
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| Zusammenfassung |
| Changes in temperature and/or ice volume associated with the Eocene-Oligocene transition
(EOT; ca. 34-33.5 Ma) have been controversial. Detailed reconstructions of marine
temperatures, particularly subtropical/tropical sea surface temperatures are critical to
determine climate forcing mechanisms and response with respect to the establishment of the
cryosphere during the EOT. Here we present high-resolution multiproxy sea surface
temperature records of foraminiferal Mg/Ca ratios and organic molecular TEX86 index. We
also reconstructed mean annual air temperatures (MAATs) using the organic molecular
MBT/CBT ratio from an expanded succession from St. Stephens Quarry, Alabama. We
constrain (sub)tropical sea surface temperatures in the latest Eocene and Oligocene and
address the issue of climatic stability during the EOT. These geochemical proxy records
are combined with bio-magneto and sequence-stratigraphic studies to constrain
the timing and magnitude of temperature and sea level change across the EOT.
Both Mg/Ca and TEX86indicate late Eocene sea surface temperatures of >32oC,
with a substantial cooling (4-6oC) across the EOT, and minimal temperatures of
27-28oC associated with the early Oligocene glacial maxima (Oi-1 event). There is a
significant reduction in sea surface temperatures and MAATs associated with the
precursor oxygen isotope shift in the latest Eocene during which MAATs decrease
from 28 to 22oC. Our data support that diminishing atmospheric CO2 levels were a
primary mechanism in Paleogene cooling and the expansion of the cryosphere. |
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