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| Titel |
Deep-sea ecosystem response to the Middle Eocene Climate Optimum (MECO) in
the North Atlantic Ocean |
| VerfasserIn |
Dorothea Bunzel, Gerhard Schmiedl, Oliver Friedrich |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129734
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| Publikation (Nr.) |
 EGU/EGU2016-9886.pdf |
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| Zusammenfassung |
| We investigated the benthic foraminiferal diversity and species composition from North
Atlantic IODP Site U1408 in order to document changes in deep-water circulation and
organic matter fluxes across the Middle Eocene Climate Optimum (MECO). Site U1408 was
drilled at a present water depth of 3022 m southeast of the coast of Newfoundland. The
benthic foraminiferal faunas are characterized by generally high species diversity
suggesting favorable environmental conditions throughout the studied interval.
Among a total of 193 benthic foraminiferal taxa the most dominant genera include
Nuttallides, Oridorsalis, Cibicidoides, Pullenia, Anomalinoides, Globocassidulina
and Gyroidinoides. Increased abundances of elongate-cylindrical infaunal species
suggest approximately 460 ka duration of the MECO (from around 40.19 to 39.73
Ma) and the presence of slightly less ventilated bottom waters and elevated food
availability during this time interval. The duration of the MECO also coincides
with the presence of the planktonic foraminifer Orbulinoides beckmanni, which
therefore is used as an Eocene biostratigraphy marker defining the end of the warm
interval with its Last Appearance Datum. Changes in the benthic foraminiferal fauna
probably reflect the onset of deep-water formation in the northern North Atlantic
Ocean as response to the long-term climatic cooling trend of the middle Eocene. The
intensification of deep-water currents and increased influence of cold and well-ventilated
deep-water masses is reflected by increased importance of the Nuttallides truempyi-fauna.
Superimposed on this long-term faunal trend are changes in the distribution of
Globocassidulina subglobosa at a period of approximately 200 ka suggesting an
eccentricity forcing of deep-water formation and associated food quality at the sea floor. |
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