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Middle Eocene-late Oligocene climate variability: calcareous nannofossil response at Kerguelen Plateau, Site 748

Middle Eocene-late Oligocene climate variability: calcareous nannofossil response at Kerguelen Plateau, Site 748
Middle Eocene-late Oligocene climate variability: calcareous nannofossil response at Kerguelen Plateau, Site 748
A major deterioration in global climate occurred through the Eocene–Oligocene time interval, characterized by long-term cooling in both terrestrial and marine environments. During this long-term cooling trend, however, recent studies have documented several short-lived warming and cooling phases. In order to further investigate high-latitude climate during these events, we developed a high-resolution calcareous nannofossil record from ODP Site 748 Hole B for the interval spanning the late middle Eocene to the late Oligocene (~ 42 to 26 Ma). The primary goals of this study were to construct a detailed biostratigraphic record and to use nannofossil assemblage variations to interpret short-term changes in surface-water temperature and nutrient conditions. The principal nannofossil assemblage variations are identified using a temperate-warm-water taxa index (Twwt), from which three warming and five cooling events are identified within the middle Eocene to the earliest Oligocene interval. Among these climatic trends, the cooling event at ~ 39 Ma (Cooling Event B) is recorded here for the first time. Variations in fine-fraction ?18O values at Site 748 are associated with changes in the Twwt index, supporting the idea that significant short-term variability in surface-water conditions occurred in the Kerguelen Plateau area during the middle and late Eocene. Furthermore, ODP Site 748 calcareous nannofossil paleoecology confirms the utility of these microfossils for biostratigraphic, paleoclimatic, and paleoceanographic reconstructions at Southern Ocean sites during the Paleogene.

Eocene, Oligocene, Nannofossils, Stable isotopes, Paleoclimatology
0377-8398
173-192
Villa, G.
85aa5759-a512-4e15-808e-ac20b94d3e14
Fiorini, C.
f13f1aa2-cb25-40e9-966c-62e0363a7159
Pea, L.
0a157f5b-c2f6-42bd-ae94-9066d285e1a3
Bohaty, S.
af9dbe78-8b9f-44f2-ba1d-20795837d2d1
Persico, D.
52019e38-cb36-4149-ba2c-a78b87126068
Villa, G.
85aa5759-a512-4e15-808e-ac20b94d3e14
Fiorini, C.
f13f1aa2-cb25-40e9-966c-62e0363a7159
Pea, L.
0a157f5b-c2f6-42bd-ae94-9066d285e1a3
Bohaty, S.
af9dbe78-8b9f-44f2-ba1d-20795837d2d1
Persico, D.
52019e38-cb36-4149-ba2c-a78b87126068

Villa, G., Fiorini, C., Pea, L., Bohaty, S. and Persico, D. (2008) Middle Eocene-late Oligocene climate variability: calcareous nannofossil response at Kerguelen Plateau, Site 748. Marine Micropaleontology, 69 (2), 173-192. (doi:10.1016/j.marmicro.2008.07.006).

Record type: Article

Abstract

A major deterioration in global climate occurred through the Eocene–Oligocene time interval, characterized by long-term cooling in both terrestrial and marine environments. During this long-term cooling trend, however, recent studies have documented several short-lived warming and cooling phases. In order to further investigate high-latitude climate during these events, we developed a high-resolution calcareous nannofossil record from ODP Site 748 Hole B for the interval spanning the late middle Eocene to the late Oligocene (~ 42 to 26 Ma). The primary goals of this study were to construct a detailed biostratigraphic record and to use nannofossil assemblage variations to interpret short-term changes in surface-water temperature and nutrient conditions. The principal nannofossil assemblage variations are identified using a temperate-warm-water taxa index (Twwt), from which three warming and five cooling events are identified within the middle Eocene to the earliest Oligocene interval. Among these climatic trends, the cooling event at ~ 39 Ma (Cooling Event B) is recorded here for the first time. Variations in fine-fraction ?18O values at Site 748 are associated with changes in the Twwt index, supporting the idea that significant short-term variability in surface-water conditions occurred in the Kerguelen Plateau area during the middle and late Eocene. Furthermore, ODP Site 748 calcareous nannofossil paleoecology confirms the utility of these microfossils for biostratigraphic, paleoclimatic, and paleoceanographic reconstructions at Southern Ocean sites during the Paleogene.

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More information

Published date: October 2008
Keywords: Eocene, Oligocene, Nannofossils, Stable isotopes, Paleoclimatology

Identifiers

Local EPrints ID: 63841
URI: http://eprints.soton.ac.uk/id/eprint/63841
ISSN: 0377-8398
PURE UUID: 9c3889a7-560b-4381-b5b6-f471fc368dcb
ORCID for S. Bohaty: ORCID iD orcid.org/0000-0002-1193-7398

Catalogue record

Date deposited: 07 Nov 2008
Last modified: 16 Mar 2024 03:52

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Contributors

Author: G. Villa
Author: C. Fiorini
Author: L. Pea
Author: S. Bohaty ORCID iD
Author: D. Persico

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