Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania

The Eocene-Oligocene transition (between ca. 34 and 33.5 Ma) is the most profound episode of lasting global change to have occurred since the end of the Cretaceous. Diverse geological evidence from around the world indicates cooling, ice growth, sea-level fall, and accelerated extinction at this tim...

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Bibliographic Details
Published in:Geology (Boulder) 2008-02, Vol.36 (2), p.179-182
Main Authors: Pearson, Paul N, McMillan, Ian K, Wade, Bridget S, Dunkley Jones, Tom, Coxall, Helen K, Bown, Paul R, Lear, Caroline H
Format: Article
Language:English
Subjects:
Africa
algae
Cenozoic
Climate change
cores
Correlation analysis
East Africa
Eocene
Extinction
Foraminifera
geochemistry
Hantkeninidae
hemipelagic environment
Invertebrata
Kilwa Group
lower Oligocene
Marine
marine environment
marine sediments
mass extinctions
microfossils
nannofossils
Oligocene
paleo-oceanography
paleoclimatology
paleoecology
Paleogene
Paleontology
Plankton
Plantae
Protista
Sediments
stratigraphic boundary
Stratigraphy
Tanzania
Tertiary
upper Eocene
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Summary:The Eocene-Oligocene transition (between ca. 34 and 33.5 Ma) is the most profound episode of lasting global change to have occurred since the end of the Cretaceous. Diverse geological evidence from around the world indicates cooling, ice growth, sea-level fall, and accelerated extinction at this time. Turnover in the oceanic plankton included the extinction of the foraminifer Family Hantkeninidae, which marks the Eocene-Oligocene boundary in its type section. Another prominent extinction affected larger foraminifera, which resulted in the loss of some of the world's most abundant and widespread shallow-water carbonate-secreting organisms. However, problems of correlation have made it difficult to relate these events to each other and to the global climate transition as widely recorded in oxygen and carbon isotope records from deep-sea cores. Here, we report new paleontological and geochemical data from hemipelagic sediment cores on the African margin of the Indian Ocean (Tanzania Drilling Project Sites 11, 12 and 17). The Eocene-Oligocene boundary is located between two principal steps in the stable-isotope records. The extinction of shallow-water carbonate producers coincided with an extended phase of ecological disruption in the plankton and preceded maximum glacial conditions in the early Oligocene by ∼200 k.y.
ISSN:0091-7613
1943-2682
DOI:10.1130/G24308A.1