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Global cooling accelerated by early late Eocene impacts?

Vonhof, H. B., Smit, J., Brinkhuis, H., Montanari, A. and Nederbragt, Alexandra J. 2000. Global cooling accelerated by early late Eocene impacts? Geology 28 (8) , pp. 687-690. 10.1130/0091-7613(2000)28<687:GCABEL>2.0.CO;2

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At Ocean Drilling Program Site 689 (Maud Rise, Southern Ocean), δ18O records of fine-fraction bulk carbonate and benthic foraminifers indicate that accelerated climate cooling took place following at least two closely spaced early late Eocene extraterrestrial impact events. A simultaneous surface-water productivity increase, as interpreted from δ13C data, is explained by enhanced water-column mixing due to increased latitudinal temperature gradients. These isotope data appear to be in concert with organic-walled dinoflagellate-cyst records across the same microkrystite-bearing impact-ejecta layer in the mid-latitude Massignano section (central Italy). In particular, the strong abundance increase of Thalassiphora pelagica is interpreted to indicate cooling or increased productivity at Massignano. Because impact-induced cooling processes are active on time scales of a few years at most, the estimated 100 k.y. duration of the cooling event appears to be too long to be explained by impact scenarios alone. This implies that a feedback mechanism, such as a global albedo increase due to extended snow and ice cover, may have sustained impact-induced cooling for a longer time after the impacts.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Uncontrolled Keywords: Eocene; meteorites; climate effects; ODP Site 689
Publisher: Geological Society of America
ISSN: 0091-7613
Last Modified: 04 Jun 2017 04:20

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