Arctic dinoflagellate migrations mark the strongest Oligocene glaciations
- 1Historical Geology, University of Leuven, Redingenstraat 16, B-3000 Leuven, Belgium
- 2Department of Palaeoecology, Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, Netherlands
- 3Institute of Geology and Paleontology, J.W. Goethe University Frankfurt, Senckenberganlage 32-34, D-60054 Frankfurt, Germany
- 4Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth NS B2Y 4A2, Canada
- 5University of California–Santa Cruz, Earth Science Department, Santa Cruz, California 95064, USA
Abstract
Here we report on mid-Oligocene globally synchronous Arctic dinoflagellate migration events, calibrated against chron C9n. We show that sudden appearances and marked abundance increases of the Arctic taxon Svalbardella at lower and middle latitudes coincide with the Oi-2b benthic δ18O glacial episode, dated as ca. 27.1 Ma. These unprecedented migrations are taken to indicate anomalously strong surface-water cooling during Oi-2b time, in turn associated with strong concomitant Antarctic ice-sheet growth and sea-level lowering. We estimate the duration of these unique Svalbardella migrations and the associated episode of profound cooling as ∼500 k.y. Our records suggest a close link between this distinct Oligocene glaciation episode, strong sea-level fall, and the classic lower-upper Oligocene, or Rupelian-Chattian, boundary, dating this boundary as ca. 27.1 Ma.
- Oligocene
- dinoflagellate cysts
- migration
- global atmospheric cooling
- sea-level change
- Rupelian-Chattian boundary
Footnotes
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↵*stefaan.vansimaeysgeo.kuleuven.ac.be
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- Accepted 3 May 2005.
- Received 18 February 2005.
- Revision received 2 May 2005.
- Geological Society of America
