Age calibration of dinoflagellate cyst and acritarch events in the Pliocene-Pleistocene of the eastern North Atlantic (DSDP Hole 610A)
De Schepper, S.; Head, M.J. (2008). Age calibration of dinoflagellate cyst and acritarch events in the Pliocene-Pleistocene of the eastern North Atlantic (DSDP Hole 610A). Stratigraphy 5(2): 137-162
In: Stratigraphy. Micropaleontology Press: New York. ISSN 1547-139X, meer
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| Auteurs | | Top |
- De Schepper, S., meer
- Head, M.J.
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| Abstract |
An independently calibrated record of dinoflagellate cyst and acritarch events is presented for the Early Pliocene through Middle Pleistocene (ca. 4.0–0.5 Ma) of eastern North Atlantic Deep Sea Drilling Project (DSDP) Hole 610A. A new age model is established for this hole and tied to marine isotope stratigraphy and magnetostratigraphy back to 3.6 Ma. New data on the range of the calcareous nannofossil Reticulofenestra pseudoumbilicus indicate that the base of this hole is about 1.0 Myr younger than previously thought. A diverse dinoflagellate cyst and acritarch record allows the significant highest and/or lowest occurrences of 19 dinoflagellate cyst and seven acritarch taxa to be recognised in Hole 610A and calibrated to the latest astronomically-tuned Neogene time scale (ATNTS 2004) via our new age model. Comparing records across the North Atlantic and Mediterranean reveals near-synchronous highest occurrences of the dinoflagellate cysts Ataxiodinium confusum (2.63–2.65 Ma), Invertocysta lacrymosa (2.72–2.74 Ma in the eastern and central North Atlantic and Mediterranean) and Impagidinium solidum (ca. 3.15–3.17 Ma), and the acritarch Leiosphaeridia rockhallensis (ca. 3.83–3.88 Ma). Highest occurrences of the dinoflagellate cyst Batiacasphaera minuta/micropapillata (3.83–ca. 3.7 Ma) and acritarch Cymatiosphaera latisepta (2.49–2.63 Ma) also provide useful markers for correlation. A precise stratigraphy for Hole 610A allows us to evaluate the impact of paleoceanographic and climatic events on the dinoflagellate cyst record. Climatic and oceanographic reorganizations associated with the onset of Northern Hemisphere glaciation appear responsible for the disappearance of many species between 2.8 and 2.6 Ma. The lowest occurrence of Impagidinium cantabrigiense (1.86 Ma) in the Olduvai Subchron is one of the few good biostratigraphic markers for the uppermost Gelasian in Hole 610A. |
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