Organic-walled dinoflagellate cyst biostratigraphy of the upper Eocene to lower Oligocene Yazoo Formation, US Gulf Coast

De Lira Mota, Marcelo Augusto; Harrington, Guy; Dunkley Jones, Tom

New data from a continuously cored succession, the Mossy Grove core, near Jackson, central Mississippi, recovered inline-formula∼137 m of marine clays (Yazoo Formation), spanning inline-formula∼5 Ma and including the critical Eocene–Oligocene transition (EOT) event. These clay-rich sediments yield well-preserved calcareous microfossil and palynomorph assemblages. Here, we present a new organic-walled dinoflagellate cyst (dinocyst) biostratigraphic framework, including the recognition of 23 dinocyst bioevents. These are integrated with new age constraints based on calcareous nannofossil biostratigraphy and a reassessment of the existing radiometric dates and planktonic foraminiferal biostratigraphy, permitting the establishment of a robust and significantly refined age model for the core. According to this new age model, a major increase in sedimentation rate – from inline-formula∼2.1 to inline-formula∼4.7 cm kyrinline-formula−1 – is observed at a core depth of inline-formula∼89.1 m (inline-formula∼34.4 Ma). In the new age model the section is significantly older than previously thought, by up to 1 Ma, with the Eocene-Oligocene boundary (inline-formula∼33.89 Ma) placed inline-formula∼34 m below the level previously identified. With these more accurate age estimates, future isotopic and palaeoecological work on this core can be more precisely integrated with other, globally distributed records of the EOT.

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De Lira Mota, Marcelo Augusto / Harrington, Guy / Dunkley Jones, Tom: Organic-walled dinoflagellate cyst biostratigraphy of the upper Eocene to lower Oligocene Yazoo Formation, US Gulf Coast. 2020. Copernicus Publications.

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Rechteinhaber: Marcelo Augusto De Lira Mota et al.

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