Major shifts in calcareous phytoplankton assemblages through the Eocene-Oligocene transition of Tanzania and their implications for low-latitude primary production

• Main Authors: Dunkley Jones, T, Bown, PR, Pearson, PN, Wade, BS, Coxall, HK, Lear, CH
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER GEOPHYSICAL UNION 2008
• Subjects: Indian-ocean; Atlantic-ocean; Eocene/oligocene boundary; Antarctic glaciation; Earliest oligocene; Coastal Tanzania; Thermal maximum; Stable-isotope; Climate-change; Nannofossil assemblages; Antarctic; Indian; Antarc*
• Online Access: https://discovery.ucl.ac.uk/id/eprint/174931/2/2008PA001640.pdf; https://discovery.ucl.ac.uk/id/eprint/174931/

A high-resolution record of exceptionally well preserved calcareous nannofossil assemblages from Tanzania is marked by two key transitions closely related to the climatic events of the Eocene-Oligocene transition (EOT). The first transition, at similar to 34.0 Ma, precedes the first positive shift in delta O-18 and coincides with a distinct interval of very low nannofossil abundance and a cooling in sea surface temperatures (SST). The second, at similar to 33.63 Ma, is immediately above the Eocene-Oligocene boundary (EOB) and is associated with a significant drop in nannofossil diversity. Both transitions involve significant reductions in the abundance of holococcoliths and other oligotrophic taxa. These changes in calcareous phytoplankton assemblages indicate (1) a widespread and significant perturbation to the low-latitude surface ocean closely tied to the EOB, (2) a potential role for reduced carbonate primary production at the onset of global cooling, and (3) a significant increase in nutrient availability in the low-latitude surface ocean through the EOT.