Two graphs from the paper.
Opal flux and barium (Ba) excess record of Sites 885/886. Both records show a big shift starting 3.6 million years ago with decrease productivity indicated by the opal record and decrease in export productivity indicated by the excess Ba (i.e., Ba not accounted for in the lithogenic component). Credit: Abell and Winckler [2023], Figure 3(b,c)
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: AGU Advances

In a new study, Abell and Winckler [2023] report that biological activity in the central subarctic North Pacific experienced elevated export productivity during the late Miocene. These findings are based on drill cores from ODP (Ocean Drilling Program) sites 885 and 886. This study is one of the few in the North Pacific with accurate age dating using extraterrestrial He, high Ba/Sc ratio, high fraction of opal or diatomatic ooze and decrease Fe-Mn minerals. Combined with previously published drill core data from the northwest and northeast, the authors present evidence for the formation of North Pacific Deep Water, which would have resulted in Pacific meridional overturning circulation (PMOC) similar to the Atlantic meridional overturning circulation (AMOC) that started to weaken at approximately 3.6 million years ago, then resulting in the present-day circulation.

Citation: Abell, J. T., &  Winckler, G. [2023].  Long-term variability in Pliocene North Pacific Ocean export production and its implications for ocean circulation in a warmer world. AGU Advances, 4, e2022AV000853.

—Vincent Salters, Editor, AGU Advances

Correction, 7 September 2023: The title and subtitle were revised to better reflect the findings of the study.

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