EGU2020-8765, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Pleistocene shifts of the Subarctic Front in the North Pacific: Evidence from planktonic foraminiferal proxy data

Lara Jacobi1, Dirk Nürnberg1, Weng-si Chao2, Ralf Tiedemann2, Lester Lembke- Jene2, Mariem Saavedra Pellitero3, Thomas Frederichs4, and Tilo von Dobeneck4
Lara Jacobi et al.
  • 1GEOMAR - Helmholtz Centre for Ocean Science Kiel, Kiel, Germany (
  • 2Alfred-Wegner-Institute - Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 3School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
  • 4MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, Germany

The North Pacific plays a key role in shaping the Earth’s climate, yet there still is a lack in understanding the complex interplay of atmosphere and ocean, and their respective circulation patterns reacting to a varying Pleistocene climate. Proxy records established on marine sediment core SO264-28-2, recovered from the Emperor Seamount Chain (Suiko Seamount; ~45°N, close to the Subarctic Front) during R/V SONNE Cruise SO264 in 2018, allow to reconstruct changes of surface and subsurface water masses in order to provide unique insight in spatial and temporal shifts of North Pacific Subarctic vs. Subtropical gyres. According to the preliminary age model based on radiocarbon dating, benthic oxygen isotopes, combined magneto-, tephra- and biostratigraphical approaches, the only 7 m long core covers the last ~1.35 Myr. This core was chosen due to its highly characteristic pattern in magnetic susceptibility and a prominent lithological change from carbonate oozes to more siliciclastic sediment sequences at ~1.2 Ma. Thus, numerous other cores from the study area can be correlated with it suggesting this core as a reference record for the North Pacific.

A continuous and synchronous cooling of both surface and subsurface ocean temperatures since ~1.35 Ma changed rapidly at 1.2 Ma to a continuous warming surface from <4 °C to ~ 8 °C while subsurface temperature remained constant below 4 °C. The long-term diverging temperatures and increasing salinities at both surface and subsurface point to the continuous northward displacement of the Subarctic Front and an increased influence of the North Pacific Tropical Water at Suiko Seamount, with most prominent, millennial-scale, changes of the gyre system and the related Kuroshio Current during interglacials. Around ~430 ka, the influence of warm and saline subtropical surface water masses declines, reflected by a rapid decrease of sea surface temperatures of 4-5 °C and a salinity inversion, whereby the subsurface water mass becomes more saline than the surface water. After ~430 ka, interglacials are very pronounced and with the prominent presence of low saline and cooler surface waters, conditions are similar to present.

How to cite: Jacobi, L., Nürnberg, D., Chao, W., Tiedemann, R., Lembke- Jene, L., Saavedra Pellitero, M., Frederichs, T., and von Dobeneck, T.: Pleistocene shifts of the Subarctic Front in the North Pacific: Evidence from planktonic foraminiferal proxy data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8765,, 2020

This abstract will not be presented.