February 6, 2017

Investigating sea ice and Bering Sea palaeoceanography during the middle Pleistocene global climatic shift

Elphidium batialis

Savannah Worne

The NERC Isotope Geoscience Facilities Steering Committee is an excellent opportunity for UK based researchers to apply for funding with which they can undertake stable isotope analyses at the NERC Isotope Geosciences Facilities (NIGF; http://www.bgs.ac.uk/sciencefacilities/nerc.html). Applying and being awarded this grant was an essential part of my PhD research and will provide a millennial-scale age model for the entire Mid-Pleistocene Transition (MPT; 0.6-1.2 Ma) at International Ocean Drilling Program Site U1343, which will underpin all subsequent data collected in the PhD project. Measurements will be made on multiple benthic foraminiferal species, using offsets to create a composite record. Our results will also be combined with previous data from this site to attain a continuous δ18O record of 1 kyr resolution. The final isotope record will be used to compare with global reference sections and define an age model.

The stable isotope age model funding by this grant will support key proxy analyses in this project, including sea ice (diatoms), productivity (opal), nutrient utilisation (δ15N), intermediate water properties (following the methodology of Knudson and Ravelo, 2015), salinity and stratification.  For example, previous work by Teraishi et al. (2013) successfully established the site U1343 diatom biostratigraphy, however results were limited by poor temporal resolution. The high resolution sea ice record (from diatoms) in this project will be used in conjunction with the isotope record to observe the pattern of sea ice development with glacial-interglacial cycles, to assess if sea ice responded to past climate changes in a predictable and linear way, or whether post-MPT sea ice expansion instead controlled termination of 100 ka glacial cycles through the “sea ice switch” mechanism of Gildor & Tziperman (2001).

Savannah Worne doing lab work

Overall, the financial support awarded by the NIGFSC is pivotal to the success and impact of this project. It will also assist with other palaeoenvironmental proxy work in this project and from wider Quaternary research from Expedition 323 in the Bering Sea.  In a wider context, this NIGFSC grant will also greatly increase the wider application and impact of this project to the both North Pacific and global palaeoceanographical research.  Furthermore, as part of the grant, I will receive a basic level of training from leading isotope scientists, which will support my future career ambitions to continue in research, as well as enable future collaboration with NIGF.