4 Feb – East Scotia Ridge expedition blog – week 3

Laura Hepburn wrapped up warm and working on her sediment samples

RRS James Cook in transit to the South Sandwich Islands

We have finished our work in the Bransfield Strait and now have a three day passage to our next working area near the southern most South Sandwich Island, Thule.

Our route takes us north-east past Gibbs, Elephant and Clarence Islands on a beautiful sunny evening and then out into the Scotia Sea where we spot many more and different whales, seals and albatrosses.

The sediment sampling in the Central Basin of the Bransfield Strait has been very successful: 27 separate Megacore deployments into hydrothermal, volcanic and biogenic mud and a 4.5 m long sample of sulfidic sediment. Laura Hepburn is working on the different types of sediments we have collected for her PhD. Processing the mud onboard involves long hours in the controlled temperature laboratory where we keep the temperature as low as we can to simulate the conditions on the seafloor. The samples are all handled within a glove bag filled with nitrogen so they don’t oxidise and we extract the fluids as quickly as possible for analysis.

On board we analyse the composition of the extracted fluids and we can see the distinctive hydrothermal signal percolating up through the sediments at Hook Ridge. Laura will take these samples and analyse the metal and isotope content in Southampton to assess the turnover of these species at the various sites and relate this to the different biological communities present at the seafloor.

For more details on our voyage and links for Schools see www.thesearethevoyages.net/jc55.