29 January 2021: Two days of hydrothermal exploration

For two days, taking turns in shifts, three teams of three people simultaneously monitored two screens: one for bathymetry, the other for the water column to spot “bubbles”, signs of hydrothermal sources, without practically blinking an eye… On land, with the teams who could not embark, the same schedule: every hour, the files were processed, there were exchanges on possible suspicions, but after 2PM, no clear sign of hydrothermalism was observable. 

Following our daily meeting with the captain, and in view of the unfavourable weather conditions, we decided to stop everything to be able to make a station which was planned for the next day. All the hands on deck to deploy standard rosettes, clean rosettes and pumps! This station, which lasted 10 hours and is now called “stop-all”, reoccupies a station occupied 20 years ago during the SWIFT campaign. Basaltic debris and bivalve shells were found there. No such sign for us, but the Radium team measured particularly high radium-223 activity on the pump filter deployed near the bottom, a likely sign of hydrothermal activity. Exploration then continued for about ten hours and a break in the weather allowed us to redeploy the pumps and CTD rosette in the hope of obtaining more information. We will have to wait a few more months to see if this hydrothermal sign is found in our other samples…

We are now on our way to our next stop: the Marion Islands/Prince Edward.