Rocks
This team will prepare, analyse and identify rock and mineralization samples made with the rock dredge or during dives of the manned submersible Nautile. They will determine the site and profile of dredging and participate in preparing Nautile’s diving routes according to the objectives of the mission and the researched data: nature of rocks on the ocean bed, research and sampling of identified or speculative hydrothermal sites, mineralization composition, possible links between rock types and structures, geological sections, etc.
The rocks from the dredge are sorted on the deck according to their nature: type of rock, texture of minerals, deformed or not, degree of freshness or alteration, etc. A representative sample of each facies is selected and referenced for further study.
During a nautical dive, the onboard scientist selects the type of samples to be made according to the environment as well as the objectives of the dive, taking care to note their exact position and describe the environment of the sampling sites. These descriptions can be correlated to the videos and photographs taken during the dives. A number is assigned to each of these samples which scientists will refer to for analysis or in their future publications. Similarly, once on land and archived, the samples will be automatically registered with an International Geo Sample Number (IGSN) .
Rock samples and mineralization are then described, photographed and cut-up into sub-samples with a diamond saw device:
- fragments the size of sugar for on-shore polished and thin sections for petrological and mineralogical studies.
- a portion is ground for preliminary, onboard X-ray analysis of chemical and mineralogical composition. The preparations will be stored and reused for more accurate analysis once back in the lab.
- a reference sample is kept and will be added to the rock and mineralization collections of the CREAM rock and core archive centre at Ifremer in Brest. These samples are testimony to previous expeditions and can be re-studied by future generations of scientists.
All sampling and analysis operations are recorded in a database and georeferenced on maps.
- Ewan Pelleter, co-chief scientist, researcher and specialized metallogenist in oceanic mineralization, Ifremer
- Audrey Boissier, geochimist, X-ray chemical composition analysis and sample preparation, Ifremer
- Sandrine Chéron, geochimist, preparation of samples and X-ray analyses of mineralogical composition, Ifremer
- Florian Besson, geologist, Ifremer
- Mathieu Rospabe, geologist specializing in petrology and geochemistry of rocks of the oceanic lithosphere, Ifremer
- Mickael Rovere, thin-section technician, sample preparation and referencing, Ifremer
- Léa Grenet, PhD student specialised in the construction of neo-volcanic zones in a context of low-magmatic contribution, University Bretagne Occidentale