iMAGE-CREATE student Caroline Gini (MUN) reports from the Mid-Atlantic Ridge
“Arc en Sub” was co-led by Muriel Andreani (Université de Lyon) and Javier Escartin (Ecole Normale Superiéure). The cruise aimed to target the Rainbow Massif (36°14’N Mid-Atlantic Ridge) in order to obtain missing data that is key to constrain the interplay between magmatic, tectonic, metamorphic processes, and the contrasting end-member styles of hydrothermal activity, including their impact on ecosystems. The following is a blogpost from PhD candidate and iMAGE-CREATE student Caroline Gini that details her experience during this campaign aboard the Pourquoi Pas?.
Arc en Sub – PhD Candidate Caroline Gini (MUN)
This past May, I landed on Sao Miguel, an island in the Azores archipelago, in the middle of the North Atlantic Ocean, to board on the Pourquoi Pas?, the largest research vessel in the French oceanographic fleet (IFREMER). I joined a team of 21 scientists, led by Muriel Andreani (Université de Lyon) and Javier Escartín (Ecole Normale Supérieure), to explore the Rainbow Massif, a large submarine mountain at 36°N on the Mid-Atlantic Ridge.
The ultramafic Rainbow Massif is located in a non-transform offset which separates two spreading ridge segments, and hosts a hydrothermal system, with both active and inactive hydrothermal sites. The goals of the Arc-En-Sub cruise were to map the massif at <3 m resolution, document and investigate the distribution of hydrothermal activity, and constrain the associated heat source at depth.
To carry out these operations, we relied on several advanced deep-sea vehicles and instruments: an autonomous underwater vehicle (AUV) for mapping, a remotely operated vehicle (ROV) for exploration and sampling, and ocean bottom seismometers (OBS) to record seismic events. To acquire high-resolution bathymetric maps of the seafloor with the multi-beam echo sounder mounted on the AUV IdefX, the vehicle was “flown” at less than 100 m above the seafloor, an operation that requires meticulous planning, to avoid crashing into the seafloor and inadvertently collecting rock samples. After generating bathymetric maps of an area, we launched the Victor6000 ROV to visually explore the seafloor and collect rocks. During a typical ROV dive, 2 pilots steer the vehicle and operate the robotic manipulator arms and cameras, while 2 scientists log live observations and direct the scientific aspect of the exploration.
For my PhD, I am interested in acoustic techniques to explore the seafloor. Thus whilst on board, I worked on AUV operations, and data acquisition and processing, in collaboration with the AUV team. A typical day for me consisted of planning the next day’s AUV dive mission, processing and cleaning the bathymetric data of the previous AUV dive, generating a bathymetric map, and preparing a map for the subsequent ROV exploration dive.
It took less than a week for everyone to adapt to life on board and operations to run without any problems. You can never be bored at sea, there is always an exciting operation happening, or rock samples to describe and curate, and interesting people to talk to and learn from. The crew of the vessel made life on board very comfortable and were keen to learn about the science and share their knowledge of their vessel.
The Arc-En-Sub cruise was a success and will keep us busy for a while! I feel fortunate to have participated, and bring back many bathymetric maps, 2kg of rocks in my suitcase, a lot of knowledge and great memories. I thank my supervisors John Jamieson and Katleen Robert for supporting my participation, the cruise leaders for the invitation, the captain and crew of the Pourquoi Pas? and the AUV and ROV teams.
Follow #arc_en_sub on Twitter or go visit the cruise website (http://arcensub.ens.fr) for more information.