Follow the AMARYLLIS- AMAGAS sea expedition of geologists from the GEOAZUR laboratory

  • Research
Published on May 17, 2023 Updated on July 4, 2023

on the May 17, 2023


An oceanographic campaign led by two researchers from the GEOAZUR laboratory was carried out off the coast of French Guiana, finishing on June 11, 2023. The AMARYLLIS-AMAGAS campaign is aiming to determine the presence of gases in submarine sediments and their impacts on giant submarine landslides. Université Côte d'Azur made it possible to follow the expedition day by day thanks to a dedicated blog.

The scientific team of the AMARYLLIS-AMAGAS campaign boarded the research vessel Marion Dufresne, the largest vessel of the French Oceanographic Fleet, in Bridgetown on the island of Barbados. The campaign was divided into two parts (legs). Leg 1 ran from May 17 to June 11; it ended in Paramaribo, Suriname. There, the scientific teams changed and leg 2 took place from June 12 to July 3. 

Multidisciplinary research

The AMARYLLIS-AMAGAS campaign is the result of the merger of two complementary research projects, AMARYLLIS and AMAGAS. These projects are based on the close collaboration of dozens of scientists and engineers working at universities and public research institutes in France and Brazil, as well as in Sweden and Germany. The official language of the campaign is English. The research to be carried out is multidisciplinary and relies in particular on sedimentology, geochemistry, stratigraphy, geophysics and geotechnics. 

Leg 1 was organized by Daniel Praeg, contract researcher at CNRS, and Sébastien Migeon, professor at Sorbonne University, both specialists in marine geosciences and attached to the Géoazur laboratory (Université Côte d'Azur – CNRS – IRD – Côte d'Azur Observatory). 

 During leg 1, the scientific team focused on two main themes:
•    The presence of gases in submarine sediments: what are the compositions of these gases? Where do they come from and how did they form? How do they rise to the surface of the seabed? What geological structures do they form? The geochemists on board particularly want to be able to collect gas hydrates, methane trapped in an ice shell, but more about that later.
•    The impact of gas on the triggering of giant submarine landslides (volume > 1000 km3): How does gas change the "cohesion" of submarine sediments? What are the environmental conditions that promote landslides? This is of particular interest to the ANR MEGA project, which involves many of the participants in leg 1.

Teams in action 24 hours a day

Team AMARILLYS To try to answer all these questions, the scientific team and the crew of the R/V Marion Dufresne took turns 24 hours a day during the 27 days of leg 1. They measured the depth of the sea floor (bathymetry) to observe the submarine "landscapes", they imaged the superposition of sediment layers deposited under the sea floor (sediment echo sounder), they took many sediment cores of lengths from 20 m to over 50 m, they measured temperature variations in the sediments (heat flow). Processing of all this data began on board. In particular, sediment cores were opened and analyzed using many tools present on the R/V Marion Dufresne. The analysis of the data will then continue for the coming months and years in the participants' respective laboratories, once the cores have been returned to dry land.