ADSR - Azores Deep-Sea Research

CRUISES / L’Atalante 2018

Luso Hydrothermal Vent-field 2018

Summary Show more ↓

Following the discovery of the Luso hydrothermal field during the scientific Blue Azores 2018 expedition that took place in May and June, a follow up one day scientific sampling mission as part of the TRANSECT scientific campaign onboard the ship RV L'Atalante took place on August 4th. The mission was coordinated by Telmo Morato, chief scientist of the deep water exploration of the Blue Azores expedition, in close collaboration with Nadine Le Bris, chief scientist of TRANSECT scientific campaign. The Portuguese team participating in the mission was composed of 4 scientists with different expertise in research areas of hydrothermal vents (e.g., geology, chemistry, ecology, microbiology) and the chief pilot of the Portuguese ROV Luso from EMEPC.

Statistics

Transits

233 km

Multibeam Bathymetry

0 km²

Filmed Seabed

1 km

Visited Areas

Stations

Dives

Video Footage Recorded

4.5 hours

Used Storage

.12 Tb

Samples

Several samples were collected with the ROV Victor 6000, namely 16 biological samples for taxonomy and genetic analyses, 7 geological samples, and several vent fluids, gases and water samples, along with in situ measurements of temperature, pH, Eh and H2S.

Highlights

All three areas were successfully visited and sampled with the ROV Victor 6000 during a 4.5 hours dive.
Samples of vent fluids and gases (e.g., methane, sulphur, carbon dioxide, hydrogen, iron and other trace metals) were collected using the VICTOR fluid sampler (PEP) and in situ measurements of physical-chemical variables were made with the ROV sensors (temperature, pH, Eh and H2S) in vent orifices of the main and secondary venting areas and in the vicinity of surrounding fauna.
In situ seawater filtration was further conducted for measurements of particulate organic matter in the different venting areas visited.
Temperature in the large and the secondary venting areas was low (<100 °C). Preliminary onboard analysis of venting fluids indicates high levels of iron in all active areas sampled and low pH.
Observations of orange-red precipitates rimming the vent orifices and covering the chimneys suggest likely formation by the deposition of iron and manganese oxyhydroxides further suggesting the iron as a dominant element of this vent system.
Geological samples were taken from the large chimney, a small active chimney in the secondary venting area, inactive chimneys, and pillow basalts in the vicinity of the vent field for mineralogical and geochemical characterization of the chimneys and determination of the age of the vent system.