3D bathymetry image of the Von Damm Vent Field.Image courtesy of the University of SouthamptonCollaborating with colleagues at the National Oceanography Centre, the team has revealed active vents in the Von Damm Vent Field (VDVF) that are unusual in their structure, formed largely of talc, rather than the more usual sulphide minerals.

Lead researcher Matthew Hodgkinson, co-supervised by Professor Steve Roberts, analysed samples from the VDVF–a vent field south of the Cayman Islands discovered by scientists and crew on board the RRS James Cook in 2010. Results of the analysis are now published in the journal Nature Communications.

Matthew comments: “This vent site is home to a community of fauna similar to those found at the Mid-Atlantic Ridge in the Atlantic Ocean, but the minerals and chemistry at the Von Damm site are very different to any other known vents.”

Steve Roberts commented: “The discovery of this new class of vent system serves to demonstrate our limited understanding of the ocean floor and the importance of and role for ‘discovery science’ in the oceans.”

Main vent at the Von Damm Vent Field.Image courtesy of the University of SouthamptonHydrothermal vents form in areas where the Earth’s tectonic plates are spreading. At these sites, circulating seawater is heated by magma below the seafloor and becomes more acidic – leaching metals from the surrounding rocks and redepositing them as the hot water spews out of vents or ‘chimneys’ at the seabed and hits the cold seawater.

The scientists have also found the VDVF system has a very energetic heat flux (the amount of energy it emits into the surrounding ocean) of around 500 megawatts. This is much more than would be expected since the VDVF, on the slopes of an underwater mountain and away from a large magma supply, is on the edge of a spreading area and not in between two separating tectonic plates. The unusual positioning of this new vent field suggests that other similar ones elsewhere in the world may have been overlooked.

Matthew Hodgkinson adds: “If more of these unusual sites exist they could be important contributors in the exchange of chemicals and heat between the Earth’s interior and the oceans, and may be missing from current global assessments of hydrothermal impact on the oceans.”

Ocean and Earth Science at Southampton