|Autosub 6000 being launched from the RRS James Cook to undertake a|
24 hour multibeam, sidescan sonar and sub-bottom profile survey.
Some of the E-tech elements are highly concentrated in hydrogenous ferromanganese (Fe-Mn) crusts, which develop on oceanic seamounts. The MarineE-tech study area is located in the north-east tropical Atlantic, about 650 km south of the Canary Islands (about 2 days sailing on the RRS James Cook), and at the south-west end of the Canary Island Seamount Province. The islands and more than 100 seamounts, which extend over a distance of some 1000 km form one of the most significant volcanic provinces in the Atlantic Ocean. Our research focuses on the Tropic Seamount, the southernmost in the archipelago (23.5° N, 20.4° W). Tropic Seamount has an area of about 770 square kilometres, comparable to the Island of Anglesey in North Wales. Previous, limited work has identified Fe-Mn crusts on this and a number of the other seamounts to the south of the Canary Islands.
|New ship-board multibeam swath bathymetry acquired over Tropic Seamount|
that will be used to select areas for detailed follow-up mapping and sampling
The primary objective of the first ROV dive was deploy a seafloor lander platform on the summit of the seamount. This has been designed by HR Wallingford, with the objective of collecting time series data on the hydrographic regime and sediment movement in the water column across the seamount. During the cruise we plan to generate sediment plumes (in an attempt to simulate potential disturbance associated with seafloor mining) on the seafloor by sucking up pelagic sediment with the ROV and blowing it into the water column. The movement of the sediment plume will be monitored for several hours by a range of sensors on the lander and compared with results of previous modelling. Additional hydrographic data will be obtained from three moorings that we have strategically positioned across the seamount. When we recover these at the end of the cruise they will have been deployed for at least 30 days, and provide a time series dataset on currents, temperature and conductivity (which can be corrected with temperature to give salinity) of the water column around the seamount. Additional data on the water column is being collected by numerous CTD deployment (we have undertaken 16 to date), which measure conductivity, temperature and depth (pressure), and can collect water samples for subsequent analysis.
|From L-R: Manipulator arm of ROV Isis holding a tube from the sediment pump and generating a plume in the water column|
to be detected by the lander; Seafloor lander placed on the seabed ready for monitoring and testing of plume.
Co-Chief Scientist JC142