The Mohn’s ridge is a seafloor spreading ridge, separating two oceanic plates, and the deposits could include important industrial metals such as copper, zinc, cobalt, nickel, vanadium, wolfram and silver.
The Norwegian Petroleum Directorate (NPD) surveyed an area of 90 x 35 kilometers (56 x 22 miles) centrally located over the spreading ridge, where water depths vary between 1,200 and 3,500 meters (3,900 and 11,500 feet). The expedition was conducted with Swire Seabed's Seabed Worker. Mapping was carried out using an autonomous underwater vehicle, a Kongsberg Hugin AUV, which mapped the seabed in long corridors, totaling 750 kilometers (466 miles). The AUV was equipped with several sensors, including seabed penetrating echo sounders. Other types of data collected include multibeam bathymetry, synthetic aperture sonar data, magnetometry and spontaneous potential field data. The AUV was operated by Ocean Floor Geophysics.
The mineral deposits form after seawater, which penetrates deep into the seabed, is heated to more than 400 degrees Celsius (750 degrees Fahrenheit) by underlying magma chambers and dissolves many minerals. The warm seawater is flushed back out to the seabed through so-called “black smokers” where the minerals are precipitated in contact with the cold seawater. When the magma chambers shift due to the spreading between the plates, the flushing of the warm water stops, and the black smokers collapse and ultimately end up as piles of gravel on the seabed.
The new area of sulfide minerals that was discovered contains many such piles of gravel and collapsed black smokers, including a 26-meter (85-foot) high, non-active tower, in addition to some active systems.
This was the NDP's first seabed mineral expedition. More are planned.