The researchers have applied Topas, a kind of strong echosounder sending signals at regular intervals into the seafloor. After finishing the first priority stations in the Troms III area, “G.O. Sars” headed towards Nordland VI, where many stations at deep water are on the priority list. On our journey southwards we collected acoustic data with Topas in order to obtain new information about the sediments below the seafloor.
According to the researchers G.O.Sars did 10-11 knots, and collected data of high quality. Along southern Troms and off Vesterålen and Lofoten they followed the deep sea plain slightly west of the continental slope. Water depths of the very gently sloping deep sea plain are more than 2000 m, and the landscape is almost flat compared to the irregular continental slope which has slope gradients of 5-10 degrees.
Topas has given new data of importance for understanding the geological development of the area. For instance, the data have shown that the ridges in the lower slope off southern Troms are made up of parallel-layered sediments. Topas image showing two ridges separated by a channel. The age of the sediments is unknown, but we think they may be several million years old.
Topas (Topographic Parametric Sonar) is a kind of strong echosounder, with ability to penetrate into the upper sediment layers, if the topographic and geological conditions are favorable. Another down-slope-trending ridge not far from this location has earlier been video-filmed in the MAREANO project, showing fine-grained sediments being exposed in near vertical slopes.
