Day 20 - 14 July
The southern face of the 2500m seamount was mapped overnight. The map shows steep cliffs that were created by movements along fault lines. Such fault movement results in earthquakes.
Hovedinnhold
Position: 73ºN, 7ºE
Temperature: 4.6 ºC
Wind speed: 11-13m/s
Wave height: 2.8m
Visibility: good
Weather: partially cloudy
A couple of months ago, seismologists at the University of Bergen registered a strong earthquake in this area.
We decided to go down with the ROV to try to collect some rock samples. We dove to around 1900m. The ROV’s sonar located a spill of rocks 50m north-west of our location. As we approached we could see that there had been a landslide. The sea-floor was covered in rocks of various sizes that had broken off the cliff face above. After filling the sampling drawer, we brought the ROV to the surface so we could learn more about the rocks in the sample.
On deck the rocks were cut open with a diamond saw and studied under the microscope. The internal structure revealed that the rock samples had been formed deep within the earth’s crust or in the mantle. There must have been strong fault movement in order to bring this kind of rock up to the surface, and to have spread them over such a large (30 km2) surface area. The map we made last night showed evidence of movement along the main faults that extends for over 10km.
The analysis of the rock samples showed that they were rich in the mineral olivine. When olivine comes in contact with water it is transformed to serpentine. In this process, water molecules are decomposed and hydrogen is formed. The hydrogen, in turn, can be used as an energy source for some specialized micro-organisms. This chemical reaction between olivine and water can thus provide the basis for life. Researchers wonder if the first life forms on earth developed in such an environment, or if such a system could provide the basis for life on other planets.
Scientists around the world are now considering such questions. We are pleased to have found a site that could function as a natural laboratory for further research in this area.
There are only two days left until we must head back to Bergen. The weather forecast predicts that the wind will increase overnight so we decided to undertake a dive to the deepest part of the rift valley; down to 3400m. This means that we will beat our own record for the deepest dive by a Norwegian submersible in Norwegian waters.
When we arrived at the sea-floor we found it to be covered in fine sediment that whirled around the ROV in a cloud. The presence of dunes and ripples in the sediment surface indicate that there can be strong currents in this area. We followed a heading towards a fault-line escarpment several hundred metres NW. En route the ROV engines were fighting hard against the currant.
Suddenly the screens in the ROV control room went black. Contact had been lost with the ROV. What had happened? To find out we had to bring the ROV back to the surface using the cable alone.
Once at the surface we were quickly able to determine the cause of the problem: a titanium tube containing the electrical circuitry had been crushed by the tremendous pressure forces present at 3400m. It was a disappointing but valuable learning experience. The tube was supposed to tolerate pressures to 4000m. Deep sea exploration is still “state-of-the-art” and the developers of deep sea equipment have little previous experience to guide them.
This latest Argus ROV had many new technological developments. The new camera systems provided excellent visual data. The robot arms handled sample gathering and recovery operations successfully. The unique sample drawer enabled researchers to collect a number of valuable sea-floor specimens.
As the ship headed into the strengthening wind for the home trip, the participants discussed a name for the ROV. Abyssator was favoured by some; abyss coming from the Greek word for the bottomless deep.