8th Training-through-Research Cruise

Geological processes at different locations along the European continental margin in the North Atlantic were studied on the TTR-8 Cruise (1998) on board R/V Professor Logachev with a wide range of equipment.

On the Portuguese margin west of Lisbon, the broad network of canyons was successfully mapped with the OKEAN side-scan sonar. The data add to and fit well with the seismic and side-scan sonar datasets collected previously in the area by Portuguese scientists.

A study conducted in the Porcupine Seabight mud mounds areas was aimed at obtaining further bottom samples for geochemical and microbiological investigations. A more detailed survey was carried out with 100 kHz side-scan sonar on one of the mounds.

ttr8 map

A better understanding of the seabed processes observed during the TTR-7 cruise (1997) was achieved as a result of this second visit. A slump affecting the upper part of the sedimentary section was mapped on the eastern Faeroes margin. Another large slide on the northern Faeroes margin was also visited and detailed studies showed the presence of a number of stages of slide development. The recognition of the latter can be crucial for the determination of potentially hazardous areas on the continental margins. The presence of a megaturbidite, whose formation is probably related to the giant Northern Faeroes Slide, was observed in cores taken downslope from the slide. Investigations of the southeastern part of the VÝring Plateau adjacent to the Storegga Slide shed more light on this area known for its numerous fluid escape structures and possible gas hydrates presence. A bottom simulating reflector (BSR) was observed and in several places it was found to be pierced by diapiric structures disturbing the sedimentary cover and reaching the seafloor at some locations. Some of the pockmarks, well seen on the long range side-scan sonar data, were carefully studied with high-resolution acoustic tools and bottom TV. The latter revealed the presence of bottom biota activity possibly related to gas seepages, anddirect observation of escaping fluids were made and videotaped. Many samples taken from the pockmarks contain gas-saturated sediments and concretions of carbonate minerals whose formation is very likely due to the methane oxidation. The complex morphology of the seabed mounds located in the northwestern part of the VÝring plateau was observed on the OREtech sonograph.

The unique nature of the Haakon Mosby mud volcano located to the southwest of Bear Isle was confirmed by extensive seismic and OKEAN survey. No other mud volcanoes were found although several mud diapiric structures were recognised and sampled.

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PDF document

cruise report post-cruise meeting abstracts
(Note: large file 47 MB)