13th Training-through-Research Cruise







The 13th cruise (TTR-13) of the “Training-through-Research” programme was carried out on board of the R/V Professor Logachev (Russia) from 10 July to 24 September 2003. The cruise started and terminated in St. Petersburg (Russia). The first group of international participants embarked in Copenhagen (Denmark) on the 13th of July.

The cruise was divided into 5 legs separated by port calls, where partial exchange of the scientific crew was made. After Copenhagen, the port calls were to: Tromsø (Norway), on 29-30 July; Reykjavik (Iceland), on 5 August; Nuuk (Greenland), on 13 and 30-31 August; Dublin (Ireland), on 14-15 September; and Copenhagen (Denmark), on 21 September. The Co-Chief Scientists of the various legs of the cruise were: M. Ivanov (Russia), N. Kenyon (UK), A. Kuijpers (Denmark), J.S. Laberg (Norway), X. Monteys (Ireland), T. Nielsen (Denmark) and N. Poulsen (Denmark).

An international team of forty-two scientists, post- and undergraduate students from the following nine countries participated: Belgium, Denmark, Georgia, Germany, Ireland, Norway, Portugal, Russia and UK. The participating students were involved in all stages of acquisition and preliminary processing of multidisciplinary set of geophysical and geological data. Daily seminars, lectures and discussions of the results facilitated high-level on-the-job training of the students and young scientists.

Cruise objectives

The objectives of the cruise were two-fold: to conduct detailed interdisciplinary investigations of geological processes on the deep continental margins of Europe and Greenland and to train students in marine geoscience research. The following scientific themes were addressed during the cruise:

1. Deep-sea depositional systems in the North Atlantic;

2. Neotectonics and down-slope processes on continental margins;

3. Contourites and turbidites in deep-water sedimentary systems;

4. Carbonate mud mounds.

Equipment

In addition to the standard equipment (described below) for geological and geophysical investigations normally used on board the Logachev, in the TTR-13 cruise the new vibracoring equipment was used to sample sandy-gravely bottom sediments, inaccessible to other coring instruments. This equipment called ‘Deep Ocean’ can core up to 10 meters of hard sediments. The vibracorer can work at various depths from 20 to 5,000 meters. It works with TV-cameras that permit to select targets for coring at the sea-bottom and fully control the coring process.

Other equipment used for research and training included a single-channel high-resolution seismic system with airgun sources, an OKEAN long-range sidescan sonar, a hull-mounted 3.5 kHz profiler, a MAK deep-towed system containing a high- to middle-resolution sidescan sonar and a 5.1 kHz sub-bottom profiler. For more detailed studies, a 6-m gravity corer, a box corer, a kasten corer, a CTD system, an underwater digital TV camera, a TV-controlled grab and a dredge were also used.

Principal results (provided by the shipboard party)

RV Professor Logachev visited 8 areas located in the North Atlantic Ocean (see the cruise map).

Norwegian margin

Areas 1 and 2: Vøring Plateau

The main objective on the Vøring Plateau was to investigate inferred complexes of mud diapirs. The Vema diapir field had been studied previously during the TTR-8 cruise in 1998. As a continuation of this work, seismic and acoustic studies of the Vigrid (Area 1) and Vivian (Area 2) diapir fields, located on the Vøring Marginal High and the Vøring Basin respectively, were conducted by TTR-13.

Area 3: Traenadjupet Slide and Lofoten Basin floor

The Traenadjupet Slide off the northern part of Norway covers an area of about 12,000 km2. It originates on the continental slope and has a well-defined termination on the lower continental rise. The distal part of the slide was studied in detail with the help of the sidescan sonar, high resolution seismic profiles and bottom sampling in order to elucidate the sediment failure processes and their ages.

The Lofoten Basin Channel was crossed on the lower slope where it has a thick unit of acoustically laminated sediments on its northern flank. A deep towed sidescan sonar line across the distal part of the channel showed erosional features on the channel floor, especially where it cuts through a probable slide deposit. The area beyond the channel, which had been proved to be difficult to sample on this and an earlier cruise, was succesefully sampled by the vibracorer and found to be sandy. A highlight of this study was the discovery of possible sand volcanoes on the channel-mouth lobe.

Area 4: Andøya Slide and Andøya Canyon

The Andøya Slide in the Lofoten Basin covers an area of about 9,700 km2. A large set of data was obtained using high-resolution sidescan sonar, onboard profiler and coring. It will help to identify the age of the most recent slide event and to study sediments that overlie the slide deposits. The adjacent Andøya Canyon was investigated with sidescan sonar, TV-system and bottom sampling in order to confirm the types of processes transporting sediments through the canyon and whether they were still active.

Norwegian Basin (Area 5)

On the passage to Reykjavik (Iceland) a seismic/hull mounted profiler line was run across several supposed diapiric structures on the floor of the basin between the Aegir and Jan Mayen Ridge. The presence of diapiric structures was confirmed.

Greenland margin


Area 6: Eirik Ridge

This very thick sedimentary ridge is located at the southern tip of Greenland and is laid down by the long term bottom currents which run along the east Greenland margin. As such it represents an excellent record of the history of global ocean circulation and climate change. Air gun and ship borne seismic profiles were used to determine the best site for obtaining a core that would have a high deposition rate during the Holocene. A deep towed profile was used to get a high resolution acoustic record and two cores were obtained for detailed analysis, and in particular to determine whether there is evidence for high frequency changes of current speed. This data is a reconnaissance for a further UK research cruise to the area in 2004 that will obtain more cores and undertake current measurements.

Area 7: Labrador Sea and Davis Strait

Principal targets of investigation within Area 7 were chosen on the basis of multi-channel seismic data of the Geological Survey of Denmark and Greenland. Positive (“diapiric-like”) structures on the sea bottom were studied by the single-channel seismic, long-range sidescan sonar, deep-towed side scan sonar, onboard profiler, underwater TV inspection and by way of bottom sampling. From two of these structures we collected samples that suggest their volcanic and crystalline basement rather than diapiric origin.

The Pre-Neogene seabed outcrops were studied on the flanks of canyons and valleys extending from the upper continental slope into the deep-water basin west of the Fylla Bank and in the Davis Strait High area. Lithology of the samples and biological specimens were preliminary identified onboard and stored for shipment ashore and further analysis.

The areas studied for possible gas or fluid seeping was proved to be strongly disturbed by iceberg ploughing, which provided an opportunity for (unexpected) studies of the glacial history of the Davis Strait area. Along with a series of gravity cores from the seep areas a unique sandy-gravely core was collected with a vibracorer in the northernmost of the plough-mark areas.

Irish margin

Area 8: Porcupine Bank

A large area of carbonate mounds was studied on the western margin of the Porcupine Bank. Recent depositional environments and processes were investigated using the high-resolution sidescan sonar, underwater TV-system and bottom sampling. Particular attention was paid to the biology of the mounds and to their relationship with the underlying basement. Several outcrops were identified and sampled for further laboratory studies.


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