12th Training-through-Research Cruise





TTR 12 map


The TTR-12 cruise was carried out from 9 June to 31 August onboard of the RV Professor Logachev owned and operated by Polar Marine Geosurvey Expedition (PMGE), departing from St. Petersburg (Russia) and terminating in Ponta Delgada (Azores, Portugal). The cruise was sub-divided into five legs separated by port calls, where partial exchange of the scientific party was made: in Foynes (Ireland) on 2–3 July, in Porto (Portugal) on 6–7 July, in Cadiz (Spain) on 18 July, in Cartagena (Spain) on 28 July and in Civitavecchia (Italy) on 12 August.

The Co-Chief Scientists of the cruise were:

Leg 1: Tove Nielsen and Mikhail Ivanov

Leg 2: Neil Kenyon, Luis Pinheiro and Mikhail Ivanov

Leg 3: Menchu Comas and Mikhail Ivanov

Leg 4: Michael Marani and Mikhail Ivanov

Leg 5: Jose Monteiro and Mikhail Ivanov.

In addition to a group of twenty-one Russian technicians who had been working with the Logachev geological and geophysical equipment, an international team of seventy-seven scientists, post- and undergraduate students from the following twelve countries participated: Bangladesh, Belgium, Denmark, Georgia, Ireland, Italy, Morocco, Portugal, Russia, Spain, Sweden and the UK.

Cruise objectives

The objectives of the cruise were two-fold: interdisciplinary investigations of geological processes on continental margins of Europe and North Africa as well as students training in marine geoscience research.

The following themes were investigated:

1. Focused fluid escapes and related mud volcanism, gas hydrates, carbonate and sulphide structures, hemosynthetic communities, etc.;

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

3. Modern deep-water sand lobes;

4. Underwater volcanism, hydrothermal activity and related mineralization;

5. Geosphere-Biosphere coupling processes manifested in specific fauna communities, hemogerms growing and deep-water coral ‘reefs’.

Equipment

Equipment used for conducting the above investigations 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

Area 1: Eastern flank of the Fugloy Ridge at the northern entrance of the Faeroe-Shetland Channel

Seamounts of unknown origin were mapped to a basinward continuation of the Fugloy Ridge (to the east of the Faeroe Islands) using seismic and two types of sidescan sonars and samples were collected. Geophysical records indicated the presence of at least two separated groups of diapirs piercing and – as demonstrated by under-water TV – outcropping at the sea floor. Bottom sampling data suggest that diapirs mainly consist of semi-lithified diatom ooze of the Miocene age with some admixture of glauconite and foraminifera. No evidence of coral settlements or recent fluid venting was reported.

Area 2: GEM Raft at the central Faeroese slope of the Faeroe-Shetland Channel

The raft was first observed on a TOBI side-scan record a few years ago, but other types of investigations had yet to be carried out. The aim was thus to confirm the existence of the GEM Raft and to gain information on its most recent episode of instability. In the study area, a deep-towed sidescan sonar MAK line and bottom sampling were performed. The existence and location of the GEM Raft were confirmed and its morphology was studied. The GEM Raft seemed to consist of an upper part and a lower part separated by a 15 km-wide plateau. The upper part of the raft was found to be the smallest and possibly the youngest. There was no indication that sediments cover the latest slump deposits and this was confirmed by bottom sampling. Buried slump deposits indicated that this upper part was previously prone to instability. The lower part of the raft showed a variety of down-slope processes, for example detached blocks, pressure ridges, slumps and debris flows. This lower part seemed to be covered by a more recent sedimentary layer, and there was no clear indication that bottom processes are still active. This was confirmed by bottom sampling.

Area 3: Rockall Trough

Intensive bottom sampling was performed in the Rockall Trough area. Sampling was mainly related to environmental studies, but with also the objective of calibrating acoustic facies for interpretation of multibeam reflectivity data. Undisturbed sediments from different parts of the area were collected and subsampled for chemical, biological and physical properties investigations. However the depth of penetration of a box corer was not always sufficient for calibration of acoustic signals with a frequency of about 10 kHz.

Area 4: Gulf of Cadiz

In the Gulf of Cadiz, a broad range of investigations were carried out, resulting in the localization in the northern part of the Gulf of a new field of carbonate chimneys, complementary to those discovered by the Anastasia-2000 and TTR-11 cruises. In the central part of the Gulf, two new, active mud volcanoes (named Captain Arutjunov and Tangier) were also studied in detail and heavy hydrocarbon gases and gas hydrates were sampled from this structure. On the Moroccan margin, a detailed study and sampling were performed on a mud volcanic field, which had been discovered earlier in 2002 by the Gent University (Belgium) group during the Belgica cruise and was mapped using seismic and multibeam methods. The investigations also led to the mapping and sampling of deep-water coral settlements in different locations, the discovery of exotic blocks of sandstones, igneous and metamorphic rocks on tops of some shallow-water mud volcanoes, and the mapping of the Gil Eanesh deep-water sandy system using the 100 kHz side scan sonar and 5.1 kHz profiler.

Area 5: Western Alboran Sea

Four new mud volcanoes and large fields of pockmarks were found in the Western Alboran Sea. Two mud volcanoes named Kalinin and Perejill were located in the Spanish part of the basin. Both structures are covered with relatively thick hemipelagic sediments and they appear dormant at present. Samples of hydro- carbon gas and clasts of ancient rocks in mud volcanic breccia were collected and will probably be of value in defining the source formation of these two volcanoes.

Area 6: Eastern Alboran Sea

Investigations in the Eastern Alboran basin focused mostly on the study of basinward continuation of the Almeria turbidite system. Its upper part was mapped ten years ago with the deep-towed sidescan sonar MAK-1M during the TTR-2 cruise. Mapping of the distal part of the system was carried out with the same instrument and revealed a very complex structure consisting of overlapping channels and sedimentary lobes.

Areas 7 and 8: Tyrrhenian Sea

In the Tyrrhenian Sea, the morphology and volcano-tectonic processes at the three biggest submarine volcanos, Marsili, Palinuro and Vavilov were studied. Mapping of the northern side of the Marsili volcano with the deep-towed sidescan sonar yielded significant information regarding its morphology and recent activity. Many small-scale features corresponding to recent activity of the volcano could be seen on acoustic records. Several areas of low-temperature hydrothermal activities were observed at the summits of the Marsili and Palinuro volcanoes using an underwater TV system.

Areas 9 and 10: Sedimentary basin to the south of the Azores plateau and the Lucky Strike field

A long seismic line was performed with two 3-litre airguns across a young sedimentary basin, which is located to the south of the Azores plateau. Seismic records demonstrated a surprisingly thick (more than 1 km) sedimentary cover. TV observations and sampling of different types of igneous rocks in the Lucky Strike segment were also carried out.













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post-cruise meeting abstracts