|11th Training-through-Research Cruise|
|The 11th cruise of the UNESCO-IOC
"Training-through- Research" programme was carried out
on board the R/V Professor Logachev (Russia) from 25
July to 3 September. The cruise got underway from
Constantsa (Romania) and terminated in Funchal, Azores
(Portugal). The cruise was subdivided into three legs
separated by two port calls, where partial exchange of
the Scientific Party was made: in Istanbul (Turkey) on
6-7 August and in Valencia (Spain) on 20-21 August. In
addition, partial exchange of the scientific party was
performed in the middle of the 2nd Leg at a roadstead
stop in Valencia (Spain) on 15 August.
An international team of 67 scientists, post- and undergraduate students (in addition to a group of Russian technicians who had been working with the Logachev equipment) from 13 countries (Belgium, Brazil, Georgia, Greece, France, The Netherlands, Portugal, Russia, Spain, Turkey, U.K., Ukraine, U.S.A.) participated in the cruise.
The objectives of the cruise were to study various geological processes, such as bottom current activity, slope processes, mud volcanism, neo-tectonics, manifestations of shallow gas, etc. in the Black and Mediterranean Seas and on the North East Atlantic margin, and to train students in marine geoscience research. During the cruise TTR was working in the western and the central parts of the Black Sea, in the Sorokin Trough (Black Sea), in the Aegean Sea, in the Gulf of Valencia (Medit
erranean Sea), in the Gulf of Cadiz and in the area of Unnamed and Seine seamounts (surroundings of Madeira Islands, NE Atlantic).
The principal results of the cruise are:
In the western Black Sea, acoustic investigations revealed a set of structures controlling fluid discharge on the continental margin. These structures, represented by fault systems and cracks, expressed in the seafloor topography were mapped with the seismics, hull-mounted profiler, and sidescan sonars (10 kHz OKEAN and 30/100 kHz MAK-1 systems). Massive methane hydrates were recovered with the bottom sampling equipment in the uppermost layers of stratified sedimentary column in the areas of fluid venting.
In the central Black Sea area, a detailed study of previously known, and possibly active, Vassoevich, Kovalevskiy and TREDMAR mud volcanoes was performed with a set of methods, including high-resolution sidescan sonar survey, underwater TV, and bottom sampling. For the first time, gas hydrates were sampled from the Kovalevskiy mud volcano. Extensive collections of various types of authigenic carbonates, reflecting different bio-geochemical processes of methan oxidation under anoxic conditions, and rock clasts from mud breccia were obtained.
In the area of the Sorokin Trough, four new mud volcanoes were discovered and named as Odessa, Tbilisi, Istanbul, and NIOZ. Two previously unknown gas hydrate accumulations were found. Existence of bacterial mats in deep water anoxic conditions, associated with active gas vents, first reported in the area by TTR-6 expedition, was confirmed. Underwater TV run across Kazakov mud volcano revealed the presence of carbonate build-ups associated with zones of active fluid discharge.
In the Aegean S
ea, the scientific aim of the study was to investigate the westward extension and propagation of the North Anatolian Fault into the N. Aegean Sea and its transition from strike-slip/transtensional to extensional deformation towards Greece. This fault is believed to be responsible for the last earthquake in Turkey. The study included 10 and 30 kHz sidescan sonar surveys and 3.5 kHz profiling. Various types of modern deformations in the uppermost part of the sedimentary sequence including small amplitude faults and fractures were recognised on the records providing valuable information on the stress field in the area.
In the Gulf of Valencia, the principle scientific task was to map in detail a large debris flow on the Ebro continental slope and rise by means of high resolution sidescan survey and underwater video transects. Few cores were collected to groundtruth acoustic and video data. The analysis of obtained data provided better understanding of main pathways and processes of sediment transport to the deep-water part of the Balearic Basin.
The area of the Gulf of Cadiz has been intensively studied during the TTR 9 and 10th expeditions. Research activity during the TTR11 Cruise was focused on detailed investigations of structures related to gas seepage. The most impressive result of this study was a realisation of the fact that carbonate build-ups, which existence was known in the area from limited dredging data obtained by Spanish scientis
ts a year earlier, are very widespread in this region and form extensive fields rather than focused accumulations. The build-ups are represented by massive carbonate crusts and unique dolomite chimneys and are believed to be related to a defluidisation of the sedimentary cover. The diameter of the chimneys varies from several centimetres to one metre. The origin of these build-ups is not completely understood by now and requires a comprehensive analytical examinations and possibly further maritime studies.
A new mud volcano was discovered in the deep-water area of the Gulf of Cadiz and named Aveiro. Other two mud volcanoes, discovered during previous TTR expeditions (Olenin and Carlos Ribeiro) were investigated with high-resolution sidescan sonar and bottom sampling.
An issue of sand transport and deposition in the deep sea was addressed during a short high-resolution sidescan sonar study of a sand lobe associated with a contourite channel. The study revealed that the lobe morphology is much more complex than it had been though before and that the channellised sediment transport plays an important part in the lobe formation.
The final part of the cruise was devoted to the investigations of Unnamed and Seine seamounts in the vicinity of the Madeira Islands. A number of underwater TV observations, CTD and bottom sampling stations were conducted. A large field of Fe-Mn-nodules was discovered on the top of the Unnamed seamount. These nodules are located at an unusual depth of 1700-1900 m, and come in various sizes and shapes. Beside common isometric nodules of about 10 cm in diameter, some very large crusts or their fragments were observed. They had an irregular morphology and were up to several metres across and dozens of centimetres thick. Neither the origin of this huge accumulation of Fe-Mn deposits, nor their chemical composition are clearly understood by now and further laboratory analyses are required.
post-cruise meeting abstracts