17th Training-through-Research Cruise

ttr 17 map

The 17th IOC “Training-through-Research” programme (11 June- 24 July 2008) was subdivided into three Legs.

 

Leg 1 mostly focused on studies of sea mounds and hydrocarbon seeps in the West Alboran Sea (westernmost part of the Mediterranean Sea). The Melilla mounds discovered by in 2006 were studied in detail with high resolution seismic, deep towed sidescan sonar, underwater TV system and sampling. These investigations confirmed the presence of large coral buildups comparable by their dimensions to carbonate mud mounds of the Porcupine Seabight in the Atlantic Ocean. This is the first and very important documentation of large-scale cold water coral reefs in the Alboran basin. Detailed investigations of the Carmen structure revealed that this was a relatively small, but extremely active deep water mud volcano. Sea floor observations showed that Carmen mud volcano, characterized by very strong gas emissions, is the most active in the entire region including the Alboran Sea and the Gulf of Cadiz. Detailed investigation leads us to a suggestion that gas most probably is stored in structure II gas hydrates form which is normally stable in temperature-pressure conditions of the sea bottom at the crater area. Abundant chemosynthetic fauna included two types of pogonofora and living chemosynthetic shells. Various methane derived carbonates have been sampled and documented for the first time from the pockmark area in the Alboran basin.

 

Leg 2 in the Gulf of Cadiz was devoted to studying mud volcanoes, coral settlements, gas hydrate accumulations and relationships between large mud/salt diapirs (diapiric ridges) and seepage structures. The study of a large diapiric body located to the east of the Mercator MV showed that the top of this structure was strongly eroded and lately covered by carbonate crusts, coral settlements and partially buried with recent sediments. A gravity core collected from this structure showed increasing pore water salinity with depth similar to those observed earlier in a crater of the Mercator MV and on some other structures. This fact can probably characterize this structure as a salt diapir or at least a diapiric structure containing some salt. The same observations were done on the Renard Ridge N-E of the Gemini MV. This suggests that a chain of topographic highs including the Don Quichotte, the Alfa and Betta mounds, the top (plateau) of the Pen Duick escarpment are just shallow crest positions or outcrops of an elongated salt diapiric ridge. Yet another remarkable new discovery on the Moroccan margin during Leg 2 is an extensive field of cold water coral settlements located along the shelf break east of the Mercator and Al Idrisi mud volcanoes. They were mapped firstly in 2002 during theTTR-12 cruise (Kenyon et al., 2003) but we were not able to interpret these peculiar features at that time. Now they were mapped with high resolution sidescan sonar, surveyed with a TV camera, and sampled. One new mud volcano has been discovered in the Portuguese deep water area. A big number of different kinds of deep water chemosynthetic species were collected on the Portuguese margin. One of the most exciting events of this part of the cruise was sampling for the first time gas hydrates from the deepest in this area Porto MV. Most of the hydrate samples are represented by perfect cubic or prismatic crystals semitransparent for the first several seconds after subsampling; they look very similar to crystals of quartz or calcite. The end of Leg 2 was spent on dragging alkaline igneous rocks of the Late Cretaceous age from outcrops of the Estremadura Spur area offshore Lisbon. In addition to different kinds of igneous rocks, remnants of huge (probably very old) cold water corals were collected. These samples may have significant interest to specialists studying history of deep water coral distribution in the Atlantic Ocean.

 

Leg 3 aimed mainly to study Cenozoic sandy systems on the Norwegian continental slope and abyssal plain of the Lofoten Basin. Mapping of the modern system, the Andoya Canyon – Lofoten Basin Channel with deep towed sidescan sonar started in 2003 (TTR-13). It was continued and accompanied with very successful sampling. Spectacular records of large recent submarine slides were obtained. Origin of small but numerous positive structures broadly distributed on the Vøring Plateau raised a lot of discussions and open questions in previous years. These structures were sampled with a TV-controlled grab and proved to be thick bacterially induced iron hydroxide crusts and chimneys with sufficient presence of phosphates. The TTR-17 research results contributed to a number of European and national research projects. Its training results contributed to the IOC Capacity Development Programme and the European Project HERMES.

 


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              cruise report
post-cruise meeting abstracts