Interdisciplinary Geoscience Studies of the Gulf of Candiz and Western Mediterranean Basins: Preliminary Results of Investigations During the TTR-14 Cruise of RV Professor Longachev

Interdisciplinary scientific studies were conducted from the RV Professor Longachev on the continental margins and in the basins of the Gulf of Cadiz and Western Mediterranean Sea during the 14th!raining-through-Research cruise of UNESCO -IOC. Work in the Gulf of Cadiz added to the dataset collected on four earlier TTR cruises in 1999-2002. The new surveys investigated a series of landslides located in the distal part of the Portimao canyon, as weIl as several WNW-ESE major tectonic lineaments, believed to be strike-slip transfer zones linked to the Africa-Eurasia Plate Boundary. The southern most known mud volcano field in the NW Moroccan margin was extended to the southwest with the discovery of the Meknes mud volcano. Additional samples of gag and gag hydrates were collected from the active Captain Arutyunov and Ginsburg mud volcanoes to complement studies already underway. New areas of carbonate crusts and chimneys near the main channel of the Mediterranean Undercurrent were covered with side scan sonar survey and sampled by a TV -guided grab. Samples of fauna associated with fluid seepage were collected in new areas of the Gulf of Cadiz as weIl as from known structures for more detailed and quantitative studies. Specimens for genetic, stable isotope and ultramicroscopy analyses were also collected. Investigations in the Alboran basin also continued the work started during TTR-9 and TTR-12 cruises and resulted in the discovery of the new mud volcano named Carmen, which is located between the Northern and Southern Mud Volcano Province. New high-resolution seismic lines obtained in the region allowed better understanding of basin architecture at shallower levels in the Alboran-Balearic transition. The lines were tied with ODP Leg 161 drilling results in order to provide seismostratigraphic constraints. The Palomares and Cartagena margin is found to be a highly deformed margin, probably with active wrench tectonics which conditions sediment dispersal and mass wasting. Morphodynamic provinces include impressive turbidite systems, from incised canyons to Jeep sea fan lobes and with ubiquitous slides on the Cartagena margin. Four areas were visited in the Balearic Basin. In the Evissa Channel four shallow slides were covered with MAK 30 kHz side scan sonar. The survey complemented the existing multibeam and seismicdata, providing higher resolution. Several 30 kHz side scan sonar lines in the Mallorca Channel were aimed at studying the sedimentary processes and showed that hemipelagic sedimentation prevails over most of the area. 30 kHz side scan sonar was used to map an extensive area (420 km2) of asymmetrical scour holes developing in the channel-to lobe transition of the Rhone neofan in the waterdepths of 2300-2600m.These sc ours are attributed to the greater turbulence in currents from the neochannel where they reach a slope of lower gradient. Details of scour morphology and distribution pattern in relation with other seabed features will help to study the flow regime of the turbidity currents. The study of the Cap de Creus Canyon System comprised a 30 kHz deep-towed side scan sonar profile, running along the axis for almost 200 km from an area just below the shelf break clown to the basin plain, where it connects with the Rhone Neofan survey. The profile shows change canyon floor morphology and evolution of bedforms clown the system from by-pass to depositional areas. The importance of slope breaks for formation of deep-water scour fields was confirmed. In the Tyrrhenian Sea RV Professor Logachev worked in two main areas: the eastern Sardiniamargin and Stromboli volcano submarine slopes. On the Sardinia marigne the work comprised extensive30 and 100 kHz deep-towed side scan surveys and bottom sampling in the braid-like pattern found an intraslope basin situated at the waterdepths of 1600-1800 m and fed by Sarrabus Canyon. The study highlighted the dominance of erosional processes in the area resulting in formation of flutes and scours. The area was difficult to core with a conventional gravity corer but a spectacular sample of gravel collected by a TV -guided grab sampler indicated the presence of widespread gravels in the braided area. Integration of multibeam, side scan sonar and sampling data showed the importance of topographic control for bedform and sediment distribution in the area. The history of failure on the slope of Stromboli was investigated following the catastrophic tsunami and submarine slide of December 2002. On the submarine slopes and the base of the Stromboli volcano MAK sonographs showed scour marks and waves in black volcaniclastic sand related to the latest failure. The sub bottom profiler showed distinct areas of erosion and deposition features including small channels, small canyons and slump scars. The debris avalanche deposits derived from the year 2002 collapse event were also imaged. Cores were taken on the far side of the Stromboli Canyon where a record of the Stromboli failures should be preserved. A significant and unexpected result was the discovery, and sampling, of an extensive pillow lava field at the base of the volcano.