Multidisciplinary Study Of Geological Processes On The North East Atlantic And Western Mediterranean Margins

This book provides acoustic images about sedimentary systems of the shelf edge, slope and deep-sea-floor. Data obtained by the European North Atlantic Margin and the STEAM Project shows areas of potential instability and deepwater sediment transport systems on the continental slope. The knowledge gained can be used by both academia and hydrocarbon industry so as to arrive at a better understanding of continental margins and the processes shaping them. It will also interest colleagues in earth sciences involved in margin surveys for environmental studies. The current global trend in marine resource development is to move into deeper water, and this book can provide examples relevant to other passive margins around the world. There is a growing need for reliable measurements in deep water and knowledge related to stabilisation. Slope stability problems will be identified with greater reliability, thus improving safety standards for coastal and offshore environmental policies.

Hardcover plus CD

The Alboran Sea represents a regional Mediterranean space where North and South worlds merges, creating a geopolitical region where marine resources and maritime activities should be managed from a national and international perspectives. It is widely known, that currently the planet is suffering a global change, and it is also affecting the Alboran Sea, its ecosystems and populations. An important first step to update a paramount vision on this region is to understand the climatic, geologic and oceanographic, including biochemical cycles, process which shapes the rich geodiversity, biodiversity, the productivity, and the sustainable use of the marine resources from Alboran Sea. The fisheries management system should take into account marine environmental variability to achieve biological sustainability of marine resources. Well-funded policy-makers’ decisions require a sound science based knowledge of the interaction between the marine environment and commercial stocks. This is because the role of marine environment in the evolution of fish stocks is sometimes even more important than the one played by fishers in the commercial exploitation of them. Finally, we should analyze the different aspects of political context that could affect the management of the resources from Alboran Sea in the context of climate change. This book reviews different aspects of the Alboran Sea to help understand the current situation from the original Tethis Ocean. The book is divided into four blocks: (i) Oceanographic, geological and ecological context (chapters 2 to 7), (ii) biodiversity and ecosystems distribution (chapters 8 to 12), (iii) fisheries resources and aquaculture (chapters 13 to 20), and (iv) conservation, management and marine polices (chapters 21 to 25).

The areas visited during the 10th Training-through-Research Programme were the Portuguese Margin, the Gulf of Cadiz, the Lucky Strike area of the Mid-Atlantic Ridge, the Rockall Trough, the Southern Faeroe margin, and the Varring Plateau (Norwegian margin). The investigations were aimed atstudying such geological processes as neotectonics, fluid migration and escape, sediment processes in canyons and sediment reworking and benthic biology in areas swept by deep-sea bottom currents as well as hydrothermal manifestations on mid-ocean ridges. A seismic and sidescan survey of the Marques de Pombal structure (Portuguese margin) allowed a better understanding of a fault system known here from previous studies such as the ARRIFAN0 and BIGSET projects. The fault pattern has been mapped and acoustic images have helped to evaluate the status of their activity. The Marques de Pombal structure showed little evidence of recent activity and is being covered by sediments. Shallow slides found in the vicinity of the structure may, however, indicate some occasional activity disturbing the overlying sedimentary cover. The Pereira de Sousa fault was found to be much more active. Six new mud volcanoes were discovered and studied in the Gulf of Cadiz. Most of them were proved to be recently active. The mud volcanism of the Gulf of Cadiz can be considered as two characteristic regions with different mud breccia lithological composition. Several types of lava sulphite ores sampled during the Azores campaign of Leg 2 allowed a better understanding of volcanic evolution and associated processes of this area. A short 3.5 kHz survey across the Porcupine Seabight mouth, combined with existing swath bathymetry data and a few cores from the area, confirmed the findings of the TTR-7 cruise that the Gollum channel system is currently inactive. The study of a canyon on the northeastern Rockall Trough margin showed that the system is inactive at the present time and the last pulse of active downslope sediment transport took place in immediate pre-Holocene time. Debris flows were found mostly on the flanks of the canyon while the axial zone showed numerous signs of erosion. Sand was not particularly common in the studied area. It is suggested that significant amounts of sand are trapped in the canyon head, possibly due to slumps blocking the narrower waist area. Abundant traces of seabed erosion found immediately beyond the canyon mouth indicate that this area is a bypass zone and sand deposition may occur further into the canyon mouth indicate that this area is a bypass zone and sand deposition may occur further into the basin plain. An extensive collection of TV-guided grab samples and seafloor video records, obtained from sites in the Northern Rockall Trough, Wyville-Thomson Ridge and Southern Faeroe Plateau, provided GOOd insight on the distribution of bottom fauna, including deep-water corals, and of coarse glaciagenie debris. New data on a BSR distribution pattern were obtained on the southeastern part of the Verring Plateau and they suggest that the formation of the Storegga Slide was not directly related to the dissolution of gas hydrates. The investigation also provided a new insight into gas hydrate formation and distribution in the area.

'Deep-Sea Sediments' focuses on the sedimentary processes operating within the various modern and ancient deep-sea environments. The chapters track the way of sedimentary particles from continental erosion or production in the marine realm, to transport into the deep sea, to final deposition on the sea floor.