Professor of Marine Geology and Geophysics
Ocean Margins
A Proposal to the European Science Foundation for an Exploratory Workshop
Summary of Proposed Research
The Ocean Margins initiative is a research programme aimed at better understanding the geological and geophysical processes that are occurring in the vicinity of the transition between continental and oceanic crust. Ocean Margins comprise of some of the largest sediment accumulations on the Earth's surface and are among the best recorders that we have of the response of the lithosphere to extension, sea level changes, and the mechanisms by which sediments are transported from the continents and into the deep sea. We propose here to hold an Exploratory Workshop that will identify a new European-led research project to better understand the geological and geophysical processes that are occurring at Ocean Margins.
The countries of Europe share one of the longest Ocean Margin systems in the world. Extending from offshore Norway in the north, to offshore Portugal and Spain in the south, and the Mediterranean Sea in the east, the Ocean Margins of Europe display a variety of margin-types. These include margins with abundant magmatism and thin sediments (e.g. offshore Norway) as well as margins with little or no magmatism and thick sediments (e.g. offshore SW approaches to UK and France). While differences in the amount of magmatism and sediments explain the diversity of present-day Ocean Margins, they obscure our understanding of the thermal and mechanical processes that are associated with the break-up of continents and the formation of new ocean basins.
During the past few years there has been renewed interest by the scientific community in the processes that are occurring at Ocean Margins. In particular, the following research "themes" have emerged :
1. Deep structure and rifting processes At present, we only have rudimentary knowledge of the dynamics of rifting and the physical and chemical processes that are involved in the break-up of continents and the formation of new ocean basins. However, Ocean Margins hold the key to better understanding such fundamental processes as the mechanics of crustal extension, magmatism, and the flux of sediment from the land to the sea. Fundamental questions to be addressed include the interactions that occur between rheology, strain rate and faulting, the role of segmentation in controlling structural styles, and the nature of the transition between oceanic and continental crust. In order to address these questions, new sophisticated methods must now be employed (e.g. 3-D seismic "grid" surveys, deep penetration seismic imaging, arrays of closely spaced Ocean Bottom Seismometers) to derive the structure beneath thick sediments and large-scale magmatic bodies. Current knowledge is limited to a few widely separated seismic transects (e.g. Voring Plateau, Hatton Bank, Goban Spur, Galicia Bank, Iberia, Valencia Trough).
2. Sedimentary Processes and Products Ocean Margins are one of the most striking morphological features of the sea floor, yet we know little of the sedimentary processes that have shaped them through time. Fundamental questions that need to be addressed include the nature and rates of down-slope and along-slope sediment transport, the controls on large-scale mass wasting and slope failure, and the processes that control the development of Ocean Margins during glacial and inter-glacial cycles. In order to address these questions we need to employ new technological methods to image the sea floor (e.g. swath bathymetry, deep-tow side-scan sonar) in order to determine the styles and sizes of individual slope failures. In addition, we need access to high-quality giant or hydraulic piston cores in deep-water sequences, combined with the use of new corers for the recovering of mixed, more sandy material. Current knowledge is limited. For example, there has been no attempt in Europe to systematically insonify its Ocean Margins as the USA has now done as part of its Economic Exclusion Zone (EEZ) project.
3. Fluid Flow One of the major results to emerge from recent studies at mid-oceanic ridges has been to shed light on the nature of high-temperature fluid flow in the uppermost part of the oceanic crust. Curiously, there has been little equivalent work on the lower temperature exchanges that are likely to occur in Ocean Margins. Fundamental questions that need to be addressed here include the distribution and intensity of water and hydrocarbon seepage's, the long-term effects of sub-sea floor circulation on sediment diagenesis and, the role that deep penetrating faults may play in fluid circulation. In order to address these questions we will need to first identify possible vents in Ocean Margins using high-resolution seismic and deep-tow sonar data and then develop a strategy to sample the fluids that emanate from them using coring and other techniques.
The link to Industry
Ocean Margins are now widely regarded by the hydrocarbon industry as a new, non-OPEC, exploration "frontier" for oil and gas deposits. Deep-water drilling west of Shetlands, for example, have revealed vast new reserves of oil and gas in water depths of > 1200 m. However, our knowledge of the geological, geophysical and geochemical processes that are occurring in such water depths have not kept pace with the advances in drilling technology. The continental slope and rise regions of Ocean Margins are among the most poorly understood features on the Earth's surface. Of particular concern to the industry has been the nature of the underlying crust (i.e. whether oceanic or continental), the correlation of seismic reflectors from the shelf to the deep-sea and, the role of large-scale mass wasting processes (e.g. landsliding). We believe therefore that a new program in Ocean Margins will address not only scientific questions, but will also be of direct relevance to the needs of European industry. The margins of western Europe and the Mediterranean Sea will be the principal focus of the new programme. However, we envisage that it will be necessary to extend the programme to at least one conjugate margin system, one convergent- margin and, one transform (i.e. strike-slip) margin.
The need for European collaboration
A strong case can be made for European collaboration in developing an Ocean Margins programme.
1. The margin offshore Europe is shared by a number of different member states. Collaboration is essential in order to co-ordinate cruises, plan ship tracks and gain access to continental shelves, slopes and rises.
2. The scientific skill base in Ocean Margins within Europe is widely distributed. Some countries have a high skill base on North Atlantic margins while others have focused their efforts on Ocean Margins in the Mediterranean Sea and the Pacific, Indian and South Atlantic Oceans. It is important to share this skill base because processes such as rifting, large-scale mass wasting and fluid flow are common to all types of margins.
3. A wide-range of platforms and instrumentation will be required. Some scientists in some European countries have access to one or more of the high cost technologies such as research ships, high resolution sidescan sonar, modern seismic systems, submersibles etc, but no one country has access to all of these technologies. Sharing technology is therefore imperative.
4. The conduct of geological and geophysical experiments at sea is expensive. The countries of Europe do not have the necessary resources to be able to launch an Ocean Margins programme by themselves.
Name and Curriculum Vitae of the Scientific Co-ordinator
Name : Anthony B. Watts Address : Department of Earth Sciences, Parks Road, Oxford OX1 3PR, UK. Tel & FAX : 44-1865-272032. cv : http://www.earth.ox.ac.uk/~tony/watts/INDEX.HTM.
List of proposed participants
We envisage that an Exploratory Workshop on Ocean Margins will be of interest to a number of scientists in Europe. In particular, the following have agreed to act as "points of contact" within their respective countries and to help develop a new programme in Ocean Margins : Prof. O. Eldhom (Norway) Dr. H-C Larsen (Denmark) Dr. A. Ribeiro (Portugal) Dr. J.-C. Sibuet (France) Dr. M. Torné (Spain) Prof. R. Von Huene (Germany) Dr. R. B. Whitmarsh (UK)
In addition, we envisage that the workshop will be of interest to national funding agencies (e.g. CNRS, NERC), industry (e.g. hydrocarbons, telecommunications, insurance, and defense) and representatives of the NSF-funded USA "Margins" programme.
Workshop Programme
The Exploratory Workshop programme will be developed in discussions between the scientific co-ordinator and the "points of contact". Currently we envisage a two-day workshop. The first day will be devoted to "keynote" talks and working group discussions on the three main research themes. The keynote talks will cover scientific as well as environmental and commercial issues. The working groups will be charged with producing a document on Ocean Margins that could be used to lever support for the programme either through the funding agencies of individual member states or by a joint solicitation to the European Community. The second day will be involved with further discussions and report writing.
Proposed Date and Location of the Workshop
The date and location of the meeting have not yet been discussed, but preference would be given for a meeting in the late summer of 1998 at a central site in Europe (e.g. the Strasbourg-Oxford axis).
Estimate of Costs
We envisage that Ocean Margins Exploratory workshop will be attended by about 15-20 scientists. The scientists will include representatives from the European academic science community, the national funding agencies, industry, and the USA "Margins" programme. In addition, we envisage that representatives from the scientific ocean drilling programmes (e.g. ODP, OD-21) may also wish to attend the workshop.
The main cost of the workshop would be travel and subsistence for the participants. Assuming that the workshop can be held at a central site, then we estimate that the total cost of the workshop will not exceed 75kFF.