2006 Strategic Environmental Assessment SEA7 Technical Report - hydrocarbon prospectivity, earthquakes, continental shelves and Rockall Trough surficial and sea-bed geology and sea-bed processes

This report is a contribution to the Strategic Environmental Assessment (SEA7) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). Investigations of the hydrocarbon prospectivity and earthquake activity include the whole of SEA7 but in this report investigations of the sea-bed sediments are restricted to the Hebrides Shelf, Rockall Trough and east Rockall Bank.

On the Hebrides Shelf, Hebrides Slope, east Rockall Bank and in the deep-water Rockall Trough the modern sea-bed sediments are mainly composed of mixtures of former glacial deposits and grains of modern interglacial biogenic carbonate shell. Former glacial deposits and modern biogenic carbonate are now mainly mixed and transported by wave-orbital currents and residual currents on Rockall Bank and by combinations of wave-orbital currents, tidal currents and residual currents on the Hebrides Shelf and upper Hebrides Slope. Below approximately 300 metres water depth in the Rockall Trough the sea-bed sediments are mainly transported by circulating deep-water residual currents.

本报告系对由贸易与工业部（现能源与气候变化部）进行的战略环境评估（SEA7）所做的贡献。对于烃类资源潜力和地震活动的调查涵盖了整个SEA7区域，但本报告中关于海底沉积物的调查仅限于赫布里底大陆架、洛克拉尔凹地和东洛克拉尔岸。在赫布里底大陆架、赫布里底斜坡、东洛克拉尔岸以及洛克拉尔凹地的深水区域，现代海底沉积物主要由前冰川沉积物与现代间冰期生物成因碳酸盐贝壳的混合物组成。前冰川沉积物与现代生物成因碳酸盐目前主要混合并经洛克拉尔岸的波浪轨道流和残余流以及赫布里底大陆架和上赫布里底斜坡上的波浪轨道流、潮汐流和残余流的组合进行输送。在洛克拉尔凹地水深约300米以下，海底沉积物主要由循环的深水残余流输送。