The Seabed and Shallow Geology Mapping of the Porcupine Bank, West of Ireland

The “Porcupine Bank” is a bathymetric high of over 40,000 km² linked to the western shelf of Ireland which lies between 51–54° N and 11–15° W approximately 100 km west of Ireland. Water depths are as shallow as 145 m over the “Porcupine Ridge”. The Bank’s location on the north eastern fringe of the Atlantic Ocean, in a critical position between the shelf edge and the main land and along the line of the Polar Front, means it may contain significant indications of glacial/interglacial changes in northern hemisphere climate and in North Atlantic Ocean circulation. But it also means that it consists of strategically important marine environments with very likely future developmental pressures. Peer-reviewed publications on the geology of the Bank are very limited and this current state of knowledge will hamper any marine ecosystem research and protection. This paper will describe the first results of a research project aiming at filling the gap of our understanding of the region’s shallow geology and subseabed resources and characteristics.

As a first step, seabed geomorphology mapping using high resolution MBES and sub bottom data have highlighted a wealth of glacially derived features such as iceberg scours and elongated ridges whose formation could be directly influenced by the presence of ice on or nearby the bank. Other features interpreted as sand waves could help understand relict or modern currents.

In addition to these surface features, this paper introduces recent geological mapping of the shallow stratigraphy of the bank using 2D seismic and sub bottom profiler data collected at a high density correlated with recently collected vibro-cores. The seismic units and corresponding lithofacies (some with radiocarbon dates) are consistently described and a regional correlation built.