Introduction: The GATEWAYS research campaign
The GATEWAYS I 2012 cruise, a research collaboration between the Marine Institute (MI) & Geological Survey of Ireland (GSI) (partners in the INFOMAR offshore mapping programme), National University of Ireland Maynooth, OGS (Trieste, Italy Campaign Blog link), University of Ulster, Coastal Marine Resource Centre (UCC) and Trinity College Dublin has begun!
The RV Celtic Voyager mobilised from Cork on Sunday 22nd April ahead of a 22day campaign of work in the Celtic Sea and North Atlantic (see current position here). Our thanks to everyone involved in facilitating the mobilisation effort from P&O, the MI and GSI.
The principal aims of the research campaign are to collect new information about current and past marine environments, particularly the palaeoclimatic/palaeoenvironmental history of the Celtic and western Irish Shelf. The concept of iceberg production ‘GATEWAYS’, ice sheet calving margins emptying into the North Atlantic (Bigg et al, 2010), links the two geographical foci of the cruise (Celtic and Western Shelves). They are now thought to have been the locations of major of ice-streams in the latest palaeoglaciological reconstructions of the last British Irish Ice Sheet (BIIS). As such, they may have formed principal routeways of rapid ice loss during the last major deglaciation of Ireland and the Irish Sea Basin (~20 thousand years ago).
Understanding the dynamics associated with modern ice streams (which drain >75% of Antarctica’s ice for example) remains a key question in modern glaciology. The campaign aims to test the model of former ice stream activity in the last BIIS by examining the sedimentary deposits on the Irish shelf. Hopefully these form a record of past glacial activity there. This will be achieved through the collection of high resolution topographic and targeted shallow seismic data, which when combined will allow us to reconstruct landforms created by any glacial activity and possible sequences of events during the glacial-deglacial cycle.
Scientific activity on board
In waters up to ~400m, a variety of observational and sampling mechanisms will be deployed to gather geophysical (sonar and seismic), video (video camera deployed in a MI frame), seismic (Geo Acoustics Sparker 200 system) data sets and sediment grab samples. Experiments being conducted running include the groundtruthing of previously collected multibeam sonar data from embayments along the SW coast (e.g. Dunmanus Bay); mapping using multibeam sonar and sidescan sonar of enigmatic elongate ridges on the floor of the Celtic Sea shelf that for 40 years have been classified as moribund tidal ridges; and imaging using shallow seismics of glacigenic landforms on the western Irish Shelf. The cruise plan is designed to form part one of a two part research project that will use the geophysical data to constrain targets for a focussed shallow drilling campaign in future years.
Bigg, G. R., R. C. Levine, et al. (2010). “Last glacial ice-rafted debris off southwestern Europe: the role of the British-Irish Ice Sheet.” Journal of Quaternary Science 25(5): 689-699.