CV17013 Geophysical Exploration of the Shallow Sub-seabed (GESS) Survey

The Geophysical Exploration of the Shallow Sub-seabed (GESS) survey is a collaborative survey undertaken by researchers in iCRAG – The Irish Centre for Research in Applied Geosciences, University College Cork and the University of Bremen (Germany). The aim of the survey is to collect geophysical acoustic data in the Irish sector of the Irish Sea and the northern Celtic Sea. The data set will be primarily used to improve knowledge on the nature and formation of recent seabed sediments that were influenced by the Irish Ice Sheet during the last glaciation and to create a 3D geological model and revise existing sub-seabed models of the seabed sediments in the Irish Sea and the northern Celtic Sea. This survey took place on board the Marine Institute's R.V. Celtic Voyager in March/April 2017 where the following was conducted: - Collection of shallow seismic data for seismostratigraphic investigations: targeted identified data gaps in the shallow seismic coverage of the Irish and Celtic Sea to create a seamless coverage for these areas. In particular, the combination of seismic gear from the University of Bremen (micro-airgun and SES echosounder) in combination with the MI Sparker system was designed to generate high fidelity data with good ground penetration. Task 2 - Collection of shallow seismic data for deglacial history investigations: usingthe combined University of Bremen and Marine Institute seismic gear, we collected a dense coverage of data on the mid-western Irish Sea tunnel valley and deeps area to improve our understanding of the Irish Sea Ice Stream retreat. In addition, off the Dungarvan/Hook area, dense coverage of seismic data gives an indication of the ice limits of both the Irish Sea Ice Stream and land-based ice sheets. Task 3 - Collection of shallow seismic, magnetometer and grab sample data for heavy mineral sands investigations: A magnetometer survey was undertaken to identify magnetic mineral concentrations with the combined seismic system used to produce a dense coverage of a potential heavy mineral sands off of Wicklow Head/Brittas Bay to determine resource thickness and a resource map. Grab samples and magnetometer data will be used to target and constrain the resource for vibrocoring to provide sample for mineralogical and geochemical analysis. Objective 1: to collect shallow seismic data to revise and define the seismostratigraphic model for the Irish Sea and Celtic Sea including palaeovalleys Objective 2 (optional): to collect shallow seismic data in the northern Irish Sea mudbelt to determine gas seepage pathways Objective 3: to collect seismic data pertinent to understanding the Pleistocene deglaciation of the Irish Sea Ice Stream, glacio-fluvial tunnel valley drainage networks and the Holocene transgression. Objective 4: to collect mutibeam, seismic and grab data off Wicklow Head/Brittas Bay to evaluate the resource potential of mineral sand.