Probability mapping for bedrock occurrence on the Irish Continental Margin: Applications for regional bedrock outcrop and habitat mapping

The Irish continental margin hosts many complex sedimentary basins, and diverse geomorphological domains displaying bedrock outcrops that can host a large variety of habitats from shallow to cryptic fauna. More recent surveying in the Irish offshore territory has indicated extensive areas of bedrock exposure. The BeTar_Drill2 (Bedrock Target analysis for ROV RockDrill sampling) project applies novel bedrock suitability mapping to the full Irish continental margin (ICM); to determine potential habitat areas from shallow to deep domains for the entire ICM; to ground truth this mapping with petrographic analysis of physical samples correlated to existing seismic data. The project’s overall aim is to improve the appraisal of the regional geology and habitat mapping of the Irish margin. 

This study has improved the Bedrock Suitability Index (BSI) previously developed for the Porcupine Bank Canyon by fine tuning the variables to the wider margin. The improved BSI model has been constructed across the southern Irish continental margin, covering more than 140,000 km2, producing a high resolution (25m2) model of predictive bedrock outcrop locations. Validation by video observations and correlations of predicted bedrock exposures has established an appropriate level of confidence with BSI accuracy. The BSI mapping reveals a strong structural control on bedrock outcrop occurrence, with BSI correlating with deep structural fabrics of the margin as expressed by fault lines.