The geological significance of electrical conductivity anomalies of the Ordovician-Silurian Moffat Shale Group, Northern Ireland

The Tellus airborne geophysical survey revealed sets of narrow, linear, north-east to south-west, mostly parallel electrical conductivity (electromagnetic – EM) anomalies in the Longford–Down area. Subsequent geological mapping and ground geophysics have demonstrated that the anomalies coincide with and match the width of bedrock outcrop of the Moffat Shale Group. Ground-based geophysical surveys show variations in conductivity with highest values corresponding to carbon-rich mudstones. These findings allow the regional airborne geophysics to be interpreted with greater confidence for incorporation into bedrock geological maps, which underpin aspects of economic and environmental decision making.