Regional interpretation of new airborne geophysical imagery of Northern Ireland

In 2006 the Geological Survey of Northern Ireland (GSNI) completed the national low-level airborne geophysical survey of Northern Ireland, as part of the Tellus Project. Datasets and imagery of the following are available: • Total magnetic field and various transformations, • Electrical conductivity (two and four frequency electromagnetic survey), • Gamma-ray (total count, uranium, thorium, potassium, caesium). Regionally, the airborne geophysical imagery refines existing structural mapping. Prominent magnetic anomalies correspond notably with major igneous complexes and the extensive Palaeocene Antrim basalts. At least four generations of Palaeocene dykes are distinguished on the basis of their magnetic signatures and major regional faults are well defined. The electromagnetic survey maps electrical conductivity differences between the Precambrian, Lower Palaeozoic and younger rocks, as well as environmental effects. Radiometric results display significant differences in the radioactivity of different lithologies, including some of the most radioactive granites in the United Kingdom. At a local scale the imagery reveals outstanding structural detail.