Airborne Surveys Preliminary Imagery
Following the delivery of the data a careful quality assurance (QC) exercise was carried out to assess the data for the purposes for which they were collected. This QC work was carried out under contract and the consultant concluded that “The data meet the contract specifications.”
Early results from the Surveys
With respect to the actual results data processing and interpretation is ongoing. However, we can present a number of preliminary images which demonstrate the spectacular nature of the information contained in the data.
Above is an image from the Cavan – Leitrim – Monaghan area generated from the magnetic data. Within the image are clear linears trending both in an east west direction and in an northwest – southeast direction. These are interpreted to be igneous rocks formed from molten lava and which are only mapped sporadically on the ground on account of the thick drape of glacial debris covering the region. The continuous nature of these rocks can be seen from this image.
As an example of the radiometric data the image at right shows the data processed to show where there are abnormally high levels of uranium which is an indicator of high levels of radon gas. This image is from Kerry where there are known instances of high indoor radon. This type of survey can assist authorities in directing further investigations for indoor radon.
Processed equivalent Uranium (eU) data from the Kerry survey area. The image shows those areas with values of eU greater than the mean plus two standard deviations, i.e., greater than 2.67ppm eU. The background image is a geological map of the region while the bright red and green areas (towards to north and middle of the diagram) are the parts of the survey are which are greater than 2.67ppm eU. It can clearly be seen from the image that the high level are closely associated with certain geological features shown on the background map.
The electromagnetic data can be processed in such a way as to reveal the 3-dimensional structure of the earth. This is particularly important for engineering and environmental studies where the thickness of the glacial sediments can be critical from a groundwater protection point of view. For example, thick clayey deposits can provide a protective layer inhibiting the ingress of contaminants to a valuable aquifer beneath. The image below shows how the data can be ‘diced and sliced’ to reveal its internal structure - it is a processed electromagnetic data from the Silvermines survey area. The image, just one of a series, shows how the earth can be represented as 3D models showing numerous features such as the thickness to the glacial overburden and the underlying structure of the bedrock which on the ground in obscured by the glacial sediments.
