Data Acquisition and Processing - helicopter Geophysical Survey at Valle, Setesdal
In june 2002, a helicpter geophysical survey was carried out over two areas at Valle, Setesdalen. The areas are named Rotemo and Rysstad-Straumfjord. The purpose of the surveys was to provide geophysical information for mineral exploration. The data were collected and processed by the Geological Survey of Norway (NGU). A total of 526 line-km of magnetic and radiometric data were flown in alternating directions at headings of South and North at Rysstad-Straumfjord, and northwest and southeast at Rotemo. Measurement noise levels were within survey specifications. Initial processing was carried out on a flight-by-flight basis. Total magnetic field measurements were collected using a cesium vapor magnetometer and corrected by removing diurnal variations as recorded at a magnetic base station at Valle. Radiometric data were reduced using three-channel processing according to procedures recommended by the International Atomic Energy Association. All final processed data were gridded using 50-m square cells. Geophysical maps were produced at a scale of 1:50 000 and are considered as standalone products. This report describes the aspects of data acquisition and processing of the survey.