Helicopter-borne magnetic and radiometric geophysical survey in Romsdalsfjorden, Møre og Romsdal

Abstract

NGU conducted an airborne magnetic and radiometric survey in Romsdalsfjorden in December 2014 and January 2015 on behalf of Statens Vegvesen.This report describes and documents the acquisition, processing and visualization of recorded datasets.The geophysical survey results reported herein are from 2750 line km, covering an area of 550km2.A Scintrex CS-3 magnetometer in a towed bird and a 1024 channels RSX-5 spectrometer installed under the helicopter belly was used for data acquisition.The survey was flown with 200 m line spacing, line direction 0 dgrees. (N to S) at an average speed of 88 km\/h. The average terrain clearance was 52 m for the bird and 80 m for the spectrometer.The collected data were processed at NGU using Geosoft Oasis Montaj software. Raw total magnetic field data were corrected for diurnal variation and leveled using standard micro-levelling algorithm.Radiometric data were processed using standard procedures recommended by International Atomic Energy Association.Data were gridded with the cell size of 50x50 m and presented as a shaded relief maps at the scale of 1:50.000.