Airborne gamma-ray spectrometric measurements over the Canadian shield

In 1967 the Geological Survey of Canada initiated a project to develop a high-sensitivity airborne gamma-ray spectrometer for the purpose of measuring surface concentrations of potassium, uranium, and thorium. The airborne spectrometer system has been in operation since the summer of 1969. It has been engaged in four types of work: experiments to establish physical and operational parameters of the system; detailed experimental surveys of areas of known economic uranium occurrence; experimental surveys at wide line spacing for the purpose of aiding geological mapping and evaluating economic potential; and cross-country reconnaissance flights in order to determine large scale regional variations in radioelement distribution within the Canadian Shield. More than 25,000 kilometers (16,000 miles) of cross-country reconnaissance survey lines have been flown over the Canadian Shield in the summers of 1969, 1970, and 1971. Data collected on these cross-country flights are summarized. (U.S.)