Airborne gamma-ray spectrometer and magnetometer survey: Medfra Quadrangle (Alaska). Final report

During the months of July, August, and September 1979, an airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten 30 x 10 NTMS quadrangles of West-Central Alaska. The results obtained over the Medfra map area are discussed. The final data are presented in four different forms: on magnetic tape; on microfiche; in graphic form as profiles and histograms; and in map form as anomaly maps, flight path maps, and computer printer maps. The histograms and the multiparameter profiles are presented with the anomaly maps and flight path map in a separate volume. Results from the geochemical analysis indicate that the formation with the highest number of uranium anomalies is the Quarternary alluvium with 34. The geologic formation believed to be the most promising for possible uranium enrichment in the Medfra Quadrangle appears to be unit Tg, Tertiary granitic rocks. By using the criteria outlined in the general section on interpretation, a total of 58 uranium anomalies have been outlined on the interpretation map. Based in part on the criteria discussed in the general interpretation section and in part on the thorium pseudo-contourmap, a total of twelve thorium anomalies have been outlined. Many of the 58 uranium anomalies outlined consist only of anomalous responses of only one of the two uranium/potassium and uranium/thorium ratios, with the other ratio being either normal or anomalous due to very low thorium or potassium values, and with little or no expression on the uranium anomaly map