Much of the Yukon-Tanma Terrane escaped Pleistocene glaciation with the result that there is <1% outcrop across much of the terrane and weathered rock commonely extends to depths of >75m. Weathering has in many cases removed all obvious signs of mineralization and has resulted in the dispersion of soluble metals in the near surface. For these reasons, exploration based on traditional prospecting methods and soil geochemical surveys has met with limited success. Geological mapping is hindered by the lack of exposure and by the complex geology. To address these problems a detailed airborne geological sruvery, combining gamma ray spectrometric, magnetic and VLF sesors, was flown in the Dawson Range, central Yukon Tanana Terrane. Spectrometric data were used to determine the average surface concentration of potassium (K), uranium (U), and thorium (Th). Lithological units are characterized by relatively consistent geochemical signatures permitting improved geological mapping based on the distribution of spectrometric domains. Alteration halves, commonly characterized by the addition of K and magnetite, are identifiable as areas of low Th'K rations and as total field magnetic highs.