Explained by Thomas D. Light, Bruce M. Gamble, and Donald Grybeck
On the choice of deposit models
The presence of placer Au deposits, greenschist facies rocks of the Ruby terrane, and local geochemical anomalies support definition of a permissive tract for low-sulfide Au-quartz veins.
On the delineation of permissive tracts
This tract is defined by Precambrian(?) and Paleozoic pelitic schists, metabasites, quartzites, orthogneiss, and marbles (Patton and others, 1989; Dover, 1994; Nokleberg and others, 1994). As, Zn, W, and Cu, are the most common stream sediment anomalies, and traces of Au, Ag and Bi are present locally.
Important examples of this type of deposit
No low-sulfide Au-quartz veins are known in the tract, but the geologic environment suggests that low-sulfide Au-quartz veins may be present.
On the numerical estimates made
No estimate of the number of undiscovered low-sulfide Au-quartz vein deposits was attempted.
Dover, J.A., 1994, Geology of part of east-central Alaska, Chapter 5 in Plafker, George, and Berg, H.C., eds., The Geology of Alaska, v. G-1 of Geology of North America: Boulder, Colorado, Geological Society of America, Decade of North American Geology series, p. 153-204.
Nokleberg, W.J., Moll-Stalcup, E.J., Miller, T.P., Brew, D.A., Grantz, Arthur, Reed, J.C., Jr., Plafker, George, Moore, T.E., Silva, S.R., and Patton, William W., Jr., 1994, Tectonostratigraphic terrane and overlap assemblage map of Alaska: U.S. Geological Survey Open-File Report 94-194, 45 manuscript p., scale 1:2,500,000.
Patton, W.W., Jr., Box, S.E., Moll-Stalcup, E.J., and Miller, T.P., 1989, Geology of west-central Alaska: U.S. Geological Survey Open-File Report 89‑554, 41 p.