National mineral assessment tract AK-WC05 (Cyprus massive sulfide)

Tract AK-WC05
Geographic region West Central, AK
Tract area 57,404sq km
Deposit type Cyprus massive sulfide
Deposit age Mesozoic


Explained by Bruce M. Gamble, Robert G. Eppinger, John W. Cady, Stanley E. Church, Byron R. Berger, Gregory T. Spanski
On the choice of deposit models
Although no massive sulfide deposits are known in this tract, the occurrence of appropriate rock units and Cu anomalies suggest that it is geologically permissible for Cyprus and Besshi massive sulfide deposits as described by Singer (1986).
On the delineation of permissive tracts
This tract covers the area of the Koyukuk magmatic arc, which consists of Upper Jurassic(?) and Lower Cretaceous andesitic volcanics (Patton and others, 1989; Nokleberg and others, 1994). The tract includes areas underlain by Koyukuk rocks as inferred from aeromagnetics. Anomalously high concentrations of elements in stream-sediment samples include As, Sb, Pb, Cu, Au, Ag, and W.
Important examples of this type of deposit
No Cyprus massive sulfide deposits are known in this tract.
On the numerical estimates made
An estimate of the number of undiscovered deposits was not attempted.
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.
Singer, D.A., 1986, Descriptive model of Cyprus massive sulfide, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 131.

Geographic coverage

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