National mineral assessment tract AK-WC06 (Cyprus massive sulfide)

Tract AK-WC06
Geographic region West Central, AK
Tract area 1,789sq km
Deposit type Cyprus massive sulfide
Deposit age Paleozoic

Rationale

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
The occurrence of appropriate rock units suggests that this tract may be permissive for Cyprus massive sulfide deposits as described by Singer (1986).
On the delineation of permissive tracts
This tract consists of mafic and ultramafic oceanic assemblages of the Kanuti, Tozitna, and Innoko subterranes (Patton and others, 1989; Nokleberg and others, 1994). Also included are some phyllite and argillite of the Slate Creek thrust panel; pillow basalts, chert, gabbro, and diabase of the Narvak complex; and mafic-ultramafic rocks of the Kanuti complex. Narvak is clearly the most common assemblage in west-central Alaska. Known mineral deposits are podiform chromite occurrences (Mt. Hurst in the Ophir quadrangle; Kaiyuh Hills in the Nulato quadrangle), and placer gold deposits and occurrences. Stream sediment anomalies are sparse and consist of scattered Cu and Zn, and one area of As.
Important examples of this type of deposit
No Cyprus massive sulfide deposits are known in this tract.
On the numerical estimates made
No estimate of the number of undiscovered deposits was attempted.
References
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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