National mineral assessment tract AK-WC15 (Porphyry Cu, BC-Ak type)

Tract AK-WC15
Geographic region West Central, AK
Tract area 15,970sq km
Deposit type Porphyry Cu, BC-Ak type
Deposit age Cretaceous - Tertiary

Rationale

Explained by Bruce M. Gamble and Marti L. Miller
On the choice of deposit models
This tract is permissive for porphyry Cu (Cox, 1986a), BC-Ak type porphyry Cu (Menzie and Singer, 1993), porphyry Cu, skarn related (Cox, 1986c), and porphyry Cu-Mo (Cox, 1986b) deposits based on presence of felsic to intermediate plutons (Patton and others, 1994), and the occurrence of numerous similar or related deposit types. St. Lawrence Island is also considered permissive for porphyry Cu type deposits on the basis of permissive host rocks.
On the delineation of permissive tracts
The geology of the area is poorly known, but several apparently high-level felsic plutons occur in the region, and others could be present at shallow depths. The presence of permissive host rocks is the primary basis for the areal delineation of this tract.
Important examples of this type of deposit
Known mineral deposits in the area include the McLeod Mo occurrence, and a porphyry Cu/porphyry Cu-Mo deposit at Round Top (Harris, 1985).
On the numerical estimates made
Because of the lack of detailed geologic information, no estimates of the number of undiscovered deposits have been attempted.
References
Cox, D.P., 1986a, Descriptive model of porphyry Cu, in Cox, D.P. and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 76.
Cox, D.P., 1986b, Descriptive model of porphyry Cu-Mo, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 115.
Cox, D.P., 1986c, Descriptive model of porphyry Cu, skarn-related deposits, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 82.
Harris, T.D., 1985, Geology of the Round Top porphyry copper-molybdenum deposit, west-central Alaska: unpublished Masters Thesis, University of Colorado, Boulder, Colorado, 55 p.
Menzie, W.D., and Singer, D.A., 1993, Grade and tonnage model of porphyry Cu deposits in British Columbia, Canada, and Alaska, U.S.A.: U.S. Geological Survey Open-file Report 93-275, 8 p.
Patton, W.W., Jr., Box, S.E., Moll-Stalcup, E.J., and Miller, T.P., 1994, Geology of west-central Alaska, in Plafker, George, and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America, The Geology of North America, v. G-1, p. 241-269.

Geographic coverage

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