National mineral assessment tract AK-SC35 (Zn-Pb skarn)

Tract AK-SC35
Geographic region South Central, AK
Tract area 15,193sq km
Deposit type Zn-Pb skarn
Deposit age Mesozoic - Tertiary

Rationale

Explained by Marti L. Miller and Thomas K. Bundtzen
On the choice of deposit models
Zn-Pb skarns (Cox, 1986; Mosier, 1986) are permissive in south-central Alaska where carbonate rock units are locally intruded by small felsic plutons.
On the delineation of permissive tracts
This permissive tract for skarn deposits in south-central Alaska is a continuation of the adjacent tract in southwestern Alaska. The area includes scattered carbonate roof pendants in proximity to porphyry Cu-type plutons similar to those described in the Lake Clark (Nelson and others, 1983) and Iliamna quadrangles (Detterman and Reed, 1980).
Important examples of this type of deposit
No Pb-Zn skarns are known in this tract.
On the numerical estimates made
Several examples of Zn-Pb skarns occur within the adjacent tract in southwest Alaska, but none are known to occur within this tract. The number of undiscovered deposits for this tract was not estimated.
References
Cox, D.P., 1986, Descriptive model of Zn-Pb skarn deposits, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 90.
Detterman, R.L., and Reed, B.L., 1980, Stratigraphy, structure, and economic geology of the Iliamna quadrangle, Alaska: U.S. Geological Survey Bulletin 1368-B, 86 p., scale 1:250,000.
Nelson, W.H., Carlson, Christine, and Case, J.E., 1983, Geologic map of the Lake Clark quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1114-A, scale 1:250,000.

Geographic coverage

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