National mineral assessment tract AK-EC19 (Cu (Au) skarn)

Tract AK-EC19
Geographic region East Central, AK
Tract area 29,265sq km
Deposit type Cu (Au) skarn
Deposit age Cretaceous - Tertiary

Rationale

Explained by Thomas D. Light
On the choice of deposit models
This tract is permissive for Cu-(Au) skarn deposits where Cretaceous or Tertiary plutons have intruded near carbonate rocks or calcareous clastic rocks (Cox and Theodore, 1986).
On the delineation of permissive tracts
This multi-part tract is defined by Paleozoic carbonate rocks. Where the environment of deposition is not known or indeterminate, thick carbonate rocks of possible shelf, slope, or deeper-water-facies are included. Paleozoic metamorphic rocks that contain minor marble units of unknown origin, such as biotite gneiss and amphibolite (PzpCb of Foster, 1976), have not been included in this tract. In the Eagle and Charley River quadrangles, geologically favorable units include the limestones of the Tindir Group, the Funnel Creek Limestone, the Hillard Limestone, and the Calico Bluff Formation. In the Livengood quadrangle favorable units include the Tolovana Limestone and the limestones of the Wickersham unit.
Important examples of this type of deposit
No Cu (Au) skarn deposits are known in this tract.
On the numerical estimates made
Because of the lack of detailed geological information, and the absence of known deposits, no estimate of the number of undiscovered Cu (Au) skarn deposits was attempted.
References
Cox, D.P., and Theodore, T.G., 1986, Descriptive model of Cu skarn deposits, in Cox, D.P. and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 86.
Foster, H.L., 1976, Geologic map of the Eagle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-922, scale 1:250,000.

Geographic coverage

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