National mineral assessment tract AK-SW09 (Kuroko massive sulfide)

Tract AK-SW09
Geographic region Southwestern, AK
Tract area 1,433sq km
Deposit type Kuroko massive sulfide
Deposit age Jurassic


Explained by Marti L. Miller, and Warren J. Nokleberg
On the choice of deposit models
Volcanic rocks of the Talkeetna Mountain Formation in southwestern Alaska are permissive for kuroko massive sulfide deposits as described by Singer (1986).
On the delineation of permissive tracts
This tract is composed of Lower Jurassic andesite to basaltic volcanic and volcaniclastic rocks of the Talkeetna Formation (Detterman and Reed, 1980). It is an extension of the adjacent tract defined in south-central Alaska.
Important examples of this type of deposit
No kuroko deposits are known within this tract, but the Johnson River kuroko massive sulfide prospect (Steefel, 1987) occurs in the extension of this tract into the Kenai quadrangle of south-central Alaska.
On the numerical estimates made
No attempt was made to estimate the number of undiscovered kuroko massive sulfide deposits in this tract. However, because of the Jurassic age of the volcanic rocks, if an estimate were to be made, then the Sierran Kuroko model of Singer (1992) would be the most appropriate tonnage and grade model to use.
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.
Singer, D.A., 1986, Descriptive model of kuroko massive sulfide, in, Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 189-190.
Singer, D.A.., 1992, Grade and tonnage model of Sierran kuroko massive sulfide, in Bliss, J.D., ed., Developments in mineral deposit modeling: U.S. Geological Survey Bulletin 2004, p. 29-32.
Steefel, C.I., 1987, The Johnson River prospect, Alaska: gold-rich sea-floor mineralization from the Jurassic: Economic Geology, v. 82, p. 894-914.

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