National mineral assessment tract AK-WC04 (Besshi massive sulfide)

Tract AK-WC04
Geographic region West Central, AK
Tract area 1,054sq km
Deposit type Besshi massive sulfide
Deposit age Paleozoic - Mesozoic


Explained by Marti L. Miller and Bruce M. Gamble
On the choice of deposit models
Several small areas in west-central Alaska contain outcrops of mixed sedimentary and tuffaceous rocks of marine origin (mainly volcanic sandstone and andesite tuff). These areas are similar to nearby areas of southwestern Alaska, and are considered permissive for Besshi massive sulfide deposits as described by Cox (1986).
On the delineation of permissive tracts
This tract is delineated on the basis of geology considered permissive for Besshi massive sulfide deposits. No Besshi-type deposits are known in the area. The permissive rock types are mixed sedimentary and tuffaceous rocks of the Koyukuk terrane in parts of the Unalakleet quadrangle (Patton and Moll-Stalcup, 1996).
Important examples of this type of deposit
No examples of Besshi massive sulfide deposits are known in west-central Alaska.
On the numerical estimates made
No estimate of undiscovered resources was attempted.
Cox, D.P., 1986, Descriptive model of Besshi massive sulfide, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 136.
Patton, W.W., Jr. and Moll-Stalcup, E.J, 1996, Geology of the Unalakleet quadrangle, west-central Alaska: U.S. Geological Survey Miscellaneous Investigations Map I-2559, scale 1:250,000.

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