National mineral assessment tract PC03 (Skarn Cu)

Tract PC03
Geographic region Pacific Coast
Tract area 68,900sq km
Deposit type Skarn Cu
Deposit age Mesozoic

Deposit model

Model code 18b
Model type descriptive
Title Descriptive model of Cu skarn deposits
Authors Dennis P. Cox and Ted G. Theodore
URL https://pubs.usgs.gov/bul/b1693/html/bull7nxq.htm
Source https://pubs.er.usgs.gov/publication/b1693

Estimates

Confidence Number of
deposits
90% 0
50% 0
10% 0
5% 0
1% 1

P(none): 0.99

Estimators: DCox, Ludington

Rationale

Explained by Dennis P. Cox, Steve Ludington, and Michael F. Diggles
On the choice of deposit models
Skarn deposits form where intermediate to felsic intrusive rocks, which are the principal sources of the metals, are emplaced into carbonate rocks. On the Pacific margin of North America, the deposits are mainly Mesozoic in age.
On the delineation of permissive tracts
The plutons of the Klamath Mountains, the Sierra Nevada, the Salinian block, and the Southern California batholith include felsic rocks that, in places, intrude minor Triassic and older carbonate-bearing rocks.
Important examples of this type of deposit
The only important skarn deposit in the Klamath Mountains is the King Solomon mine in the Cecilville district, which produced nearly a metric ton of gold (Hotz, 1971). There are no significant copper skarn deposits in the tract.
On the numerical estimates made
Although no significant deposits of this type are known in the tract, the region is permissive in terms of the overall geologic environment. Since no clear examples are known and since carbonate rocks make up a small proportion of the terrane intruded by plutons, it seemed most appropriate to make a small estimate. For the 90th, 50th, 10th, 5th, and 1st percentiles, the team estimated 0, 0, 0, 0, and 1 or more deposits consistent with the copper skarn model of Jones and Menzie (1986).
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.
Hotz, P.E., 1971, Geology of lode gold districts in the Klamath Mountains, California and Oregon: U.S. Geological Survey Bulletin 1290, 91 p.
Jones, G.M., and Menzie, W.D., 1986, Grade and tonnage model of Cu skarn deposits, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 86-89.

Geographic coverage

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