National mineral assessment tract GB31 (Sediment-hosted Au)

Tract GB31
Geographic region Great Basin
Tract area 87,400sq km
Deposit type Sediment-hosted Au
Deposit age Phanerozoic

Deposit model

Model code 26a
Model type descriptive
Title Descriptive model of carbonate-hosted Au-Ag
Authors Byron R. Berger
URL https://pubs.usgs.gov/bul/b1693/html/bull7m7b.htm
Source https://pubs.er.usgs.gov/publication/b1693

Estimates

Confidence Number of
deposits
90% 1
50% 2
10% 6
5% 9
1% 16

Estimators: Stoeser, Nutt, Albino, Ludington, Wallace, Nash, Berger, Spanski

Rationale

Explained by Douglas B. Stoeser
On the choice of deposit models
Western Utah is characterized by suitable host rocks, such as silty or argillaceous carbonaceous limestone and dolomite, and known sediment-hosted gold deposits. The descriptive model of Berger (1986) and the grade and tonnage model of Mosier and others (1992) were used for the assessment.
On the delineation of permissive tracts
The criteria used to define the permissive tract for sediment-hosted gold are broad; the basic requirement is the presence of suitable host rocks and an intrusive heat source in the underlying crust. Suitable host rocks are primarily silty or argillaceous carbonaceous limestone and dolomite. Since such rocks underlie western Utah, it was agreed that the most of the Great Basin province of Utah and southernmost Idaho was permissive.
Important examples of this type of deposit
One large (Mercur) and four small sediment-hosted gold deposits (Barney's Canyon, Melco, Tecoma and possibly Goldstrike) occur in Utah. Another possibly relevant occurrence is King's Canyon, which is difficult to classify. In Idaho, the Black Pine deposit is another example.
On the numerical estimates made
The group felt positive about the potential for further discoveries. For the 90th, 50th, 10th, 5th, and 1st percentiles, the team estimated 1, 2, 6, 9, and 16 or more deposits consistent with the grade and tonnage model of Mosier and others (1992).
References
Berger, B.R., 1986, Descriptive model of carbonate-hosted Au-Ag, in Cox, D.P., and Singer, D.A., eds., Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 175.
Mosier, D.L., Singer, D.A., Bagby, W.C., and Menzie, W.D., 1992, Grade and tonnage model of sediment-hosted Au, in Bliss, J.D., ed., Developments in mineral deposit modeling: U.S. Geological Survey Bulletin 2004, p. 26-28.

Geographic coverage

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