Sierran Arc

A composite island-continental margin arc that formed during subduction of the Farallon Plate beneath western North America
Tract ID 003pCu9007
Country United States of America
Commodity Cu
Study area name United States revised
Tectonic setting mixed
Deposit type porphyry copper
Grade-tonnage model General porphyry copper model (Singer and others, 2008)
Geologic age
Geologic feature age Cretaceous
Generalized age Mesozoic
Oldest rocks age 145.5Ma
Youngest rocks age 65.5Ma
Age range 80Ma
Identified Cu resources 7,000,000metric tons
Known prospects 7
Mean Cu (t/sq km) 102t/sq km
Map scales used 500K

Results of the assessment

Assessment date 2010
Estimators Steve Ludington, Jane Hammarstrom, Gilpin Robinson, and 1996 Team
Assessment depth 1km
Quantitative assessment Yes

Estimated number of deposits

Number of deposits Confidence level
3 50%
11 10%
14 5%
14 1%
Mean estimated deposits 4.73 ±4.6 (0.97%)
Probability of mean 0.3
Probability of no copper 0.17

Estimated deposit density

Known
deposits
Total
deposits
Area
(sq km)
Deposit density
per 100,000 sq km
7 11.73 175,915 7

Mean estimated tonnage

Copper 18,000,000
Molybdenum 490,000
Gold 460
Silver 5,900
Ore 3,600

Undiscovered copper resource

Confidence level 50% 10% 5%
Tonnage 7,400,000 47,000,000 75,000,000

Economic analysis

Fraser country California
Fraser type 0.95%
Fraser high 0.05%
Typical cost 1%
High cost 0%
Infrastructure setting Typical
Comments on depth skew shallow
Expected depth distribution
0 - 250m 0.35
250m - 500m 0.25
500m - 1km 0.4
Economically recoverable resources
Copper 12,000,000t
Molybdenum 240,000t
Gold 250t
Silver 3,700t
Probability no econ recoverable 0.26
Econ NPV 3,700x $1M
Exp dollars 15.9x $1M/100,000 sq km
Exp value class Medium

Bibliographic references

General U.S. Geological Survey National Mineral Resource Assessment Team (2002)
Economic Robinson and Menzie (2012)

Deposits and prospects associated with this tract

Name Type State Country Development Details
Bounder prospect Nevada United States Occurrence Details
Ely deposit Nevada United States Occurrence Details
Fish Creek prospect Nevada United States Occurrence Details
Lights Creek deposit California United States Occurrence Details
Monte Cristo prospect Nevada United States Occurrence Details
SFS deposit Nevada United States Occurrence Details
Sullivan deposit Nevada United States Past Producer Details
Buckingham-Copper Basin deposit Nevada United States Occurrence Details
Crescent Peak prospect Nevada United States Occurrence Details
Red Hills prospect Nevada United States Occurrence Details
Victoria prospect Nevada United States Occurrence Details