Commodities
PrimaryGold
Commodity typeM
Deposit
Deposit typedisseminated
Model173: Sediment-hosted Au
Deposit sizeN
Orebody formdisseminated
Ore controlA northwesterly-trending fault is the main feeder structure for mineralizing fluids. Wider, thicker, and higher grade portions of the orebody occur at intersections of this main feeder zone with northwest-striking high-angle normal faults. Thin-bedded silty limestones are a lithologic control of gold deposition.
Geology
Host rockWebb Formation
StructurePaleozoic thrusting and folding and Tertiary age high angle faulting have affected rocks in the mine area. Limestone beds are gently folded along ENE-trending fold axes, forming anticlines and synclines that plunge 10-40 degrees to the east. The dominant Tertiary fault sets strike northwest and north-south; other sets strike east-northeast and northeast., The deposit is located in a window of lower plate rocks below the Roberts Mountain Thrust and lying along the NW-trending Battle Mountain-Eureka Trend of mineral deposits.
AlterationMineralization is closely associated with major decalcification and to a lesser extent with silicification of host rocks and jasperoid development along high-angle structures. Also evident is remobilization of carbon and oxidation and redistribution. Minor bleaching, calcite veining, argillization. All alteration types occur mainly up dip from the feeder structure. The oxidation of pyrite and subsequent remobilization of iron oxides have produced spectacular brick-red to dark yellow brown banding in the oxidized, decalcified limestone. In many areas the ore exhibits intense liesegang banding. Most of the calcite veining is characterized by 0.1-30 cm veins located up dip from the orebody. Argillization is rare. Illitic clays have been locally altered to montmorillonite and allophane.
Economic & production
Development statusProspect
Identification
Deposit ID10310541
Alternate namesAfghan deposit
RegionNA
Data scoreB
Coordinates39.72605, -116.32413
References
Geology and Mineralization of the Gold Bar District, Southern Roberts Mountains, Eureka County, Nevada, 1998, French, G.M., Fenne, F.K., Maus, D.A., Rennebaum, T.D., and Jennings, T.A., in Sediment-hosted Gold Deposits of the Eureka (Ruby Hill Mine) and Gold Bar Districts, East-Central Nevada, Geological Society of Nevada Special Publication No., 27, 1998 Spring Field Trip Guidebook.Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.NBMG MI-96 thru MI-99Simpson Park Mtns. Land Status, 1979Amer. Mines (2000), 1999Amer. Mines (2001) 2000Maher, 1997Castleworth (Pan Nevada) website, Feb. 2006.BLM Claim Microfiche, 1997