Big Springs Mine

Elko County, Nevada, United States

GoldSilverAntimonyArsenicZincCopper

⌖ Show on map USGS source ↗

Commodities

PrimaryGold

SecondarySilver

TertiaryAntimony, Arsenic, Zinc, Copper

Commodity typeM

Deposit

Deposit typeSediment-hosted Au

Model173: Sediment-hosted Au

Deposit sizeS

Orebody formIrregular

Ore controlMineralization at Big Springs was controlled by an E-W shear zone that also truncates the northern mineralized zone .Ore deposits are localized at intersections of NE-trending faults with this E-W-trending fault zone and fold axes.

Materials

Ore mineralsGold, Marcasite, Arsenopyrite, Pyrite, Sphalerite, Chalcopyrite, Stibnite

GanguePyrite

Geology

Host rockArgillite,Chert,Conglomerate,Siltstone,Sedimentary Rock,Limestone,Diorite,Quartz Monzonite · Schoonover Sequence

StructureDeformation related to the Antler Orogeny is the earliest tectonic event recorded in the Big Springs rocks, during which siliceous western assemblage rocks were emplaced over eastern assemblage carbonate and siltstone along the Roberts Mountain thrust fault. Compressional deformation of the Sonoma Orogeny occurred in the late Permian, during which the foredeep accumulated Schoonover Sequence was thrust over both the allochthonous western and autochthonous eastern assemblage rocks. Sonoma tectonism in the Big Springs area is evidenced by SE-verging overturned folds and imbricate thrust faults, all of which have been cut by later normal faults. A strong N75W fabric is manifested in folds and shears throughout the Independence Range and may be related to the Wells fault. This structural zone may have been reactiviated during the formation of the NW-striking Northern Nevada Rift Zone and Basin and Range extensional faulting., Deposits are structurally controlled at intersections of NE-trending and E-W-trending fault zones and fold axes. The E-W structure is part of a large ore-controlling shear zone that also truncates the northern mineralized zone at Big Springs. Many of the dikes occur along the NE-trending and E-W-trending fault intersections. A strong N75W fabric is manifested in folds and shears throughout the Independence Range and may be related to the Wells fault. This structural zone may have been reactiviated during the formation of the NW-striking Northern nevada Rift Zone and Basin and Range extensional faulting.

Tectonic settingAntler foredeep basin

AlterationPropylitic alteration is common throughout the volcanic rocks of the Dorsey Creek member. Gold mineralization occurs locally when the propylitically altered rocks are overprinted by quartz-sericite-pyrite-dolomite alteration

Economic & production

Development statusProducer

Discovery year1982

Identification

Deposit ID10310525

MRDS IDM242936

Alternate namesMac Ridge, North Sammy Creek, South Sammy Creek, 701 deposit, 131 deposit, 401 deposit, 601 deposit, Mesona claims, Jack Creek project, Bull Run

RegionNA

Data scoreB

Coordinates41.5605, -115.97557

References

NBMG MI-1986 - 2004, The Nevada Mineral Industry, 1986.Bonham, H.F., 1986, NBMG Map 91.Prospectus - Freeport Gold, Co. 1985.1983 Annual Report to Stockholders of Bull Run Gold Mines, Ltd.NBMG, 1988, MI-1987.Numerous Press Releases, NBMG Mining District File 79-A.EIS Report - Big Springs Project, on file at NBMGUSDA Forest Service, 1987, Environmental Assessment - Big Springs Project, Elko County, Nevada.LaPointe, D. D., Tingley, J. V., Jones, R. B., 1991, Mineral Resources Of Elko County, Nevada, NBMG Bulletin 106.Adams, O. F., 1996, Stratigraphy, structure, and exploration potential of the Big Springs gold deposits, Northern Independence Range, Nevada in Coyner, A. R., and Fahey, P.L., eds., Geology and Ore Deposits of the American Cordillera: Geological Society of Nevada Symposium Proceedings, Reno/Sparks, Nevada, April, p.1-13.Youngerman, A., 1992, Structural control, alteration, and primary mineralization at the Big Springs gold mine, Elko County, Nevada, unpublished M. Sc. Thesis, University of Nevada, 80p.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.Gateway Gold Corp. press release, 9/16/2004).