Mine detail: Big Springs Mine

Previously called 'Mesona claims601 deposit401 deposit131 deposit701 depositSouth Sammy CreekNorth Sammy CreekMac RidgeJack Creek projectBull Run'

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Location

Lat / long:

41.5605, -115.97557

Resource(M)

Primary:	Gold
Secondary:	Silver
Tertiary:	Antimony, Arsenic, Zinc, Copper
Ore:	Gold, Marcasite, Arsenopyrite, Pyrite, Sphalerite, Chalcopyrite, Stibnite
Gangue:	Pyrite
Orebody form:	Irregular
Discovery year:	1982

Production

Operation type:	Surface
Deposit type:	Sediment-hosted Au
Production size:	Small
Development status:	Producer

Geology

Host rock:	Schoonover Sequence
Host type:	Argillite,Chert,Conglomerate,Siltstone,Sedimentary Rock,Limestone,Diorite,Quartz Monzonite
Structure:	Deformation 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:	Antler foredeep basin
Alteration processes:	Propylitic 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

References

MRDS	M242936
DEP	10310525
Reference	{Deposit:: NBMG MI-1986 - 2004, The Nevada Mineral Industry, 1986.}{Deposit:: Bonham, H.F., 1986, NBMG Map 91.}{Deposit:: Prospectus - Freeport Gold, Co. 1985.}{Deposit:: 1983 Annual Report to Stockholders of Bull Run Gold Mines, Ltd.}{Deposit:: NBMG, 1988, MI-1987.}{Deposit:: Numerous Press Releases, NBMG Mining District File 79-A.}{Deposit:: EIS Report - Big Springs Project, on file at NBMG}{Deposit:: USDA Forest Service, 1987, Environmental Assessment - Big Springs Project, Elko County, Nevada.}{Deposit:: LaPointe, D. D., Tingley, J. V., Jones, R. B., 1991, Mineral Resources Of Elko County, Nevada, NBMG Bulletin 106.}{Deposit:: 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.}{Deposit:: 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.}{Deposit:: 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.}{Deposit:: Gateway Gold Corp. press release, 9/16/2004).}
Reporter	La Pointe, D.D., Schruben, Paul G.