Northeast Oregon -Idaho massive sulfide

Region West, Northwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Permissive tracts PC13 for Massive sulfide, Kuroko-type and PC09 Massive sulfide, Cyprus-type extracted and merged from the 1995 National Assessment (U.S. Geological Survey National Mineral Resource Assessment Team, 2002).
Identified resources Identified resources of copper, gold, silver, and zinc; historical production of copper, gold, and silver.
Production Iron Dyke (1910-1928): 34,967 troy oz Au, 258,489 troy oz Ag, and 14,417,920 lbs Cu (Brooks and Ramp, 1968).
Status Past mining; previous exploration.
Estimated resources Red Ledge: Four massive sulfide bodies total 6 million metric tons and collectively average 2.9% Zn, 0.9% Cu, 80.8 grams/metric ton Ag, and 0.9 grams/metric ton Au (Fifarek and others, 1994).
Geologic maps Ferns and others (2006), scale 1:100,000; Schuster and others (1997), scale 1:250,000; Bond and others (1978), scale 1:5000,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Island arc volcanic terranes in the Blue Mountains of northeastern Oregon are considered permissive environments for Kuroko-type massive sulfide deposits. These include the Wallowa and Huntington terranes in Oregon, Idaho and southeasternmost Washington (Brooks and Vallier, 1978; Walker and MacLeod, 1991). The Baker mélange terrane is also included because it incorporates some fragments of arc volcanic and plutonic rocks. Plutonic bodies that intrude these terranes were excluded from the permissive tracts.
Deposits Red Ledge, Iron Dyke (MRDS dep_id: 10127565).
Evidence from mineral occurrences MRDS; Vallier and Brooks (1994).
Geochemical evidence Unknown.
Geophysical evidence Unknown.
Evidence from other sources Unknown.
Comments U.S. Geological Survey National Mineral Resource Assessment Team (2002) assessment tracts PC09 and PC13. Major deposits in PC13 (Red Ledge, Iron Dyke); no important deposits in PC09.
Cover thickness and description Unknown.
Authors Allen K. Andersen, Deborah A. Briggs, Laurel G. Woodruff.
New data needs None requested at this time.
Geologic mapping and modeling needs None requested at this time.
Geophysical survey and modeling needs None requested at this time.