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Allard

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Porphyry copper deposit in Colorado, United States

Names and other identifiers

GMRAP ID 53
Tract name Eastern Alkaline Province (003pCu3010x)
Site status deposit

Geographic location

Country United States
State or province Colorado
Geographic location -108.088055556, 37.406944444
Geologic map unit -108.088055556, 37.406944444
Nearby data
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Geologic information

Deposit type Porphyry copper
Age (Ma) 68Ma
Age determination method unknown
Age range 70–65 Ma
Age reference Singer and others (2008)
Minerals arsenopyrite, bornite, calcite, chalcocite, chalcopyrite, chlorite, domeykite, enargite, fluorite, galena, hematite, kaolinite, magnetite, marcasite, pyrite, sericite, sphalerite, tennantite
Associated rocks breccia, pegmatite, syenite, trachyte dike, limestone, monzonite, conglomerate, monzonite porphyry, diorite porphyry, sandstone, shale
Tectonic setting postconvergence
Stratigraphic age Late Cretaceous

Commodity and development information

Development status Occurrence
Major commodities Cu
Tonnage (Mt) 200Mt
Cu grade (%) 0.4%
Ag grade (g/t) 5g/t
Contained copper 800,000t
Gold-Moly ratio -9999

Reference information

Comments 10–200 ppb Au, 100–170 ppb Pt.
Study area name United States
References Armstrong (1969); Cunningham and others (1994); Eckel (1949); Niemuth (1994); Werle and others (1984); Singer and others (2008); Singer and others (2005)
Site reference U.S. Geological Survey National Mineral Resource Assessment Team (2002)
Armstrong, R.L., 1969, K-Ar dating of laccolithic centers of the Colorado Plateau and vicinity: Geological Society of America Bulletin, v. 80, p. 2081–2086. (Also available at http://dx.doi.org/10.1130/0016-7606(1969)80[2081:KDOLCO]2.0.CO;2.)Cunningham, C.G., Naeser, C.W., Marvin, R.F., Luedke, R.G., and Wallace, A.R., 1994, Ages of selected intrusive rocks and associated ore deposits in the Colorado mineral belt: U.S. Geological Survey Bulletin 2109, 31 p. (Also available at http://pubs.usgs.gov/bul/2109/report.pdf.)Eckel, E.B., 1949, Geology and ore deposits of the La Plata district, Colorado, with sections by J.S. Williams, F.W. Galbraith, and others: U.S. Geological Survey Professional Paper 219, 179 p., 27 plates. (Also available at http://pubs.er.usgs.gov/publication/pp219.)Niemuth, N.J., 1994, The primary copper industry of Arizona, 1992: Arizona Department of Mines and Mineral Resources Special Report 20, 58 p. (Also available at http://mines.az.gov/DigitalLibrary/ADMMR_Reprints/CopperReports/cu1992SR20.pdf.)Singer, D.A., Berger, V.I., and Moring, B.C., 2005, Porphyry copper deposits of the world—Database, map, and grade and tonnage models: U.S. Geological Survey Open-file Report 2005-1060, [9] p. and digital data, accessed December 31, 2013, at http://pubs.usgs.gov/of/2005/1060/.Singer, D.A., Berger, V.I., and Moring, B.C., 2008, Porphyry copper deposits of the world—Database and grade and tonnage models, 2008: U.S. Geological Survey Open-File Report 2008-1155, [45] p. and digital data, accessed December 31, 2013, at http://pubs.usgs.gov/of/2008/1155/.Werle, J.L., Ikramuddin, Mohammed, and Mutschler, F.E., 1984, Allard stock, La Plata Mountains, Colorado—An alkaline rock-hosted porphyry copper-precious metal deposit: Canadian Journal of Earth Sciences, v. 21, p. 630–641. (Also available at http://dx.doi.org/10.1139/e84-069.)