El Arco

Porphyry copper deposit in Baja California, Mexico

Names and other identifiers

GMRAP ID 184
Tract name Southern California Batholith (003pCu3001x)
Site status deposit

Geographic location

Country Mexico
State or province Baja California
Geographic location -113.396892972, 28.032788298
Geologic map unit -113.396892972, 28.032788298
Nearby data

Geologic information

Deposit type Porphyry copper
Age (Ma) 164.1Ma
Age determination method Re-Os molybdenite
Age range 164.6–163.8 Ma
Age reference Valencia, Barra and others (2006)
Minerals apatite, azurite/malachite, biotite, carbonate, chalcocite/digenite, chalcopyrite, chlorite, chrysocolla, copper, copper wad, covellite, cuprite, dioptase, epidote, goethite/limonite, galena, gold, kaolinite, molybdenite, pyrite, sericite, sphalerite
Associated rocks granodiorite, quartz monzonite, andesite breccia, andesite porphyry, aplite, diabase dikes, granodiorite porphyry
Tectonic setting island arc
Stratigraphic age Middle Jurassic

Commodity and development information

Development status Prospect
Major commodities Cu, Au
Tonnage (Mt) 1,016Mt
Cu grade (%) 0.518%
Au grade (g/t) 0.12g/t
Contained copper 5,260,000t
Gold-Moly ratio -9999

Reference information

Comments According to Southern Copper Corp. (2006, 2007), resources contain 846 Mt of sulfide ore and 170 Mt of leaching ore. Covered by Quaternary sand and gravel. Post-ore Albian metamorphism (~95 Ma, Ar-Ar). Mine is slated to begin production in 2012 (Daniel, 2007). Location based on Servicio Geológico Mexicano 1:250,000-scale Isla San Estaban Map H12-10; recent zircon and molybdenite ages show age to be Jurassic; K-Ar ages from the porphyry stock range from 94 to 107 Ma are now interpreted as thermally reset by emplacement of Peninsular Ranges batholith.
Study area name Mexico
References Daniel (2007); Romero-Rojas and others (1998); Singer and others (2008); Valencia, Barra and others (2006); Valencia-Moreno and others (2007); Weber and Lopez-Martinez (2006); Singer and others (2008); U.S. Geological Survey (2007); Southern Copper Corp. (2006); Southern Copper Corp. (2007)
Site reference Hammarstrom and others (2010)
Daniel, F.J., 2007, Update 3–Major new Grupo Mexico mine to begin output in 2012: Reuters Web page accessed August 22, 2008, at http://www.reuters.com/article/bondsNews/idUSN0640844420070606.
Romero-Rojas, S.A., Maraver-Romero, D.A., and de la O-Burrola, Francisco, 1998, Carta geológico-minera, Isla San Esteban H12-10, Baja California y Sonora [Mexico]: Pachuca, Hidalgo, Servicio Geológico Mexicano, 1 sheet, scale 1:250,000.
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/.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/.Southern Copper Corp., 2006, Annual Report—2005: Southern Copper Corp. Annual Report, 48 p., accessed February 27, 2014, at http://sec.edgar-online.com/southern-copper-corp/10-ka-amended-annual-report/2006/03/28/Section2.aspx. (Available for download at www.edgar.com.)Southern Copper Corp., 2007, Southern Copper Corp—Rising copper prices, attractive dividend yield, 2 p.: Southern Copper Corp. press release, May 31, 2007, 2 p., accessed February 27, 2014, at http://seekingalpha.com/article/36947.U.S. Geological Survey, 2007, Mineral Resources Data System (MRDS): U.S. Geological Survey database, accessed December 15, 2007, at http://tin.er.usgs.gov/mrds/.Valencia, V.A., Barra, F., Weber, B., Ruiz, J., Gehrels, G., Chesley, J., and Lopez-Martinez, M., 2006, Re/Os and U/Pb geochronology of the El Arco porphyry copper deposits, Baja California Mexico—Implications for the Jurassic tectonic setting: Journal of South America Earth Sciences, v. 22, p. 39–51. (Also available at http://dx.doi.org/10.1016/j.jsames.2006.08.005.)Valencia-Moreno, M., Ochoa-Landín, Lucas, Noguez-Alcántara, Benito, Ruiz, Joaquin, Pérez-Segura, Efrén, 2007, Geological and metallogenetic characteristics of the porphyry copper deposits of México and their situation in the world context, in Alaniz-Álvarez, S.A., and Nieto-Samaniego, Á.F., eds., Geology of México—Celebrating the centenary of the Geological Society of México: Geological Society of America Special Paper 422, p. 433–458. (Also available at http://specialpapers.gsapubs.org/content/422/433/F8.expansion.html.)Weber, Bodo, and Lopez-Martinez, Margarita, 2006, Pb, Sr, and Nd isotopic and chemical evidence for a primitive island arc emplacement of the El Arco porphyry copper deposit (Baja California, Mexico): Mineralium Deposita, v. 40, p. 707–725. (Also available at http://dx.doi.org/10.1007/s00126-005-0028-4.)