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Patterns in the copper isotope composition of minerals in porphyry copper deposits in southwestern United States / Ryan Mathur in Economic geology, Vol. 105 N° 8 (Décembre 2010) 

Public ISBD [article]  in Economic geology > Vol. 105 N° 8 (Décembre 2010) . - pp. 1457-1467 Titre : Patterns in the copper isotope composition of minerals in porphyry copper deposits in southwestern United States Type de document : texte imprimé Auteurs : Ryan Mathur, Auteur ; Molly Dendas, Auteur ; Spencer Titley, Auteur Année de publication : 2011 Article en page(s) : pp. 1457-1467 Note générale : Géologie économique Langues : Anglais (eng) Mots-clés : Porphyry  copper  deposits  Isotope  composition  United-States Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : Cu isotope measurements of minerals from American southwest porphyry Cu deposits reveal a positive relationship with the grade of Cu and display spatial patterns. We measured the Cu isotope composition of 87 minerals contained within veins from drill core and hand specimen samples from three deposits (the Silver Bell, Ray, and Morenci mines). The overall range of Cu isotope ratios varies from −13.5 to +8.3 per mil. The deposits possess three different Cu reservoirs in which each has unique Cu isotope signatures, where δ65Cu for leach cap minerals < hypogene minerals < supergene enrichment minerals. The pattern exists in all three deposits and resulted from oxidative weathering of Cu at surface and reprecipitation of Cu at depth. A Rayleigh distillation model mimics the Cu isotope patterns found in the leach cap and quantifies the degree of leaching. A comparison of the isotopic composition of the three reservoirs among the three deposits reveals distinct differences—the Silver Bell mine possesses leach cap minerals that are more depleted in 65Cu and enrichment minerals that are more enriched in 65Cu than both the Morenci and Ray mines. A possible explanation for the difference among the deposits could indicate that the Silver Bell deposit experienced a greater degree of leaching than the Ray and Morenci deposits. The comparative analysis of the Cu isotope data reveals the exploration potential of using Cu isotope fractionation in the supergene environments. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/105/8/1457.abstract [article] Patterns in the copper isotope composition of minerals in porphyry copper deposits in southwestern United States [texte imprimé] / Ryan Mathur, Auteur ; Molly Dendas, Auteur ; Spencer Titley, Auteur . - 2011 . - pp. 1457-1467. Géologie économique Langues : Anglais (eng) in Economic geology > Vol. 105 N° 8 (Décembre 2010) . - pp. 1457-1467 Mots-clés : Porphyry  copper  deposits  Isotope  composition  United-States Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : Cu isotope measurements of minerals from American southwest porphyry Cu deposits reveal a positive relationship with the grade of Cu and display spatial patterns. We measured the Cu isotope composition of 87 minerals contained within veins from drill core and hand specimen samples from three deposits (the Silver Bell, Ray, and Morenci mines). The overall range of Cu isotope ratios varies from −13.5 to +8.3 per mil. The deposits possess three different Cu reservoirs in which each has unique Cu isotope signatures, where δ65Cu for leach cap minerals < hypogene minerals < supergene enrichment minerals. The pattern exists in all three deposits and resulted from oxidative weathering of Cu at surface and reprecipitation of Cu at depth. A Rayleigh distillation model mimics the Cu isotope patterns found in the leach cap and quantifies the degree of leaching. A comparison of the isotopic composition of the three reservoirs among the three deposits reveals distinct differences—the Silver Bell mine possesses leach cap minerals that are more depleted in 65Cu and enrichment minerals that are more enriched in 65Cu than both the Morenci and Ray mines. A possible explanation for the difference among the deposits could indicate that the Silver Bell deposit experienced a greater degree of leaching than the Ray and Morenci deposits. The comparative analysis of the Cu isotope data reveals the exploration potential of using Cu isotope fractionation in the supergene environments. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/105/8/1457.abstract