Exploration potential of Cu isotope fractionation in porphyry copper deposits

Mathur, Ryan; Titley, Spencer R.; Barra, Fernando; Brantley, Susan L.; Wilson, M E; Phillips, Allison L.; Munizaga, Francisco; Maksaev, Víctor; Vervoort, Jeff D.; Hart, Garret L.

doi:10.1016/j.gexplo.2008.09.004

Cited by 219 publications

(158 citation statements)

References 17 publications

(33 reference statements)

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“…For Cu isotopic analysis, two elements are commonly used for this purpose, Zn [5,[43][44][45][46][47][48] and Ni [49][50][51][52][53][54]. According to the literature, both elements seem to be well-suited for mass bias correction affecting the Cu isotope ratio, although marginal precision improvements have been recorded when Ni is used [49][50][51][52][53][54].…”

Section: Resultsmentioning

confidence: 99%

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology

et al. 2012

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Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of "non-traditional" isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ 65 Cu results with similar uncertainty budgets in all cases (±0.02-0.04 per mil in delta units, k02, n0 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without oncolumn fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ 65 Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic separation using TRU-Spec resin. Tin isotopic analysis was performed relying on Sb as an internal standard used for mass bias correction. The reproducibility over a period of 1 month (n042) for the mass bias-corrected Sn isotope ratios is in the range of 0.06-0.16 per mil (2 s), for all the ratios monitored.

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Section: Resultsmentioning

confidence: 99%

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology

et al. 2012

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“…Complete dissolution was visually confirmed. The solutions were dried and copper was separated using ion exchange chromatography described by Mathur et al (2009).…”

Section: Methods For Cu Isotope Data Presentedmentioning

confidence: 99%

“…Any data from the following sources that had listed chalcocite as an analyzed phase was included [27,[29][30][31][32][33][34][35][36]. Data from Morenci, Ray, Chuquicamata, and Spence provide type examples of supergene enrichment in classic porphyry copper deposits.…”

Section: Types Of Chalcocite Considered and Deposits Analyzedmentioning

confidence: 99%

Origins of Chalcocite Defined by Copper Isotope Values

et al. 2018

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The origin of chalcocite is explored through a comparison of the copper isotope values of this mineral from supergene enrichment, sedimentary copper/red bed, and high-temperature hypogene mineralization around the world. Data from the literature and the data presented here ( = 361) reveal that chalcocite from high-temperature mineralization has the tightest cluster of values of 65 Cu = 0 ± 0.6 in comparison to sedimentary copper/red bed 65 Cu = −0.9 ± 1.0 and supergene enrichment 65 Cu = +1.9 ± 1.8. Although the errors of the means overlap, large portions of the data lie in different values, allowing for distinguishing ranges for 65 Cu of <−1‰ for sedimentary copper/red bed, between −1 and +1 for high-temperature hypogene, and >+1 for supergene enrichment chalcocite. The copper isotope values of sedimentary copper/red bed and supergene enrichment chalcocite are caused by redox reactions associated with the dissolution and transport of copper, whereas the tighter range of copper isotope values for hypogene minerals is associated with processes active with equilibrium conditions.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] As a result, the residual primary copper-rich minerals (Cu(I)) have their δ 65 Cu values shifted toward lower values as the leaching processes proceed. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In the case of our sample, primary cubanite grains near the weathered surface of the sample were significantly affected by dissolution during low-temperature oxidation and weathering processes, and copper (Cu(I)) in the cubanite grains was probably leached, and precipitated as thin secondary minerals (malachite) (Cu(II)). Thus, these grains show lower δ…”

Section: Application To Cubanite Micro-grains From the Mihara Mine Jmentioning

confidence: 99%

“…Previous copper isotope measurements of copper-rich minerals from various environments have revealed a significantly large variation in the δ 65 Cu values from -16.5 to 10.0 , relative to the NIST-SRM976 standard. 2 This variation is quite large compared with other non-traditional stable isotopes (e.g., Fe and Zn), 1 presumably due to significant isotope fractionations during redox reactions (oxidation states 0, +1 and +2 of Cu are not uncommon in nature, compared with Fe and Zn) that occurred at relatively low temperatures. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Therefore, the copper isotopes are potentially an excellent tracer of geological and biological processes.…”

Section: Introductionmentioning

confidence: 99%