Cadmium isotope fractionation in the Fule Mississippi Valley-type deposit, Southwest China
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High-precision cadmium (Cd) isotope compositions are reported for sphalerite, galena, and smithsonite from the Fule Zn–Pb–Cd deposit, a typical Mississippi Valley-type deposit in Southwest China. Dark sphalerite has lighter δ114/110Cd values (0.06 to 0.46 ‰) than light sphalerite (0.43 to 0.70 ‰), and the Cd in galena is primarily in the form of sphalerite micro-inclusions with δ114/110Cd of −0.35 to 0.39 ‰. From early to late stages, δ114/110Cd values of smithsonite regularly increase from 0.19 to 0.42 ‰, whereas Cd/Zn ratios decrease from 252 to 136; the δ114/110Cd variation pattern of supergene smithsonite reflects kinetic Rayleigh fractionation during low-temperature processes. From the bottom to the top of the orebody, the dark sphalerite has different patterns in δ114/110Cd values, Cd/Zn ratios, δ34S values, and Fe concentrations compared to the light sphalerite, indicating that dark and light sphalerite formed by different processes. The varying patterns of δ144/110Cd values and Cd/Zn ratios within light sphalerite are similar to those of layered smithsonite, and the δ144/110Cd values have a positive correlation with δ34S values, indicating that Cd isotope fractionation in the light sphalerite was due to kinetic Rayleigh fractionation. Instead, in dark sphalerite, the δ144/110Cd values have a negative correlation with δ34S values and a positive correlation with the Cd/Zn ratio. Thus, it can be concluded that dark sphalerite could be modeled in terms of two-component mixing (basement fluid and host-rock fluid), which is in agreement with previous explanations for the negative correlation between δ66Zn and δ34S in some typical Zn–Pb deposits. We propose that the significant variation in Cd isotope composition observed in the Fule Zn–Pb–Cd deposit confirms that Cd isotopes can be used for tracing fluid evolution and ore formation.
KeywordsCadmium and sulfur isotopes Cd-bearing minerals Zn–Pb–Cd deposits Stable isotope fractionation
This work was financially supported by National Natural Science Foundation of China (Nos. 41503011, 41573007, 40930425, and 41173026), the Strategic Priority Research Program of CAS (XDB18030302), 973 Program (2014CB440904), CAS/SAFEA International Partnership Program for Creative Research Teams (No. KZZD-EW-TZ-20) and CAS “Light of West China”.
- Belissont R, Boiron MC, Luais B, Cathelineau M (2014) LA-ICP-MS analyses of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerites from the Noailhac–Saint-Salvy deposit (France): insights on incorporation mechanisms and ore deposition processes. Geochim Cosmochim Acta 126:518–540CrossRefGoogle Scholar
- Clayton RN (1981) Isotopic thermometry. In: Newton RC, Navrotsky A, Wood BJ (eds) Thermodynamics of minerals and melts. Springer Verlag, New York, pp. 85–109Google Scholar
- Cloquet C, Rouxel O, Carignan J, Libourel G (2005) Natural cadmium isotopic variations in eight geological reference materials (NIST SRM 2711, BCR 176, GSS-1, GXR-1, GXR-2, GSD-12, Nod-P-1, Nod-A-1) and anthropogenic samples, measured by MC-ICP-MS. Geostandard Geoanal Res 29:95–106CrossRefGoogle Scholar
- Huang ZL, Chen J, Han RS, Li WB, Liu CQ, Zhang ZL, Ma DY, Gao DR, Yang ML (2004) Geochemistry and ore-formation of the Huize giant lead-zinc deposit, Yunnan Province, China: discussion on the relationship between Emeishan flood basalts and lead-zinc mineralization (in Chinese). Geological Publishing House, Beijing, pp. 50–146Google Scholar
- Lambelet M, Rehkämper M, Flierdt T, Xue ZC, Kreissig K, Coles B, Porcelli D, Andersson P (2013) Isotopic analysis of Cd in the mixing zone of Siberian rivers with the Arctic Ocean—new constraints on marine Cd cycling and the isotope composition of riverine Cd. Earth Planet Sci Lett 361:64–73CrossRefGoogle Scholar
- Leach DL, Sangster DF, Kelley KD, Large RR, Garven G, Allen CR, Gutzmer J, Walters S (2005) Sediment-hosted lead-zinc deposits: a global perspective. In: Hedenquist JW, Thompson JFH, Goldfarb RJ, Richards JP (eds) Economic geology 100th anniversary volume. Society of Economic Geologists, Littleton, pp. 561–607Google Scholar
- Si RJ (2005) Ore deposit geochemistry of the Fule dispersed element-polymetallic deposit, Yunnan Province. A dissertation submitted to Chinese Academy of Sciences for a doctor degree. Guiyang (In Chinese with English abstract)Google Scholar
- Tu GC, Gao ZM, Hu RZ, Zhang Q, Li CY, Zhao ZH, Zhang BG (2004) The geochemistry and deposit-forming mechanism of disperse elements. Geological Publishing House, Beijing, pp. 69–115 in ChineseGoogle Scholar