Abstract
The enrichment of lead isotopic composition of nonuranium minerals, in the first place galena in 206Pb and 207Pb, as compared to common lead is a remarkable feature of uranium deposits. The study of such lead isotopic composition anomalous in 206Pb and 207Pb in uranium minerals provides an opportunity for not only identification of superimposed processes resulting in transformation of uranium ores during deposit history but also calculation of age of these processes under certain model assumptions. Galena from the Chauli deposit in the Chatkal–Qurama district, Uzbekistan, a typical representative of hydrothermal uranium deposits associated with domains of Phanerozoic continental volcanism, has been examined with the highprecision (±0.02%) MC-ICP-MS method. Twenty microsamples of galena were taken from polished sections. Six of them are galena hosted in carbonate adjacent to pitchblende spherulites or filling thin veinlets (approximately 60 μm) cutting pitchblende. Isotopically anomalous lead with 206Pb/204Pb and 207Pb/204Pb values reaching 20.462 and 15.743, respectively, has been found in these six microsamples in contrast to another fourteen in which the Pb–Pb characteristics are consistent with common lead. On the basis of these data and with account for the 292 ± 2 Ma age for the Chauli deposit, the age of epigenetic transformation of uranium ores of this deposit has been estimated. During this process, radiogenic lead partly lost from pitchblende was captured into galena. The obtained date is 170 Ma. In the Chatkal–Qurama district, these epigenetic processes are apparently caused by the interaction of uranium minerals with activated underground water under tectonic activity and relief transformation, which took place from the post-Permian (i.e., after the Chauli formation) to the Jurassic period.
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References
Chernyshev, I.V., Uranium–lead geochronology of the formation and transformation of hydrothermal uranium deposits, Gidrotermal’nye mestorozhdeniya urana (Hydrothermal uranium Deposits), Moscow: Nedra, 1978, pp. 376–398.
Chernyshev, I.V., Chugaev, A.V., and Shatagin, K.N., “High-precision Pb isotope analysis by multicollector-ICP-mass-spectrometry using 205Tl/203Tl normalization: optimization and calibration of the method for the studies of Pb isotope variations, Geochem. Int., 2007, vol. 45, no. 11, pp. 1065–1076.
Chernyshev, I.V., Kovalenker, V.A., Gol’tsman, Yu.V., et al., Rb–Sr isochron dating of Late Paleozoic epithermal ore-forming processes: a case study of the Kairagach gold deposit, Kurama ore district, Central Tien Shan, Geochem. Int., 2011 (a), vol. 49, no. 2, pp. 107–119.
Chernyshev, I. V., Bortnikov, N. S., Chugaev, A. V., Gamyanin, G. N., and Bakharev, A. G., Metal sources of the large Nezhdaninsky orogenic gold deposit, Yakutia, Russia: results of high-precision MC-ICP-MS analysis of lead iso-topic composition supplemented by data on strontium isotopes, Geol. Ore Deposits, 2011 (b), vol. 53, no. 5, pp. 353–373.
Chugaev, A.V., Chernyshev, I.V., Safonov, Yu. G., Saroyan, M. R., Lead isotopic characteristics of sulfides from large gold deposits of the Baikal–Patom highland (Russia): evidence from high-precision MC–ICP–MS isotopic analysis of lead, Dokl. Earth Sci., 2010, vol. 434, no. 4, pp. 1366–1369.
Eckelmann, W.R. and Kulp, J.L., Uranium lead method of the age determination. Part 1. Lake Athabasca, Bull. Geol Soc. Am., 1957, vol. 68, no. 9, pp. 35–53.
Geologiya i poleznye iskopaemye Respubliki Uzbekistan (Geology and Mineral Resources of Uzbekistan), Shayakubov, T.Sh. and Dalimov, T.N., Ed., Tashkent: Universitet, 1998.
Golubev, V.N. and Chernyshev, I.V., Radiogenic lead in sulfide minerals of uranium deposits and its geochronological significane, Izotopnaya geokhronologiya v reshenii problem geodinamiki i rudogeneza (tezisy dokladov) (Isotope Geochronoloy in the Solution of Problems of Geodynamics and Ore Genesis), St.-Petersburg, 2003, pp. 132–135.
Golubev, V.N. and Chernyshev, I.V., Radiogenic lead in sulfide minerals from uranium deposits and its geochronological significance, International Conference “Uranium Geochemistry”, Nancy-France, 2003, pp. 169–172.
Golubev, V.N., Chernyshev, I.V., Agapova, A.A., et al., Geochronological study of uraninites on separate grains, in Mass-spektrometriya i izotopnaya geologiya (Mass-Spectrometry and Isotope Geology), Moscow: Nauka, 1983, pp. 74–89.
Golubev, V.N., Makar’ev, L.B., and Bylinskaya, L.V., Deposition and remobilization of uranium in the North Baikal region: evidence from the U–Pb isotopic systems of uranium ores, Geol. Ore Deposits, 2008, vol. 50, no. 6, pp. 482–490.
Halliday, A.N., Lee, D.C., Christensen, J.N., et al., Application of multiple collector-ICPMS to cosmochemistry, geochemistry, and paleooceanography, Geochim. Cosmochim. Acta, 1998, vol. 62, no. 6, pp. 919–940.
Hills, J.H. and Richards, J.R., Pitchblende and galena ages in the Alligator Rivers region, North Territory, Australia, Miner. Deposita, 1976, vol. 11, no. 2, pp. 133–154.
Laverov, N.P. and Chernyshev, I.V., Temporal relation of uranium deposits with continental volcanism, in Geokhronologiya i problemy rudoobrazovaniya (Geochronology and Problems of Ore Formation) Barsukov, V.L, Ed., Moscow: Nedra, 1977, pp. 5–18.
Laverov, N.P., Chernyshev, I.V., and Golubev, V.N., Isotope constraints on the age and genesis of hydrothermal uranium deposits in volcanic belts, Geol. Ore Deposits, 1993, vol. 35, pp. 22–30.
Rehkamper, M. and Halliday, A.N., Accuracy and longterm reproducibility of lead isotopic measurements by MCICP-MS using an external method for correction of mass discrimination, Int. J. Mass Spec. Ion Proc., 1998, vol. 58, pp. 123–133.
Stacey, J.S. and Kramers, I.D., Approximation of terrestrial lead isotope evolution by a two-stage model, Earth Planet. Sci. Lett., 1975, vol. 26, no. 2, p. 207.
Uranovye i molibden-uranovye mestorozhdeniya v oblastyakh razvitiya kontinental’nogo vnutrikorovogo magmatizma (Uranium and Molybdenum–Uranium Deposits in the Development Areas of Intracrustal Magmatism), Moscow: IFZ RAN, IGEM RAN, 2012.
Volkov V.N., Gol’tsman Yu.V., Arakelyants M.M., et al., Radiometric age of hyperacidic volcanism in late-orogenic troughs of the Chatkal–Kurama Zone, Central Tien Shan, Stratigraphy. Geol. Correlation, 1997, vol. 5, no. 1, pp. 79–95.
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Original Russian Text © I.V. Chernyshev, V.N. Golubev, A.V. Chugaev, 2017, published in Geologiya Rudnykh Mestorozhdenii, 2017, Vol. 59, No. 6, pp. 576–586.
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Chernyshev, I.V., Golubev, V.N. & Chugaev, A.V. Anomalous Lead Isotopic Composition of Galena and Age of Altered Uranium Minerals: a Case study of Chauli Deposits, Chatkal–Qurama District, Uzbekistan. Geol. Ore Deposits 59, 551–560 (2017). https://doi.org/10.1134/S107570151706006X
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DOI: https://doi.org/10.1134/S107570151706006X