Geologicheskii Vestnik

The aim of the research is to study the factors that controlled the fractionation of rare-earth elements in ore pyrite and to assess, on this basis, possible sources of matter in gold-sulfide ores of the Mindyak deposit (Southern Urals), the genesis of which is a controversial problem. The mineralization of the orogenic type deposit is localized in a polymictic olistostrome with carbonaceous clayey-siliceous cement Determination of REE contents was carried out in ore pyrite and in the host rocks using inductively coupled plasma mass spectrometry (ICP-MS) on an ELAN 9000 mass spectrometer (Perkin Elmer) at the Institute of Geology and Geochemistry UB RAS. In the early pyrite and late polysulfide-carbonate-quartz ore associations of the deposit, two types of pyrite were found. The REE patterns in one of them inherit the peculiarities of the composition of lanthanides in the carbonaceous shales of the olistostrome cement, and in the other, in their varieties enriched in syngenetic globular pyrite mineralization. The behavior of REE in pyrite and the fluid coexisting with it was also influenced by temperature, oxidation-reduction conditions and alkalinity of the mineral formation environment. Pyrite of the early ore association, crystallized under hightemperature reducing conditions from afluid of increased alkalinity, has higher concentrations of lanthanides compared to the low-temperature pyrite of late polysulfide-carbonate-quartz ores. It was found that in the low-temperature environment of the late ore stage there was a slight oxidation and a decrease in the alkalinity of the fluid. Fractionation of REE in ore pyrite from the Mindyak deposit is mainly associated with the processes of mobilization of components from the olistostrome cement by the mineral-forming fluid, which can be considered as one of the sources of ore matter.

Southern Urals, orogenic gold deposit, carbonaceous shale, pyrite, rare-earth elements, anomalies of europium and cerium

• Goryachev N.A., Vikent`eva O.V., Bortnikov N.S., Prokof`ev V.Yu., Alpatov V.A., Golub V.V. (2008) Natalkinskoe zolotorudnoe mestorozhdenie mirovogo klassa: raspredelenie RZE`, flyuidny`e vklyucheniya, stabil`ny`e izotopy` kisloroda i usloviya formirovaniya rud (severo-vostok Rossii) [Worldclass Natalka gold deposit: REE distribution, fluid inclusions, stable oxygen isotopes and ore formation conditions (northeast Russia)]. Geologiya rudny`x mestorozhdenij, 50 (5), 414–444. (In Russian).
• Znamenskij S.E. (2017) Redkozemel`ny`e e`lementy` i ittrij v kal`cite i pirite Orlovskogo mestorozhdeniya zolota (Yuzhny`j Ural) [Rare earth elements and yttrium in calcite and pyrite of the Orlovskoye gold deposit (Southern Urals)]. Litosfera, (1), 135–146. (In Russian).
• Znamenskij S.E., Michurin S.V. (2013) Usloviya obrazovaniya zoloto-sul`fidnogo mestorozhdeniya Mindyak (Yuzhny`j Ural):strukturny`e i izotopno-geoximicheskie aspekty [Conditions for the formation of the Mindyak gold-sulfide deposit (Southern Urals): structural and isotope-geochemical aspects]. Litosfera, (4), 121–135. (In Russian).
  Murzin V. V., Bortnikov N.S., Sazonov V.N. (2003) Proisxozhdenie rudoobrazuyushhego flyuida na Mindyakskom zolotorudnom mestorozhdenii (Yuzhny` j Ural) [Origin of ore-forming fluid at the Mindyak gold deposit (Southern Urals)]. E`volyuciya vnutrikontinental`ny`x podvizhny`x poyasov: tektonika, magmatizm, metamorfizm, sedimentogenez, polezny`e iskopaemy`e: Mat-ly` nauchnoj konferencii (IX Chteniya A.N. Zavariczkogo). Ekaterinburg: IGiG UrO RAN, 197–199. (In Russian).
• Sazonov V.N., Ogorodnikov V.N., Koroteev V.A., Polenov Yu.A. (1999) Mestorozhdeniya zolota Urala [Gold deposits of the Urals]. Ekaterinburg: UGGGA, 570 p. (In Russian).
• Akagi T., Masuda A.A. (1998) Simple thermodynamic interpretation of Ce anomaly. Geochemical Journal, 32, 301–314. DOI: 10.2343/geochemj.32.301
• Bau M., Möller P. (1992) Rare Earth Element Fractionation in Metamorphogenic Hydrothermal Calcite, Magnesite and Siderite. Mineralogy and Petrology, 45, 231–246. DOI: 10.1007/BF01163114
• Chugaev A.V., Znamensky S.E. (2018) Lead Isotope Characteristics of the Mindyak Gold Deposit, Southern Urals: Evidence for the Source of Metals. Geol. Ore Deposits, 60 (1), 52–61. DOI: 10.1134/S1075701518010026
• Elderfield H., Sholkovitz E.R. (1987) Rare earth elements in the pore waters of reducing nearshore sediments. Earth and Planetary Science Letters, 82, 280–288. DOI: 10.1016/0012-821X(87)90202–0
• Groves D.I., Santosh M. (2016) The giant Jiaodong gold province: The key to a unified model for orogenic gold deposits? Geoscience Frontiers, 7, 409–417. DOI: 10.1016/j.gsf.2015.08.002
• McDonough W.F., Sun S. (1995) The composition of the Earth. Chemical Geology, 120, 223–253. DOI: 10.1016/0009–2541(94)00140–4
• Мöller P., Dulski P., Savascin Y., Conrad M. (2004) Rare earth elements, yttrium and Pb isotope ratios in thermal spring and well waters of West Anatolia, Turkey: a hydrochemical study of their origin. Chemical Geology, 206, 97–118. DOI: 10.1016/j.chemgeo.2004.01.009
• Rimskaya-Korsakova M.N., Dubinin A.V. (2003) Rare Earth Elements in Sulfides of Submarine Hydrothermal Vents of the Atlantic Ocean. Doklady Earth Sciences, 389A (3), 432–436.
• Schwinn G., Markl G. (2005) REE systematics in hydrothermal fluorite. Chemical Geology, 216, 225–248. DOI: 10.1016/j.chemgeo.2004.11.012
• Shao-Yong J., Ji-Min Y., Jian-Jun L. (2004) Trace and rare earth element geochemistry in tourmaline and cassiterite from the Yunlong tin deposit, Yunnan, China: implication for migmatitic-hydrothermal fluid evolution and ore genesis. Chemical Geology, 209, 193–213. DOI: 10.1016/j.chemgeo.2004.04.021
• Sverjensky D. (1984) Europium redox equilibria in aqueous solution. Earth Planet Science Letters,  67, 70–78. DOI: 10.1016/0012-821X(84)90039–6
• Zeng Z., Ma Y., Yin X., Selby D., Kong F., Chen S. (2015) Factors affecting the rare earth element compositions in massive sulfides from deep-sea hydrothermal systems. Geochemistry, Geophysics, Geosystems., 16, 2679–2693. DOI: 10.1002/2015GC005812
• Znamenskii S.E., Puchkov V.N., Michurin S.V. (2015) Sources of ore-forming fluids and formation environments of orogenic Au deposits in the Main Uralian Fault zone (Southern Urals). Doklady Earth Sciences, 464 (1), 910–913. DOI: 10.1134/S1028334X1509024X