Native gold from placers of the Evotinskii region (Aldano-Stanovoy Shield): mineralogical and geochemical features, and possible primary sources

The Evotinskii Ore and Placer Region (EOR) is located in the central part of the Aldano-Stanovoy Shield and is characterized by a significant presence of gold-bearing placers, many of which have undergone extensive mining activities. Despite geological investigations that have been conducted since the 1930s, the main sources of numerous placers remain largely unidentified. This study employed traditional mineralogical and geochemical methods, along with LA-ICP-MS analysis, to investigate placer gold within the Evotinskii Ore and Placer Region. The findings indicate that native gold within the placers of the EOR is predominantly represented by particles measuring between 0.1 and 1.2 mm, which primarily exhibit forms of cementation, fracture, and interstitial characteristics. The degree of roundness varies, and high-fineness shells and intergranular high-fineness veins are not uncommon. Structural etching revealed a multi-phase, granular, concentric, and vaguely zonal internal structure of the native gold. Furthermore, granulation and twinning structures were also identified. The LA-ICP-MS analysis of the native gold from the placers indicated a diverse array of trace element impurities within the particles. These extensive investigations suggest that the primary sources of placer gold are likely to be ore occurrences similar to the P. Pinigin deposit, as well as sulfide and epithermal occurrences associated with alkaline Mesozoic magmatism, which are prevalent in the Central-Aldan ore region. The possibility of a certain amount of gold originating from mineralizations associated with porphyry systems and iron ore deposits cannot be excluded. The discovery of ore-like particles may signify the proximity of bedrock sources and enhances the potential of the region for the discovery of previously unidentified ore occurrences.

1. Vetluzhskikh V.G., Kazansky V.I., Kochetkov A.Ya. Gold ore deposits of the Central Aldan. Geology of Ore Deposits. 2002;44(6):467–499. (In Russ.)

2. Kochetkov A.Ya. Mesozoic ore-bearing ore-magmatic systems of Central Aldan. Geology and Geophysics. 2006;47(7):850–864. (In Russ.)

3. Maksimov E.P., Uytov V.M., Nikitin V.M. CentralAldan gold-uranium-ore magmatogenic system (AldanoStanovoy shield, Russia). Pacific Geology. 2010;29(2): 3–26. (In Russ.)

4. Kravchenko A.A., Smelov A.P., Berezkin V.I., Po pov N.V. Geology and genesis of Precambrian gold-bearing metabasites of the central part of the Aldan-Stanovoy shield (using the example of the P. Pinigin deposit). Yakutsk: Offset; 2010. 148 p. (In Russ.)

5. Kravchenko A.A., Okrugin A.V., Beryozkin V.I., et al. Geodynamics and ore-bearing behavior of Proterozoic mafic rocks of the central part of the Aldan-Stanovoy Shield (South of the North-Asian Craton). Geodynamics and Tectonophysics. 2024;15(3):1–17. (In Russ.) https://doi.org/10.5800/GT-2024-15-3-0756

6. Petrovskaya N.V. Native gold. Moscow: Nauka; 1973. 348 p. (In Russ.)

7. Savva N.E., Preis V.K. Atlas of native gold of NorthEast of USSR. Moscow: Nauka; 1990. 292 p. (In Russ.)

8. Okrugin A.V., Zhuravlev A.I., Mokhnachevskii G.V. Mineralogical, geochemical and morphological features of placer gold of South-Eastern part of Siberian platform. Otechestvennaya geologia [Domestic Geology]. 2013;(5): 19–27. (In Russ.)

9. Chapman R.J., Mortensen J.K. Characterization of gold mineralization in the Northern Cariboo Gold District, British Columbia, Canada, through integration of compositional studies of lode and detrital gold with historical placer production: a template for evaluation of orogenic gold districts. Economic Geology. 2016;111(6): 1321–1345. https://doi.org/10.2113/econgeo.111.6.1321

10. Nikolaeva L.A., Gavrilov A.M., Nekrasova A.N., et al. Native gold of ore and placer deposits of Russia. Moscow: TSNIGRI; 2003. 184 p. (In Russ.)

11. Gerasimov B.B. The use of typomorphic features of placer gold of the Anabar Region for Determining ots sources. Minerals. 2023;13(4):1–19. https://doi.org/10.3390/min13040480

12. Nikiforova Z.S. Mineralogical method as an effective way to predict gold ore types of deposits in platform areas (East of the Siberian Platform). Minerals. 2024:14(6):631. https://doi.org/10.3390/min14060631

13. Nikolaeva L.A., Yablokova S.V. Typomorphic features of native gold and their using in prospecting works. Ores and Metals. 2007;(6):41–57. (In Russ.)

14. Yablokova S.V., Milyaev S.A., Pozdnyakova N.N. New data on native gold typochemistry in different types of deposits. Ores and Metals. 2011;(2):28–31. (In Russ.)

15. Milyaev S.A., Samosorov G.G.., Yablokova S.V., et al. Geochemical features of native gold as direct signs of oreformational belonging of ore and placer gold occurences. Ores and Metals. 2020;(3):22–31. (In Russ.). https://doi.org/10.47765/0869-5997-2020-10018

16. Gauert C., Schannor M., Hecht L., et al. A Comparison of in situ analytical methods for trace element measurement in gold samples from various South African gold deposits. Geostandards and Geoanalytical Research. 2016;40(2):267–289. https://doi.org/10.1111/j.1751-908X.2015.00362.x

17. Liu H., Beaudoin G. Geochemical signatures in native gold derived from Au-bearing ore deposits. Ore Geology Reviews. 2021;132:104066. https://doi.org/10.1016/j.oregeorev.2021.104066

18. Chapman R.J., Banks D.A., Styles M.T., et al. Chemical and physical heterogeneity within native gold: implications for the design of gold particle studies. Mineralium Deposita. 2021;56(8):1563–1588. https://doi.org/10.1016/10.1007/s00126-020-01036-x

19. Greenough J.D., Tetland M. Trace Element Composition of Placer Gold Across the Okanagan Fault, Kelowna, British Columbia, Canada. Geoscience Canada. 2023;50(4):239–315, https://doi.org/10.12789/geocanj.2023.50.202

20. Omang B.O., Suh C.E., Lehmann B., Vishiti A., et al. Microchemical signature of alluvial gold from two contrasting terrains in Cameroon. Journal of African Earth Sciences. 2015;112:1–14. https://doi.org/10.1016/j.jafrearsci.2015.09.004

21. Fominykh P.A., Artemiev D.A., Nevolko P.A., Kolpakov V.V. LA ICP MS analysis of native gold from alluvial placers – genetic interpretation (Ikovskoye placer field, NW Salair Ridge). Metallogeny of Ancient and Modern Oceans. 2020;(1):162–165. (In Russ.)

22. Parfenov L.M., Kuzmin M.I. Tectonics, geodynamics, and metallogeny of the territory of the Sakha Republic (Yakutia). Moscow: MAIK; 2001. 571 p. (In Russ.)

23. Parfenov L.M., Popeko L.I., Tomurtogoo O. Problems of tectonics Mongolo-Okhotsk orogeny belt. Pacific Geology. 1999;5:24–43. (In Russ.)

24. Radkov A.V., Molchanov A.V., Artemiev D.S., et. al. State Geological Map of the Russian Federation. Scale 1:1000000 (third generation). Aldan-Zabaikalskaya series. Sheet O-51-Aldan. Saint Petersburg: VSEGEI Cartographic Factory; 2015. 365 p. (In Russ.)

25. Vorona I.D., Reutov L.M. Explanatory note to the state geological map of the USSR at a scale of 1:200000, Aldan series, sheet O-51-XXIV. Moscow: SSTPL of geo logy and protection; 1963. 105 p. (In Russ.)

26. Ivanov A.I., Loskutov E.E., Ivanov M.S., Zhuravlev A.I. Petrography, geochemical features and absolute dating of the mesozoic igneous rocks of Medvedev and Taezhniy massifs (Southeast Russia, Aldan Shield). Minerals. 2022;12(12):1516. https://doi.org/10.3390/min12121516

27. Prokopiev I.R., Doroshkevich A.G., Ponomarchuk A.V., et al. Gold ore mineralization of Dzheltulinskii, Amginskii and Medvedev Mesozoic alkaline massifs of Aldan shield (Yakutia): data review on inclusions in minerals. In: Kuzhuget R.V. (ed.) The metallogeny of gold in the Central-Asian orogenic belt and its frame: Proceedings of the international scientific and practical conference dedicated to the Decade of Science and Technology in the Russian Federation and the 300th anniversary of the Russian Academy of Science, Kyzyl, September 05–08, 2024. Kyzyl: TuvIENR SB RAS; 2024, pp. 71–77. (In Russ.)

28. Gamyanin G.N., Goncharov V.I., Goryachev N.A. Gold-Rare metal deposits of North-East of Russia. Pacific Geology. 1998;17(3):94–103. (In Russ.)

29. Litvinenko I.S., Shilina L.A. Maldonite, juthenbo gaardtite and varieties of native gold from ore occurrences of the Nizhne-Myakitsky ore and placer district (NorthEast Russia). Notes of Russian mineralogical society. 2020;CXLIX(3):18–37. (In Russ.) https://doi.org/10.31857/S0869605520030041

30. Birch W.D., Ciobanu C.L. Maldonite from the type locality, Maldon, Victoria, Australia: a new investigation of its occurrence. Australian Journal of Mineralogy. 2009;15:25–38.

31. Kondratieva L.A., Anisimova G.S., Kardashevskaia V.N. Ore Mineralogy and typomorphism of native gold of the Spokoininsky cluster of the Aldan-Stanovoy gold province. Minerals. 2023;13(4):543, https://doi.org/10.3390/min13040543.

32. Samusikov V.P. Concentration patterns of isomorphic impurity elements in minerals during hydrothermal ore formation. Geology and Geophysics. 2010;51(3):338– 352. (In Russ.)

33. Molchanov A.V., Terekhov A.V., Shatov V.V., et al. Gold-bearing ore regions and districts of Aldan-Stanovoy province. Regional Geology and Metallogeny. 2017;(71): 93–111. (In Russ.).