Ore composition and native gold characteristics of an ore occurrence in Eastern Transbaikalia

The article deals with the characteristics of the ores of an ore occurrence of the Munginsky cluster located on the western flank of one of the commercial fields of Eastern Transbaikalia. The ores of this promising ore occurrence are underexplored, especially in the technological aspect, which served the basis for studying their composition and characterizing native gold as their main commercial component. The composition of ores and altered rocks was studied by the following methods: atomic emission spectral quantitative analysis, X-ray fluorescence, as well as phase atomic absorption and atomic emission analysis with inductively coupled plasma ICP-AES. The mass fraction of total and organic carbon was determined in the Central Fire Assay Laboratory of JSC Pokrovsky Rudnik, Blagoveshchensk. The proportion of carbonate carbon dioxide was determined by the method of titrimetric determination of carbon dioxide. The content of gold was given according to the data of assay melting, the content of silver – according to the data of atomic absorption analysis. Petrographic and mineragraphic studies were carried out using an optical microscope Olympus BX-51. The mineral composition of the ore sample was also estimated based on the results of X-ray diffraction analysis. The quantitative mineral composition was studied on the crushed material of the original ore with a particle size of -2 mm using the microscopic study data of transparent and polished thin sections on a microscope Nikon Eclipse LV 100 POL. The content of iron hydroxides was determined from the weight difference after the sample was treated with a 10 % oxalic acid solution in a water bath. Comparison of the results obtained on the ore occurrence with the materials on the ore composition of the closest deposit located in 30 km demonstrates that on the one hand they are similar and uniform, and on the other hand they feature some differences. Their common parameters include a rather high degree of sulfide content of ores and similar chemical and mineral composition with the predominance of arsenopyrite, an increased role of bismuth as well as the predominance of fine gold and its similar morphological characteristics. This fact allows to consider the ore occurrence under investigation as an integral part of a single ore system of the closest deposit.

1. Abramov B.N. Forming conditions and petrogeochemical particularities of fluid-explosive productions from gold deposits of Eastern Transbaikalia. Litosfera = Lithosphere (Russia). 2015;(1):86-97. (In Russ.).

2. Abramov B.N. Verkhne-Aliinsky gold deposit: Conditions of formation, petrogeochemical features of rocks and ores (Munginsk ore cluster, Eastern Transbaikalia). Litosfera = Lithosphere (Russia).2016;(4):92-101. (In Russ.).

3. Laverov N.P., Narseev V.A., Petrovskaya N.V., Safonov Yu.G. Baleiskoe ore field (geology, mineralogy, genesis issues). Moscow: Central Research Institute of Geological Prospecting for Base and Precious Metals; 1984. 271 p. (In Russ.).

4. Goryachev N.A., Nikanyuk T.S., Budyak A.E. On ore mineralization of the Verkhne-Aliinsky deposit (TransBaikal, Russia). In: Sovremennye napravleniya razvitiya geokhimii: materialy Vseros. konf. s uch. zarubezhn. uchenykh, posvyashch. 65-letiyu Instituta geokhimii im. A.P. Vinogradova i 105-letiyu so dnya rozhd. akad. L.V. Tausona = Modern development trends in geochemistry: materials of All-Russian conference with the participation of foreign scientists dedicated to the 65th anniversary of the A.P. Vinogradov Institute of Geochemistry and the 105th birth anniversary of the Academician L.V. Tauson. 21–25 November 2022, Irkutsk. Irkutsk: V.B. Sochava Institute of Geography SB RAS; 2022, vol. 1, p. 147–148. (In Russ.).

5. Yurgenson G.A., Grabeklis R.V. Baleiskoe ore field. In: Mestorozhdeniya Zabaikal'ya = Transbaikal deposits. Moscow: Geoinformmark; 1995, vol. 1, book. 2, p. 19–32. (In Russ.).

6. Vinogradov A.P. The average content of chemical elements in the main types of igneous rocks of the earth's crust. Geokhimiya. 1962;7:555-571. (In Russ.).

7. Gladkov V.G., Korol'kov A.T., Letunov S.P., Vorosov A.D. Morphological features of stockwork mineralization of the Baley type (materials of the detailed open-cast mapping on a scale of 1:1000). In: Usloviya obrazovaniya i razmeshcheniya zolotorudnykh mestorozhdenii Sibiri = Conditions of gold deposit formation and location in Siberia. Novosibirsk; 1975, p. 129. (In Russ.).

8. Prokof'ev V.Yu. Geochemical features of ore-forming fluids of hydrothermal gold deposits of various genetic types (according to the study of fluid inclusions). Novosibirsk: Nauka; 2000. 190 p. (In Russ.).

9. Maltzeva G.D., Nikanuk T.S. Conditions of ore formation of some hydrothermal gold deposits. Izvestiya Sibirskogo otdeleniya Sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya, poiski i razvedka rudnykh mestorozhdenii = Proceedings of the Siberian Department of the Section of Earth Sciences, Russian Academy of Natural Sciences. Geology, Prospecting and Exploration of Ore Deposits. 2011;2:25-30. (In Russ.).

10. Nikanuk T.S., Maltzeva G.D. Ore composition of the Verkhne-Aliinsk gold ore deposit. Izvestiya Sibirskogo otdeleniya Sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya, poiski i razvedka rudnykh mestorozhdenii = Proceedings of the Siberian Department of the Section of Earth Sciences, Russian Academy of Natural Sciences. Geology, Prospecting and Exploration of Ore Deposits. 2008;6:50-59. (In Russ.).

11. Nikanjuk T.S., Mal'tzeva G.D. Substance composition as the basis for technological estimation of gold-bearing ores of Higher-Aliinsk gold ore deposit. Izvestiya Sibirskogo otdeleniya Sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya, poiski i razvedka rudnykh mestorozhdenii = Proceedings of the Siberian Department of the Section of Earth Sciences, Russian Academy of Natural Sciences. Geology, Prospecting and Exploration of Ore Deposits. 2009;1:69-76. (In Russ.).

12. Simonov Yu.I., Maksimov S.S. Geodynamic model of volcano-plutonic structures of Transbaikalia and principles of large-scale gold forecasting. In: Struktury rudnykh polei vulkanicheskikh poyasov: materialy Vsesoyuzn. Soveshch. = Structures of ore fields of volcanic belts: Materials of the All-Union meeting. Vladivostok; 1985, iss. 1, p. 16–18. (In Russ.).

13. Chechetkin V.S., Trubachev A.I. Mineral resources of Transbaikalia. Chita: Transbaikal State University; 2013. 231 p. (In Russ.).

14. Trubachev A.I., Sekisov A.G., Lavrov A.Yu. Associations of minerals and elements in ores and dressing products of east Baikal base and precious metal deposits. Izvestiya Sibirskogo otdeleniya Sektsii nauk o Zemle Rossiiskoi akademii estestvennykh nauk. Geologiya, poiski i razvedka rudnykh mestorozhdenii = Proceedings of the Siberian Department of the Section of Earth Sciences, Russian Academy of Natural Sciences. Geology, Prospecting and Exploration of Ore Deposits. 2016;3:44-56. https://doi.org/10.21285/0130-108X-2016-56-3-44-56.

15. Andreeva M.G. Composition and distribution features of mineral associations and zoning elements within the Baleiskoe ore field and its periphery. Trudy TsNIGRI. 1971;96(1):32-45. (In Russ.).

16. Borodaevskaya M.B. Some features of small intrusion formation petrogenesis of post-Upper Jurassic age in one of the regions of Eastern Transbaikalia. Izvestiya Akademii nauk SSSR. Seriya Geologicheskaya. 1956;6:70-91. (In Russ.).

17. Krivolutskaya N.A. Paragenetic associations of minerals and ore formation conditions at the Klyuchevskoye gold deposit (Eastern Transbaikalia, Russia). Geologiya rudnykh mestorozhdenii. 1997;4:344-361. (In Russ.).

18. Plyusnin G.S., Spiridonov A.M., Litvintsev K.A., Kochetkova L.F., Gnilusha V.A., Kuznetsova C.B. Rb-Sr age of alkaline granites of the Kariisky ore cluster (Eastern Transbaikalia). Doklady Akademii nauk SSSR. 1989;307(4):967-971. (In Russ.).

19. Spiridonov A.M., Zorina L.D., Kitaev N.A. Goldbearing ore-magmatic systems of Transbaikalia. Novosibirsk: Geo; 2006. 291 p. (In Russ.).

20. Spiridonov A.M., Zorina L.D., Letunov S.P., Prokof’ev V.Yu. The fluid regime of ore formation in the balei gold-bearing ore-magmatic system (eastern Transbaikalia). Geologiya i geofizika = Russian Geology and Geophysics. 2010;51(10):1413-1422. (In Russ.).

21. Komarov P.V., Tomson I.N. Mineralization age and plutonogenic mineragenic cycles on the example of Eastern Transbaikalia. Otechestvennaya Geologiya = National Geology. 1995;10:26-36. (In Russ.).

22. Petrovskaya N.V. Native gold (general characteristics, typomorphism, genesis issues). Moscow: Nauka; 1973. 348 p. (In Russ.).

23. Petrovskaya N.V., Safonov Yu.G., Sher S.D. Formations of gold deposits. In: Rudnye formatsii endogennykh mestorozhdenii = Ore formations of endogenous deposits. Moscow: Nauka; 1976, vol. 2, p. 3–110. (In Russ.).

24. Petrovskaya N.V. The nature of gold-bearing mineral associations and gold ore formations in the USSR. In: Geneticheskie problemy rud = Genetic problems of ores. Moscow: Gosgeoltekhizdat; 1960, p. 145–159. (In Russ.).

25. Nikolaeva L.A., Yablokova S.V. Typomorphic features of native gold and their use in geological exploration. Rudy i metally = Ores and Metals. 2007;6:41-57. (In Russ.).