Morphological features of ore reserves of the Novo-Uchaly vms deposit (Southern Urals)

Background. The Novo-Uchaly copper-zinc VMS deposit in the Southern Urals (54°10΄54˝N and 59°20΄45˝E) is represented by a steeply dipping lens of Eifelian volcanics (rhyodacites and basalts), which are crumpled into a strongly compressed anticlinal fold. The ore deposit is blind and localised at the convergence of felsic (bottom) and mafic (top) rocks. The deposit is located at depths of 550 m (in the northern part) and 1050 m (in the southern part). The deposit thickness reaches 186 m. The length along the strike and along the dip equals 1250 m and 900 m, respectively. The ore body is intruded by gabbro-diorite and gabbro-diabase dikes. The main ore minerals are pyrite, sphalerite and chalcopyrite, as well as non-metallic minerals, such as quartz, barite and calcite. Unlike most of the Ural VMS deposits, this deposit is the zinc subtype (Zn >> Cu). The ores are predominantly massive and solid sulphide, being banded or brecciated in some parts. The main elements extracted are copper, zinc and sulphur, but gold, silver, cadmium, indium, cobalt, nickel, selenium and tellurium are also obtained.

Aim. To clarify the morphology of the ore deposit, to study the ore mineral composition of the upper horizons of its northern part and to determine the underlying reasons for the complex lenticular structure of the sulphide reserve.

Materials and methods. In the period 2017—2019, employees of the Institute of Ore Deposits, Petrography, Mineralogy and Biochemistry of the Russian Academy of Sciences (IGEM RAS) together with geologists of the Uchaly Mining and Processing Plant carried out a geological and mineralogical mapping of the deposit in the course of exploration works.

Results. The ore contours and mineral composition of the northern part of the ore body were significantly clarified. A series of dikes of variable morphology was identified. A comparison was made of the results with current theories about the structure of the ore deposit. Detailed geological sections were determined and illustrate the complex lenticular structure of the ore deposit complicated by pinch and swell areas. The deposit was formed by processes of dynamic metamorphism.

Conclusion. The geological and mineralogical structure of the deposit determined in the study enabled us to propose a schematic reconstruction of the conditions leading to the formation of its folded structure. The findings will help to re-assess the reserves and improve the system of operational exploration and delineation.

1. Bobokhov A.S. The geological structure of the Uchaly and Uzelga ore fields, the manifestation of volcanism and volcanogenic massive sulfide mineralization in them // Middle Devonian volcanism of the Bashkir Trans-Urals and its connection with volcanogenic massive sulfide mineralization, Ufa. 1983. P. 87—102 (In Russian).

2. Galiullin I.B., Chadchenko A.V., Krylatov V.A., et al. Exploration Work Within the Mining Allotment of the Novo-Uchaly Copper Volcanogenic Massive Sulfide Deposit in the Uchaly District of the Bashkortostan Republic in 2009—2012. Exploration work from the daylight surface in 2010—2012. Book 1. Uchaly, 2012 (In Russian).

3. State Report on the State and Use of Mineral Resources of the Russian Federation in 2016 and 2017, Moscow, 2018. 372 p. (In Russian).

4. Maslov V.A., Artyushkova O. V. Stratigraphy of the Paleozoic Formations in the Uchaly District of Bashkiria. Ufa: IG Ufa Scientific Center RAS, 2000. 140 p. (In Russian).

5. Seravkin I.B., Pirozhok P.I., Skuratov V.N. Mineral resources of the Uchaly ore mining and processing enterprise. Ufa: Bashkir Book Publishing House, 1994. 328 p. (In Russian).

6. Nestoyanova O.A., Lennykh G.A. Explanatory Note to the State Geological Map of the Urals. Scale 1: 200 000. Sheet N-40-XVIII (Uchaly). 1955 (In Russian).

7. Pshenichny G.N., Volkinstein M.Ya., Nikolaichenkov Yu.S., et. al. Novo-Uchaly copper-zinc-pyritic deposit of the Southern Urals. Ufa: Ufa Sci. Center RAS, 1999. 395 p. (In Russian).

8. Orlov M.P., Chadchenko A.V., Pirozhok P.I., Kulbakov A.M. New ore objects in the mineral resource base of OJSC Uchalinsky // Metallogeny of Ancient and Modern Oceans — 2009. Ore Formation Models and Evaluation of Deposits. Miass: IM UB RAS, 2009. P. 337—338 (In Russian).

9. Pirozhok P.I., Chadchenko A.V., Orlov M.P., Moiseev I.B., Kulbakov A.M. Additional exploration and operational exploration of volcanogenic massive sulfide deposits: methodology and results // Subsoil UseXXI Century. 2009. No. 3. P. 15—22 (In Russian).

10. Pirozhok P.I., Chadchenko A.V., Staheev N.P. Novo-Uchaly field: discovery, evaluation, development prospects // University News. Mountain Journal. 2001. No. 3. P. 21—27 (In Russian).

11. Salikhov D.N., Kholodnov V.V., Puchkov V.N., Rakhimov I.R. Magnitogorsk zone of the Southern Urals in the Late Paleozoic: magmatism, fluid regime, metallogeny, geodynamics. Moscow: Nauka, 2019. 392 p. (In Russian).

12. Seravkin I.B., Kosarev A.M., Puchkov V.N. Geodynamic conditions of formation of massive sulfide deposits in the Magnitogorsk megazone, Southern Urals, and prospection criteria // Geology of ore deposits. 2017. Vol. 59. No. 3. P. 220—237. DOI: 10.7868/S0016777017030054

13. Chadchenko A.V., Pirozhok P.I., Orlov M.P., Kulbakov A.M. Mineral resources base: state and development prospects // Subsoil Use-XXI Century. 2009. No. 3. P. 9—14 (In Russian).

14. Bortnikov N.S., Vikentyev I.V. Endogenous metallogeny of the Urals. In: Mineral deposit research for a high-tech world; Jonsson E., Ed.; Uppsala, 2013. P. 1508—1511.

15. Corriveau L., Spry P.G. Metamorphosed hydrothermal ore deposits. In: Scott, S.D. (Ed.), Geochemistry of Mineral Resources, second ed. Treatise on Geochemistry. Vol.13. Elsevier, New York, 2014. P. 175—194.

16. Debreil J.-A., Ross P.-S., Mercier-Langevin P. The Matagami district, Abitibi Greenstone Belt, Canada: volcanic controls on Archean volcanogenic massive sulfide deposits associated with voluminous felsic volcanism // Economic Geology. 2018. Vol. 113. P. 891—910.

17. Franklin J. M., Gibson H. L., Jonasson I. R., Galley A. G. Volcanogenic massive sulfide deposits // Economic Geology. 2005, 100th Ann. P. 523—560.

18. Galley A.G., Hannington M.D., Jonasson I.R. Volcanogenic massive sulphide deposits. In Mineral Deposits of Canada: A Synthesis of Major Deposit-types, District Metallogeny, the Evolution of Geological Provinces, and Exploration Methods. Spec. Publ. No. 5; Goodfellow, W. D., Ed.; Geolog. Assoc. Can., Miner. Depos. Division, 2007. P. 141—161.

19. Hannington M.D. Volcanogenic massive sulfide deposits. In: Scott, S.D. (Ed.). Geochemistry of Mineral Resources, second ed. Treatise on Geochemistry. Vol. 13. Elsevier, New York, 2014. P. 462—486.

20. Monecke T., Gibson H., Goutier J. Volcanogenic massive sulfide deposits of the Noranda camp // Economic Geology. 2017. Vol. 19. P. 169—223.

21. Puchkov V.N. General features relating to the occurrence of mineral deposits in the Urals: What, where, when and why. Ore Geology Review 2017. Vol. 85. P. 4—29. https://doi.org/10.1016/j.oregeorev.2016.01.005

22. Shanks III W.C.P., Thurston R. Volcanogenic Massive Sulfide Occurrence Model. U.S. Geol. Survey Sci. Invest. Rep. 2010-5070-C. 2012.

23. Vikentyev I.V. Selenium, tellurium and precious metal mineralogy in Uchalinsk copper-zinc-pyritic district, the Urals. 3rd Inter. Conf. Compet. Mater. Technol. Proc. IOP Conf. Ser. Mater. Sci. Eng. 2016, 123, 1—6. doi: 10.1088/1757899X/123/1/012027

24. Vikentyev I.V., Belogub E.V., Novoselov K.A., Moloshag V.P. Metamorphism of volcanogenic massive sulphide deposits in the Urals. Ore geology // Ore Geology Reviews. 2017. Vol. 85. P. 30—63. DOI: 10.1016/j.oregeorev.2016.10.032