Petrological and geochemical characteristic of the rocks of the Voznesensky intrusive massif (Southern Urals): Оn the question of the composition and sources of magma producing gold and copper porphyry mineralization

Research subject. The petrological and geochemical features of the rocks of the Voznesensky intrusive massif and its dyke series were studied in order to clarify the composition, possible sources and geodynamic settings of magma generation that produced Au- and Cu-porphyry mineralization.

Methods. The content of petrogenic oxides was determined by the chemical method, trace elements – by ICP-MS analysis.

Results. Among the rocks of the Voznesensky massif, which have the geochemical characteristics of suprasubduction formations, varieties with calc-alkaline and adakite-like properties were established. The main phase of the massif is represented by gabbro-diorites and diorites belonging to the calc-alkaline series. Ore-bearing dykes of gabbro-diorites, diorites and granodiorites of the Au-porphyry Bolshekaransky deposit are of calc-alkaline composition, while the post-ore dykes of granodiorites and plagiogranites of this deposit exhibit adakite-like characteristics.

Conclusions. The ore-bearing dyke series of the Voznesensky deposit is represented by calc-alkaline diorites and adakite-like granodiorites and plagiogranites. The metallogenic specialization of the dykes was influenced by the silicic acidity and the redox state of the ore-generating melts. Granitoids with Cu-porphyry mineralization, compared to their gold-bearing varieties, crystallized from more acidic melts with a higher degree of oxidation. It is assumed that the main mantle component of magmas for the Voznesensky rocks were relatively weakly depleted spinel peridotites of the suprasubduction lithospheric mantle. Calc-alkaline magmas were melted from a mantle substrate previously metasomatized by aqueous fluids, and magmas with adakite-like properties – metamorphosed by melts of basalts and sedimentary rocks of slab. Melting of slab rocks may have been associated with additional heating due to friction caused by changes in direction and/or velocity of oblique subduction.

1. Avdeiko G.P., Palueva A.A., Kuvikas O.V. (2011) Adakites in the subduction zones of the Pacific Ring: a review and analysis of geodynamic conditions of formation. Vestn. KRAUNTs. Nauki o Zemle, 17(1), 45-60. (In Russian)

2. Castillo P.R., Janney P., Solidum R.U. (1999) Petrology and geochemistry of Camiguin Island, southern Philippines: Insights to the source of adakites and other lavas in a complex arc setting. Contrib. Mineral. Petrol., 134(1), 33-51.

3. Chappell B.W., White A.J.R. (1992) I- and S-type granites in the Lachlan Fold Belt. Trans. Royal Soc. Edinburgh: Earth Sci., 83, 1-26.

4. Coban H. (2007) Basalt magma genesis and fractionation in collision- and extension provinces: a comparison between eactern, central western Anatolua. Earth Sci. Rev., 80, 219-239.

5. Defant M.J., Drummond M.S. (1990) Derivation of some modern arc magmas by melting of young subducted lithosphere. Nature, 347, 662-665.

6. Ellam R.M. (1992) Lithospheric thickness as a control on basalt geochemistry. Geology, 20(2), 153-156.

7. Fershtater G.B. (2013) Paleozoic intrusive magmatism of the Middle and South Urals. Ekaterinburg, RIO UB RAS, 368 p. (In Russian)

8. Fershtater G.B., Bea F. (1996) Geochemical typification of the Ural ophiolites. Geokhimiya, 3, 195-218. (In Russian)

9. Grabezhev A.I. (2009) Sr-Nd-C-OHS isotope-geochemical characteristics of copper-porphyry fluid-magmatic systems of the Southern Urals: probable sources of matter. Lithosfera, (6), 66-89. (In Russian)

10. Grabezhev A.I., Belgorodsky E.A. (1992) Productive granitoids and metasomatites of copper-porphyry deposits. Ekaterinburg, Nauka Publ., Ural. otd-e, 199 p. (In Russian)

11. Grabezhev A.I., Shardakova G.Yu., Larionov A.N. (2008) Ore-magmatic system of the Voznesensky copper-porphyry deposit. Ezhegodnik-2007. Ekaterinburg, IGG UrO RAN, 253-259. (In Russian)

12. Grabezhev A.I., Shardakova G.Yu., Ronkin Yu.L. (2017) Systematics of U-Pb ages of zircons from granitoids of porphyry copper deposits of the Urals. Lithosfera, (5), 113-126. (In Russian)

13. Emel’yanova T.A., Lelikov E.P. (2016) Geochemistry and petrogenesis of Late Mesozoic-Early Cenozoic volcanics of the Okhotsk and Japan marginal seas. Geokhimiya, 6, 522-535. (In Russian)

14. Igneous rocks (1983). Moscow, Nauka Publ., V.1, 367 p. (In Russian)

15. Ivanov K.S. (1998) Main features of geological history (1.6–0.2 billion years) and the structure of the Urals: Dr. geol.and min. sci. diss. in the form of a scientific report IGG UC RAS. Ekaterinburg, 252 p.

16. Ishihara S. (1977) The magnetite-series and ilmenite-series granitic rocks. Min. Geol., 27, 293-305.

17. Kay S.M., Mpodozis C. (2001) Central Andean ore deposits linked to evolving shallow subduction system and thickening crust. GSA today, 11, 4-9.

18. Kosarev A.M. (2015) Geology and geochemical features of the Early Paleozoic volcanics of the Sakmara and Voznesensk- Prisakmar zones in the South Urals. Lithosfera, 2, 40-64. (In Russian)

19. Kosarev A.M., Puchkov V.N., Seravkin I.B., Kholodnov V.V., Grabezhev A.I., Ronkin Y.L. (2014) New data on the age and geodynamic position of copper- porphyry mineralization in the Main Uralian Fault zone (Southern Urals). Dokl. Earth Sci., 495(1), 1317-1321.

20. Krasnobaev A.A., Valizer P.M. (2018) Zircons and zircon geochronology of the gabbro of the Nuralinsky massif (South Urals). Lithosfera, 18(4), 574-584. (In Russian)

21. Krasnobaev A.A., Valizer P.M., Perchuk A.L. (2018) Ordovician age of the dunite-wehlite-clinopyroxenite banded complex of the Nurali Massif (South Ural, Russia) according to SHRIMP U-Pb zircon dating. Vestn. MGU. Ser. 4. Geologiya, 1, 60-70. (In Russian)

22. Krivtsov A.I. (1983) Geological foundations of forecasting and prospecting for porphyry copper deposits. Moscow, Nedra Publ., 256 p. (In Russian)

23. Martin H., Smithies R.H., Rapp R., Moyen J.-F., Champion D. (2005) An overview of adakite, tonalite-trondhjemite- granodiorite (TTG) and sanukitoid: relationships and some implications for crustal evolution. Lithos, 79(1-2), 1-24.

24. Martynov Yu.A., Chashchin A.A., Simanenko V.P., Martynov A.Yu. (2007) Maastrich-Danish andesite series of the Eastern Sikhote-Alin: mineralogy, geochemistry and questions of petrogenesis. Petrologiya, 15(3), 295-316. (In Russian)

25. Maslov V.A., Artyushkova O.V. (2010) Stratigraphy and correlation of Devonian deposits of the Magnitogorsk megazone of the Southern Urals. Ufa, DesignPoligraf- Service Publ., 288 p. (In Russian)

26. McCoy D., Newberry R.J., Layer P., D.Marchi J.J., Bakke A., Mastermann J.S., Minehane D.L. (1997) Plutonic-Related Gold Deposits of Inerior Alaska. Econ. Geol. Monograph, 9, 191-241.

27. McDonough W.F., Sun S. (1995) The composition of the Earth. Chem. Geol., 120, 223-253.

28. Middlemost E.A.K. (1994) Naming materials in magma/igneous rock system. Earth Sci. Rev., 37, 215-224.

29. Mishin L.F. (2010) Geochemistry of europium in igneous rocks of continental marginal volcanic belts. Geokhimiya, 6, 618-631. (In Russian)

30. Pearce J.A. (1983) Role of the sub-continental lithosphere in magma genesis at active continental margins (Eds C.J. Hawkesworth and M.J. Norry). Continental basalts and mantle xenoliths. Cambridge, Massachusetts: Shiva Publ., 230-249.

31. Pearce J.A., Harris N.B.W., Tindle A.G. (1984) Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. J. Petrol., 25(4), 956-983.

32. Peccerillo A., Taylor S.R. (1976) Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contrib. Mineral. Petrol., 58, 63-81.

33. Plank T., Langmuir C.H. (1998) The chemical composition of subducting sediment and its consequences for the crust and mantle. Chem. Geol., 145, 325-394.

34. Plotinskaya O.Yu., Grabezhev A.I., Tessalina S., Seltmann R., Groznova E.O., Abramov S.S. (2017) Porphyry deposits of the Urals: Geological framework and metallogeny. Ore Geol. Rev., 85, 153-173.

35. Puchkov V.N. (2010) Geology of the Urals and the Cis-Urals (topical issues of stratigraphy, tectonics, geodynamics and metallogeny). Ufa, DesignPoligrafService Publ, 280 p. (In Russian)

36. Putrica K., Busby C. (2007) The tectonic significance of high-K2O volcanism in the Sierra Nevada, California. Geology, 35(10), 923-926.

37. Richards J.P., Spell T., Rameh E., Razique A., Fletcher T. (2012) High Sr/Y magmas reflect arc matyrity, high magmatic water content, and porphyry Cu ± Mo ± Au potential: examples from the Tethyan arcs of Central and Eastern Iran and Western Pakistan. Econ. Geol., 107, 295-332.

38. Savel’eva G.N. (1987) Gabbro-ultramafic complexes of the Urals ophiolites and their analogues in the modern oceanic crust. Moscow, GIN AN SSSR, 246 p. (In Russian)

39. Seravkin I.B., Kosarev A.M., Salikhov D.N., Znamenskii S.E., Rodicheva Z.I., Rykus M.V., Snachev V.I. (1992) Volcanism of the Southern Urals. Moscow, Nauka Publ., 197 p. (In Russian)

40. Shand S.J. (1949) The study of rocks. N.Y., The MacMillan Company, 236 p.

41. Sillitoe R.H. (2010) Porphyry Copper Systems. Econ. Geol., 105, 3-41.

42. Sinclair W.D. (2007) Porphyry deposits. Mineral deposits Canada: A synthesis of major deposit-types, district metallogeny, the evolution of geological provinces and exploration methods. Geol. Assoc. Can., Miner. Depos. Divis., Spec. Publ., 5, 223-243.

43. Stern CR, Kilian R (1996) Role of the subducted slab, mantle wedge and continental crust in the generation of adakites from the Andean Austral Volcanic Zone. Contrib. Mineral. Petrol., 123, 263-281.

44. Sylvester G. (1988) Strike-slip faults. Geol. Soc. Amer. Bull., 1000(11), 1666-1703.

45. Wu Z., Barosh P., Zhang Q., Wu J., Yang Y. (2018) A thickness Gauge for the lithospere based on Ce/Yb and Sm/ Yb of mantle-derived magmatic rocks. Acta Geologica Sinica, 92(6), 2120-2135.

46. Yang X.M., Lentz D.R., Chi G., Thome K.G. (2004) Petrocmemical characteristics of gold-related granitoids in southwestern New Brunswick, Canada. Explor. Min. Geol., 31, 34-47.

47. Znamenskii S.E. (1994) Late Ordovician-Early Silurian volcano- intrusive complex of the northern part of the Magnitogorsk megasyclinorium and associated mineralization (South Ural). Ufa, Ufa SC of the RAS, 20 p. (In Russian)

48. Znamenskii S.E. (2019) Positive flower structure of the Yalchigulovsky fault in the South Urals. Geol. Vestnik, 2, 24-31. (In Russian)

49. Znamenskii S.E., Ankusheva N.N., Artem’ev D.A. (2020) Formation conditions, composition and sources of ore-forming fluids of the Bolshoi Karan gold-porphyry deposit (South Urals). Lithosfera, 20(3), 397-410. (In Russian)

50. Znamenskii S.E., Kosarev A.M., Znamenskaya N.M., Timofeev S.P., Shafigullina G.T. (2017) Structural control and geochemistry of dikes of the Bolshoi Karan gold-porphyry deposit (South Urals). Geologiya. Izv. Otd-ya nauk o Zemle i prirodnykh resursov Akademii Nauk Respubliki Bashkortostan, 24, 39-46. (In Russian)

51. Znamenskii S.E., Kosarev A.M., Shafigullina G.T. (2019a) Facial composition, geochemical features and geodynamic settings of the formation of the Late Emsk island arc complexes of the Main Ural fault zone in the Southern Urals. Vestn. Perm. Univ. Geologiya, 18(1), 1-16. (In Russian)

52. Znamenskii S.E., Shafigullina G.T., Znamenskaya N.M., Kosarev A.M. (2019b) Voznesenskoe porphyry copper deposit (South Urals): structural control and geochemistry of intrusive rocks. Vestn. Akad. Nauk Resp. Bashkortostan, 2, 25-35. (In Russian)