Composition of minerals (apatite, magnenite, ilmenite and others) as an index of conditions of layered massive ore formation in the laminated gabbro of Kusa intrusion (the Southern Urals)

Research subject. In this research, we carried out a series of mineralogical, petrological and geochemical studies to investigate ore zones present in the Kusa ilmenite-magnetite deposit located within the boundaries of a similarly-named laminated gabbro massif. Here, ore bodies occur at various intrusion horizons among laminated apogabbroid amphibolites of a different basicity. In the intrusion section, the composition of halogens (Cl, F) in co-existing fluid-bearing minerals (apatite, am-phibole, staurolite) was analyzed.

Materials and methods. In order to investigate the composition of mineral samples, their polished sections were examined using an electronic-microprobe analyzer JXA-5. The content of petrogenic and microelement components (CRF and ICP-MS methods) in the rock and ore samples was determined using the facilities of the Laboratory of Physical and Chemical methods, UBRAS Institute of Geology and Geochemisty.

Results. It is established that the content of Cl and F in the apatite, amphibole and staurolite under study, as well as the chemical composition of ilmenite, magnetite, and hombombite components, depend on the position of the ore bodies in the intrusion. Thus, the apatites from the near-ore rocks in the central part of the deposit showed the highest Cl concentrations of up to 4.1%, while those located in the near-contact parts of the intrusion demonstrated a much lower Cl content of 2%. The central ore-bearing zone having the maximal Cl content features the largest formation of ore bodies, which (including magnetite) contain higher amounts of Fe₂O₃, Cr and V The presence of fluid-bearing minerals (apatite, scapolite, etc.) with high chlorine concentrations of up to 2.44% is this deposit is established.

Conclusions. The identified peculiarities of halogen distribution in the apatite of bipyroxene gabbro, as well as the inheritance of relations TiO₂/FeO in bipyroxene gabbro, in massive magnetite-ilmenite ores and in near-ore rocks point to a single magmatic source of these formations.

1. Alexeev A.A., Alexeeva G.V., Kovakv S.G. (1992) Kusin-sko-Kopanskii rassloennyi complex: novye dannye, pred-stavleniya i perspektivy [Kusa-Kopansky laminated complex: new data, views and perspectives]. Ufa, BSC UB RAS, 240 p. (In Russian)

2. Alexeev A.A., Alexeeva G.V., Kovalev S.G. (2000) Ras-sloennye intruzii Zapadnogo sklona Urala [Laminated intrusions of the Urals western slope]. Ufa, Gilem Publ., 20 p. (In Russian)

3. Bocharnikova T.D. (2009) Halogens in gabbro-norites of the Kusa and Kopan intrusions and their role in petro-and ore-genesis. Ezhegodnik-2008. Proc., IGG UB RAS, 156, 129-131. (In Russian)

4. Bocharnikova T.D., Glavatskikh S.P., Kholodnov V.V. (2010) Baddeleyite find in magnetite-ilmenite ores of the Kusa gabbro intrusion (Southern Urals). Vestnik Ural’skogo otdeleniya Rossiiskogo mineralogicheskogo obshchestva, (7). Ekaterinburg, IGG UB RAS, 11-13. (In Russian)

5. Bocharnikova T.D., Kholodnov V.V., Pribavkin S.V., Voronina L.K. (2003) Halogen distribution in laminated gab-broids of the Kusa intrusion. Ezhegodnik-2002. Ekaterinburg, IGG UB RAS, 224-227. (In Russian)

6. Bochrnikova T.D., Kholodnov V.V., Shagalov E.S. (2011) Composition and sources of fluids in skarns of mineral mines of the Kusa- Kopan complex (Southern Urals). Litosfera, (5), 124-130. (In Russian)

7. Bocharnikova T.D., Kholodnov V.V., Voronina L.K. (2003) A specific character of halogen-containing fluid of ore-bearing gabbroids of the Kuvash-Mashak riftogen-ic structure (the Southern Urals). Маterialy V Respub-likanskoi geologicheskoi konferentsii “Geologiya i perspektivy rasshireniya syr’evoi bazy Bashkortostana i sopredel’nykh territorii” [Materials of the V Republic Geological Conference “Geology and perspectives of widening the raw material base of Bashkortostan and the adjacent territories”], (2), Ufa, BSC UB RAS, 109-111. (In Russian)

8. Bocharnikova T.D., Kholodnov V.V., Voronina L.K. (2005) Regular variation of the ilmenite and magnetite composition from ore deposits in the Kusa gabbro massif profile. Ezhegodnik-2004. Ekaterinburg, IGG UB RAS, 313217. (In Russian)

9. Bocharnikova T.D., Kholodnov V.V., Voronina L.K. (2006). Particularities of the halogen distribution in co-existing apatite, amphibole and staurolite from the Kusa intrusion ore zones. Ezhegodnik-2005. Ekaterinburg, IGG UB RAS, 143-146. (In Russian)

10. Bocharnikova T.D., Pribavkin S.V., Kholodnov V.V., Voronina L.K. (2005) Hegbomite from ilmenite-magne-tite ores from the Kusa massif (Southern Urals). Zapiski RMO, (2), 84-90. (In Russian)

11. Bocharnikova T.D., Voronina L.K. (2008). The fist find of eskolaite in magnetite-ilmenite ores of the Kusa gabbro intrusion. Ezhegodnik-2007. Ekaterinburg, IGG UB RAS, 226-229. (In Russian)

12. Boudreau A.E., Mathez E.S., Mc Callum L.S. (1986) Galo-gen geochemistry of the Stillwater and Bushveld complexes: evidence for transport of the platinum-group elements by Cl- rich fluids. J. Petrol., 27(4), 967-986.

13. Boudreau A.E., Mc Callum L.S. (1989) Investigations of the Stillwater Complex: PtV. Apatites as indicators of evolving fluid composition. Contrib. Miner. Petrol., 102(2), 138-153.

14. Fershtater G.B., Kholodnov V.V., Borodina N.S. (2001) Conditions of formation and genesis of the Riphean il-menite titano-magnetite deposits of the Urals. Geol. Rudn. Mestorozhd., 3(2), 112-128. (In Russian)

15. Fershtater G.B., Kholodnov V.V., Pribavkin S.V., Borodina N.S., Bocharnikova T.D., Gottman I.A. (2005) Rifto-genic magmatism and ferro-mineralization of the Southern Urals. Geol. Rudn. Mestorozhd., 47(5), 421-443. (In Russian)

16. Fominykh V.G. (1968) Titanomagnetites of the Kusa gabbro-diabase intrusion. Mineraly mestorozhdenii poleznykh is-kopaemykh Urala [Minerals of the Urals fossile deposits]. Sverdlovsk, UB AS SSSR, 155-159. (In Russian)

17. Fominikh V.G., Andreev M.I. (1970) Corund amphibolite of the Kusa deposit. Ezhegodnik 1969 (osnovnye rezul’taty rabot 1969 goda). Sverdlovsk, UB AS USSR, 155-159. (In Russian)

18. Formatsii titano-magnetitovykh rud i zhelezistykh kvartsitov: zhelezorudnye mestorozhdeniya Urala [Formations of titano-magnetite ores and ferruginous quartzites: iron-ore deposits of the Uals]. (1984) (Chief ed. A.M. Dym-kin). Sverdlovsk, UF AS USSR, 264 p. (In Russian)

19. Gongalskii B.I., Krivolutskaya N.A. (1993) Chaineiskii rassloennyi pluton [The Chiney laminated pluton]. Novosibirsk, Nauka Publ., 181 p. (In Russian)

20. Gongalskii B.I., Krivolutskaya N.A., Ariskin A.A., Nikolaev G.S. (2008) Structure, compoasition and formation of the Chiney anorthosite gabbro-norite massif in northern Trans-Baikalia. Geokhimiya, (7), 1-30. (In Russian)

21. Ivanov O.K. (2004) Titano-magnetite composition variations on the profile of one of the layers of the Kopan laminated intrusion, S. Urals. Ural’skii geologicheskii zhurnal, (3). Ekaterinburg, 69-80.

22. Karpova O.V. (1974) Titanomagnetitovye rudy Yuzhno-go Urala [Titano-magnetite ores of the Southern Urals]. Moscow, Nauka Publ., 152 p. (In Russian)

23. Kholodnov V.V., Bocharnikova T.D., Pribavkin S.V. (2002) Petrochemical characteristics of the Kusa deposit laminated series rocks. Ezhegodnik-2001. Ekaterinburg, IGG, UB RAS, 141-147. (In Russian)

24. Kholodnov V.V., Bocharnikova T.D., Shagalov E.S. (2012) Composition, age and genesis of magnetite-ilmenite ores of middle-Riphean stratificated Medvedevsky massif (the Kusa-Kopansky complex of the Southern Urals). Litosfera, (5), 145-165. (In Russian)

25. Kholodnov V.V., Bushlyakov I.N. (2002). Galogeny v en-dogennom rudoobrazovanii [Halohens in endogenic ore-formation]. Ekaterinburg, UB RAS, 395 p. (In Russian)

26. Kholodnov V.V., Fershtater G.B., Ronkin Yu.L., Borodina N.S., Pribavkin S.V., Lepikhina O.P. (2010) Sm-Nd-Rb-Sr- age of gabbroids, granitoids and titano-magne-tite ores from laminated intrusions of the Kusa-Kopansk complex (the Southern Urals). Dokl. Akad. Nauk, 432(5), 650-654. (In Russian)

27. Kholodnov V.V., Shagalov E.S., Bocharnikova T.D., Konovalova E. V. (2015) Composition and conditions of Ti-Fe-V mineralization in bipyroxene gabbro of Medve-devsky deposit (the Southern Urals). Pt I. Petrochemical and geochemical characteristics of rocks and ores. Litosfera, (6), 69-83. (In Russian)

28. Kholodnov V.V., Shagalov E.S., Bocharnikova T.D., Konovalova E.V. (2016) Composition and conditions of Ti-Fe-V mineralization in bipyroxene gabbro of Medve-devsky deposit (the SouthernUrals). Pt II. Stageness of ore-formation as a result of evolution of ore-bearing fusion. Litosfera, (2), 48-69. (In Russian)

29. Kravtsova L.I. (1963) Geological structure and history of formation of the Kopan gabbro massif in the Southern Urals. Маgmatizm, metamorfizm, metallogenia Urala. Tr. Pervogo Ural’skogo petrograficheskogo soveshchaniya [Magmatism, metamorphism, metallogeny of the Ural. Proc. of the first Uralian petrographic conference], (1). Sverdlovsk, UB AS USSR, 467-480. (In Russian)

30. Krupenin M.T., Garayeva A.A., Kl’ukin Yu.I., Baltybaev Sh.K., Kuznetsov A.B. (2013) Fluid regime of magnesite metasomatism at the Satka deposits of South-Ura-lian province (termocriometry of fluid inclusions). Litosfera, (2), 120-134. (In Russian)

31. Malyshev I.I., Panteleev P.G., Pek A.V. (1934) Titano-mag-netitovye mestorozhdeniya Urala [Titano-magnetite deposits of the Urals]. Leningrad, AS USSR Publ., 272 p. (In Russian)

32. Myasnikov V.S. (1959) Some particularities of the deposits of titano-magnetite ores of the Southern Urals and metamorphism manifestation in them. Geol. Rudn. Mestoro-zhd., (2), 49-62. (In Russian)

33. Myasnikov V.S., Nikolayeva E. G., Karpova O.V. (1970) Mineral composition of the Kusa massif orthoamphibolites (the Southern Urals). Mineraly bazitov v sv’azi s voprosami petrogenezisa [Basite minerals in connection with petrogenesis problems]. Moscow, Nauka Publ., 34149. (In Russian)

34. Pavlov A.L. (1983) Genezis magmaticheskikh magneti-tovykh mestorozhdenii [Genesis of magmatic magnetite deposits]. Novosibirsk, Nauka Publ., 204 p.

35. Pribavkin S.V., Borodina N.S., Fershtater G.B., Kholodnov V.V., Bocharnikova T.D. (2003) Near-ore high-barite mineral associations in the Kusa gabbro massif (Southern Urals). Dokl. Akad. Nauk, 391(1), 95-98. (In Russian)

36. Shagalov E.S., Sustavov S.G., Kholodnov V.V. (2017) High-chlorine and sulfate mineral associations in the Kusa-Kopansk complex rocks. Ural’skaya mineralogicheskaya shkola - 2017. Sb. Statei studentov, aspirantov, nauch-nykh sotrudnikov, prepodavatelei vuzov geologicheskogo profilya [Uralian mineralogical school-2017. Collection of papers of students, post-graduates, scientific collaborators and HEE teachers of geological profile]. Ekaterinburg, IGG UB RAS, 233-237. (In Russian)

37. Sharkov E.V. (2006) Formirovanie rassloennykh intruzivov i svyazannogo s nimi orudeneniya [Formation of laminated intrusives and associated mineralization]. Moscow, “Nauchnyi mir” Publ., 365 p. (In Russian)

38. Shteinberg D.S., Kravtsova L.I., Varlakov A.S. (1959) Main features of geological structure of the Kusa gabbro intrusion and the ore deposits, occurring in it. Trudy gorno-geologicheskogo Instituta, (40), 13-40. (In Russian)

39. Sun S.S. (1982) Chemical composition and origin jf the Faiths primive mantle. Geochim. Cosmochim. Acta, 46, 179-192.

40. Titano-magnetitovye mestorozhdeniya Urala [Titano-magnetic deposits of the Urals]. (1936) Pt 2. Moscow, AS USSR Publ., 176 p. (In Russian)

41. Ueidzher L., Braun G. (1970) Rassloennye izverzhennye po-rody [Laminated eruptive rocks]. Moscow, Mir Publ., 551 p. (In Russian)

42. Uillemz Dzh. (1973) Vanadium magnetite ores of the Bushveld complex. Маgmaticheskie rudnye mestorozhdeniya [Magmatic ore deposits]. Moscow, Nedra Publ., 129150. (In Russian)

43. Zakrzewski M.A. (1977) Hegbomite from the Fe-Ti deposit of Liganga (Tansania). Neues Jahrb. Mineral. Monatsh., 373-380.