Ontogenic analysis of magnetite-ilmenite-spinel intergrowths of ore-bearing amphibole gabbro of the Serebryansky Kamen intrusion (Central Urals) and their relationships with rock-forming silicates, apatite and Cu sulfdes allowed us to reveal a number of features indicating their nearly synchronous formation. Morphological features of minerals of ore-bearing amphibole gabbro suggest their possible crystallization from silicate, iron oxide and sulfde melts under close-to-eutectic conditions. It is found that regularly oriented ilmenite lamellas in magnetite, which are typically interpreted as exsolution structures, often intersect the boundaries of variously oriented magnetite grains, which is inconsistent with traditional interpretation of their origin. The ontogenetic features of minerals should be taken into account in petrological reconstructions.

Keywords: amphibole gabbro, Serebryansky Kamen intrusion, Pt-bearing belt of the Urals, magnetite, ilmenite, spinel.

Received 01.12.2022, accepted 06.12.2022

A.V. Kozlov, St. Petersburg Mining University, 21 Liniya 2, St. Petersburg, 199106 Russia; alexkoz-spggi@yandex.ru

V.V. Mikhaylov, Institute of Geology and Geochemistry UB RAS, ul. Akademika Vonsovskogo 15,Yekaterinburg, 620016 Russia; 

S.Yu. Stepanov, Institute of Geology and Geochemistry UB RAS, ul. Akademika Vonsovskogo 15,Yekaterinburg, 620016 Russia; 

V.V. Shilovskikh, St. Petersburg State University, Research Center «Geomodel», Universitetskaya nab. 7/9, St. Petersburg, 199034 Russia;

N.S. Vlasenko, St. Petersburg State University, Research Center «Geomodel», Universitetskaya nab. 7/9, St. Petersburg, 199034 Russia

1. Anikina E.V., Alekseev A.V. (2010) [Mineral-geochemical characteristic of Au-Pd mineralization of the Volkovsky gabbro pluton (Uralian Platinum Belt)]. Litosfera [Lithosphere], 5, 75–100. (in Russian)
2. Amcoff O., Figueiredo B.R. (1990) Mechanisms of retrograde changes in oxide minerals from the Proterozoic Serrote da Laje deposit, northeastern Brazil. Mineralium Deposita, 25, 313–322.
3. Betekhtin A.G., Genkin A.D., Filimonova A.A., Shadlun T.N. (1958) [Ore textures and structures]. Мoscow, Gosgeoltekhizdat, 435 p. (in Russian)
4. Betekhtin A.G., Genkin A.D., Filimonova A. A., Shadlun T.N. (1964) [Structural and textural features of endogic ores]. Moscow, Nedra, 508 p. (in Russian)
5. Buddington A.F., Lindsly D.H. (1964) Iron-titanium oxide minerals and synthetic equivalents. Journal of Petrology, 5, 310–357.
6. Charlier B., Namur O., Malpas S., de Marneffe C., Duchesne J-C., Vander Auwera J., Bolle O. (2010) Origin of the giant Allard Lake ilmenite ore deposit (Canada) by fractional crystallization, multiple magma pulses and mixing. Lithos, 117 , 119–134.
7. Duchesne J.C. (1970) Microtextures of Fe-Ti oxide minerals in the south-rogaland anorthositic complex (Norway). Annales Societe geologique de Belgique, 935, 527–544.
8. Efmov A.А. (2006) [Pt–Pd copper-titanium-magnetite mineralization in gabbro of the Serebryansky Kamen]. Regionalnaya geologia i metallogeniya [Regional Geology and Metallogeny], 28, 112–115. (in Russian)
9. Efmov A.А. (2010) [Summary of centennial study of the Uralian Platinum Belt]. Lithoshera [Lithosphere], 5, 134–153. (in Russian)
10. Gongalsky B.I., Krivolutskaya N.А. (1993) [The Chinea stratifed pluton]. Novosibirsk, Nauka, 184 p. (in Russian)
11. Hou T., Charlier B., Holtz F., Veksler I., Zhang Z., Thomas R, Namur O. (2018) Immiscible hydrous Fe–Ca–P melt and the origin of iron oxide-apatite ore deposits. Nature Communications, 9(1415).
12. Ivanyuk G.Yu., Kalashnikov A.O., Pakhomovsky Ya.A., Bazai A.V., Goryainov P.M. Mikhailova J.A., Yakovenchuk V.N., Konopleva N.G. (2017) Subsolidus evolution of the magnetite-spinel-ulvospinel solid solutions in the Kovdor phoscorite-carbonatite complex, NW Russia. Minerals, 7, 215.
13. Kashin S.A. (1941) [Problem of the Urals disseminated Cu ores associated with gabbroids]. Sovetskaya geolgiya [Soviet Geology], 2, 63–68. (in Russian)
14. Kashin S.А. (1948) [Copper-titanomagnetite mineralization in mafc intrusive rocks of the Urals]. Trudy Instituta geologicheskikh nauk [Proceedings of the Institute of Geological Sciences], 91(9), 132 p. (in Russian)
15. Lindsley D.H. (2003) Do Fe-Ti oxide magmas exist? Geology: Yes; Experiments: No! / Ilmenite deposits and their geological environment, Duchesne J.-C., Korneliussen A. (eds.). Norges Geologiske Undersokelse Special Publication, 9, 34–35.
16. Mazurov M.P., Grishina S.N., Titov A.Т. (2004) [Magnetites from Mg skarns at the contacts of dolerites with salt]. Geologiya i geofzika [Geology and Geophysics], 45(10), 1198–1207. (in Russian)
    [Minerals. Handbook, II(3)] (1989) Moscow, Nauka, 676 p. (in Russian)
17. Nixon G., James M. (2018) Cu-PGE sulphide mineralization in the Tulameen Alaskan-type intrusion: Analogue for Cu-PGE reefs in layered intrusions? British Columbia Geological Survey Geofle 2018-2.
18. Pavlov A.L. (1993) [Genesis of igneous magnetite deposits]. Novosibirsk, Nauka, 208 p. (in Russian)
19. Polkanov A.A., Eliseev N.A, Eliseev E.N., Kavardin G.I. (1967) [The Gremyakha-Vyrmes pluton in the Kola Peninsula]. Moscow-Leningrad, Nauka, 236 p. (in Russian)
20. Poltavets Y.A., Poltavets Z.I., Nechkin G.S. (2011) Volkovsky deposit of titanomagnetite and copper-titanomagnetite ores with accompanying noble-metal mineralization, Central Urals, Russia. Geology of Ore Deposits, 53(2), 126–139.
21. Popov V.A. (2011) [Practical genetic mineralogy]. Yekaterinburg, UrO RAN, 167 p.
22. Ramdohr P. (1962) [Ore minerals and their intergrowths]. Moscow, Inostrannaya literatura, 1932 p. (in Russian)
23. Schwartz G.М. (1934) [Solid solution decay structures] In: Kriterii vozrastnykh sootnosheniy rudoobrazuyushchikh mineralov po mikroskopicheskim issledovaniyam [Criteria of Age Relations of Ore-Forming Minerals based on Microscopic Studies]. Moscow-Leningrad-Novosibirsk, Gosudarstvennoe nauchno-tekhnicheskoe izdatel’stvo, 129– 148. (in Russian)
24. Simanenko L.F., Sharova O.I., Shcheka S.А. (2012) New data on titanomagnetite exsolution textures from pyroxenites of the Koksharovsky massif (Primorye). Russian Journal of Pacifc Geology, 31(4), 93–105.
25. [State Geological Map of the Russian Federation on a scale of 1:200 000. Second edition. Sredneuralskaya series. Sheet O-40-VI (Kytlym). Explanatory Note] (2010). St. Petersburg, Kartografcheskaya fabrika VSEGEI, 213 p. (in Russian)
26. Tan W., Liu P., He H., Wang C.Y., Liang X. (2016) Mineralogy and origin of exsolution in ti-rich magnetite from different magmatic Fe-Ti oxide-bearing intrusions. The Canadian Mineralogist, 54, 539–553.
27. Trofmov N.N., Golubev A.I. (2008) [Pudozh Gora precious metal magnetite deposit]. Petrozavodsk, Karel’skiy nauchny tsentr RAN, 123 p. (in Russian)
28. [Unpublished report on results of complex prospecting works for copper-titanium-magnetite and titanium-magnetite ores in area of the Serebryansky Kamen] (1978). Uralskoe Territorialnoe Geologicheskoe Upravlenie, I, 111 p. (in Russian)
29. Woodruff L.G., Nicholson S.W., Fey D.L. (2013) A deposit model for magmatic iron-titanium-oxide deposits related to Proterozoic massif anorthosite plutonic suites. U.S. Geological Survey Scientifc Investigations Report 2010–5070–K, 47 p.
30. Zavaritsky A.N. (1955) [Igneous rocks]. Moscow, AN SSSR, 480 p. (in Russian)