EBSD analysis of olivine microstructures in ophiolitic ultramafic rocks with predominantly lherzolite composition (on the example of the Kraka and Syum-Keu massifs)

   Research subject. Ultramafic rocks from mantle sections of the Kraka (Southern Urals) and Syum-Keu (Polar Urals) ophiolite massifs.

   Methods. Electron backscatter diffraction (EBSD) was the primary method used to study olivine microstructures. Mineral compositions were determined by energy-dispersive microanalysis (SEM/EDS). EBSD data were processed using the HKL Channel 5 and MTEX software packages.

   Results. The mineralogical, geochemical, and microstructural characteristics of lherzolite, harzburgite, and dunite samples from these massifs were studied. Olivine from the Kraka ultramafic rocks exhibits a crystallographic fabric controlled by slip systems (010)[100], (001)[100], and {0kl} [100]. In addition, multiple-slip deformation is most strongly developed in dunites. The microstructure of olivine from the Syum-Keu ultramafic rocks records two stages of ductile deformation: early (upper mantle) and late (lower crustal). The former corresponds to a higher-temperature flow according to the {0kl}[100] system, while the latter corresponds to a lower-temperature flow according to the {110}[001] system.

   Conclusions. Olivine in the Kraka peridotites preserves mantle-stage microstructures, where most low-angle boundaries are relatively straightforward and correspond to kink-band types. In the Syum-Keu peridotites, these microstructures are partially or completely transformed by superimposed static recrystallization (annealing). Elevated temperatures and pressures, together with the observed olivine fabric, indicate the formation of the Kraka ultramafic rocks at the spinel/plagioclase facies boundary in the upper mantle. Conversely, the Syum-Keu ultramafic rocks record lower P–T conditions, likely corresponding to lower crustal environments. These results generally support the previously developed concept suggesting a longer evolution of mantle ultramafic rocks in the Syum-Keu massif relative to the Kraka massif, and they are consistent with a suprasubduction origin of both complexes.

1. Arai S. (1994) Characterization of spinel peridotites by olivine-spinel compositional relationships : Review and interpretation. Chem. Geol., 113, 191-204. doi: 10.1016/0009-2541(94)90066-3

2. Bachmann F., Hielscher R., Schaeben H. (2010) Texture analysis with MTEX – Free and open source software toolbox. Solid State Phenom., 160, 63-68. doi: 10.4028/www.scientific.net/SSP.160.63

3. Ballhaus C., Berry R., Green D.H. (1991) High pressure experimental calibration of the olivine-orthopyroxene-spinel oxygen geobarometer: implication for the oxydation state of the upper mantle. Contrib. Mineral. Petrol., 107, 27-40. doi: 10.1007/BF00311183

4. Brey G.P., Köhler T. (1990) Geothermobarometry in 4-phase lherzolites: 2. New thermobarometers, and practical assessment of existing thermobarometers. J. Petrol., 31, 1353-1378. doi: 10.1093/petrology/31.6.1353

5. Burtman V.V., Moldavantsev Yu.E., Perfil’ev A.S., Shults S.S. (1974) Variscide oceanic crust of the Urals and Tien Shan. Sov. Geol., (3), 23-36. (In Russ.)

6. Carter N.L. (1976) Steady state flow of rocks. Rev. Geophys. Space Phys., 14(3), 301-360.

7. Changyi J., Sanyuan A. (1984) On chemical characteristics of calcic amphiboles from igneous rocks and their petrogenesis significance. J. Mineral. Petrol., 4(3), 1-9. (In Chinese) doi: 10.19719/j.cnki.1001-6872.1984.03.001

8. Chaschukhin I.S., Votyakov S.L., Schapova Yu.V. (2007) Crystal chemistry of Cr-spinel and oxythermobarometry of ultramafic rocks of folded areas. Ekaterinburg, IGG UrO RAN, 310 p. (In Russ.)

9. Chernyshov A.I., Yurichev A.N. (2016) The structural evolution of dunites and chromites of the Kharcheruz massif (Polar Urals). Geotectonics, 50(2), 196-208 (translated from Geotektonika, (2), 62-77).

10. Czamanske G.K., Wones D.R. (1973) Oxidation during magmatic differentiation, Finnmarks Complex, Oslo Area, Norway. Pt 2. The mafic silicate. J. Petrol., 14(3), 349-380. doi: 10.1093/petrology/14.3.349

11. Denisova E.A. (1989) Folded structure of ultramafic tectonites in the Southern Ural massifs. Geotectonika, (4), 52-62. (In Russ.)

12. Denisova E.A. (1990а) Structure and deformation structures of ophiolite massifs with a lherzolite-type section. Geotectonika, (2), 14-27. (In Russ.)

13. Denisova E.A. (1990б) Structure of the ultrabasic massif South Kraka (Southern Urals). Izv. AN SSSR. Ser. Geol., (1), 45-63. (In Russ.)

14. Dobretsov N.L., Moldavantsev Yu.E., Kazak A.P., Ponomareva L.G., Savelyeva G.N., Savelyev A.A. (1977) Petrology and metamorphism of ancient ophiolites. Novosibirsk, Nauka Publ., 220 p. (In Russ.)

15. Dushin V.A. (2020) Geological structure and magmatism of the Shchuchya megablock (Polar Urals). Izv. UrGGU, 4(60), 35-56. (In Russ.)

16. Electron backscattered diffraction in Material Science. (2009) (Ed. by J. Schwartz, M. Kumar, B.L. Adams, D.P. Field). New York, Springer Science + Business Media, 528 p. doi: 10.1007/978-0-387-88136-2

17. Gataullin R.A., Saveliev D.E., Kiseleva D.V. (2025) Ultramafic and mafic rocks of the Northern Kraka massif (Southern Urals): Petrography, mineralogy and geochemistry. Geosfernye Issledovaniya, (2), 47-60. doi: 10.17223/25421379/35/4

18. Goncharenko A.I. (1989) Deformation and petrostructural evolution of alpine-type ultramafics. Tomsk, Izd-vo Tomskogo un-ta, 404 p. (In Russ.)

19. Green D.H., Falloon T.J. (1998) Pyrolite: A Ringwood concept and its current expression. The Earth’s mantle composition, structure and evolution. New York, Cambridge University Press, 311-378.

20. Gurskaya L.I., Smelova L.V., Kolbantsev L.R., Lyakhnitskaya V.D., Lyakhnitsky Yu.S., Shakhova S.N. (2004) Platinum group metals of chromite-bearing massifs of the Polar Urals. St.Petersburg, VSEGEI, 306 p. (In Russ.)

21. Jung H. (2017) Crystal preferred orientations of olivine, orthopyroxene, serpentine, chlorite, and amphibole, and implications for seismic anisotropy in subduction zones : a review. Geosci. J., 21, 985-1011. doi: 10.1007/s12303-017-0045-1

22. Karato S.-I. (2008) Deformation of Earth Materials. An introduction to the rheology of Solid Earth. New York, Cambridge University Press, 463 p.

23. Karato S.-I., Jung H., Katayama I., Skemer Ph. (2008) Geodynamic significance of seismic anisotropy of the upper mantle: new insights from laboratory studies. Annu. Rev. Earth Planet. Sci., 36, 59-95. doi: 10.1146/annurev.earth.36.031207.124120

24. Kazantseva T.T. (1987) Allochthonous structures and formation of the Ural crust. Moscow, Nauka Publ., 158 p. (In Russ.)

25. Leake B.E., Woolley A.R., Arps C.E.S., Birch W.D., Gilbert M.C., Grice J.D., Hawthorne W.C., Kato A., Kisch K.J., Krivovichev V.G., Lithout K., Laird J., Mandarino J.A., Maresch W.V., Nickel E.A., Rock N.M.S., Schumacher J.C., Smith D.C., Stephenson N.C.N., Ungaretti L., Whittaker E.J.W., Youzhi G. (1997) Nomenclature of amphiboles; report of the subcommittee on amphiboles of the International Mineralogical Association commission on new minerals and mineral names. Canad. Miner., 35, 219-246.

26. Makeev A.B., Brianchaninova N.I. (1999) Topomineralogy of ultrabasites of the Polar Urals. St.Petersburg, Nauka Publ., 252 p. (In Russ.)

27. Nicolas A., Bouchez J.L., Boudier F., Mercier J.C. (1971) Textures, structures and fabrics due to solid state flow in some European lherzolites. Tectonophys., 12, 55-86. doi: 10.1016/0040-1951(71)90066-7

28. Parkinson I.J., Pearce J.A. (1998) Peridotites from the Izu-Bonin–Mariana forearc (ODP Leg 125): Evidence for mantle melting and melt-mantle interaction in a suprasubduction zone setting. J. Petrol., 39, 1577-1618. doi: 10.1093/petroj/39.9.1577

29. Perevozchikov B.V., Plotnikov A.V., Makiev T.T. (2007) The nature of variations in the composition of ore and accessory chrome spinel of the ultramafic massif Syum-Keu (Polar Urals). Izv. Vuzov. Geologiya i Razvedka, (4), 32-39. (In Russ.)

30. Perevozchikov B.V., Bulykin L.D., Popov I.I., Orfanitsky V.L., Andreev M.I., Snachev V.I., Danilenko S.A., Cherkasov V.L., Chentsov A.M., Zharikova L.N., Klochko A.A. (2000) Register of chromite occurrences in alpine-type hyperbasitic rocks of the Urals. Perm, KamNIIKIGS, 474 p. (In Russ.)

31. Perfiliev A.S., Ruzhentsev S.V. (1973) Structural position of gabbro-ultramafic complexes in folded belts. Geotectonika, (3), 14-26. (In Russ.)

32. Poirier J.-P. (1985) Creep of crystals. High-temperature deformation processes in metals, ceramics and minerals. London, Cambridge University Press, 287 p.

33. Prior D.J., Boyle A.P., Brenker F., Cheadle M.J., Day A., Lopez G., Peruzzo L., Potts G.J., Reddy S.M., Spiess R., Timms N.O., Trimby P.W., Wheeler J., Zetterstrom L. (1999) The application of electron backscattered and orientation contrast imaging in the SEM to textural problems in rocks. Amer. Miner., 84, 1741-1749.

34. Puchkov V.N. (1997) Structure and geodynamics of the Uralian orogen. Orogeny Through Time (Ed. by J.-P. Burg, M. Ford). London, Geological Society, 201-236.

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

36. Putirka K.D. (2008) Thermometers and barometers for volcanic systems. Rev. Mineral. Geochem., 69, 61-120. doi: 10.2138/rmg.2008.69.3

37. Ringwood A.E. (1975) Composition and structure of the Earth’s mantle. New York, McGraw-Hill, 618 p.

38. Saveliev D.E. (2018) Kraka ultramafic massifs (the Southern Urals): features of structure and composition of peridotite-dunite-chromitite assamblages. Ufa, Bashk. Ehntsik. Publ., 304 p. (In Russ.)

39. Saveliev D.E., Gataullin R.A. (2021) Lherzolites of the Aznagulovskaya area: composition and P-T-fO₂ formation conditions. Vestn. ANRB, 40(3), 15-25. (In Russ.)

40. Saveliev D.E., Shilovskikh V.V., Makatov D.K., Gataullin R.A. (2022) Accessory Cr‐spinel from peridotite massifs of the South Urals: morphology, composition and origin. Mineral. Petrol., 116, 401-427. doi: 10.1007/s00710-022-00791-1

41. Saveliev D.E., Snachev V.I., Savelieva E.N., Bazhin E.A. (2008) Geology, petrogeochemistry and chromitonosity of gabbro-hyperbasite massifs of the Southern Urals. Ufa, DesignPolygraphService Publ., 320 p.

42. Savelieva G.N. (1987) Gabbro-Ultrabasitic Complexes of the Urals Ophiolites and Their Analogs in the Recent Oceanic Crust. Moscow, Nauka Publ., 246 p. (In Russ.)

43. Savelyeva G.N., Denisova E.A. (1985) Structure and petrology of the Middle Kraka ultramafic massif in the Southern Urals. Geotektonika, (4), 33-68. (In Russ.)

44. Savelyeva G.N., Suslov P.V. (2014) Structure and composition of mantle peridotites at the boundary with crustal complexes of ophiolites in the Syum-Keu massif, Polar Urals. Geotectonics, 48(5), 347-358 (translated from Geotektonika, (5), 3-16). doi: 10.1134/S0016852114040074

45. Savelieva G.N., Batanova V.G., Sobolev A.V. (2016) Pyroxene–Cr-spinel exsolution in mantle lherzolites of the Syum-Keu ophiolite massif (Arctic Urals). Russ. Geol. Geophys., 57, 1419-1436 (translated from Geol. Geofiz., 57(10), 1808-1827). doi: 10.1016/j.rgg.2015.12.001

46. Shabutdinov T.D., Saveliev D.E., Gataullin R.A., Samigullin A.A. (2024) Mineralogical Features of Ultramafic and Mafic Rocks of Syum-Keu Ophiolite (Polar Urals, Russia): Implications for Petrology and Paleogeodynamics. Minerals, 14, 1245. doi: 10.3390/min14121245

47. Shmelev V., Arai S., Tamura A. (2019) Heterogeneity of mantle peridotites from the Polar Urals (Russia): Evidence from new LA-ICP-MS data. Earth Sci., 1(3), 431-450. doi: 10.1007/s12583-019-1224-y

48. Shmelev V.R. (1991) Ultrabasites of the Syum-Keu massif (Arctic Urals): structure, petrology, and dynamometamorphism. Ekaterinburg, IGG UrO AN SSSR, 80 p. (In Russ.)

49. Shmelev V.R. (2011) Mantle ultrabasites of ophiolite complexes in the Polar Urals: Petrogenesis and geodynamic environments. Petrology, 19, 618-640 (translated from Petrologiya, 19(6), 649-672). doi: 10.1134/S0869591111060038

50. Skemer Ph., Katayama I., Jiang Z., Karato S.-I. (2005) The misorientation index: Development of a new method forcalculating the strength of lattice-preferred orientation. Tectonophys., 411, 157-167. doi: 10.1016/j.tecto.2005.08.023

51. Snachev V.I., Savelyev D.E., Rykus M.V. (2001) Petrogeochemical features of rocks and ores of the gabbro-ultrabasic massifs of Kraka. Ufa, IG UNTs RAN, 212 p. (In Russ.)

52. Sokolov G.A. (1948) Chromites of the Urals, their composition, crystallization conditions, and distribution patterns. Tr. IGN AN SSSR, 97(12), 128 p. (In Russ.)