STRUCTURAL EVOLUTION OF THE CHEKA PLUTON (SOUTHERN URALS): PETROMAGNETIC STUDIES AND FRACTURE ANALYSIS

The Cheka pluton, located in the Magnitogorsk megazone of the Southern Urals and composed of the alkaline granitoids, is meridionally elongated (1–2)×6.5 km. The fracture and anisotropy of magnetic susceptibility analysis was made on the Cheka pluton for the first time. The study materials comprise fracture measurements and core samples. The fractures were classified as either prototectonic or tectonic using the Stereonet software. The prototectonic fractures were classified into three standard types in accordance with the system proposed by G. Cloos: S, Q, and L. The system of tectonic fractures corresponds to the Riedel model, which confirms the formation of the pluton as a dextral magmatic strike-slip duplex supposed earlier. The analysis of magnetic mineralogy revealed that the most prevalent magnetic mineral is fine- to-medium-grained magnetite. Using the anisotropy of magnetic susceptibility data, the main direction of melt flow during the formation of the pluton was determined to be 36° NE. This direction is in close alignment with the orientation of one of the prototectonic fracture systems, which has a strike azimuth of 39° NE. The constructed complex structure model indicates that the Triassic granitoid plutons of the Magnitogorsk megazone were most likely formed during the right-lateral transpression, associated with a local strike-slip fault-related extension zone. These conditions are generally consistent with the Triassic rifting and dextral strike-slip motion in the Southern Urals.

1. Allmendinger R.W., Cardozo N.C., Fisher D., 2012. Structural Geology Algorithms: Vectors and Tensors. Cambridge University Press, New York, 289 p. https://doi.org/10.1017/CBO9780511920202.

2. Anisoft 4.2, 2009. Software. Available from: https://agico.cz/text/software/anisoft/anisoft.php (Last Accessed 10 April, 2024).

3. Archanjo C.J., Launeau P., Bouchez J.L., 1995. Magnetic Fabric vs. Magnetite and Biotite Shape Fabrics of the Magnetite-Bearing Granite Pluton of Gameleiras (Northeast Brazil). Physics of the Earth and Planetary Interiors 89 (1–2), 63–75. https://doi.org/10.1016/0031-9201(94)02997-P.

4. Archanjo C.J., Launeau P., Hollanda M.H.B.M., Macedo J.W.P., Liu D., 2009. Scattering of Magnetic Fabrics in the Cambrian Alkaline Granite of Meruoca (Ceará State, Northeastern Brazil). International Journal of Earth Sciences 98, 1793–1807. https://doi.org/10.1007/s00531-008-0342-z.

5. Archanjo C.J., Trindade R.I.F., Bouchez J.L., Ernesto M., 2002. Granite Fabrics and Regional-Scale Strain Partitioning in the Seridό Belt (Borborema Province, NE Brazil). Tectonics 21 (1), 3-1–3-14. https://doi.org/10.1029/2000TC001269.

6. Bhattacharyya D.S., 1966. Orientation of Mineral Lineation Along the Flow Direction in Rocks. Tectonophysics 3 (1), 29–33. https://doi.org/10.1016/0040-1951(66)90023-0.

7. Bijaksana S., Megantara G., Muchtar C., Arandi M.G.K., Fajar S.J., 2022. Identification of Magnetic Coercivity Components in Natural Substances Using Max Unmix Web-Application. Journal of Magnetism and Its Applications 2 (1), 1–4. https://doi.org/10.53533/JMA.v2i1.17.

8. Bolshakov V.A., Gapeev A.K., Yasonov P.G., 1987. Piezochemical Remanent Magnetization as a Result of a Change in Coercive Force of the Samples from the Hypergenesis Zones. Bulletin of the USSR Academy of Sciences. Physics of the Earth 9, 55–63 (in Russian)

9. Borradaile G.J., Henry B., 1997. Tectonic Applications of Magnetic Susceptibility and Its Anisotropy. Earth-Science Reviews 42 (1–2), 49–93. https://doi.org/10.1016/S0012-8252(96)00044-X.

10. Burov B.V., Yasonov P.G., 1979. Introduction to Differential Thermomagnetic Analysis of Rocks. KSU, Kazan, 160 p. (in Russian)

11. Cardozo N., Allmendinger R.W., 2013. Spherical Projections with OSXStereonet. Computers & Geosciences 51, 193–205. https://doi.org/10.1016/j.cageo.2012.07.021.

12. Charpentier L.J.J., 2003. Magnetic Fabrics of Granitic Plutons and Gneisses Northwestern Ontario. Master Thesis (Master of Science). Thunder Bay, Canada, 162 p.

13. Chervyakovsky S.G., 1974. On the Role of Autometasomatic Processes in Formation of Alkaline Granitoids from the Malaya Cheka Complex. In: Metasomatism and Ore Formation. Collected Papers. Ural SC of the USSR Academy of Sciences, Sverdlovsk, p. 159–169 (in Russian)

14. Chervyakovsky S.G., 1981. The Main Features of Geochemical Specialization of Alkaline Granitoids of the Magnitogorsk Megaanticlinorium. In: Rare Elements in Granitoids of the Urals. Collected Papers. Ural SC of the USSR Academy of Sciences, Sverdlovsk, p. 89–103 (in Russian)

15. Chukhrov F.V., Zvyagin B.B., Ermilova L.P., Gorshkov A.M., 1975. The Formation and Transformation of Lepidocrocite (γ-FeOOH). In: Hypergenic Iron Oxides in Geological Processes. Nauka, Moscow, p. 48–61 (in Russian)

16. Cloos H., 1922а. Der Gebirgsbau Schlesiens und die Stellung seiner Bodenschätze. Verlag von Gebrüder Borntraeger, Berlin, 107 p.

17. Cloos H., 1922b. Tektonik und Magma. Band I. Verlag von Gebrüder Borntraeger, Berlin, 141 p.

18. Day R., Fuller M., Schmidt V.A., 1977. Hysteresis Properties of Titanomagnetites: Grain-Size and Compositional Dependence. Physics of the Earth and Planetary Interiors 13 (4), 260–267. https://doi.org/10.1016/0031-9201(77)90108-X.

19. Dias J.M., Cruz C., Sant’Ovaia H., Noronha F., 2022. Assessing the Magnetic Mineralogy of the Pre-Variscan Manteigas Granodiorite: An Unexpected Case of a Magnetite-Series Granitoid in Portugal. Minerals 12 (4), 440. https://doi.org/10.3390/min12040440.

20. Dietl C., Koyi H.A., de Wall H., Gößmann M., 2006. Centrifuge Modelling of Plutons Intruding Shear Zones: Application to the Fürstenstein Intrusive Complex (Bavarian Forest, Germany). Geodinamica Acta 19 (3–4), 165–184. https://doi.org/10.3166/ga.19.165-184.

21. Dunlop D.J., 2002. Theory and Application of the Day Plot (Mrs/MS versus Hcr/Hc) 2. Application to Data for Rocks, Sediments, and Soils. Journal of Geophysical Research: Solid Earth 107 (3), 2057. https://doi.org/10.1029/2001JB000487.

22. Egli R., 2004. Characterization of Individual Rock Magnetic Components by Analysis of Remanence Curves. Studia Geophysica et Geodaetica 48, 391–446. https://doi.org/10.1023/B:SGEG.0000020839.45304.6d.

23. Ferré E.C., Wilson J., Gleizes G., 1999. Magnetic Susceptibility and AMS of the Bushveld Alkaline Granites. Tectonophysics 307 (1–2), 113–133. https://doi.org/10.1016/S0040-1951(99)00122-5.

24. Furina M.A., Tevelev A.V., Kosheleva I.A., Pravikova N.V., 2010. The Main Features of the Chemical Composition of the Triassic Alkaline Rocks of the Magnitogorsk Zone, the Southern Urals. Moscow University Geology Bulletin 2, 62–68 (in Russian)

25. Georgiev N., Henry B., Jordanova N., Jordanova D., Naydenov K., 2014. Emplacement and Fabric-Forming Conditions of Plutons from Structural and Magnetic Fabric Analysis: A Case Study of the Plana Pluton (Central Bulgaria). Tectonophysics 629, 138–154. https://doi.org/10.1016/j.tecto.2014.02.018.

26. Grégoire V., Darrozes J., Gaillot P., Nédélec A., Launeau P., 1998. Magnetite Grain Shape Fabric and Distribution Anisotropy vs Rock Magnetic Fabric: A Three-Dimensional Case Study. Journal of Structural Geology 20 (7), 937–944. https://doi.org/10.1016/S0191-8141(98)00022-4.

27. Jasonov P.G., Nurgaliev D.К., Burov B.V., Heller F., 1998. A Modernized Coercivity Spectrometer. Geologica Carpathica 49, 224–225.

28. Lanza R., Tonarini S., 1998. Palaeomagnetic and Geochronological Results from the Cambro-Ordovician Granite Harbour Intrusives Inland of Terra Nova Bay (Victoria Land, Antarctica). Geophysical Journal International 135 (3), 1019–1027. https://doi.org/10.1046/j.1365-246X.1998.00692.x.

29. Lyra D.S., Savian J.F., Bitencourt M.F., Trindade R.I.F., Tomé C.R., 2018. AMS Fabrics and Emplacement Model of Butia Granite, an Ediacaran Syntectonic Peraluminous Granite from Southernmost Brazil. Journal of South American Earth Sciences 87, 25–41. https://doi.org/10.1016/j.jsames.2017.12.006.

30. McNulty B.A., Tobisch O.T., Cruden A.R., Gilder S., 2000. Multistage Emplacement of the Mount Givens Pluton, Central Sierra Nevada Batholith, California. GSA Bulletin 112 (1), 119–135. https://doi.org/10.1130/0016-7606(2000)112%3C119:MEOTMG%3E2.0.CO;2.

31. Petit J.P., 1987. Criteria for the Sense of Movement on Fault Surfaces in Brittle Rocks. Journal of Structural Geology 9 (5–6), 597–608. https://doi.org/10.1016/0191-8141(87)90145-3.

32. Puchkov V.N., 2000. Paleogeodynamics of the Southern and Middle Urals. Gilem, Ufa, 146 p. (in Russian)

33. Riedel W., 1929. Zur Mechanik Geologischer Brucherscheinungen. Zentralblatt fur Mineralogie, Geologie und Paleontologie B, 354–368.

34. Rudakova A.V., Pravikova N.V., Tevelev A.V., 2007. Structure, Chemistry and Formation Conditions of the Berezovskii Volcanic Complex in the Southern Part of the Magnitogorsk Megazone (Southern Urals). Moscow University Geology Bulletin 1, 47–52 (in Russian)

35. Salikhov D.N., Holodnov V.V., Puchkov V.N., Rakhimov I.R., 2019. The Late Paleozoic Magnitogorsk Zone in the Southern Urals: Magmatism, Fluid Flow Regime, Metallogeny, and Geodynamics. Nauka, Moscow, 392 p. (in Russian)

36. Salikhov D.N., Moseichuk V.М., Puchkov V.N., Holodnov V.V., Andreichev V.L., Bayanova T.B., 2013. Оn the Age of Alkaline Granitoids of Magnitogorsk Gabbro-Granite Series. Lithosphere 5, 165–171 (in Russian)

37. Salikhov D.N., Moseychuk V.M., Kholodnov V.V., Rakhimov I.R., 2014. Carboniferous Intrusive-Volcanic Magmatism of Magnitogorsk-Bogdanovskiy Graben in the Light of New Geological and Geochemical Data. Lithosphere 5, 33–56 (in Russian)

38. State Geological Map of the Russian Federation, 2018. Southern Urals Series. Scale 1:200000. Sheet N-40-XXXVI (Kvarkeno). Explanatory Note. Moscow Branch of VSEGEI, 226 p. (in Russian)

39. Stevenson C.Т.Е., Owens W.Н., Hutton D.H.W., 2007. Flow Lobes in Granite: The Determination of Magma Flow Direction in the Trawenagh Bay Granite, Northwestern Ireland, Using Anisotropy of Magnetic Susceptibility. GSA Bulletin 119 (11), 1368. https://doi.org/10.1130/B25970.1.

40. Tarling D.H., Hrouda F., 1993. The Magnetic Anisotropy of Rocks. Chapman & Hall, London, 217 p.

41. Tauxe L., Gee J.S., Staudigel H., 1998. Flow Directions in Dikes from Anisotropy of Magnetic Susceptibility Data: The Bootstrap Way. Journal of Geophysical Research: Solid Earth 103 (B8), 17775–17790. https://doi.org/10.1029/98JB01077.

42. Tevelev A.V., Kosheleva I.A., Furina M.A., Belyatsky B.V., 2009. Triassic Magmatism of the Southern Urals: Geochemistry, Isotopy, and Geodynamics. Moscow University Geology Bulletin 2, 29–38 (in Russian)

43. Tevelev A.V., Pravikova N.V., Borisenko A.A., Shestakov P.A., Koptev E.V., Sobolev I.D., Volodina E.A., Novikova A.S., Kazansky A.Yu., 2023. First Results of U-Pb-Dating of Zircons from the Early Carboniferous Volcanites of the Magnitogorsk Megazone (Southern Urals) and the Problem of Isotopic Age of Alkaline Granitoids. In: Tectonics and Geodynamics of the Earth’s Crust and the Mantle: Fundamental Problems-2023. Proceedings of the LIV Tectonic Meeting (January 31 – February 4, 2023). Vol. 2. GEOS, Moscow, p. 143−147 (in Russian)

44. Tevelev Al.V., Furina M.A., 2010. Kinematics of the Early Mesozoic Shear Zones in the Southern Urals. In: Tectonics and Geodynamics of the Phanerozoic Foldebelts and Platforms. Proceedings of the XLIII Tectonic Meeting (February 02–05, 2010). Vol. 2. GEOS, Moscow, p. 341–346 (in Russian)

45. Tevelev Al.V., Kosheleva I.A., Furina M.A., Belyatsky B.V., 2008. Triassic Geodynamics of the Southern Urals in the Light of New Isotopic Data. In: General and Regional Problems of Tectonics and Geodynamics. Proceedings of the XLI Tectonic Meeting (January 29 – February 02, 2008). Vol. 2. GEOS, Moscow, p. 317–321 (in Russian)

46. Tevelev Al.V., Tevelev Ark.V., 1996. Conjugate Evolution of Shallow Basins and Magmatic Chambers Under Extension Induced by a Strike Slip. Doklady Earth Sciences 347 (2), 194–196.

47. Villaseca C., Ruiz-Martínez V.C., Pérez-Soba C., 2017. Magnetic Susceptibility of Variscan Granite-Types of the Spanish Central System and the Redox State of Magma. Geologica Acta 15 (4), 379–394. DOI:10.1344/GeologicaActa2017.15.4.8.

48. Žák J., Kratinová Z., Trubač J., Janoušek V., Sláma J., Mrlina J., 2011. Structure, Emplacement, and Tectonic Setting of Late Devonian Granitoid Plutons in the Teplá–Barrandian Unit, Bohemian Massif. International Journal of Earth Sciences 100, 1477–1495. https://doi.org/10.1007/s00531-010-0565-7.