DEFORMATION REGIMES AND LOW-RANK PALEOTECTONIC STRESSES OF THE WESTERN TIAN SHAN IN THE MESOZOIC – CENOZOIC

There is a description of the results of studies of deformation regimes and reconstruction of stress fields of certain time intervals of the Mesozoic – Cenozoic history of the western part of the Tien Shan based on the geological and structural data and earthquake focal mechanisms. The relevance of research is determined by the existing difficulties in the age reference of paleostress fields, which is associated with the retrospective nature of the initial data and the features of geological evolution, as well as the existence of controversial, unresolved issues regarding the development of the western periclinal part of the Tien Shan in the Mesozoic – Cenozoic. The aim of the research is to reconstruct the rank components of paleostresses in the earth’s crust in the western part of the Tien Shan at separate stages of the Mesozoic – Cenozoic development. The time intervals for which the stress field diagrams were obtained represent cyclically manifested phases of the first-rank rhythms, which are characterized by alternation of different deformation modes. The method for reconstructing paleostresses was based on the concept of the formation of superimposed systems of cracks of various generations, which were sequentially manifested at various stages of the development of deformation processes. Analysis of the data showed that with increasing age of rocks the number of different fracture systems actually increases – the earlier systems are superimposed by the later. At the same time, the characteristic elements in Quaternary rocks manifest themselves in different ways in the older rocks. This allows them to be used for the reconstruction of the Late Cenozoic stress field based on mass measurements of fracturing in rocks of earlier Mesozoic – Cenozoic ages. Based on the step-by-step identification of the heterochronous cracks system and determination of a pair of maxima of the fracture density with asymmetric scattering, region-based diagrams of the first-rank stress fields were obtained for different stages of manifestation of Mesozoic – Cenozoic deformation regimes: 1 – from the Permian-Triassic to the Middle Jurassic; 2 – Middle-Late Jurassic; 3 – Late Jurassic – Early Cretaceous; 4 – Late Cretaceous – Paleocene – Eocene; 5 – Oligocene – Quaternary. The results obtained indicate the alternation of compression and extension phases, first-rank for the region, and give an idea of the main trends in its geodynamic evolution. They can be used in the development of a tectodynamic model of the region.

1. Akhmedzhanov M.A., Borisov O.V., 1977. Tectonics of the Premesozoic Formations of the Central and Southern Tien Shan. Fan, Tashkent, 183 p. (in Russian)

2. Babaev A.G., Simonenko A.N., Babaev G.A., 1990. Formations of the Jurassic Paleo-Sedimentary Basins of Uzbekistan and Their Oil-and-Gas Content. Fan, Tashkent, 292 p. (in Russian)

3. Belousov T.P., Kurtasov S.F., Mukhamediev Sh.A., 1997. The Earth’s Crust Divisibility and Paleostresses in Seismoactive and Oil-and-Gas-Bearing Regions. IPE RAS, Moscow, 324 p. (in Russian)

4. Borisov O.M., 1982. Fault Tectonics of Middle Asia. In: Metallogenic Problems of Middle Asia. Fan, Tashkent, p. 37–53 (in Russian)

5. Bubniak I.M., Vikhot Yu.M., Nakapelyukh M.V., 2013. The Stress-and-Strain State of the Southeastern Part of the Skyba and Boryslavpokuttya Nappes of the Ukrainian Carpathians. Geodynamics & Tectonophysics 4 (3), 313–326 (in Russian) https://doi.org/10.5800/GT-2013-4-3-0103.

6. Chernyshev S.N., 1983. Rock Fractures. Nauka, Moscow, 240 p. (in Russian)

7. Dalimov T.N., Troitsky V.I., 2005. Evolutionary Geology (History of Geological Evolution of the Earth). University, Yangiyo’l Poligraf Servis, Tashkent, 583 p. (in Russian)

8. Dzhamalov D.B., Abdullaev R.N., Tulyaganova N.Sh., 2016. Paleo-Transform Faults and Their Role in Formation of the Earth’s Crust of the Tien Shan. Geology and Mineral Resources 5, 3–10 (in Russian).

9. Gintov O.B., 2005. Field Tectonophysics and Its Application in Studies of Deformation of the Earth’s Crust. Phoenix, Kiev, 572 p. (in Russian)

10. Gintov O.B., Murovskaya A.V., Mychak S.V., 2013. Field Tectonophysics in Solutions of Geodynamic Evolution Problems of the Ukraine Territory. Geodynamics & Tectonophysics 4 (3), 281–299 (in Russian) https://doi.org/10.5800/GT-2013-4-3-0101.

11. Goncharov M.A., Talitsky V.G., Frolova N.S., 2005. Introduction to Tectonophysics. Textbook. University Book House, Moscow, 496 p. (in Russian) .

12. Gzovsky M.V., 1975. Fundamentals of Tectonophysics. Nauka, Moscow, 536 p. (in Russian)

13. Kalmet’eva Z.A., Moldobekov B.D., Abdybachaev U.A., 2019. Correlation of the State of Crustal Stresses, Seismicity and Landslide Activity (Fergana Basin, Tien Shan). Geodynamics & Tectonophysics 10 (4), 995–1009 (in Russian) https://doi.org/10.5800/GT-2019-10-4-0454.

14. Leonov M.G., Morozov Yu.A., Stephanov Yu.P., Bakeev R.A., 2018. Zones of Concentrated Deformation (Flower Structures): Field Observations and Modeling Data. Geodynamics & Tectonophysics 9 (3), 693–720 (in Russian) https://doi.org/10.5800/GT-2018-9-3-0368.

15. Lordkipanidze L.N., Tsai O.G., 2017. Analysis of the Schemes from the Catalogue of the Faults of the Central and Southern Tien Shan and Adjacent Areas. Geology and Mineral Resources 1, 3–10 (in Russian)

16. Myagkov D.S., Rebetsky Yu.L., 2019. Mathematical Models Simulating the Formation of the Stress‐Strain State of Epiplatform Orogens. Geodynamics & Tectonophysics 10 (1), 21–41 (in Russian) https://doi.org/10.5800/GT-2019-10-1-0402.

17. Nikolaev P.N., 1977. Methods of Statistical Analysis of Fractures and Reconstruction of Tectonic Stresses. Proceedings of Higher Educational Establishments. Geology and Exploration 12, 103–115 (in Russian)

18. Nikolaev P.N., 1992. Method of Tectonic-Dynamic Analysis. Nedra, Moscow, 295 p. (in Russian)

19. Omonov Kh.A., Khan R.S., Sultanov I.S., 2016. Improvement of Current Methods to Conduct Regional Studies in the Folded System of the Southern Tien Shan. Geology and Mineral Resources 4, 19–24 (in Russian)

20. Parfeevets A.V., Sankov V.A., 2018. Geodynamic Conditions for Cenozoic Activation of Tectonic Structures in Southeastern Mongolia. Geodynamics & Tectonophysics 9 (3), 855–888 (in Russian) https://doi.org/10.5800/GT-2018-9-3-0374.

21. Rebetsky Yu.L., 2015. On the Specific State of Crustal Stresses in Intracontinental Orogens. Geodynamics & Tectonophysics 6 (4), 437–466 (in Russian) http://dx.doi.org/10.5800/GT-2015-6-4-0189.

22. Rebetsky Yu.L., 2016. On Small Tangential Mass Forces That May Exist in the Lithosphere. Their Role in Tectonics and Geodynamics. Geodynamics & Tectonophysics 7 (4), 691–704 (in Russian) https://doi.org/10.5800/GT-2016-7-4-0229.

23. Rebetsky Yu.L., Sim L.A., Marinin A.V., 2017. From Slickensides to Tectonic Stress. Techniques and Algorithms. GEOS, Moscow, 234 p. (in Russian)

24. Sankov V.A., Parfeevets A.V., Miroshnichenko A.I., Byzov L.M., Lebedeva M.A., Sankov A.V., Dobrynina А.А., Kovalenko S.N., 2017. Late Cenozoic Faulting and the Stress State in the South-Eastern Segment of the Siberian Platform. Geodynamics & Tectonophysics 8 (1), 81–105 (in Russian) https://doi.org/10.5800/GT-2017-8-1-0233.

25. Seminsky K.Zh., 2005. Mapping of the Faultblock Structure of the Crust at the Current Level of Development of Tectonophysics. Geophysical Journal 27 (1), 85–96 (in Russian)

26. Seminsky К.Zh., 2014. Specialized Mapping of Crustal Fault Zones. Part 1: Basic Theoretical Concepts and Principles. Geodynamics & Tectonophysics 5 (2), 445–467 (in Russian) https://doi.org/10.5800/GT-2014-5-2-0136.

27. Sherman S.I., 2012. Destruction of the Lithosphere: Faultblock Divisibility and Its Tectonophysical Regularities. Geodynamics & Tectonophysics 3 (4), 315–344 (in Russian) https://doi.org/10.5800/GT-2012-3-4-0077.

28. Sherman S.I., Dneprovsky Yu.I., 1989. Stress Fields of the Earth’s Crust and Geological and Structural Methods for Their Study. Nauka, Novosibirsk, 158 p. (in Russian)

29. Sim L.A., 2013. Overview of the State of Knowledge on Paleotectonic Stresses and Their Implications for Solution of Geological Problems. Geodynamics & Tectonophysics 4 (3), 341–361 (in Russian) https://doi.org/10.5800/GT-2013-4-3-0105.

30. Sitdikov B.B., 1985. Neotectonics of the Western Tien Shan (by the Example of the Central Kyzyl Kum and Fergana Basin). Fan, Tashkent, 144 p. (in Russian)

31. Umurzakov R.A., 2012. On Reconstruction of Paleotectonic Stresses at Certain Stages of the Alpine History of the Western Tien Shan. In: Current Problems of Geodynamics and Geoecology of the Intracontinental Orogens. Proceedings of the 5th International Symposium (June 19–24, 2011). Vol. 1. Research Station RAS, Bishkek, p. 127–133 (in Russian)

32. Yuryev A.A., Umarov A.U., 1971. Geomorphology and Neotectonics of Western Uzbekistan. Fan, Tashkent, 115 p. (in Russian)