On the formation of Malo-Botyobinsky region faults, Yakutian diamond-bearing province (physical modeling results)

The purpose of study is to clarify the specifics of the formation of kimberlite-controlling faults in Malo-Botuobinsky region, Yakutian diamond-bearing province, using physical modeling of rupture genesis for the sedimentary cover with alternating movements of the foundation blocks. Physical modeling for equivalent materials has been carried out at the Tectonic Physics Laboratory of the Earth's Crust Institute. As the model material, an aqueous suspension of montmorillonite clay with viscosity of 10⁶-10⁷ Pa·s has been used. For the purpose of the experiment, a special setup “Basement 3” has been made. The setup consists of a series of linearly elongated blocks imitating the fault-block structure of the Vilyui-Markhinsk fault zone of the Siberian platform within the study area. In the series of 12 experiments, the effect of the experimental setup dies’ velocity and displacement vector on the specific structural paragenesis of the secondary faults formed in the model platform cover has been studied. The comparison of the fault networks obtained in experiments with different boundary conditions, and the fault-block structure scheme of the Mirny kimberlite field and the kimberlitic bodies plans has clarified the specifics of the kimberlitic-controlling faults formation in the study area. The conclusion is that the fault network within the area of dynamic influence of the Vilyui-Markha faults has been formed at a relatively low rate of the platform basement blocks displacement. This is confirmed by the fact that the fault network with the parameters comparable with the natural model is observed at a low speed of the experimental setup dies displacement. The extension structures that are most favorable for ore deposition are observed in the models with a slow rate of the experimental setup dies displacement. Besides, they are formed in the fault zones with alternating block displacements only at the second stage of model deformation (after changing the direction of the basement blocks movement) in strike-slip or transtension conditions. In the second-stage transtension conditions, openings of this type are not observed; and under transpression, the tension is observed not only for the e -type openings, but also for the cleavage planes of the second stage model deformation. The highest amplitude tension structures of all types tend to belong to the central parts of the model fault zones.

physical modeling, fault formation, alternating basement movements, Yakutian diamond-bearing province, strike-slip faults, basement, Siberian platform

1. Gladkov A.S., Zinchuk N.N., Bornyakov S.A., Sherman S.I., Manakov A.V., Matrosov V.A., Garat M.N., Dzyuba I.A. New data on the internal structure and the mechanism of formation of kimberlite-bearing fault zones in the Malo-Botuobinskii region (the Yakut diamond-bearing province). Doklady Akademii nauk [Doklady Earth Sciences], 2005, vol. 402, no. 3, рр. 366–369. (In Russ.).

2. Khar'kiv A.D., Boris E.I., Ivanov I.N., Shchukin V.N. On the character of MaloBotuobinsky pipes. Sovetskaya geologiya, 1972, no. 8, рр. 51–65. (In Russ.).

3. Boris E.I., Frantsesson E.V. On distribution of kimberlite bodies in Malo-Botuobinsky region, Western Yakutia. Izvestiya vysshikh uchebnykh zavedenii. Geologiya i razvedka [Proceedings of Higher Schools. Geology and Exploration], 1992, no. 5, рр. 68–75. (In Russ.).

4. Vaganov V.I., Varlamov V.A., Fel'dman A.A., Golubev Yu.K., Prusakova N.A., Olofinskii L.N., Boiko A.N. Prospecting systems for diamond fields. Otechestvennaya geologiya, 1995, no. 3, рр. 42–53. (In Russ.).

5. Riedel W. Zur Mechanik geologischer Brucherscheinungen. Centralblatt fur Mineralogie, Geologie und Palaontologie. Abt. B: Geologie und Palaontologie. Stuttgart: Schweizerbart, 1929, рр. 354–368.

6. Gzovskii M.V. Modeling of tectonic stressand-fault fields. Izvestiya Akademii nauk SSSR. Seriya geofizicheskaya [Bulletin of the Academy of Sciences of the USSR. Geophysics Series], 1954, no. 6, рр. 527–545. (In Russ.).

7. Sherman S.I., Bornyakov S.A., Buddo V.Yu. Oblasti dinamicheskogo vliyaniya razlomov [Areas of fault dynamic influence]. Novosibirsk: Nauka Publ., 1983, 112 р. (In Russ).

8. Schreurs G. Experiments on strike-slip faulting and block rotation. Geology, 1994, vol. 22, рр. 567–570.

9. Dooley T.P., Schreurs G. Analogue modelling of intraplate strike-slip tectonics: a review and new experimental results. Tectonophysics, 2012, vol. 574-575, рр. 1–71.

10. Schellart W.P., Strak V. A review of analogue modelling of geodynamic processes: approaches, scaling, materials and quantification, with an application to subduction experiments. Journal of Geodynamics, 2016, vol. 100, рр. 7–32.

11. Shemenda A.I. Similarity criteria in mechanical modeling of tectonic processes. Geologiya i geofizika [Russian Geology and Geophysics], 1983, vol. 24, no. 10, рр. 10–19. (In Russ).

12. Sherman S.I. Physical experiment in tectonics and similarity theory. Geologiya i geofizika [Russian Geology and Geophysics], 1984, vol. 25, no. 3, рр. 8–18. (In Russ).

13. Seminskii K.Zh. Strukturno-mekhanicheskie svoistva glinistykh past kak model'nogo materiala v tektonicheskikh eksperimentakh [Structural and mechanical properties of clayey pastes as model material in tectonic experiments]. Irkutsk: AllRussian Institute of Scientific and Technical Information of the Russian Academy of Sciences Publ., 1986, 131 р. (In Russ).

14. Seminskii K.Zh., Seminskii Zh.V. Spetskartirovanie razlomnykh zon zemnoi kory i ego vozmozhnosti v issledovanii strukturnogo kontrolya kimberlitov v Alakit-Markhinskom pole Yakutskoi almazonosnoi provintsii [Special mapping of fault zones of the Earth's crust and its potential for the study of kimberlite structure control in the AlakitMarkha field, Yakutian diamond-bearing province]. Irkutsk: Irkutsk National Research Technical University Publ., 2016, 204 р. (In Russ).

15. Cheremnykh A.V., Gladkov A.S., Cheremnykh A.S. Eksperimental'noe issledovanie razryvoobrazovaniya v chekhle platformy pri aktivizatsii razlomov fundamenta (Nakynskoe kimberlitovoe pole Yakutskoi almazonosnoi provintsii) [Experimental study of the platform cover faulting in the conditions of active basement fault formation (Nakynsky kimberlite field, Yakutian diamond province)]. Materialy dokl. Vseros. konf. s mezhdunar. uch. “Tektonofizika i aktual'nye voprosy nauk o Zemle” [Proceedings of the All-Russian conference “Tectonophysics and topical issues of Earth Sciences”]. Vol. 2. Moscow, 2016, рр. 188–195. (In Russ).

16. Cheremnykh A.V. Strukturoobrazuyushchaya rol' znakoperemennykh dvizhenii v zonakh sdviga [Structure-forming role of alternating movements in the shear zones]. Materialy Vseros. nauch.-tekhn. konf. s mezhdunar. uch. “Geonauki2018: aktual'nye problemy izucheniya nedr” “Geologiya, poiski i razvedka poleznykh iskopaemykh i metody geologicheskikh issledovanii” [Proceedings of the All-Russian Research-and-technical Conference with Int. participation "Geosciences-2018: topical issues of subsoil study” “Geology, survey and exploration of mineral resources and methods of geological research”]. Ed. 18. Irkutsk, 2018, рр. 242–249. (In Russ).

17. Hancock P.L. Brittle microtectonics: Principles and practice. Journal of Structural Geology, 1985, vol. 7, no. 3/4, рр. 437–457.

18. Sylvester A.G. Strike-slip faults. Geological Society of America Bulletin, 1988, vol. 100, рр. 1666–1703.

19. Lobatskaya R.M. Strukturnaya zonal'nost' razlomov [Structural zonality of faults]. Moscow: Nedra Publ., 1987, 128 р. (In Russ).