SEISMIC INHOMOGENEITIES IN THE UPPER CRUST OF THE ALDAN-STANOVOY SHIELD AND IN ITS TOTAL CRUST (PROFILE 3-DV)

In accordance with the detailed first-arrival data, the near-surface part of the Earth’s crust consists of three layers. The upper discontinuous layer is represented by the Mesocenozoic deposits in local basins. The two inhomogenous layers decrease in thickness towards the north from 1.5 km to total thinning in the Stanovoy block and from 4 km in the Chulman basin to 1 km in the Aldan. It is implied that the nature of thinning lies in weathering and disintegration of crystalline rocks. Their underlying boundary at a depth of 1–4 km with a longitudinal wave velocity of 6.0–6.2 km/s can be assigned to the unchanged Early Precambrian basement surface.

The deep seismic sounding data show that the two-layer crust thickness of the Stanovoy block reaches 40 km, and the three-layer crust in the Aldan block is as thick as 50 km. These blocks are separated by the vertical zone beneath the Stanovoy ridge with contrast inhomogeneities in the crust and step-like increase in the Moho depth beneath the Chulman basin.

There was discovered an isostatic imbalance of the lithosphere, correlated with seismicity of the Chulman basin.

1. Didenko A.N., Efimov A.S., Nelyubov P.A., Sal’nikov A.S., Starosel’tsev V.S., Shevchenko B.F., Goroshko M.V., Gur’yanov V.A., Zamozhnyaya N.G., 2013. Structure and Evolution of the Earth’s Crust in the Region of Junction of the Central Asian Fold Belt and the Siberian Platform: Skovorodino–Tommot Profile. Russian Geology and Geophysics 54 (10), 1236–1249. https://doi.org/10.1016/j.rgg.2013.09.008.

2. Goshko E.Yu., Efimov A.S., Sal’nikov A.S., 2014. The Recent Structure and the Assumed History of Formation of the Crust in the South-Eastern Segment of the North Asian Craton along Reference Profile 3-DV. Geodynamics & Tectonophysics 5 (3), 785–798 (in Russian) https://doi.org/10.5800/GT-2014-5-3-0155.

3. Imaev V.S., Imaeva L.P., Kozmin B.M., 2005. Seismotectonics of Olekmo-Stanovaya Seismic Zone (South Yakutia). Lithosphere 2, 21–40 (in Russian)

4. Kheraskova T.N., Yakovlev D.V., Pimanova N.N., Berezner O.S., 2018. Conjugation with the Central Asian Foldbelt: Interpretation of the 3DV and Tynda–Amurzet Transects. Geotectonics 52, 1–21. https://doi.org/10.1134/S0016852118010089.

5. Popova M.V., Sobolev P.N., 2014. Atlas of Rocks of the Northeast Russia within 3-DV Reference Geophysical Profile (the Town of Skovorodino – the Settlement of Khandyga). Book 1. SNIGGiMS, Novosibirsk, 197 p. (in Russian)

6. Roudnitskaya D.E., Staroseltsev V.S., Salnikov A.S., 2013. The Construction of the Earth’s Crust Macromodel Applying the Reapak-Technology along the 3-DV Geotraverse (East Siberia). Geophysics 1, 19–26 (in Russian)

7. Smelov A.P., Timofeev V.F., 2003. Terrane Analysis and the Geodynamic Model of the Formation of the North Asian Craton in the Early Precambrian. Pacific Geology 22 (6), 42–54 (in Russian)

8. Smelov A.P., Zedgenizov A.N., Timofeev V.F., 2001. The Aldan-Statovoy Shield. In: L.M. Parfenov, M.I. Kuzmin (Eds), Tectonics, Geodynamics and Metallogeny of the Sakha Republic (Yakutia). MAIK Nauka/Interperiodika, Moscow, p. 81–104 (in Russian)

9. Suvorov V.D., Melnik E.A., 2021. Transition Zone from the Siberian Craton to the Verkhoyansk-Kolyma Folded System According to Seismic Data (Reference 3-DV Profile). Izvestiya, Physics of the Solid Earth 57 (6), 864–877. https://doi.org/10.1134/S1069351321060100.

10. Suvorov V.D., Melnik E.A., Mishenkina Z.R., Salnikov A.S., 2016. Velocity Model of the Chulman Depression (Aldan Shield) According to the First Arrivals Data. Technologies of Seismic Prospecting 2, 109–117 (in Russian) https://doi.org/10.18303/1813-4254-2016-2-109-117.

11. Suvorov V.D., Melnik E.A., Pavlov E.V., 2022a. Structural-Tectonic Zoning of the Earth’s Crust in the Eastern and Southern Margins of the Siberian Craton from the Seismic Density Data (3-DV Profile). Dobretsov’s Readings: Science First Hand: Proceedings of the First All-Russian Scientific Conference in Memory of Nikolay Leontyevich Dobretsov, Academician of RAS, an Outstanding Scientist and an Organizer of Science (August 1–5, 2022). Publishing House of SB RAS, Novosibirsk, p. 315–318 (in Russian)

12. Suvorov V.D., Melnik E.A., Pavlov E.V., 2022b. Upper-Crustal Structure of the Aldan-Stanovoy Shield and Its Total Crust Structure from the Seismic Data (Southern Part of 3-DV Profile). Proceedings of the XVIII International Scientific Conference (May 18–20, 2022). Vol. 2. Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, p. 121–128 (in Russian)

13. Suvorov V.D., Pavlov E.V., Melnik E.A., 2021. Seismic Density Inhomogeneities and Isostasy of the Crust of the Eastern Margin of the Siberian Craton (3-DV Reference Profile). In: Faulting in the Lith sphere and Associated Processes. Tectonophysical Analysis. Abstracts of the All-Russian Meeting Dedicated to the Memory of Professor S.I. Sherman (April 26–30, 2021). ISU Publishing House, Irkutsk, p. 51–52 (in Russian) DOI:10.26516/978-5-9624-1919-0.2021.1-233.

14. Tingdong Li, Daukeev S.Z., Kim B.C., Tomurtogoo O., Petrov O.V. (Eds), 2008. Atlas of Geological Maps of Central Asia and Adjacent Areas. Scale 1:2500000. Geological Publishing House, Beijing.

15. Zelt C.A., Smith R.B., 1992. Seismic Traveltime Inversion for 2-D Crustal Velocity Structure. Geophysical Journal International 108 (1), 16–34. https://doi.org/10.1111/j.1365-246X.1992.tb00836.x.