FEATURES OF THE DEEP STRUCTURE OF THE UPPER CRUST AND MINERAGY IN THE SIKHOTE-ALIN FRAGMENT OF THE REFERENCE GEOLOGICAL-GEOPHYSICAL PROFILE 8-DV
V. M. Solovyev, A. S. Salnikov, V. S. Seleznev, T. V. Kashubina, N. A. Galyova, A.E. Shenmaier
1Altai‐Sayan Branch of Geophysical Survey of the Russian Academy of Sciences,Novosibirsk, Russia
2Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
3Seismological Branch of Geophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russia
4A.P. Karpinsky Russian Geological Research Institute, St. Petersburg, Russia
Keywords: deep seismic profile, longitudinal and transverse waves, P- and S-wave velocities and their ratios, deep seismic section, earth's crust, mineragenic zone
Abstract
The article presents the results of deep seismic studies based on P- and C-wave data on the 500-kilometer Sikhote-Alin fragment of the 8-DV reference geophysical profile. Deep seismic sections of the upper crust (to a depth of 15-20 km) with the distribution of longitudinal and shear wave velocities were constructed. The P-wave velocity over most of the Middle Amur Basin and the East Sikhote-Alin volcano-plutonic belt varies from 4-5 km/s in the uppermost part of the section to 5.8-6.3 km/s at depths of 7-15 km. The Sikhote-Alin orogenic belt in the section along the profile is represented by an anticlinal structure with high-velocity (up to 5.5-5.8 km/s) rocks uplifted in the central part; At great depths of 10-20 km within its limits, the P-wave velocity values were 6.1-6.3 km/s. In the upper part of the section, the S-wave velocity value within the profile as a whole is 2.7–2.9 km/s; reduced values (2.6–2.8 km/s) are observed in the central and eastern parts of the Middle Amur Depression and the eastern section of the East Sikhote-Alin volcano-plutonic belt, increased velocity values up to 3.35 km/s are observed in the central part of the Sikhote-Alin orogenic complex. At depths of 5–15 km within the section, the S-wave velocity increases to 3.4–3.65 km/s. The same behavior of the upper part of the earth's crust to a depth of 15–20 km was established by the values of P- and S-wave velocities, their ratio, and Poisson's ratio. The analysis of the relationship between the identified anomalies and the location of large mineragenic zones of the Amur region was carried out in the profile section. The previously established correspondences on the 2-DV, 3-DV, 1-SB and Vostochno-Stan fragment profile 8-DV on the confinement of ore deposit series to zones of low P- and S-Stan velocity ratios and Poisson's ratio in the upper part of the earth's crust were confirmed. The relationship between the identified surface seismic anomalies and deep (at depths of 5–20 km) roots (intermediate magmatic foci), which can be considered ore-supplying, was substantiated..
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