Structure of the Earth crust and upper mantle along seismological profile Mezen–Timan–Pechora (MEZTIMPECH)

Abstract

Object of study. The article was devoted to investigation of the depth structure of the Earth’s crust and upper mantle along the Mezen–Timan–Pechora seismic profile (MEZTIMPECH), crossing the southern parts of the Mezen syneclise, the Timan ridge and the Pechora syneclise. Total profile length was 525 km. Materials and methods. In the course of writing the article, the data obtained by performing seismic surveys using the earthquake exchange wave method were used. The processing involved seismic data using the methods of deep seismic sounding, reflected waves, a common depth point, a correlated method of refracted waves, and materials from well geophysical surveys. In interpreting the research results, generalizing models of the deep structure of the territory were employed. Research results. As a result of the interpretation of the records of the method of exchange waves of earthquakes and the subsequent mathematical modeling, a geological and geophysical section was constructed to a depth of about 100 km and a number of seismic boundaries were identified. The pivotal boundaries of the exchange were: Ф0 – the surface of the Riphean folded basement, Ф – the surface of the pre-Riphean crystalline basement, M – the surface of Mohorovich, identified with the roof of the upper mantle. Additionally, horizons K1–K4 – in the crust of the Earth, M1, M2 – in the upper mantle were traced. Four regional geoblocks were distinguished in the seismic section, differing in depth of the basement surface, the Moho sectionand the underlying structural features of the consolidated crust: the Kirov-Kazhim aulacogen, the Vychegda depression, the Timan ridge and the Pre-Ural downfold. Conclusions. The results of deep seismic studies reflected regional features of the structure of the Earth’s crust and were the basis for the construction of tectonic models of large geological objects.