LATITUDINAL ZONATION OF PERMAFROST IN THE YAMALO-NENETS AUTONOMOUS OKRUG ACCORDING TO TRANSIENT ELECTROMAGNETIC SOUNDING DATA
E.V. Ageenkov1, V.V. Potapov1, E.Yu. Antonov1, A.N. Shein2, V.V. Olenchenko1
1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Arctic Research Center, Salekhard, Russia
Keywords: permafrost, saline rocks, relict frozen strata, transient electromagnetic soundings, Yamalo-Nenets Autonomous Okrug
Abstract
To determine the current state of the permafrost in the Yamalo-Nenets Autonomous Okrug and assess its transformation in connection with modern climate changes, transient electromagnetic (TEM) sounding was performed at ten sites along the submeridional profile from the Siberian Uvaly Hills in the south to the Pur-Taz Lowland in the north with a step of about 50 km. An interpretation of geoelectric models was carried out and the results of drilling surveys of permafrost were compared with those provided by the Arctic Research Center from its archive. As a result of the interpretation of geoelectric sections, modern and relict permafrost strata and closed taliks were identified. It was found that the modern base of permafrost lies at depths from 50 to 130 m. A comparison of the results of modern TEM surveys with archival reference geocryological sections did not show significant differences in the position of geocryological boundaries. However, it is necessary to note the significant distance between the TEM sites, as well as, often, considerable distances between them and reference boreholes. The greatest differences between the modern and archival data are noted in the northern part of the profile, which is probably due to the increased salinity of the rocks at the TEM survey sites.
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