Earth’s Cryosphere, 2019, Vol. XXIII, No. 5, p. 15-23
SUBSEA PERMAFROST IN THE OB AND TAZ BAYS, THE KARA SEA
S.I. Rokos, D.A. Kostin, S.N. Kulikov
Arctic Marine Engineering-Geologycal Expeditions (AMIGE),
19, Karla Marksa str., Murmansk, 183025, Russia; office@amige.ru
During the 1995–2013 geotechnical drilling in the Ob Bay and Taz Bay offshore areas (depth interval: from 10–20 m to 50–70 m below seabed) permafrost was exposed in four boreholes. The identified permafrost strata varied considerably in ice content, salinity and temperature. Thus, low-temperature (–4.1…–4.8 °С as minimum), generally highly saline sediments containing no segregated ice lenses were reported from BH-1 and BH-2 in the northern offshore part of the Ob Bay. Whereas BH-3 which is located nearby exposed frozen soils with relatively high temperature (–0.9…–1.2 °С), having low to medium salinity, and rich in ice inclusions. Permafrost deposits exposed by a single borehole drilled in the port of Yamburg are varied in their composition, ice content and salinity. These are ranked as Holocene coastal cryorelics (i.e. relatively young). Formations exposed by BH-3 are referred to the Sartan island-type relic permafrost (rather ancient). Besides, subsea permafrost strata established in the port of Yamburg are found to have submerged as a results of the port water area deepening/widening works. Most of the Ob and Taz Bays offshore area is interpreted as an extensive open talik.
Kara Sea, Ob Bay, Taz Bay, permafrost, ground, salinity, Quaternary deposits