Earth’s Cryosphere, 2011, Vol. XV, No. 4, p. 60-62

OFFSHORE PERMAFROST IN THE KARA SEA

P.V. Rekant, A.A. Vasiliev*

All Russian Institute of Ocean Geology, 1, Angliysky pr., St. Petersburg, 190121, Russia; rekant@mail.ru
* Institute of Earth’s Cryosphere, Siberian Branch of the Russian Academy of Sciences, 86, Malygina str., Tyumen, 625026, Russia

Problems of identifying submarine permafrost in the Kara Sea shelf from seismic-acoustic data are considered. Seismic-acoustic markers indicate the presence of permafrost in the southeastern Kara Sea and in the Yamal shelf to depths of 120 m. Additionally, acoustic permafrost (APF) markers are inferred near the Severnaya Zemlya within local seafloor highs surrounded with 100–120 m isobaths. The existence of permafrost at greater sea depths is most likely an exception and may be due to neotectonic subsidence. The permafrost extent in the Kara Sea has been mapped with GIS tools and the respective database on its setting has been developed. The submarine permafrost table lies at 5–60 m below the sea floor. According to statistical processing of the collected seismic-acoustic data, the subbottom depth to permafrost is most often (47 %) in the range 10–20 m. Gas seeps showing up as noise in seismic-acoustic wavefields are hypothesized to have a genetic relationship with submarine permafrost.