J. G. Samoilovich XX Polar Symposium Gennadyi G. Mathishov Lublin, 1993 Gennadyi A. Tarasov Institute of Marine Biology, Russian Academy of Sciences

LATE WEI CH SE LI AN DEGLACIATION AND GLACI-MARGINAL FORMATIONS IN THE MURMAN OFFSHORE, THE

During the maximum of Late Weichselian Glaciation both Fennoscandia and a great part of the Barents Sea have been covered with the ice. Particularly there are no glacially accumulated formations (drifts) older than 14 ka along the North-Scandinavian and Murman Cast. Their presence supposed to be north- ward. For the first time the Barents Sea submarine ridge forms were called terminal moraine by V. Tanner in 1930. There was stretched for about 100 km eastward the chain of glaci-marginal formations from Vard Island passing Ribachi (Fisherman) Peninsula to the Kildin Island. In the seventies G. Matishov and M. Marthinussen confirmed it by means of echosounding and bottom sampling data. Two glaci-marginal complexes have been fixed along the Murman Coast: 1) internal (coastal and near the shore not farther than 10 km) and 2) external (25-55 km offshore). The internal complex of glaci-marginal features is remarkable for geomorp- hology. So, there are the lard ridges in the Pechenga Bay, in Kildin Island along the Murman Coast between Voronya and Teriberka Rivers. A typical pattern of the submarine terminal moraine morphologically expressed as an arc-formed ridge, is situated near Teribersky Cape. Its height is to 60-100 m, width is 2-4 km and length about 30 km. A corss-section shows its asymmetry: the northside wing slopes 3-5°, south slope reaches 30°. The bottom sediments represent sands with pebbles and cobbles on the top of ridge, and tills (dense clay with aleurite-sand and coarse fragments) somewhat farther off. The submarine offshore drifts and those on land are regarded as the whole. It's probably the ice border position of Salpausselka I Glaciation stage (time interval 11.3-10.8 ka). East of the Voronya River moraine sediments replace sandur (outwash) ones. The area of submarine fluvioglacial fans in the submarine coastal slope of the Kola Trough is a facial continuation of sandur fields in the marine plain with submarine linear chains of the eskers in the valley of the Kcharlova River and comes from Varzina River locality. The external complex of glaci-marginal formations takes less contrast showing forms relatively internal. It is situated above the relatively deep waters

439 to 200 m in the Nordcape Depression and in the Kola Trough and stretches to shallow-waters of the White Sea mouth. The system of subparallel terminal moraine ridges has two lines on the westside: one passes through Sere and Magere Island, then across the Nordkin and Varanger Peninsulas, the second line turns up a quite open sea shelf 20-60 km offshore. B. Andersen considered that these lines trace two stops of Scandinavian Ice Sheet retreat: 1) in the period 15-16 ka (northern shelf line), and 2) in the period 13 ka (coastal-fiord line). Farther to the east two lines of terminal moraine ridges draw closer to one another and become a single belt from the Teribersky Cape offshore to the Kcharlov Island, then still farther to the east we can see a divergency of this belt: one of the moraine lines goes along the East Murman Coast to the Svyatoy Nos Cap, and another turns to the Kanin Nos Cape of Kanin Peninsula. In such a way the Late Weichselian Ice Sheet extended to the Timan-Kanin province in the period of maximum glaciation. Subsequent (geological) events were connected with degradation of glaciers and predominance of melted water erosional and accumulative processes. As an example of erosional forms of the Murman shelf glacial relief there can be closed hollows („cattle holes"), and other major incisions. Similar forms are typical for all glacial shelves of North Europe and North America. A genesis of major incisions is a controversial problem now. We like the hypothesis by R. Wingfield who suggests that hollows were made by glacier waterfalls. The waterfalls appeared as a result of burst and draining intraglacier lakes. Such lakes and the phenomenon of the process are named with the specific Icelandic term „jokilhlaup" (glacier outburst flood). However, most sequences of Upper Quaternary sediments, especially with marine material deposited in the buried major incision. Periglacial (distal) deposits, located on the other side of ice front, may be observed in a wide belt from 70 to 200 km off Murman Coast. They represent fluvoglacial, aluvial, deltaic and eolian phases of arctic maritime plain. An unusual position is held by geological bodies, forming loaf-like hills of submarine relief. They are siesmoacoustically homogeneous (without inside phantom reflectors), that is why they are named „transparent formations" consisting of untextural aleurities, loess-like or naturally „cold loess", typical for the arctic deserts. But eolian genesis of „transparent formation" is being discussed. The alternative hypothesis suggests that they deposited as submarine supraglacial flow-tills.

Adresses of the authors: dr J. G. Samoilovich, prof, dr Gennadyi G. Matishov, Dr. Gennadyi A. Tarasov, Murmansk Institute of Marine Biology, Vladimirska 17, 183023 Murmansk,

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