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1) Institute of Geology KarRS RAS, Petrozavodsk; Russia 2) Geological Survey of Norway; Trondheim, Norway 3) Geological Museum, University of Copenhagen; Denmark 4) Institute of Geology, University of Copenhagen; Denmark 5) Bjerknes Centre for Climate Research, University of
Bergen; Norway 6) Nordic Laboratory for Luminescence Dating, Riso,
Denmark
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Since 1996 stratigraphic research had been carried out in the Arkhangelsk
District in the frame of the International EU program Quaternary
Environment of Eurasian North (QUEEN). More than 100 key sections of
the Upper Pleistocene sediments have been investigated along the sea
shore and river banks. The results of this study were published in the
special issue of Boreas, 35 (2006) comprising 10 articles. Tills of five different glacial events and intervening terrestrial and
marine interstadial sediments have been distinguished above the Eemian
marker strata. The oldest ice advance occurred in the Early Weichselian
(100-90 kyr ago) from a Kara Sea ice sheet that dammed a large lake in
the Pechora Lowland. The lake had the outlet to the west through a
passage in the Timan Ridge and further towards the Barents Sea via an
ice-free corridor between the Scandinavian Ice Sheet and the Kara Sea
Ice Sheet. The next glaciation occurred in the form of an ice cap over
the Timan Ridge (75-70 kyr ago). Shortly after deglaciation, it was
replaced by an ice sheet that advanced from the Barents Sea (70-65 kyr
ago). Configuration of this ice sheet suggests that it coalesced with
the Scandinavian Ice Sheet. In this case a huge ice dammed lake formed
in the White Sea basin, again with an outlet via the passage in the
Timan Ridge, but this time eastwards into the Pechora Lowland. The rapid
decay of this ice sheet was followed by a marine transgression and
interstadial environments (65-55 kyr ago). The next glaciation was
started on the Kara Sea shelf (55-45 kyr ago). The river runoff in the
Arkhangelsk region of that time was directed northward indicating that
the Barents Sea was ice free. That glaciation was replaced by a long
(45-20 kyr ago) ice-free period before the Scandinavian ice advance from
the west 20-17 kyr ago. Ice from Barents Sea at that time span just
barely reached the northernmost margin of north-western Russia. The eastern flank of the Last Scandinavian Ice Sheet (SIS) reached its
maximum position 18-16 kyr ago. At that time SIS margin was running from
the Cape Kanin Nos across the bottom of White Sea southward to the mouth
of the Kuloi River. It bypassed the eastern part of the Kuloi Plateau,
blocked the lower and middle reaches of the Pinega River and then turned
westward into the Severnaya Dvina lowland. A few proglacial ice dammed
lakes were formed along the eastern ice margin. They discharged eastward
into the Mezen basin.
In the 200-600 km wide zone between the former maximum margin of SIS and
the Neva terminal belt deglaciation was accompanied by formation of
large fields of stagnant ice that originated by progressive detachment
of ice lobes. The resultant hummocky moraines with randomly scattered
periglacial and ice-dammed lakes are widespread over the enormous area.
Stagnant ice was melting until the beginning of the Holocene. |
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Reference:
Demidov I.N., Larsen E., Kjaer K.H., Funder S.,
Houmark-Nielsen M., Grosfjeld K., Jensen M., Linge H., Lysa A., Murray A. |
