IGCP 415: Working Group 1

The last two years' activity of QUEEN groups working in the Russian Arctic was reported at the 2nd QUEEN workshop in St. Petersburg, Feb. 5-8, 1998. Results related to the GRAND problems were presented by the Russian-German-Swedish project `Taimyr` and Russian-Norwegian project PECHORA. Both projects have been ongoing since 1993.

Significant progress has been made in solving the problem of age of the last ice sheet in the Taimyr Peninsula by H. Hubberten and his colleagues. C. Siegert et al. for eastern Taimyr reported remnants of and Early Weichselian ice sheet in the form of buried glacial ice overlain by terrestrial sediments with old radiocarbon dates. In the mountains of central Taimyr, P. Moeller and D. Bolshiyanov have found no Late Weichselian moraines but only thick glacimarine and deltaic gravels formed during disintegration of an Early Weichselian glaciation. M. Melles et al. reported on drilling of bottom sediments of deep glacial lakes, which showed a thick sequence of pre-Holocene silts with a couple of interstadial warmings, not covered by till. Pollen and other proxy data of project `Taimyr` suggest a dry climate with severe permafrost for the time span around 20 ka.

In general, the recent data on the Taimyr Peninsula are in full accord with the conclusion, based on previous Russian results, that the last ice sheet of Arctic Siberia reached its maximum during isotope stage 4, and since then no ice dam has blocked discharge of Siberian rivers into the Arctic Ocean (Astakhov, 1992, 1998).

In the west, participants of the project PECHORA (V. Astakhov, J. Mangerud, J.I. Svendsen and others) have finished mapping morains of the southwestern margin of the last Kara ice sheet on the European mainland and in the Polar Urals. The dominant ice flow from the Kara Sea has been confirmed. Buried glacier ice, similar to fossil glaciers previously described from Yamal and other places in Siberia, has also been found west of the Urals at the base of the Early Weichselian till.

The most important result is shorelines of a large proglacial Lake Komi dammed by an ice front above the Arctic Circle. This last ice dam occurred before 37 ka, as evidenced by many radiocarbon dates on mammal bones and terrestrial plants from fluvial formations postdating Lake Komi. These dated sediments, containing Palaeolithic artifacts and mammoth fauna, have never been covered by glacial ice or lakes. Thermoluminescence dates from beach sand of Lake Komi have yielded ages 76 to 93 ka. Beach formations of Lake Komi occur at 110 m a.s.l. maximum, whereas traces of Early Weichselian proglacial lakes have been found in West Siberia not higher than 70 m a.s.l. (Astakhov, 1992). However, in West Siberia, a spillway to the south is known, while an overflow from a higher Lake Komi has not been found yet.

The periglacial evidence and dating of sediments from atop the uppermost till indicate an Early Weichselian age for the last ice sheet of the Pechora Basin and Polar Urals. This age is independently supported by two series of finite AMS dates from sediments, overlying the icy Kara till on the western Yamal Peninsula, obtained by a Russian-Latvian-American expedition (V. Gataullin, S. Forman and others). Sedimentological and geomorphological data for the Late Weichselian of the Pechora Basin also testify to a very dry climate with no fluvial sedimentation but with pervading aeolian and frost activity.