664
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
meandering Pleistocene river systems on the Laptev Sea shelf. Our study suggests that deltas
were formed along the low-stand paleoshore line which functioned as point-sources of
sediment input onto the upper continental slope of the Arctic Ocean. On the shelf, the river
channels were probably filled between termination la and the early Holocene, when the
transgression reached the present-day 30m-isobath. The filled channels were then covered by
sediments of which the reflection geometry suggests that they are of Holocene age.
Some paleochannels north of the Taymyr Peninsula and north of the New Siberian Islands
can geographically hardly be related to the large Siberian rivers. This suggests further
investigations in order to test whether local glaciation and subsequent drainage from
deglaciation can explain the observed pattern.
Nearly throughout the entire investigated area, the existence of a post-sedimentary reflector
about 2 to 20m sub-bottom suggests that submarine permafrost is common on the Laptev Sea
shelf. It is not evident from this study whether the permafrost continuous under the
paleochannels or not.
There are three observations which indicate that most of the Laptev Sea shelf area was not
covered by an extended ice sheet during the last glacial maximum: (i), the acoustic penetration
into the Pleistocene sediments indicates no overconsolidation by an ice sheet, (ii), the existence
of paleochannels are indicative for continuation of Eurasian river-drainage during the
Weichselian and (iii), a strong post-sedimentary reflector indicates the existence of relict
submarine permafrost.
Acknowledgements
We are indebted to the crew of RV "Polarstern" and our fellow scientists for their help in
collecting the data. We thank K. Hinz, M. Block and N. Romanovskii for the constructive
discussions. This is contribution no. 1342 of the Alfred Wegener Institute.
References
Allen, J.R.L. (1983) Studies in fluviatile sedimentation: Bars, bar-complexes and sandstone sheets (Lowsinuosity braided streams) in the Brownstones (L. Devonian), Welsh Borders. Sedim. Geol., 33, 237-293.
Blanchon, P. and J. Shaw (1995) Reef drowning during the last deglaciation: Evidence for catastrophic sea-level
rise and ice-sheet collapse. Geology, 23 (1), 4-8.
Chappell, J. and N.J. Shackleton (1986) Oxygen isotopes and sea level. Nature, 324,137-140.
Damuth, J.E. (1978) Echo character of the Norwegian-Greenland Sea: relationship to Quaternary sedimentation.
Mar. Geol., 28, 1-36.
Dunayev, N.N. and J.A. Pavlidis (1990) A model of the late Pleistocene glaciation of Eurasiatic arctic shelf. In:
Arctic research - Advances and prospects (Vol. 2), Proceedings of the conference of Arctic and Nordic
Countries on coordination ofresearch in the Arctic, Kotlyakov, V.M. and V.E. Sokolov (eds.), Academy of
Sciences of the USSR, Leningrad, December 1988,70-72.
Fairbanks, R.G. (1989) A 17,OOO-year glacio-eustatic sea level record: influence of glacial melting rates on the
Younger Dryas event and deep-ocean circulation. Nature, 342, 637-642.
Flint, R.F. (1971) Glacial and Quaternary Geology. John Wiley and Sons, New York, 892pp.
Fiichtbauer, H. (1988) Sedimente und Sedimentgesteine, Teil II: Sediment-Petrologie. Schweizerbart'sche
Verlagsbuchhandlung, Stuttgart, 1141pp.
Fiitterer, D.K. (ed.; 1994) The expedition ARCTIC93. Leg ARK-IX/4 of RV "Polarstern" 1993. Ber.
Polarforsch., 149, 244pp.
Grosswald, M.G. (1990) Late Pleistocene ice sheet in the Soviet Arctic. In: Arctic research - Advances and
prospects (Vol. 2), Proceedings of the conference of Arctic and Nordic Countries on coordination of research
in the Arctic, Kotlyakov, V.M. and V.E. Sokolov (eds.), Academy of Sciences of the USSR. Leningrad.
December 1988, 18-23.
Holmes, M.L. and J.S. Creager (1974) Holocene history of the Laptev Sea continental shelf. In: Marine
Geology and Oceanography of the Arctic Seas, Herman, Y. (ed.), Springer-Verlag, New York, 211-230.
Miall, D.A. (1977) A review of the braided-river depositional environment. Earth-Sci. Rev., 13, 1-62.
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
meandering Pleistocene river systems on the Laptev Sea shelf. Our study suggests that deltas
were formed along the low-stand paleoshore line which functioned as point-sources of
sediment input onto the upper continental slope of the Arctic Ocean. On the shelf, the river
channels were probably filled between termination la and the early Holocene, when the
transgression reached the present-day 30m-isobath. The filled channels were then covered by
sediments of which the reflection geometry suggests that they are of Holocene age.
Some paleochannels north of the Taymyr Peninsula and north of the New Siberian Islands
can geographically hardly be related to the large Siberian rivers. This suggests further
investigations in order to test whether local glaciation and subsequent drainage from
deglaciation can explain the observed pattern.
Nearly throughout the entire investigated area, the existence of a post-sedimentary reflector
about 2 to 20m sub-bottom suggests that submarine permafrost is common on the Laptev Sea
shelf. It is not evident from this study whether the permafrost continuous under the
paleochannels or not.
There are three observations which indicate that most of the Laptev Sea shelf area was not
covered by an extended ice sheet during the last glacial maximum: (i), the acoustic penetration
into the Pleistocene sediments indicates no overconsolidation by an ice sheet, (ii), the existence
of paleochannels are indicative for continuation of Eurasian river-drainage during the
Weichselian and (iii), a strong post-sedimentary reflector indicates the existence of relict
submarine permafrost.
Acknowledgements
We are indebted to the crew of RV "Polarstern" and our fellow scientists for their help in
collecting the data. We thank K. Hinz, M. Block and N. Romanovskii for the constructive
discussions. This is contribution no. 1342 of the Alfred Wegener Institute.
References
Allen, J.R.L. (1983) Studies in fluviatile sedimentation: Bars, bar-complexes and sandstone sheets (Lowsinuosity braided streams) in the Brownstones (L. Devonian), Welsh Borders. Sedim. Geol., 33, 237-293.
Blanchon, P. and J. Shaw (1995) Reef drowning during the last deglaciation: Evidence for catastrophic sea-level
rise and ice-sheet collapse. Geology, 23 (1), 4-8.
Chappell, J. and N.J. Shackleton (1986) Oxygen isotopes and sea level. Nature, 324,137-140.
Damuth, J.E. (1978) Echo character of the Norwegian-Greenland Sea: relationship to Quaternary sedimentation.
Mar. Geol., 28, 1-36.
Dunayev, N.N. and J.A. Pavlidis (1990) A model of the late Pleistocene glaciation of Eurasiatic arctic shelf. In:
Arctic research - Advances and prospects (Vol. 2), Proceedings of the conference of Arctic and Nordic
Countries on coordination ofresearch in the Arctic, Kotlyakov, V.M. and V.E. Sokolov (eds.), Academy of
Sciences of the USSR, Leningrad, December 1988,70-72.
Fairbanks, R.G. (1989) A 17,OOO-year glacio-eustatic sea level record: influence of glacial melting rates on the
Younger Dryas event and deep-ocean circulation. Nature, 342, 637-642.
Flint, R.F. (1971) Glacial and Quaternary Geology. John Wiley and Sons, New York, 892pp.
Fiichtbauer, H. (1988) Sedimente und Sedimentgesteine, Teil II: Sediment-Petrologie. Schweizerbart'sche
Verlagsbuchhandlung, Stuttgart, 1141pp.
Fiitterer, D.K. (ed.; 1994) The expedition ARCTIC93. Leg ARK-IX/4 of RV "Polarstern" 1993. Ber.
Polarforsch., 149, 244pp.
Grosswald, M.G. (1990) Late Pleistocene ice sheet in the Soviet Arctic. In: Arctic research - Advances and
prospects (Vol. 2), Proceedings of the conference of Arctic and Nordic Countries on coordination of research
in the Arctic, Kotlyakov, V.M. and V.E. Sokolov (eds.), Academy of Sciences of the USSR. Leningrad.
December 1988, 18-23.
Holmes, M.L. and J.S. Creager (1974) Holocene history of the Laptev Sea continental shelf. In: Marine
Geology and Oceanography of the Arctic Seas, Herman, Y. (ed.), Springer-Verlag, New York, 211-230.
Miall, D.A. (1977) A review of the braided-river depositional environment. Earth-Sci. Rev., 13, 1-62.