Late Pleistocene Paleo river Channels on the Laptev Sea Shelf -
Implications from Sub-Bottom Profiling
H.P. Kleiber and F. Niessen
Alfred-Wegener-Institut fur Polar- und Meeres[orschung, Postfach 120161, D-2 7515 Bremerhaven, Germany
Received 19 March 1997 and accepted in revised form 28 November 1997
Abstract - Bottom and sub-bottom reflection patterns received by the PARASOUND
system (4 kHz) document 24 filled paleoriver channels in the uppermost sediments (I-13m)
of the Laptev Sea shelf. The surfaces of the paleochannel fillings range from 32 to 97 m
below the present sea level. The rivers are supposed to have been active during Weichselian
time when the sea level was up to 120 m below that of today. They were probably filled
during termination I until the transgression reached the present-day 30 m-isobath. The
observed paleoriver channels are most likely related to the Olenek, Lena and lana rivers and
to local drainage systems on the Taymyr Peninsula and the New Siberian Islands. In the
depth range of 2 to 20 m sub-bottom, a strong post-sedimentary ret1ector is commonly
found, interpreted as the surface of submarine permafrost. The formation of paleoriver
channels and permafrost is associated with subaerial exposure and suggest that most of the
Laptev Sea shelf area was not covered by a large ice sheet during the last glacial maximum.
Introduction
Presently, central Siberian rivers (e.g, Lena) drain large amounts of freshwater loaded with
sediments into the Laptev Sea which is one of three epicontinental seas located along the
northern coast of central Asiatic Russia (Holmes and Creager, 1974) (Figure I). Therefore, the
Laptev Sea is a key location for understanding sediment transport processes and rates into the
Arctic Ocean and their variability under different climatic conditions. Knowledge about
existence and location of paleochannels on the shelf is fundamental because channels indicate
major trajectories of sediment transport in Pre-Holocene time. Then channels control past
sediment input and distribution on the upper continental slope of the Laptev Sea and thus local
sediment budgets of the Arctic Ocean. Also, evidence for river drainage across the shelf would
provide a valuable argument against the presence of a large ice sheet on the Laptev Sea shelf
(Grosswald, 1990) and support the formation of permafrost on the exposed shelf during the
period of late Pleistocene glacial-eustatic regression described by Romanovskii this (volume)
High resolution sub-bottom profiling surveys were carried out during two expeditions (ARKIX/4 and ARK-XIII) by the RV "Polarstern" (Ftitterer, 1994; Rachor, 1997) (Figure I). The
profiles show evidences for the existence of numerous filled paleochannels on the Laptev Sea
shelf. Examples of preliminary results are published in Ftitterer (1994), Ntirnberg et al. (1995)
and Rachor (1997). In this study a complete investigation of occurrence of paleochannels in the
Laptev Sea profiles of the ARK-IX/4 and ARK-XIII expeditions is presented. Different to
earlier investigations (Holmes and Creager, 1974; Treshnikov, 1985), which suggested
paleori ver channels based on bathymetry, we used sub-bottom structures for channel
identification. The advantage is that the erosive incision and the different sedimentary structures
of the channel fillings and the surrounding strata can be observed. Also, limited information
about the depths and widths of the paleochannels can be obtained.
In: Kassens, H., H.A. Bauch, l. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, 1. Thiede and L. Timokhov (cds.)
Land-Occan Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999. 657-665.
Implications from Sub-Bottom Profiling
H.P. Kleiber and F. Niessen
Alfred-Wegener-Institut fur Polar- und Meeres[orschung, Postfach 120161, D-2 7515 Bremerhaven, Germany
Received 19 March 1997 and accepted in revised form 28 November 1997
Abstract - Bottom and sub-bottom reflection patterns received by the PARASOUND
system (4 kHz) document 24 filled paleoriver channels in the uppermost sediments (I-13m)
of the Laptev Sea shelf. The surfaces of the paleochannel fillings range from 32 to 97 m
below the present sea level. The rivers are supposed to have been active during Weichselian
time when the sea level was up to 120 m below that of today. They were probably filled
during termination I until the transgression reached the present-day 30 m-isobath. The
observed paleoriver channels are most likely related to the Olenek, Lena and lana rivers and
to local drainage systems on the Taymyr Peninsula and the New Siberian Islands. In the
depth range of 2 to 20 m sub-bottom, a strong post-sedimentary ret1ector is commonly
found, interpreted as the surface of submarine permafrost. The formation of paleoriver
channels and permafrost is associated with subaerial exposure and suggest that most of the
Laptev Sea shelf area was not covered by a large ice sheet during the last glacial maximum.
Introduction
Presently, central Siberian rivers (e.g, Lena) drain large amounts of freshwater loaded with
sediments into the Laptev Sea which is one of three epicontinental seas located along the
northern coast of central Asiatic Russia (Holmes and Creager, 1974) (Figure I). Therefore, the
Laptev Sea is a key location for understanding sediment transport processes and rates into the
Arctic Ocean and their variability under different climatic conditions. Knowledge about
existence and location of paleochannels on the shelf is fundamental because channels indicate
major trajectories of sediment transport in Pre-Holocene time. Then channels control past
sediment input and distribution on the upper continental slope of the Laptev Sea and thus local
sediment budgets of the Arctic Ocean. Also, evidence for river drainage across the shelf would
provide a valuable argument against the presence of a large ice sheet on the Laptev Sea shelf
(Grosswald, 1990) and support the formation of permafrost on the exposed shelf during the
period of late Pleistocene glacial-eustatic regression described by Romanovskii this (volume)
High resolution sub-bottom profiling surveys were carried out during two expeditions (ARKIX/4 and ARK-XIII) by the RV "Polarstern" (Ftitterer, 1994; Rachor, 1997) (Figure I). The
profiles show evidences for the existence of numerous filled paleochannels on the Laptev Sea
shelf. Examples of preliminary results are published in Ftitterer (1994), Ntirnberg et al. (1995)
and Rachor (1997). In this study a complete investigation of occurrence of paleochannels in the
Laptev Sea profiles of the ARK-IX/4 and ARK-XIII expeditions is presented. Different to
earlier investigations (Holmes and Creager, 1974; Treshnikov, 1985), which suggested
paleori ver channels based on bathymetry, we used sub-bottom structures for channel
identification. The advantage is that the erosive incision and the different sedimentary structures
of the channel fillings and the surrounding strata can be observed. Also, limited information
about the depths and widths of the paleochannels can be obtained.
In: Kassens, H., H.A. Bauch, l. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, 1. Thiede and L. Timokhov (cds.)
Land-Occan Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999. 657-665.