454
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
From this study there is no statement possible about the deposition which occurred in Lake
Taymyr during Early Weichselian because the deeper fill of the basins was not penetrated by the
GeoChirp system. However, because all sediments of Mid-Weichselian age or younger are
non-glacial in origin, we suggest that the last glacial episode on the Taymyr Peninsula probably
occurred during Early Weichselian (marine isotope stage 4, about 60 ka B.P., Figure 10). This
is consistent with findings of fossil glacier ice in permafrost of possibly Early Weichselian age
near Lake Labaz, about 200 km south of Lake Taymyr (Melles et aI., 1996; Siegert et aI., this
volume).
Conclusions
There are 3 major conclusions which can be drawn from this study:
I Thicknesses of at least 60 m of muddy unconsolidated sediments have accumulated in the
central part of Lake Levinson Lessing and probably date as far back as Early Weichselian.
Only the top 24 m have been cored (PG 1228). In both lakes, however, the total thickness of
the unconsolidated fill remain unknown because sound penetration is insufficient. In Lake
Levinson Lessing two units (L3 and L4) older than the cored record of PG 1228 are found.
In Lake Taymyr, one unit (T4) older than the cored record of PGI227 (basal age:
Pleistocene) is identified for which the original thickness and lateral distribution remain
uncertain because major post-depositional erosion truncated large parts of this unit. Evidence
of gas in unit T4 suggests accumulation of organic matter which might have occurred during
a warmer climate of Mid Weichselian times.
2 Both lakes show similar trends in the variation of unit geometry and seismic character which
can be explained by lake level changes. Similar to the approach of sequence stratigraphy in
marine deposits, High System Tracks overlain by Low System Tracks overlain by
Transgressive System Tracks can be defined. There is only one depositional cycle seen in
both lakes Taymyr and Levinson Lessing because the units I to 4 show individual
characteristics and none of the units are repeated in the sequence. The total variation of lake
levels was probably more than 60 m in Lake Taymyr and is associated with tectonic control
of the outlet. Lake level variations were less in Levinson Lessing and probably did not
always occur synchronously to those in Lake Taymyr.
3 Glaciation of the Levinson Lessing and Taymyr lake basins during the last glacial maximum
(Late Weichselian, marine isotope stage 2) can be excluded on the basis of this study. This
implies that large parts of the Taymyr Peninsula were probably ice-free during the above
period as suggested by Dunayev et al. (1988). However, an earlier glacial excavation of the
basin of Levinson Lessing is suggested which probably occurred during Early Weichselian
time (Marine Isotope Stage 4) and might have affected large areas of the Taymyr Peninsula,
similarto the reconstruction suggested by Elverh¢i et al. (1993) for Marine Isotope Stage 2.
Acknowledgements
We are grateful to all participants of the expedition Taymyr 1995 for their help in transporting
the equipment and setting up the Levinson Lessing camp. M. Melles, D. Bolshyanov and A.
Oufimzev are thanked for the logistic organisation of the field work. W. Korth is acknowledged
for post-processing the GPS data. Useful comments of the two reviewers (A. Pugin and J.
Merkt) helped to improve the manuscript. Financial support was provided by the German
Ministry of Education, Science, Research and Technology (BMBF; Grant No. 03PLOI4A, B).
This is contribution number 1483 of the Alfred Wegener Institute.
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
From this study there is no statement possible about the deposition which occurred in Lake
Taymyr during Early Weichselian because the deeper fill of the basins was not penetrated by the
GeoChirp system. However, because all sediments of Mid-Weichselian age or younger are
non-glacial in origin, we suggest that the last glacial episode on the Taymyr Peninsula probably
occurred during Early Weichselian (marine isotope stage 4, about 60 ka B.P., Figure 10). This
is consistent with findings of fossil glacier ice in permafrost of possibly Early Weichselian age
near Lake Labaz, about 200 km south of Lake Taymyr (Melles et aI., 1996; Siegert et aI., this
volume).
Conclusions
There are 3 major conclusions which can be drawn from this study:
I Thicknesses of at least 60 m of muddy unconsolidated sediments have accumulated in the
central part of Lake Levinson Lessing and probably date as far back as Early Weichselian.
Only the top 24 m have been cored (PG 1228). In both lakes, however, the total thickness of
the unconsolidated fill remain unknown because sound penetration is insufficient. In Lake
Levinson Lessing two units (L3 and L4) older than the cored record of PG 1228 are found.
In Lake Taymyr, one unit (T4) older than the cored record of PGI227 (basal age:
Pleistocene) is identified for which the original thickness and lateral distribution remain
uncertain because major post-depositional erosion truncated large parts of this unit. Evidence
of gas in unit T4 suggests accumulation of organic matter which might have occurred during
a warmer climate of Mid Weichselian times.
2 Both lakes show similar trends in the variation of unit geometry and seismic character which
can be explained by lake level changes. Similar to the approach of sequence stratigraphy in
marine deposits, High System Tracks overlain by Low System Tracks overlain by
Transgressive System Tracks can be defined. There is only one depositional cycle seen in
both lakes Taymyr and Levinson Lessing because the units I to 4 show individual
characteristics and none of the units are repeated in the sequence. The total variation of lake
levels was probably more than 60 m in Lake Taymyr and is associated with tectonic control
of the outlet. Lake level variations were less in Levinson Lessing and probably did not
always occur synchronously to those in Lake Taymyr.
3 Glaciation of the Levinson Lessing and Taymyr lake basins during the last glacial maximum
(Late Weichselian, marine isotope stage 2) can be excluded on the basis of this study. This
implies that large parts of the Taymyr Peninsula were probably ice-free during the above
period as suggested by Dunayev et al. (1988). However, an earlier glacial excavation of the
basin of Levinson Lessing is suggested which probably occurred during Early Weichselian
time (Marine Isotope Stage 4) and might have affected large areas of the Taymyr Peninsula,
similarto the reconstruction suggested by Elverh¢i et al. (1993) for Marine Isotope Stage 2.
Acknowledgements
We are grateful to all participants of the expedition Taymyr 1995 for their help in transporting
the equipment and setting up the Levinson Lessing camp. M. Melles, D. Bolshyanov and A.
Oufimzev are thanked for the logistic organisation of the field work. W. Korth is acknowledged
for post-processing the GPS data. Useful comments of the two reviewers (A. Pugin and J.
Merkt) helped to improve the manuscript. Financial support was provided by the German
Ministry of Education, Science, Research and Technology (BMBF; Grant No. 03PLOI4A, B).
This is contribution number 1483 of the Alfred Wegener Institute.