Siegert et al.: Paleoclimatic Indicators from Permafrost Seguences
489
Figure 5: Lacustrine Ice Complex at the northern shore bank of Labaz Lake. LAOI5.
sediment formation. This material was likely redeposited in younger sediments.
The study site LA06 is located on a WSW-exposed steep slope of a terrace-like remnant with
an altitude of around 70 m a.s.I.(Figure 2). In all other directions, the ,lake-terrace, gradually
passes into the surrounding flat lake plain with an altitude of 60 m a.s.l. The upper part of the
section was studied and sampled in 1994, while the lower part was sampled in the summer of
1995 following some earth slides.
The lower part of section LA06 (Figure 9) consisted of vaguely laminated loess-like silt.
Small colour changes from dark grey to brownish-grey and varying amounts of organic detritus
caused the lamination. In beds enriched with fine plant material, vivianite segregations occur.
The grain size distribution in the sequence was very uniform and characterized by domination
of silt particles (60-83%) while the clay content amount to 40%. Only in the upper 1.5 m was
some sandy material present « 250 !lm; up to 2-8%). A high ground-ice content (60-80
weight%) and a specific lattice-like cryostructure with overlapping subvertical ice streaks as
shown in Figure 10 characterized the lower 4 m of the silt sequence. Quite similar
cryostructures have been obtained via experimental freezing of sapropelic sediments under
489
Figure 5: Lacustrine Ice Complex at the northern shore bank of Labaz Lake. LAOI5.
sediment formation. This material was likely redeposited in younger sediments.
The study site LA06 is located on a WSW-exposed steep slope of a terrace-like remnant with
an altitude of around 70 m a.s.I.(Figure 2). In all other directions, the ,lake-terrace, gradually
passes into the surrounding flat lake plain with an altitude of 60 m a.s.l. The upper part of the
section was studied and sampled in 1994, while the lower part was sampled in the summer of
1995 following some earth slides.
The lower part of section LA06 (Figure 9) consisted of vaguely laminated loess-like silt.
Small colour changes from dark grey to brownish-grey and varying amounts of organic detritus
caused the lamination. In beds enriched with fine plant material, vivianite segregations occur.
The grain size distribution in the sequence was very uniform and characterized by domination
of silt particles (60-83%) while the clay content amount to 40%. Only in the upper 1.5 m was
some sandy material present « 250 !lm; up to 2-8%). A high ground-ice content (60-80
weight%) and a specific lattice-like cryostructure with overlapping subvertical ice streaks as
shown in Figure 10 characterized the lower 4 m of the silt sequence. Quite similar
cryostructures have been obtained via experimental freezing of sapropelic sediments under