428
Land-Ocean Systems in the Siberian Arctic: Dvnamics and History
and overlying sediment, and thus starting the coring process at defined depths. Nine
deployments of the piston corer, with an overlap of approx. 50 cm each, yielded a complete
sediment sequence from the sediment/water interface to a depth of 22.37 m. The cores were cut
into 1 m sections, sealed with plastic caps and flexible tape and stored in thermostatted boxes at
positive temperatures during transport via Khatanga and St. Petersburg to Potsdam. For
detailed descriptions concerning the coring technique see Melles et al. (1994).
Prior to opening the cores, physical properties of the sediment were measured using a nondestructive Multi Sensor Core Logging system (Geotek Ltd. UK) at the Alfred Wegener
Institute (AWl) in Bremerhaven (described in detail in Weber et aI., 1997). Wet bulk densities
and porosities were calculated from y-ray absorption at 1 cm intervals, and susceptibility values
were determined correspondingly using a Bartington MS2 loop sensor.
Subsampling of the core segments and additional analyses were carried out at AWl Potsdam.
The cores were halved longitudinally; one half was used for sampling and the other for the
archive. Following photographic documentation and macroscopic description, subsamples (1
cm thick sediment slices) were taken from the core. They were freeze-dried and ground to < 63
11m particle size. Water content was calculated from the differences between wet and dry
weights. Total carbon, sulfur, and nitrogen contents were determined using a CNS-932 Mikro
analyzer (LECO Corporation). The total organic carbon content was measured with a CS
10011000 S (ELTRA) in corresponding samples after treatment with hydrochloric acid (10%) to
remove the carbonate-bound carbon. In addition, sediment slabs of 2 x 10 x 1.5 cm were used
for the preparation of large-sized thin sections, which were investigated using a petrographic
microscope.
Radiocarbon dating was carried out on a sample of terrestrial plant remains found in sufficient
amount at a sediment depth of 467 cm in core PG 1228. The measurement was conducted by
14C Accelerator Mass Spectrometry (AMS) at the Research Laboratory for Archaeology and
History of Art, Oxford. The 14C age was calibrated to calendar years BP (before 1950) using
the OxCal v2.l8 program based on the Stuiver and Reimer (1993) 14C calibration curve.
Results and discussion
Stratigraphy
The stratigraphy of sediment core PG1228, as presented in Figure 5, is based mainly on a
correlation of regional pollen assemblage zones (PAZ), determined for this core with
radiocarbon dated pollen records from Siberia and other areas of the northern hemisphere
(Hahne and Melles, this volume). Holocene sedimentation rates of 0.7 mm/a, calculated from
the pollen stratigraphy, are supported by those determined by 210Pb measurements in shallow
sediments (Hagedorn, pers. comm.). In addition, the agreement of PAZ LL8 with the Atlantic
period is confirmed by the radiocarbon age of 5650 ± 90 14C yr BP (Lab No.: OxA-6526) of
terrestrial plant remains from 467 cm sediment depth, corresponding to a calibrated age of
6670-6280 cal. yr BP.
Lithology and sedimentary structures
The sediment core PG 1228 is clearly dominated by minerogenic sediment components. The
organogenic components include terrestrial plant detritus, algal material and fossil coal and
methane, considerable amounts of which expanded during sediment recovery from about 108 m
water depth as a result of a pressure release of far more than 1000 kPa . Vivianite and pyrite
accretions occur as mm-scale concretions in the upper 9 m of the sediment column. There is no
evidence of postsedimentary destruction of sedimentary structures by bioturbation.
Land-Ocean Systems in the Siberian Arctic: Dvnamics and History
and overlying sediment, and thus starting the coring process at defined depths. Nine
deployments of the piston corer, with an overlap of approx. 50 cm each, yielded a complete
sediment sequence from the sediment/water interface to a depth of 22.37 m. The cores were cut
into 1 m sections, sealed with plastic caps and flexible tape and stored in thermostatted boxes at
positive temperatures during transport via Khatanga and St. Petersburg to Potsdam. For
detailed descriptions concerning the coring technique see Melles et al. (1994).
Prior to opening the cores, physical properties of the sediment were measured using a nondestructive Multi Sensor Core Logging system (Geotek Ltd. UK) at the Alfred Wegener
Institute (AWl) in Bremerhaven (described in detail in Weber et aI., 1997). Wet bulk densities
and porosities were calculated from y-ray absorption at 1 cm intervals, and susceptibility values
were determined correspondingly using a Bartington MS2 loop sensor.
Subsampling of the core segments and additional analyses were carried out at AWl Potsdam.
The cores were halved longitudinally; one half was used for sampling and the other for the
archive. Following photographic documentation and macroscopic description, subsamples (1
cm thick sediment slices) were taken from the core. They were freeze-dried and ground to < 63
11m particle size. Water content was calculated from the differences between wet and dry
weights. Total carbon, sulfur, and nitrogen contents were determined using a CNS-932 Mikro
analyzer (LECO Corporation). The total organic carbon content was measured with a CS
10011000 S (ELTRA) in corresponding samples after treatment with hydrochloric acid (10%) to
remove the carbonate-bound carbon. In addition, sediment slabs of 2 x 10 x 1.5 cm were used
for the preparation of large-sized thin sections, which were investigated using a petrographic
microscope.
Radiocarbon dating was carried out on a sample of terrestrial plant remains found in sufficient
amount at a sediment depth of 467 cm in core PG 1228. The measurement was conducted by
14C Accelerator Mass Spectrometry (AMS) at the Research Laboratory for Archaeology and
History of Art, Oxford. The 14C age was calibrated to calendar years BP (before 1950) using
the OxCal v2.l8 program based on the Stuiver and Reimer (1993) 14C calibration curve.
Results and discussion
Stratigraphy
The stratigraphy of sediment core PG1228, as presented in Figure 5, is based mainly on a
correlation of regional pollen assemblage zones (PAZ), determined for this core with
radiocarbon dated pollen records from Siberia and other areas of the northern hemisphere
(Hahne and Melles, this volume). Holocene sedimentation rates of 0.7 mm/a, calculated from
the pollen stratigraphy, are supported by those determined by 210Pb measurements in shallow
sediments (Hagedorn, pers. comm.). In addition, the agreement of PAZ LL8 with the Atlantic
period is confirmed by the radiocarbon age of 5650 ± 90 14C yr BP (Lab No.: OxA-6526) of
terrestrial plant remains from 467 cm sediment depth, corresponding to a calibrated age of
6670-6280 cal. yr BP.
Lithology and sedimentary structures
The sediment core PG 1228 is clearly dominated by minerogenic sediment components. The
organogenic components include terrestrial plant detritus, algal material and fossil coal and
methane, considerable amounts of which expanded during sediment recovery from about 108 m
water depth as a result of a pressure release of far more than 1000 kPa . Vivianite and pyrite
accretions occur as mm-scale concretions in the upper 9 m of the sediment column. There is no
evidence of postsedimentary destruction of sedimentary structures by bioturbation.