528
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
of the 230Th ex activity_ As presented by Niirnberg et al. (1995) the upper 50 cm of this
sediment core can be associated with the oxygen isotope stage I. Further the abundance of
Gephyrocapsa spp. in the core section between 200 and 300 cm was related to the isotope
oxygen stage 5. However Baumann (1990) showed that in sediments from the Nansen Basin,
the coccolithophoride Gephyrocapsa spp. was also recorded in the oxygen isotope stage 3.
23
8
2
3
5
6 l
i
6
5
2i5
4
5
3
:::l
0
PS247 14
4
S
6
8
'Oll
t
:!:!.
i5
5 ..... N
J
100
fZ:
Core Deph leml
~
Turbidites
Figure 9: 23D-rh ex activities of the sediment cores PS 1533-3 and PS 2471-4 versus core depth [emJ.
230Th ex and lOBe
In this study we compare the 230Thex- and lOBe profiles of PS 2471-4 (Figure 9, Figure 10)
with the radionuclide profiles of PS 1533-3 from the Yermak Plateau (Eisenhauer et aI., 1994),
where an age-depth model is available. Characteristic for the 23
23
PS 2471-4 at a core depth of 265 cm. Because of missing 230Thex data for the upper 15 cm of
the core, the transition at 211, fixed at a depth of 20 cm, is rather uncertain. According to this
model the three turbitide layers were deposited during the glacial stages 4 and 6. The
comparison of the lOBe-profile to that of core PS 1533-3 confirms the age-depth model derived
from 230Th ex . From the lOBe concentrations we calculated the depositional lOBe fluxes during
the isotopic stages 2, 3 and 5 (Table 9). The average lOBe flux amounts to [(2.32 ± 0.50) .10 6
at cm-2 a-I]. It is by at least one order of magnitude lower than the flux in the shelf area, but
higher than the fluxes of [(0.1 - 0.6) .10 6 at cm- 2 a-I] in the central part of the Arctic Ocean
(Strobl et aI., in prep.). We did not evaluate the flux during stage 4 because the sedimentation
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
of the 230Th ex activity_ As presented by Niirnberg et al. (1995) the upper 50 cm of this
sediment core can be associated with the oxygen isotope stage I. Further the abundance of
Gephyrocapsa spp. in the core section between 200 and 300 cm was related to the isotope
oxygen stage 5. However Baumann (1990) showed that in sediments from the Nansen Basin,
the coccolithophoride Gephyrocapsa spp. was also recorded in the oxygen isotope stage 3.
23
8
2
3
5
6 l
i
6
5
2i5
4
5
3
:::l
0
PS247 14
4
S
6
8
'Oll
t
:!:!.
i5
5 ..... N
J
100
fZ:
Core Deph leml
~
Turbidites
Figure 9: 23D-rh ex activities of the sediment cores PS 1533-3 and PS 2471-4 versus core depth [emJ.
230Th ex and lOBe
In this study we compare the 230Thex- and lOBe profiles of PS 2471-4 (Figure 9, Figure 10)
with the radionuclide profiles of PS 1533-3 from the Yermak Plateau (Eisenhauer et aI., 1994),
where an age-depth model is available. Characteristic for the 23
23
PS 2471-4 at a core depth of 265 cm. Because of missing 230Thex data for the upper 15 cm of
the core, the transition at 211, fixed at a depth of 20 cm, is rather uncertain. According to this
model the three turbitide layers were deposited during the glacial stages 4 and 6. The
comparison of the lOBe-profile to that of core PS 1533-3 confirms the age-depth model derived
from 230Th ex . From the lOBe concentrations we calculated the depositional lOBe fluxes during
the isotopic stages 2, 3 and 5 (Table 9). The average lOBe flux amounts to [(2.32 ± 0.50) .10 6
at cm-2 a-I]. It is by at least one order of magnitude lower than the flux in the shelf area, but
higher than the fluxes of [(0.1 - 0.6) .10 6 at cm- 2 a-I] in the central part of the Arctic Ocean
(Strobl et aI., in prep.). We did not evaluate the flux during stage 4 because the sedimentation