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| Titel |
Noble gases in the sediment pore water as proxies for physical transport processes and past environmental conditions in Lake Van (Turkey) |
| VerfasserIn |
Y. Tomonaga, M. S. Brennwald, R. Kipfer |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062592
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| Zusammenfassung |
| Since many decades unconsolidated sediments have been proposed as a potential archive for
noble-gas records to reconstruct past environmental conditions in lakes and oceans. In
addition, the accumulation of non-atmospheric noble-gas isotopes allows tracing the
geochemical origin and transport processes of the pore fluids [7]. For instance, the abundance
of terrigenic He isotopes reflects the residence time and transport dynamics of the dissolved
species in the pore space. The 3He-4He ratio of terrigenic He can be used to constrain the
geochemical origin of the pore fluids [3, 7]. However, methods for reliable and robust
noble-gas analysis in pore water of unconsolidated sediments have been developed only
recently [1, 6].
Lake Van (Turkey) is one of the largest terminal lakes and the largest soda lake on Earth.
The physical conditions of the lake are known to react sensitively to changes in the
hydrological cycle and to the environment of the lake catchment [2]. Therefore, the noble-gas
record in the sediments of Lake Van have a great potential as an archive to reconstruct past
climate evolution in eastern Anatolia where the atmospheric south-western jet stream
intersects the northern branch of the subtropical high pressure belt [4]. Also, the basin of
Lake Van is situated in a tectonically active region characterized by the presence of major
faults and volcanos and is known to accumulate mantle fluids [3, 7]. Noble-gas isotopes
are therefore expected to yield insights into the origin and transport processes of
terrigenic fluids in the sediment pore space and their release into the water body
[7].
In this study we present noble-gas and salinity data measured in the pore water of
sediment samples collected in Lake Van. Noble-gas data from short cores (~ 2 m) taken at
different sites throughout the lake basin are discussed from the point of view of the fluid
transport in the pore space. In this context, we interpret the latest results from the noble-gas
samples acquired in 2010 during the ICDP PaleoVan drilling operations from 220 m long
cores [4, 5]. Noble-gas measurements are further linked to salinity measurements in terms
of past lake level fluctuations and physical conditions of the water body of Lake
Van.
References
[1]   Brennwald, M. S., Hofer, M., Peeters, F., Aeschbach-Hertig, W., Strassmann,
K., Kipfer, R., and Imboden, D. M. (2003). Analysis of dissolved noble gases in
the pore water of lacustrine sediments. Limnol. Oceanogr. Methods 1, 51–62.
[2]Â Â Â Kaden, H., Peeters, F., Lorke, A., Kipfer, R., Tomonaga, Y., Karabiyikoglu,
M. (2010). Impact of lake level change on deep-water renewal and oxic conditions
in deep saline Lake Van, Turkey. Water Resources Research 46, W11508.
[3]   Kipfer, R., Aeschbach-Hertig, W., Baur, H., Hofer, M., Imboden, D. M.,
Signer, P. (1994). Injection of mantle type helium into Lake Van (Turkey): the
clue for quantifying deep water renewal. Earth and Planetary Science Letters
125Â (1-4), 357–370.
[4]Â Â Â Litt, T., Krastel, S., Sturm, M., Kipfer, R., Orcen, S., Heumann, G., Franz,
S. O., Ulgen, U. B., Niessen, F. (2009). ‘PALEOVAN’, International Continental
Scientific Drilling Program (ICDP): site survey results and perspectives.
Quaternary Science Reviews 28Â (15-16), 1555–1567.
[5]   Litt, T., Anselmetti, F., Cagatay, M. N., Kipfer, R., Krastel, S., Schmincke,
H.-U., and the PaleoVan science team (2011). A 500,000 year-long sedimentary
archive drilled in Eastern Anatolia (Turkey): The PaleoVan Drilling Project. Eos
92Â (51), 477–479.
[6]   Tomonaga, Y., Brennwald, M. S., Kipfer, R. (2011). An improved method
for the analysis of dissolved noble gases in the pore water of unconsolidated
sediments. Limnology and Oceanography: Methods 9, 42–49.
[7]   Tomonaga, Y., Brennwald, M. S., Kipfer, R. (2011). Spatial distribution and
flux of terrigenic he dissolved in the sediment pore water of Lake Van (Turkey).
Geochimica et Cosmochimica Acta 75Â (10), 2848–2864. |
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