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| Titel |
Assessment of soil n-alkane δD and branched tetraether membrane lipid distributions as tools for paleoelevation reconstruction |
| VerfasserIn |
F. Peterse, M. T. J. Meer, S. Schouten, G. Jia, J. Ossebaar, J. Blokker, J. S. Sinninghe Damsté |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 12 ; Nr. 6, no. 12 (2009-12-03), S.2799-2807 |
| Datensatznummer |
250004214
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| Publikation (Nr.) |
 copernicus.org/bg-6-2799-2009.pdf |
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| Zusammenfassung |
| δ18O values of pedogenic minerals forming from soil water are
commonly used to reconstruct paleoelevation. To circumvent some of the
disadvantages of this method, soil n-alkane δD values were recently
proposed as a new tool to reconstruct elevation changes, after showing that
soil n-alkane δD values track the altitude effect on precipitation
δD variations (r2=0.73 along Mt. Gongga, China). To verify the
suitability of soil n-alkane δD values as a paleoelevation proxy we
measured the δD of soil n-alkanes along Mt. Kilimanjaro (Tanzania).
At midslope, soil n-alkane δD values are possibly influenced by the
present precipitation belt, causing D-depletion in precipitation, and hence
in the soil n-alkanes. Consequently, soil n-alkane δD values do not
linearly relate with altitude (r2=0.03), suggesting that, in this case,
they can not serve as an unambiguous proxy to infer past elevation changes.
In contrast, it was recently shown that the MBT/CBT temperature proxy, which
is based on the distribution of branched glycerol dialkyl glycerol
tetraether (GDGT) membrane lipids, is linearly related with MAT, and thus
altitude (r2=0.77), at Mt. Kilimanjaro. This suggests that this proxy
may be more suitable for paleoelevation reconstruction for this region.
However, application of the MBT/CBT proxy on the altitude gradient along Mt.
Gongga showed that, although the MBT/CBT-derived temperature lapse rate
(−5.9°C/1000 m) resembles the measured temperature lapse rate
(−6.0°C/1000 m), there is a relatively large degree of scatter (r2=0.55).
Our results thus show that both proxies can be subject to relatively large
uncertainties in their assessment of past elevation changes, but that a
combination of the soil n-alkane δD and MBT/CBT proxies can likely
result in a more reliable assessment of paleoelevation. |
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