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| Titel |
Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments |
| VerfasserIn |
E. Dietze, F. Maussion, M. Ahlborn, B. Diekmann, K. Hartmann, K. Henkel, T. Kasper, G. Lockot, S. Opitz, T. Haberzettl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 1 ; Nr. 10, no. 1 (2014-01-16), S.91-106 |
| Datensatznummer |
250116897
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| Publikation (Nr.) |
 copernicus.org/cp-10-91-2014.pdf |
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| Zusammenfassung |
| Grain-size distributions offer powerful proxies of past environmental
conditions that are related to sediment sorting processes. However, they are
often of multimodal character because sediments can get mixed during
deposition. To facilitate the use of grain size as palaeoenvironmental proxy,
this study aims to distinguish the main detrital processes that contribute to
lacustrine sedimentation across the Tibetan Plateau using grain-size
end-member modelling analysis. Between three and five robust grain-size
end-member subpopulations were distinguished at different sites from
similarly–likely end-member model runs. Their main modes were grouped and
linked to common sediment transport and depositional processes that can be
associated with contemporary Tibetan climate (precipitation patterns and lake
ice phenology, gridded wind and shear stress data from the High Asia
Reanalysis) and local catchment configurations. The coarse sands and clays
with grain-size modes >250 μm and <2 μm were
probably transported by fluvial processes. Aeolian sands (~200 μm) and coarse local dust (~60 μm),
transported by saltation and in near-surface suspension clouds, are probably
related to occasional westerly storms in winter and spring. Coarse regional
dust with modes ~25 μm may derive from near-by
sources that keep in longer term suspension. The continuous background dust
is differentiated into two robust end members (modes: 5–10 and
2–5 μm) that may represent different sources, wind directions
and/or sediment trapping dynamics from long-range, upper-level westerly and
episodic northerly wind transport. According to this study grain-size
end members of only fluvial origin contribute small amounts to mean Tibetan
lake sedimentation (19± 5%), whereas local to regional aeolian
transport and background dust deposition dominate the clastic sedimentation
in Tibetan lakes (contributions: 42 ± 14% and 51 ± 11%).
However, fluvial and alluvial reworking of aeolian material from nearby
slopes during summer seems to limit end-member interpretation and should be
crosschecked with other proxy information. If not considered as a stand-alone
proxy, a high transferability to other regions and sediment archives allows
helpful reconstructions of past sedimentation history. |
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