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| Titel |
Coexistence of bedforms: the star dune paradigm |
| VerfasserIn |
Clement Narteau, Deguo Zhang, Olivier Rozier |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046849
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| Zusammenfassung |
| Star dunes are giant pyramidal dunes composed of interlaced arms with sinuous crests and
slip faces oriented in various directions. The radial symmetry and the size of the pattern seem
to illustrate a high degree of complexity between multidirectional wind regime and
topography. However, compared to other dune types, little is known about the formation and
the evolution of star-dunes, which are ubiquitous in major depositional centres of modern
sand seas. Here, we report simulations in which the star dune morphology results only from a
combination of longitudinal dunes produced by primary winds and their respective sand
fluxes in crestal areas. Using 3D sedimentary structures produced by the model, we
find that the both arm morphology and growth rate depend non-linearly on the
frequency at which the wind changes direction and not only on the relative amount of
time spent on individual direction. Then, radiating arms can detach to interact with
other dunes in the neighbourhood. We infer that this is an important mass exchange
mechanism in star-dune fields. Our results show that polymodal crest orientations
may be stable bedform configurations, thus allowing to solve more efficiently the
inverse problem consisting in reconstructing the climatic conditions from dune
shape. |
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