Zibar

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Zibar is the name for a flat, almost symmetrical dune structure without a slip side.

Initial description

The name Zibar, which comes from Arabic , was first introduced into the scientific literature in 1953 by DA Holm.

Dimensions

In the plan, Zibar shapes are straight to winding, but they can also be completely irregular. Their wavelengths are 150 to 400 meters and their heights reach the meter range.

Association and Origin

Zibar shapes emerge from poorly sorted, bimodal residual sands, which can be found in corridors and basins between large dunes or generally as a base in desert plains .

Zibar forms can appear together with sickle dunes and longitudinal dunes , the latter in turn arising from the extended horns of the sickle dunes . Nielson and Kocurek (1986) also observed that with increasing grain size Zibar forms dunes with Abrutschhängen rounded ( Engl. Slip faces ) to replace.

The origin of the Zibar forms is still not fully understood. Their association with blown areas of poorly sorted sands superficially indicates an affinity for larger ballistic ripples . However, their high wavelength, which is a multiple of realizable saltation lengths , speaks against this . Another formation mechanism must therefore be considered. The association with transverse dune shapes established by Nielson and Kocurek suggests that in areas with poorly sorted, coarse sand supply, the formation of a slope on the lee side does not occur and that only Zibar shapes can form here.

Occurrence

literature

  • JRL Allen: Sedimentary Structures. Their Character and Physical Basis . In: Developments in Sedimentology . tape 30 . Elsevier Science Publishers, 1984, ISBN 0-444-41238-7 .
  • N. Lancaster: Geomorphology of Desert Dunes . Routledge, London 1995, ISBN 0-415-06093-1 .

Individual evidence

  1. ↑ A. Warren: Sedimentology . tape 19 , 1972, p. 37-44 .
  2. ↑ HTU Smith: Eolian geomorphology, wind direction and climatic change in North Africa . US Air Force, Cambridge Research Laboratory, Rep. 63-443, 1963.
  3. ↑ a b G. Kocurek, RC Ewing: Aeolian dune field self-organization - implications for the formation of simple versus complex dune-field patterns . In: Geomorphology . tape 72 , 2005, p. 94-105 .
  4. ↑ J. Nielson, G. Kocurek: Climbing zibars of the Algodones . In: Sedimentary Geology . tape 48 , 1986, pp. 1-15 .