Grain fabrics of natural and experimental low-angle aeolian sand deposits

Abstract

This paper considers the two-dimensional grain fabrics of 23 natural and 3 experimental aeolian sand deposits. The generally low strength of the fabrics is thought to be an inherent characteristic of the investigated sediment type rather than a result of postdepositional disturbance. On a statistical basis, the 26 fabric plots can be grouped into three types of distribution patterns. In the first type, unimodal preferred orientation of elongate grains is unambiguous. In the second type, unimodal preferred orientation is either weakly developed or absent. In the third type, preferred orientation is bimodal or polymodal. The natural fabric samples are from three different exposures of Weichselian aeolian coversand. The fabric data from these sites do not contradict other available information on the paleodirection of the sand-transporting wind. The experimental fabric samples were produced in a wind tunnel. The experiments suggest that particle alignmenf by wind occurs almost instantaneously and that fabric strength does not depend on mode of deposition.