Studying the Morphologic Maturation of Aeolian Sand Grains During Transportation Process of Wind Erosion (Case study: Khartouran Erg)

Document Type: Research Paper

Authors

1 Assistant Professor, International Desert Research Center, University of Tehran, Tehran, Iran

2 Assistant Professor, Faculty of Natural Resources, University of Yazd, Yazd, Iran

Abstract

Wind, in the duration of its erosional process, affects considerable changes in a grain's morphology
from its removal (detachment) step to sedimentation. In other word, a grain undergoes its gradual
evolution during the transit process. In this project, the maturation of Aeolian sand grains had been
studied upon as based on texture maturity indicator which includes: sorting, mean size grain, roundness as
well as abrasion coefficient parameters. The study area is the transport region of Khartouran Erg
sediments, which founded on the basis of ground index of wind erosion. According to these indicators,
the direction of prevailing or strong winds is notably mentioned. In a later step, four transects are selected
in different area in alignment with wind direction. Samples of sediment grains are taken at varied
distances in any one of the transects. The samples were taken from the windward slope of Rebdou
landform. The samples were evaluated to using granulometry and morphoscopy techniques. Grain size
analysis of was done using dry sieve analysis while morphoscopy of grains carried out by studying the
quartz grains of 150 to 300 μm diameter by using binocular microscope. Results indicate a gradual
maturity (evolution) in sediment texture in all transects starting from the upper parts (near sand source)
toward the lower parts (in transportation area).Also, results indicate that from among the four indicators
of grain maturity namely: sorting, grain size, roundness and abrasion coefficient the respective factors of
either " abrasion coefficient index" or" roundness index " in the first value and then" sorting" and finally
"grain’s mean size index" are the ones accounted for validation for determination of maturity.

Keywords