Grain Size and Surface Processes of the Pyramid Dune in the Mogao Grottoes of China
The pyramid dune at the top of the Mogao Grottoes is composed of fine sands with a diameter between 2.44 Φ and 2.94 Φ and a standard deviation in 0.24-0.65.The skewness varying between 0.03 and 0.31 with a mean value of 0.11 indicates that the sands belonging positive skews.The kurtosis is between 0.78 and 1.72 with a mean value of 1.28 ranging from broad to narrow scare.The pattern of grain size characteristic of the main arm (NWW-ESE direction) is similar to that of the transverse dune.Erosion is occurred at the toe and deposition around the dune top.Abundant fine blown sand is moved toward the crest of main arms by the frequent local wind with low speed,leading to homegeny grain size distributions at the toe and the top.The secondary arm (SW direction) is controlled by stronger NW wind regime and its grain size distribution pattern is similar to longitudinal dune.The whole slope,especially the dune top,suffers erosion and the diameter of sand increases from the toe to the top.
Mogao Grottoespyramid dunemain armsecondary armgrain sizesurface process
NETL
NSTL
万方数据
维普
