Abstract:

On the basis of field survey， Ground-penetrating radar （GPR） was used to detect the internal structure of vegetation linear dunes in the southeastern Gurbantunggut Desert， and radar facies image information was obtained. Combined with regional natural geography and morphological characteristics， the evolution model of vegetation linear dunes internal structure was preliminarily discussed. The results indicate that： （1） GPR reveals the shallow （3-5 m） structure information below the dune surface， which can identify high-angle dipping， convex and wedge cross-bedding in the middle-upper part of dunes and crest， and sub-horizontal to low-angle dipping bedding in interdunes and the middle-lower part of dunes， which reflects the strong wind erosion and deposition activity in the upper part of dune， and the accretion in the middle-lower parts of dune wings and interdunes. （2） From desert edge to the center， the shallow sedimentary structure assemblage of dune slope changes from asymmetrical to symmetrical， the dune cross-section morphology showed the same variation， but no evidence of lateral dune migration have been found. （3） According to different scale dune structure sequence， the evolution mode could be divided into four stages： shrub dunes， shadow shrub dunes， longitudinal dune chains and vegetation linear dunes. With the continuous merging and integration of overlapping shrub dunes， the width and height of linear dunes increase， frequent wind activity at the dune crest， and the types of high-angle dipping， convex and wedge cross-bedding increase. （4） The causes of massive bedding （below 3-5 m， not hit the bottom） and GPR signal attenuation should be further verified. Besides， to systematic clarify the evolution process of vegetation linear dunes in study area， it is necessary to supplement more GPR data and chronology study.

Key words: ground-penetrating radar, Gurbantunggut Desert, vegetated linear dune, sedimentary structure, development model