Abstract:

The internal sedimentary structure of sand dunes is often manifested as bedding structures， providing crucial information for the study of dune formation and evolution. This study focuses on a relatively mature parabolic sand dune located on the southern margin of the Hobq Desert. This thesis discusses the dynamics and depositional features of parabolic sand dunes through a combination of remote sensing dynamic monitoring and observational analysis of manually excavated profiles. The results indicate a consistent correlation between the dune morphology， dynamics， and internal structures. The dune undergoes forward movement and lateral expansion in the form of inner-side erosion and outer-side interception by vegetation， and here are variations in the types of bedding in different parts of the dune. Due to the absence of a consistent sand source， the sedimentary structures observed at the nose of the parabolic dune primarily consist of parallel bedding with grain sequence interaction and medium-low dip angle cross-bedding， and coarse sand lenses are present in the bedding of the crest and leeward slope. The sedimentary structures on both arms of the dune are relatively consistent， primarily characterized by parallel bedding and middle-high dip angle cross-bedding. The lower layers of inner slopes exhibit eastward-inclined foreset beds， while the upper layers of inner slopes exhibit inward-inclined climbing beds. On the outer slopes of two arms， there is outward-inclined high dip angle foreset beds. The sedimentary structural features of the sand dune reflect its primary depositional processes. In the southern margin of the Hobq Desert， the deposition processes of parabolic sand dunes involve sand ripple deposition and particle fall deposition. Additionally， on the outer slopes of the two arms， there is particle flow deposition resulting from gravity collapse. Due to the complexity of surface processes， relying solely on dune bedding may not accurately determine regional airflow directions.

Key words: parabolic dunes, sedimentary structure, evolution, Hobq Desert