The Tsakhiurtyn Hundi Lakeland – geological and geomorphological factors influencing the development of small lakes south of the Arts Bogd Massif (Gobi-Altai Range, Mongolia)

Abstract

This study analyses the geological and geomorphological conditions in which palaeolakes developed in the southern margin of the Arts Bogd Massif (Mongolia), identifying and documenting fifteen dry lakes in the Shereegiin Gashuun Basin, in the area called the Tsakhiurtyn Hundi Lakeland. The lake basins were formed by a combination of tectonic and aeolian processes. Their occurrence is closely related to regional fault structures and subsidence of the bedrock within a pull-apart basin. Aeolian processes, including deflation and sedimentation of silts, further influenced the palaeolakes’ morphology and their evolution. Field study and remote data analysis have made it possible to determine the factors shaping the dynamics of the alluvial-pluvial processes involved, and the structural conditions determining the formation of the basins. Nowadays, the lakes are dry, and their bottoms are filled with clayey and clayey-sandy sediments with clearly marked palaeoshorelines. Analyses have shown that geomorphological processes such as aeolian erosion and the accumulation of alluvial fan deposits significantly influenced the geometry of the former reservoirs