Sand cover sediments on the Tibetan Plateau are often interpreted as indicative of cold and/or dry conditions. This study focuses on two areas of sand deposition north and south of the Donggi Cona lake on the north-eastern Tibetan Plateau. Dune sections and surface samples from both dune fields are compared based on their grain-size characteristics and geochemistry. Sections are interpreted in terms of past climate conditions.

Sedimentological analysis of the two dune fields shows no significant difference between both. Geochemical analysis shows that the sediment compositions of the dune fields differ significantly in their Ca and Sr content. This suggests that the dune fields have a different source. The southern dune field seems to be related to a large former floodplain, whereas the northern dune field is related to a large alluvial fan-former lake complex. The high Ca and Sr concentrations in the northern dune field might originate from autogenic carbonate production within the former lake system.
The northern dune field shows sediment sorting from the former lake in the direction of transport. Coarse sands are found at low elevations, whereas finer sediments are found at higher elevations. Sorting is most pronounced in the north, due to high elevation differences and orientation of the mountains perpendicular to the main wind direction. In the south, valleys are in line with the main wind direction and reach lower elevations. Therefore, sorting processes only play a minor role.
The onset of dune formation has been dated to the end of the last glacial for both dune fields. The last centuries, the material is remobilized by a higher human imprint on the landscape.

This study shows that transport distance and direction of sandy sediments are related to very local morphological conditions. The sand deposits are formed during the same epoch but have different source areas.