Gobi deposits play a significant role as sand sources for dunes in the Badain Jaran Desert, Northwest China

Abstract

The Badain Jaran Desert has the world’s tallest dunes, but the sand sources for these dunes are unclear. Previous research suggested that the Qilian Mountains and Altai Mountains are the main sand sources, with sand transport primarily by hydrological processes. However, there is a large area of Gobi (i.e., desert pavement formed on the alluvial fans) surfaces upwind of the desert, and we hypothesized that the Gobi surface might also be a sand source. Sand geochemical characteristics can be used to identify sediment sources. To test our hypothesis, we collected 26 samples from the Gobi surface, 22 samples from sand dunes on the Gobi surface, 2 samples from dry lacustrine deposits, and 7 samples from the Heihe River’s banks. We then analyzed their geochemical characteristics and used principal-components analysis to quantify the similarity between sand source and deposition areas. We found that the Rb/Sr, Ba/Sr, Y/Zr, Rb/Zr, K/Ba, and K/Rb ratios can be used to identify the sand provenance. Based on these ratios, the geochemical characteristics for all samples were generally similar between the Gobi surface and the Badain Jaran Desert, suggesting that the Gobi surface was an important source of sand for the desert’s dunes, and can provide about 69% of the sediment for the Badain Jaran Desert. Sand was also transported by drainage from the Gobi surface into the Heihe River, where river bank deposits became an additional source of sand. Thus, both wind and hydrodynamic forces controlled the sand transport.