Bilutu megadunes and lakes in the Badain Jaran Desert

The Badain Jaran Desert (BJD) hosts the largest megadunes in the world and the unique megadune-lake system (Chen et al., 2019). Most of the megadunes are over 300m high, with the highest, the Bilutu Sand Peak, a compound transverse dune, of 450m (Dong et al., 2004). Currently, there are more than 100 lakes in the site, mostly smaller than 1km2. The bottom age of the desert is ca. 1100 ka. The site is located in the transitional zone between the Asian summer monsoon and the Westerlies, and it is west of the Yabrai Fault. The climate changes and tectonic evolution of Yabrai Fault play important roles in the formation and maintenance of the unique megadune-lake system in the BJD. During the humid periods since MIS 15, extensive lakes developed. Climate changes led to fixation, reactivation and ultimate formation of megadunes. Uplift of the Yabrai Mountains formed a topographic barrier, which suppresses and enhances sand transport by affecting climate, wind and water circulation (Wang et al., 2015; Du et al., 2019). The megadunes in the BJD are becoming higher and steeper because of the upward migration and accumulation of sands that originate from the lake basin (wang et al., 2019).