Wind erosion caused clustered development and rapid growth of nebkhas in the eastern Qaidam Basin of the Tibetan Plateau

Abstract

The formation of nebkhas is more complex and more sensitive to environmental changes than non-phytogenic dunes because of the influence of shrubs. To understand the relations between nebkha formation and wind erosion, this study determined the various phases of clustered development and rapid growth of nebkhas in the Qaidam Basin based on statistical analysis of optically stimulated luminescence (OSL) aeolian sand ages from multiple nebkha profiles. The results revealed two clustered development phases of nebkhas that approximately correspond to 920 CE and 1460 CE, and revealed three rapid growth phases after nebkhas development that corresponded to approximately 1020, 1300, and 1580 CE. By comparing these phases to well-established paleoclimate records, we determined that these phases of clustered development and rapid growth of nebkhas thereafter all occurred under the cold or cold-dry climate background. Accordingly, we can infer that the cold or cold-dry climate resulted in reduced herbaceous vegetation cover and strong wind erosion, whereas shrubs developed or persisted because of strong adaptability and subsequently intercepted shifting sands. Therefore, the short-term history of wind erosion can be reconstructed in arid and semiarid regions, provided that a sufficient number of OSL ages from nebkha sediments is available.