Pseudo-feathery dunes in the Kumtagh Desert

The Kumtagh Desert is the last explored desert in China. The unique patterns on aerial photographs and satellite images have led Previous researchers to the conclusion that the Kumtagh Desert is the only place over the world where typical feathery duties are developed, and that some unique wind regimes are Lit work. Recent field investigation reveals that the feathery patterns in fact reflect the albedo contrasts between the seif duties, bright dune-like drifts and the dark inter-dune lag sediments. The wind regime in the area containing the so-called feathery dunes is typical of the regime that produces seif dunes that were considered to be shafts of the feathery dunes, and the vanes of the feathery duties are in fact bright chine-like drifts with indistinct height front the surroundings rather than true transverse duties. Further analysis indicates that the sediments of seif duties, dune-like drifts and dark inter-dune flats differ in g-rain size distribution, mineralogy, reflectance spectrum and particle micro-morphology. Sediments that Constitute seif dunes and dune-like drifts are finer and poorly rounded, contain relatively more quartz, and hence have higher albedo. while the sediments that constitute the dark inter-dune flats are coarser and better rounded, contain far less quartz but relatively more andesite and dacite. and hence have lower albedo. As a result, What Was Originally perceived as unique feathery duties are in fact only pseudo-feathery dunes composed primarily of seif duties. This discovery also demonstrates that blowing sand drifts call form dune-like patterns that remain visible for long periods of time. It is important to distinguish between the patterns of true duties and those of dune-like drifts (pseudo-dunes) that cause albedo contrasts in interpreting remote sensing images. (C) 2008 Elsevier B.V. All rights reserved.