Kumtagh Desert Research Articles

“Raked” linear dunes in the Kumtagh Desert, China

Linear dunes are extensive in sand seas and dune fields around the world, but they take a range of forms due to the complex factors that control their development. “Raked” linear dunes, composed of primary ridges and subsidiary ridges that lie almost perpendicular to the primary ridges, were recently identified in the northern part of China's Kumtagh Desert. The primary ridges are typical linear dunes, but the subsidiary ridges display vestiges of barchan dunes. The subsidiary ridges are sufficiently short that they do not greatly affect the general appearance of the linear dunes. However, the raked linear dunes in the Kumtagh Desert have several unique characteristics that distinguish them from typical linear dunes. These dunes develop in an environment that is deficient in available sediment, and under a wind regime typical of linear dunes: an environment with a high wind energy and a directional variability index (RDP/DP) around 0.5. The raked linear dunes appear to have evolved from barchans following a modified form of Tsoar's (1984) model. Barchans formed under a northern wind regime were modified by an eastern wind regime oriented at an oblique angle to the barchans. The strengths of the two wind regimes are similar. Under these conditions, the barchans became reoriented, with the limbs farthest from the eastern winds extending to form subsidiary ridges and the limbs closest to the eastern winds forming the primary ridges, which appear to form mainly from dune collisions.

Activity of Wind-Blown Sand and the Formation of Feathered Sand Ridges in the Kumtagh Desert, China

We study the activity of wind-blown sand and its effects on the evolution of feathered sand ridges in the Kumtagh Desert, China, and attempt to reveal the formation process of feathered sand ridges using wind-tunnel experiments, remote sensing data, and detailed field observations from 2005 to 2008. The prevailing wind direction in the Kumtagh Desert is easterly in winter and north-easterly in other seasons. The average annual wind speed is 5.9 ms−1, and winds sufficiently strong to entrain sand occur on 143 days per annum. The sand transport rate within 0.4 m of the ground is strongly influenced by local landforms, and is related to wind speed by a power function. Wind erosion occurs on the crest, the windward slope of crescent sand ridges and inter-ridge sand strips, where the blowing sand cloud is in an unsaturated state; in contrast, sand accumulation occurs on the leeward slope of the crescent sand ridges, where the blowing sand cloud is in an over-saturated state. These results indicate that the development of feathered sand ridges in the Kumtagh Desert is mainly controlled by the local wind regime. The dominant winds (from the north, north-north-east and north-east) and additional winds (from the east-north-east, east and east-south-east) determine the development of crescent sand ridges, but winds that are approximately parallel to sand ridges form the secondary inter-ridge sand strips.

Pseudo-feathery dunes in the Kumtagh desert reclassified as linear dunes and zibars

Dunes with apparent feathery patterns are common in the harsh and inaccessible Kumtagh desert in China. A recent paper by Dong et al. [Dong, Z., Qu, J., Wang, X., Qian, G., Luo, W., Wei, Z., 2008. Pseudo-feathery dunes in the Kumtagh desert. Geomorphology 100, 328–334] argued that the dunes are pseudo-feathery dunes with the different forms (linear versus marginal feather vanes) being related to grain composition differences. Field studies in the region and sedimentological analyses revealed that the dune ‘feathers’ are created by dunes of different heights, rather than by differences in material composition. The dunes are, in fact, linear dunes and zibars corresponding with the rachises and vanes, respectively, and appearing as feathery patterns in aerial photographs and satellite images.

Gravel bodies in the Kumtagh Desert and their geomorphological implications

Although developed in predominantly arid environments, desert geomorphology sometimes bears information about past environmental change. China’s Kumtagh Desert has only recently been studied by researchers. These investigations revealed the existence of several unique features compared with other Chinese deserts, including gravel bodies distributed in the northern part of the desert. This paper summarizes the results of previous research in the region, as well as information obtained from remote sensing and field investigations, then discusses the geological background, underlying Quaternary geomorphology, and the types, development stages, and geomorphological implications of the desert’s gravel bodies. Four main types of gravel bodies and four developmental stages were identified. It is suggested that the great elevation difference between the Altyn Tagh Mountains and the Kumtagh Desert caused by uplift of the Qinghai-Tibetan Plateau constitutes the overall background for the development of gravel bodies, but subsequent climatic events were the direct causes of their evolution. The gravel bodies resulted from alluvial deposits on loose fine sediments mainly of aeolian origin that were subsequently subjected to wind erosion. Erosion cycles then progressively scattered these gravels to form gravel sheets. The gravel bodies have three main geomorphological implications: they record anomalous ancient climate events after the dune field formed and have little influence on the development of nearby seif dunes in the northeast, demonstrate that the Altyn Tagh Mountains are the main sediment source for the Kumtagh Desert, and suggest that the evolution of the environment and geomorphology of the Kumtagh Desert have been influenced by neotectonic movements.

Pseudo-feathery dunes in the Kumtagh Desert

Abstract 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 dunes are developed, and that some unique wind regimes are at work. Recent field investigation reveals that the feathery patterns in fact reflect the albedo contrasts between the seif dunes, 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 dunes are in fact bright dune-like drifts with indistinct height from the surroundings rather than true transverse dunes. Further analysis indicates that the sediments of seif dunes, dune-like drifts and dark inter-dune flats differ in grain 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 dunes are in fact only pseudo-feathery dunes composed primarily of seif dunes. This discovery also demonstrates that blowing sand drifts can form dune-like patterns that remain visible for long periods of time. It is important to distinguish between the patterns of true dunes and those of dune-like drifts (pseudo-dunes) that cause albedo contrasts in interpreting remote sensing images.