Dune Morphology And Genesis Of The Tengger Desert In The Trellis

Latticed dune based on two sets of nearly perpendicular sand ridges formed grid-like sand dunes on a flat surface.Compared with the other major types of dunes, the research of latticed dunes is in a relatively low degree. For the causes, the division and the morphological types of latticed dunes there are many dispute and divergent, different dune researchers have different views and opinions. This article mainly studies about the latticed dune in the Tengger Desert, using Google Earth to find the Tengger Desert latticed dunes’concentrated position, measure and calculate the primary and secondary ridges’toward and dune height, then make some classification. This article take Shapotou region as an example, studies about the The wind conditions and sand drift potential characteristics and The particle size characteristics by the information provided by the Shapotou stations. On the basis of the research results, the formation of latticed dunes on the southeast edge of Tengger Desert is assumed that in order to provide a reference to the morphology and genesis study of latticed dune in Tengger Desert.The main conclusions of this article are as follows:(1) The classification and geographical distribution of the latticed dune in the Tengger Desert. Depend on the number of ridges and the ratio measured by primary ridges and the secondary ridges, the latticed dune can be classified into three types: square dunes. long grating sand dunes and honeycomb dune. And find that the large-scale distribution is in the the Alashan surrounding region, the middle-scale is in the Minqin surrounding and the southeastern edge of the Tengger Desert region is thesmallest dunes.(2) The wind conditions and sand drift potential characteristics in Shapotou region. The Shapotou sand-wind is5m/s and annual average wind speed is2.75m/s. where the maximum wind speed is17.1m/s, mainly from the northwest wind and the northwest north wind. followed by easterly and northerly. By calculating, the research area sand drift potential (DP) is roughly340.95VU per year, the annual synthetic sand drift potential (RDP) is approximately equal to96.70VU, and the synthetic drift potential direction (RDD) is299.11°. annual synthesis drift potential the direction of the prevailing wind direction is consistent(3) The particle size characteristics of the latticed dunes in Shapotou region. Calculation shows that the average particle size of the primary ridges are between2.43φ-2.78φ, the secondary ridges are between2.13φ-2.63φ. The sorting coefficient of the primary ridges are from0.26to0.58, the secondary ridges are from0.39to0.60. The skewness of the primary ridges are in the range of-0.33-0.07, the secondary ridges are in the range of-0.33-0.47. the kurtosis values of the primary ridges are from0.66to1.41, the secondary ridges arefrom0.65to1.65.(4) The formation of latticed dunes in Shapotou region. From its geological structure in the Quaternary, mainly to weathering and erosion effects, formed intermittently erosion hilly. And in Gantang-Zhongwei Basin, the settlement between two mountains deposited very thick loose sediments, which provided sandy material for sand dunes. Secondly, in the research area, the main wind direction is perpendicular to the primary ridges of latticed dunes. Subframe oblique under the role of air, air deflection into the dune ridges line in the leeward possessed longitudinal airflow.The particle size research shows that in the primary ridges, the smallest sand is at the top, and from the top to the hill, the average particle size is getting bigger. But in the secondary ridges, the particle size in the windward slope bases, the leeward slope bases and the top of the sand dunes are relatively big. The same particle size change of the leeward and windward slope from the top of the hill to the bottom of slope is from coarse to fine.The secondary ridges do not have the sand fallen slope formation process, its formation mechanism is the same of the longitudinal dunes.To sum up, the latticed dunes in southeastern edge of the Tengger Desert are superposed by the transversal dunes which are formed by the primary wind direction (northwest wind) and the longitudinal dunes which are formed by the alternative effect of the secondary wind (northeasterly) and the primary wind direction.