Stratigraphic evidence for late-Holocene aeolian sand mobilization and soil formation in south-central Kansas, U.S.A.

Stratigraphic evidence and radiocarbon dating of sediments from the Great Bend Sand Prairie in Kansas indicates that significant deposits of aeolian sand have accumulated in the region during the late Holocene. Radiocarbon ages obtained from total humates in buried soils suggest that five periods of late-Holocene stability and soil formation are preserved in dune fields at approximately 2300, 1400, 1000, 700, 500 and 300 years B.P. Reactivation of aeolian sand in the past 1000 years has resulted in a variety of well defined, parabolic dunes. In general, events in the region correspond with established chronologies elsewhere on the Great Plains and in particular correlate well with dune fields in north-eastern Colorado. Overall, results indicate that the threshold of landscape stability on the Great Bend Sand Prairie can easily be crossed in the current climatic regime.     

REGIONAL-SCALE TROUGHING OVER THE SOUTHWESTERN UNITED STATES: TEMPORAL CLIMATOLOGY,TELECONNECTIONS, AND CLIMATIC IMPACT

Regional-scale middle- and upper-tropospheric troughing over the southwestern United States represents a departure from the modal circulation pattern for western North America. Once developed, southwestern troughs often are associated with positive vorticity advection aloft, surface cyclone formation, and moisture advection over areas of the western Great Plains and Intermountain West. These trough systems may play an important role in the precipitation climatology of the western and central United States. However, very little work has focused on the temporal climatology, developmental characteristics, or climatic impacts of southwestern troughs. This study provides a detailed climatology of southwestern troughing that focuses on: (1) the temporal frequency of these events; (2) the teleconnective circulation changes that are associated with their development; and (3) the importance of these systems in the precipitation climatology of the western and central United States.

The temporal climatology of southwestern troughs reveals that most of these systems occur during spring and autumn, with somewhat fewer events in winter and very few events in summer. An examination of 500-mb geopotential height and 24-hr height change composites during trough development shows that much of the wave-train activity that accompanies trough onset is limited to the North Pacific and North American regions. These changes are characterized by the amplification and eastward movement of a ridge/trough couplet over the eastern Pacific, which is preceded by synoptic-scale transient wave activity over the western and central Pacific. While southwestern troughs occur less than 30% of the time, southwestern trough-derived precipitation comprises over 60% of the monthly totals for some sites.     

Variable vegetation cover and episodic sand movement on longitudinal desert sand dunes

Longitudinal (linear) sand dunes of the Simpson and Strzelecki dunefields in eastern central Australia present a paradox. Low levels of activity today stand in contrast to luminescence dating which has repeatedly shown deep deposits of sand on dune crests dating to within the late Holocene. In order to investigate the nature of dune activity in the Simpson–Strzelecki dunefield, vegetation and sand mobility were investigated by detailed vegetation survey and measurement of rippled area and loose sand depth of dunes at three sites along a climatic gradient. The response of both vegetation and sand movement to inter-annual climate variability was examined by repeat surveys of two sites in drought and non-drought conditions. Projected plant cover and plant + crust cover were found to have inverse linear relationships with rippled area and the area of deep loose sand. No relationship was found between these measures of sand movement and the plant frontal area index. A negative exponential relationship between equivalent mobile sand depth on dune surfaces and both vascular plant cover and vascular + crust cover was also found. There is no simple threshold of vegetation cover below which sand transport begins. Dunes with low perennial plant cover may form small dunes with slip faces leading to a positive feedback inhibiting ephemeral plant growth in wet years and accelerating sand transport rates. The linear dunefields are largely within the zone in which plant cover is sufficient to enforce low sand transport rates, and in which there is a strong response of vegetation and sand transport to inter-annual variation in rainfall. Both ephemeral plants (mostly forbs) and crust were found to respond rapidly to large (> 20 mm/month) rainfall events. On millennial time-scales, the level of dune activity is controlled by vegetation cover and probably not by fluctuations of wind strength. Land use or extreme, decadal time-scale, drought may destabilise dunes by removing perennial plant cover, accelerating wind erosion.     

科尔沁沙地奈曼旗固沙造林沙丘土壤微生物区系的变化

在科尔沁沙地西南部的流动沙丘上固沙造林,不同造林时间和不同造林树种的沙丘土壤中细菌、放线菌和真菌等类群和生理群的微生物生长情况不同、林地土壤中微生物都比流动沙丘中繁殖旺盛。造林时间长的沙丘又比造林时间短的沙丘土壤微生物增殖量大。有林木生长的沙丘上层土壤也比下层土壤微生物的数量大,沙丘结皮层中尤为明显。     

Textural attributes, mineralogy and provenance of sand dune fields in the greater Al Ain area, United Arab Emirates

Sand dunes and interdune sediments around Al Ain city have markedly high carbonate contents which increase towards Jabal Hafit mountain and the Arabian Gulf coast. The dunes are composed predominantly of well-sorted fine sands, consisting of unstrained quartz and carbonate grains together with minor proportions of chert and feldspars. Scanning electron microscope (SEM) examination reveals that quartz grains display various mechanically- and chemically-formed surface textures. The heavy minerals are dominated by opaques and pyroxenes with minor tourmaline, garnet, rutile, epidote, monazite, zircon, hornblende and staurolite.Interdune sediments consist of fine and very fine, poorly- to extremely poorly-sorted sands together with small concentrations of gravel, silt and clay. The light sand fractions compositionally resemble those of dunes but contain, in addition, gypsum, anhydrite, halite and celestite. Percentages of pyroxenes are higher whereas those of zircon, tourmaline and rutile are lower than in dunes. X-ray diffractometry reveals that the clay fractions consist solely of palygorskite. Generally, interdune sediments are much less mature texturally and mineralogically than dune sands; the maturity of both types of sediments decreases toward the NE of the study area.Sand dunes in the various districts of the greater Al Ain area are genetically related. Also, there is a partial genetic relationship between the dunes and interdune sediments; both are mainly multicyclic. Their major parts were brought mainly by the dominant north-west (El Shamal) winds from older dune fields in other localities in U.A.E., Qatar and El-Rub El-Khali. Local contributions to the dune fields from Jabal Hafit mountain, the Oman Mountains and the calcareous coast of the Arabian Gulf were, in cases, significant. Also, authigenesis by groundwater under highly evaporitic conditions played a major role in the formation of interdune sediments through the genesis of the clay and some nonclay minerals.     

A model for the active origin and development of source-bordering dunefields on a semiarid fluvial plain: A case study from the Xiliaohe Plain, Northeast China

Source-bordering dunefields have been reported in some drylands of the planet, but scarcely in China where there are extensive drylands. This article reports them in China for the first time, and presents a model for their active origin and development on a semiarid fluvial plain by means of satellite image analyses and field investigations. Local- and regional-scale examples are chosen to analyze the spatial patterns of dunefields, as well as the relationships with the fluvial systems in the central part of Naiman Banner where the Jiaolai River runs, and the lower Laoha River, and the middle and lower Ulijimulun River (principal tributaries of the Xiliaohe River). The active origin and development of source-bordering dunefields can be divided into four stages in terms of the spatial patterns of dunefields and channel dynamics: Stage I — individual dunes on the downwind margins of river valleys where running water constantly erodes the steep slopes of valley and where the downwind slopes orient to local dominant winds; Stage II — individual local-scale dunefields formed by deflation of the steep valley slopes and extending antecedent dunes downwind, together with the downstream displacement of meanders; Stage III — individual large-scale dunefield belts along the downwind margins of river valleys formed through frequent lateral migrations of channel; Stage IV — regional-scale dunefields formed mainly by river diversions due to climatic changes or tectonic movements. On the one hand, it is the running water's lateral migration, especially meandering, that prepares suitable places for aeolian systems in terms of both wind flow fields and sand sources, and subsequently it can further cause separate local-scale source-bordering dunefields to link together as a regional-scale dunefield belt given sufficient time. On the other hand, diversions of the river are bound to occur following changing hydrologic regimes resulting from tectonic movements or significant climate change (at regional and millennium scales). As a result, when some dunefield belts as well as the adjacent channels are abandoned, new channels work elsewhere in the same way to actively form new source-bordering dunefields and even dunefield belts at a regional scale.     

呼伦贝尔沙地末次冰盛期晚期至全新世风成沙表面矿物特征及环境意义

运用扫描电镜与能谱分析,研究呼伦贝尔沙地末次冰盛期晚期以来全样风成沙的微区形态和粘土矿物成分。呼伦贝尔沙地的沙粒磨圆度较好,在扫描电镜观察下保存了水成沙粒的特征,意味着沙地物源曾经流水作用到达该区域。颗粒表面同时留有风力搬运的碟型坑等撞击痕迹,为干枯河床沙丘活化、风力搬运流动扩张的过程提供证据。末次冰盛期晚期风成沙颗粒大且表面光滑洁净,未见次生粘土矿物,反映出冰期地表无植被发育,区域沙漠活化、流动性加强。而全新世适宜期的褐色沙质土壤砂粒表面同时发育鳞片状自生粘土矿物和同沉积粘土颗粒及团块。能谱分析表明：全新世适宜期,风化自生粘土矿物有蒙脱石和伊利石,在相对温湿气候条件下,发育干旱碱性土壤,反映出冰后期植被发育、土壤化作用增强。     

Late Holocene dune activity in the Eastern Platte River Valley, Nebraska

Large-scale dune activity in the Nebraska Sand Hills and elsewhere on the western Great Plains has been linked to prehistoric “megadroughts” that triggered the activation of regional dune fields. The effect of megadroughts on the smaller dune fields east of the Nebraska Sand Hills has never been assessed, however. This study focuses on the Duncan dune field near the confluence of the Loup and Platte rivers in eastern Nebraska. Seventeen optically stimulated luminescence age estimates were obtained and reveal two periods of dune activation that occurred between 4.4 to 3.4 ka and 0.8 to 0.5 ka. Significantly, both periods chronologically overlap large-scale dune activity identified in the Nebraska Sand Hills. Geochemical evidence indicates that the Duncan dunes received sand not only from the terrace underlying them, but also from the Loup River. These data link dune activity in the Duncan area, at least indirectly, to increased sediment supply from streams that drain the Sand Hills during megadroughts, implying the activation of the dunes occurred as an indirect response to regional megadroughts. Calculations of dune migration rates, however, argue in favor of local, drought-driven hydrologic changes as a causative factor in dune activation, in other words, a direct effect of megadroughts. Whether the impact was direct or indirect, it is highly likely that the repeated reactivation of the Duncan dunes resulted in some way from regional, large-magnitude droughts. Other paleoclimate proxies from the Great Plains tend to support this conclusion. We conclude that the megadroughts that have been identified in the Sand Hills and other Great Plains dune fields were indeed regional events with far-reaching effects.     

Limited change in dune mobility in response to a large decrease in wind power in semi-arid northern China since the 1970s

The climatic controls on dune mobility, especially the relative importance of wind strength, remain incompletely understood. This is a key research problem in semi-arid northern China, both for interpreting past dune activity as evidence of paleoclimate and for predicting future environmental change. Potential eolian sand transport, which is approximately proportional to wind power above the threshold for sand entrainment, has decreased across much of northern China since the 1970s. Over the same period, effective moisture (ratio of precipitation to potential evapotranspiration) has not changed significantly. This “natural experiment” provides insight on the relative importance of wind power as a control on dune mobility in three dunefields of northern China (Mu Us, Otindag, and Horqin), although poorly understood and potentially large effects of human land use complicate interpretation. Dune forms in these three regions are consistent with sand transport vectors inferred from weather station data, suggesting that wind directions have remained stable and the stations adequately represent winds that shaped the dunes. The predicted effect of weaker winds since the 1970s would be dune stabilization, with lower sand transport rates allowing vegetation cover to expand. Large portions of all three dunefields remained stabilized by vegetation in the 1970s despite high wind power. Since the 1970s, trends in remotely sensed vegetation greenness and change in mobile dune area inferred from sequential Landsat images do indicate widespread dune stabilization in the eastern Mu Us region. On the other hand, expansion of active dunes took place farther west in the Mu Us dunefield and especially in the central Otindag dunefield, with little overall change in two parts of the Horqin dunes. Better ground truth is needed to validate the remote sensing analyses, but results presented here place limits on the relative importance of wind strength as a control on dune mobility in the study areas. High wind power alone does not completely destabilize these dunes. A large decrease in wind power either has little short-term effect on the dunes, or more likely its effect is sufficiently small that it is obscured by human impacts on dune stability in many parts of the study areas.     

柴达木盆地西南缘山前沙丘区沙丘地貌形态特征

沙丘形态特征是风沙地貌研究的重要内容。通过野外实地考察及Google Earth高分辨率影像,对柴达木盆地西南缘山前沙丘区风沙地貌的空间分布格局进行分析和描述,并探究主要沙丘的形态参数特征。结果表明：（1）基于沙丘的形态-动力学分类原则,研究区沙丘共划分为12类;从发育规模来看,简单型沙丘占比大,复合型、复杂型沙丘占比小;从形态特征来看,以横向沙丘为主。（2）基于沙丘类型的空间变化特征,研究区可划分为5个亚区,风况和河流是导致沙丘类型空间分布差异的主要因素。（3）研究区各类型沙丘发育规模小,这与沙丘发育时间短、沙源供应少密切相关。新月形沙丘的形态参数宽度（w）与高度（h）之间呈良好的线性相关关系,可表达为w=9.47h+14.89。沙丘高度（h）与间距（λ）呈幂函数关系,且幂指数n均小于1。本研究丰富了柴达木盆地风沙地貌的研究内容,为后续的沙丘发育演化模式研究奠定了基础,同时对格库铁路防沙治沙和安全运行具有重要的参考价值。     

Factors controlling the survival of coastal dunes during multiple hurricane impacts in 2004 and 2005: Santa Rosa barrier island, Florida

Santa Rosa Island is an 85 km-long, wave-dominated low-lying barrier island situated along the northwestern Florida coast, facing the Gulf of Mexico. The entire island was severely impacted by Ivan, a strong category 3 hurricane that made landfall about 45 km to the west in September of 2004. Ten months later in July of 2005, Dennis, another category 3 hurricane, made landfall about 30 km east of the western tip of the island. Santa Rosa Island is characterized by well-developed but relatively low dunefields, described in this paper as incipient and established dunes, based on the presence of grassy and woody types of vegetation, respectively. The dunes were severely eroded by the two hurricanes. This paper investigates the factors controlling the regional-scale destruction and survival of the dunefields.Dune survival is controlled by: 1) hurricane characteristics, including intensity, duration, and frequency, and 2) morphological parameters including width of the barrier island, height and width of the dunefields, vegetation type, distance of the dunes to the ocean, and continuity of the dunefields. Three processes of dune destruction are described including, from most to least severe, inundation, overwash, and scarping. The interaction of all the above factors determines the different dune responses to the storm impacts. In general, the extensive and densely woody vegetated dunefields near the bay-side shoreline survived the storms, while the discontinuous dunes with grassy vegetation near the Gulf shoreline were almost completely destroyed.     

The evolution of Holocene coastal dunefields, Jutland, Denmark: A record of climate change over the past 5000 years

Coastal dunefields have developed on the west coast of Jutland in Denmark over the past 5000 years. The dunefields are situated in a temperate climate zone with frequent high energy wind events. Dunefield development was characterized by repeated periods of transgressive dune formation punctuated by periods of dune stabilization and soil formation. The chronology of dunefield evolution is based on Accelerator Mass Spectrometry (AMS) radiocarbon dating of peaty palaeosols (24 samples) and Optically Stimulated Luminescence (OSL) dating of aeolian sand deposits (19 samples). These dates indicate that the completeness of the stratigraphic record varies considerably, but that the timing of aeolian activity events was identical in the dunefields examined here. Initiation of aeolian activity occurred around 2200 BC, 800 BC, AD 100, AD 1050–1200, and between AD 1550 and 1650. Proxy-climate data from bogs in southwestern Sweden suggest that these periods of dunefield activity were initiated during wet/cool summers. Most likely these climatic situations were associated with a more frequent passage of cyclones across Denmark in the summer seasons (increased storminess) causing aeolian sand movement and dune formation. The continued removal of vegetation in Jutland between 4000 BC and AD 1850 allowed the aeolian sand, when first activated, to move more and more easily across the coastal plains; the final phase of aeolian sand movement between AD 1550–1650 and 1900 had catastrophic implications for many coastal inhabitants in the region.     

毛里塔尼亚努瓦克肖特沙丘粒度分布特征及其环境意义

毛里塔尼亚努瓦克肖特地区位于撒哈拉沙漠西部,基本被沙漠包围且常年遭受沙漠侵蚀,进行该地区沙漠粒度特征的研究,将对判别沙漠物质来源和沉积过程等具有重要参考意义。对努瓦克肖特周边纵向沙丘不同部位采集的50个沙样粒度进行分析。结果表明：沙丘沉积物的粒度以细沙和极细沙为主,两者所占比例超过60%;总体粒度要细于国内典型沙漠线性沙丘。沙丘东南坡、丘顶和西北坡整体上以细沙为主,其次为极细沙,二者含量依次递减,粉沙含量依次增加。沙丘沙粒径最细者为西北坡（5.13 φ）,最粗者为东南坡（3.07 φ）,分选性随粒径增加而变好。3个部位峰态存在明显差异,东南坡以中等和尖窄峰态为主,丘顶以尖窄峰态为主,西北坡为以宽平峰态为主,但三者均以正偏偏态为主。丘间地粒级级配趋势一致性最好,均以细沙为主,平均粒径大于沙丘各部位,平均粒径为2.76 φ,分选性优于沙丘,全为近对称中等峰态。该地区地表沙粒沉积环境和成因复杂,超过70%的沙样为风成沉积造成,其余为沿岸沉积造成。     

青海湖西岸风成沙丘特征及成因

沙漠化是青海湖周围生态环境恶化中一个非常突出的问题,尤其湖西岸沙丘是近十多年来才形成的风沙堆积,并逐年扩大,已成为青海湖区第二大风沙堆积区。通过对青海湖西岸沙丘的分布、形态、物源及粒度特征的分析,对其形成进行了研究,并对布哈河三角洲的形成发育与沙漠化之间的关系进行了初步探讨。认为河流的自然摆动和截直造成了该三角洲东北缘的停止发育,加之气候的持续干旱和严重的鼠害,是导致研究区土地沙化、沙漠面积不断扩大的一个主要因素。     

The airflow field and dynamic processes of pyramid dunes

Dune sedimentary structure and wind tunnel experimental results show that the pyramid dunes on the cliff top surface of Dunhuang Mogao Grottoes are formed under three wind directions (NE, SW and NW); the deformation and separation variety of chain dune. The local air circulation (SW) is key to the development of the pyramid dunes. Analysing the morphological dynamic processes indicates that inherent relations exist between trihedral pyramid dunes and other complex sand dune types (linear, reticulate and polyhedral pyramid dunes). The wind regime of multidirection, in conjunction with the connected main and subsidiary sand ridges, resulted in the geomorphological forms adapted to the near-surface air streams. It is concluded that integrated studies, including sedimentary structures and wind tunnel experiments, can make more efficient contributions to an overall, systematic and thorough understanding of the developmental processes of the pyramid dunes than previously used single-study methods.     

探地雷达在沙漠研究中的应用综述

沙丘层序的建立一直是风沙地貌与沙漠第四纪地质研究中的一个难点问题,而揭示沙丘沉积构造是解决该问题的基础和关键。探地雷达（GPR）是近年兴起的探测沙丘沉积构造的较新和较有效的手段,因风成沙沉积具有均一性好、低电导性、低含水性及低密度性等特点,使GPR在沙丘探测中得到良好的探测效果。借助GPR可研究：（1）一般沙丘的构造和层序、高大沙丘的浅层构造与层序、横向沙山的较完整层序等;（2）沙丘历史时期的移动方向和速率、沙丘的发育过程;（3）沙丘与沙漠的环境变化过程;（4）沙丘和沙漠的水文信息等。在应用过程中,需要注意沙丘含水量、电磁波频率选择、杂波干扰、波速理论值与实际偏差、数据处理和图像解译等方面的问题。目前,GPR在沙漠研究中尚未普及,本文旨在通过综述其在沙漠研究中的进展和存在问题,以期促进GPR在沙丘发育过程和沙漠演化过程研究中的应用。     

古尔班通古特沙漠西南缘新月形沙丘内部沉积构造特征研究

沙丘内部沉积构造保存了沙丘动力演变过程的重要信息。以古尔班通古特沙漠西南缘固定、半固定新月形沙丘区为研究区域,利用探地雷达在春、秋两季对固定、半固定新月形沙丘内部构造进行探测,获取了不同规模形态的固定、半固定新月形沙丘深约8 m的内部构造图像信息。通过图像增益处理、解译和对比分析表明：（1） 古尔班通古特沙漠固定、半固定新月形沙丘共有5种沙丘内部构造雷达相,即高倾角斜层理、楔状交错层理、上凸形交错层理、低倾角-近水平层理和块状层理,其中前4种主要分布在3~5 m的浅层,而块状层理主要分布在4~5 m以下的深度。（2） 高倾角斜层理、楔状交错层理主要分布在高大新月形沙丘（链）的迎风坡上部和丘顶地带,前者为背风坡前积层埋藏而成,反映高大新月形沙丘迎风坡上部和丘顶风沙活动较频繁,沙丘“固身缩顶”后埋藏的前积纹层因风蚀而出露,后者为迎风坡风蚀坑和风蚀槽中由风沙流充填而成的构造或在丘顶风向的季节性变化形成的构造。（3） 与灌丛沙丘相关的上凸形交错层理广泛分布在新月形沙丘的迎风坡中下部,在背风坡也有局部出现,表明灌丛沙丘在沙丘表层的风沙过程中占有重要地位;而深部的块状层理可能是早期风积层受到强烈的生物扰动,原生层理消失而产生。（4） 以上沙丘内部构造的类型与组合分布特点,反映了研究区新月形沙丘总体上趋于稳定或衰退状态,这与现代沙丘“固身缩顶”的地貌变化特征相一致。例如,迎风坡中上部和丘顶常见风蚀槽,背风坡因坡度变缓、前积层发育趋缓,现代风沙活动主要集中于新月形沙丘的上部和丘顶等。由此可见,研究区固定、半固定新月形沙丘内部构造及其组合分布特征异于流动新月形沙丘,也与半个多世纪以来北疆沙漠气候变暖变湿、平均风速减弱、植被盖度增加的区域自然地理环境变化趋势有一定的吻合性。     

The Manawatu Dunefield: Environmental Change and Human Impacts

Four stages of environmental change are apparent in the Manawatu coastal landscape: the first stage was that of a world wide sea level rise and initiation of the first major dune phase (Foxton or phase I) in the Manawatu. This was followed by a second dune‐building phase (Motuiti or phase II), which was probably initiated by climate change. The second stage occurred in the last 600 to 1000 or so years when Maori first occupied the area, rapidly causing the extinction of a range of fauna, significantly altering the vegetation cover and potentially initiating or assisting the development of a new dune phase (Waitarere or phase 111). The latter part of the Waitarere phase (phase IV) or episode may have been initiated by Europeans in the last 150 years. The third stage of environmental change occurred in the period 1940 to 1990 when large scale sand sheets and transgressive dunefields were significantly stabilised by humans, and parabolic dunes were created. A fourth stage is just beginning where an entirely new suite (or episode) of parabolic dunes has developed from blowouts within the foredune in the last 10 years. Overall, human impact has wrought major environmental changes to one of the greatest examples of Holocene dunefields in New Zealand.     

Occurrence and significance of a cold-water carbonate pseudomorph in microbialites from a saline lake

Micron-scale pseudomorphs of calcite after ikaite were discovered in microbialites from Manito Lake, a large hypersaline lake in the Great Plains of western Canada. Although environmental conditions in the lakes of this region (seasonally cold temperatures, high salinities and elevated productivity) suggest that ikaite should be common, this is the first documentation of lacustrine ikaite in Canada and the Great Plains region of North America. The calcite pseudomorphs form a porous dendritic fabric, comprise the interiors of massive shoreline microbialite mounds and pinnacles, and are encased in centimeter-scale, laminated dolomite-aragonite rinds. Because of the limited thermodynamic stability of ikaite at or near freezing temperatures, the psuedomorphs of this mineral provide evidence of an extended cold episode during the first millennium AD. The Manito deposits also show high δ¹³C values, indicating elevated productivity and δ¹⁸O signatures are consistent with precipitation in a cold, somewhat fresher lake than present.     

雅鲁藏布江河谷风沙地貌的初步观察

青藏高原上发育有不少风沙堆积地貌,尤以雅鲁藏布江中上游宽谷中为普遍和典型,其主要形态类型有新月形沙丘、沙丘链、沙堆、沙包、沙坡地等,可分流动和半固定、固定两大类。其成因主要是雅鲁藏布江谷地与高空西风气流相一致,就地起沙所形成;并认为高原上的一些黄上状堆积物的形成与古风沙堆积有一定的关系。风沙作用对高原经济建设带来危害,目前,人类活动多集中在雅鲁藏布江中游,故这一地区有沙漠化扩大的趋势,应引起重视和注意。