The sediment samples from different geomorphological positions of typical linear dunes were collected in the northeastern, eastern, central, southern and western parts of the Kumtagh Desert which is located in the west of China, and analyzed by means of sieving. The results show that the main grain composition of linear dunes is medium sand, fine sand and very fine sand, their proportions being 28.85%, 30.92% and 25.98% respectively, and the cumulative content of these three size fractions accounts for different percentages in the surface sediments of the foot and middle of windward slope, the top of the dune, the middle and foot of leeward slope, being 69.45%, 90.62%, 91.72%, 96.22% and 80.72% respectively. The linear dunes in the Kumtagh Desert are divided into two categories according to the profile shape and the characteristics of grain size parameters of the dunes. The profile shape of the first type is not symmetrical, their sediments gradually tend to become finer, better sorted from the foot to the top on both slopes, and the dunes of the first type are distributed in the northeast, central, southern and western desert. The profile shape of the second type is more symmetrical than that of the first type, the sediments on two middle slopes are the finest, those on the top are the coarsest and those at the foot take second place, and the sorting characteristics show no obvious regularity. The dunes of the second type are located in the east of desert. This paper discussed the causation of grain size characteristics of two types of linear dunes, and drew a preliminary conclusion that the formation of the first type of linear dunes is mainly caused by wind sorting, while the second type of linear dunes are the results of wind sorting and the source of sediments, and may be caused by underlying physiognomy, weathering and wind sorting as well.
[1] Laneaster N.Linear dunes[J].Progress in Physical Geography,1982,6(4):475-504.
[2] Pye K,Tsoar H.Aeolian Sand and Sand Dunes[M].London,UK:Cambridge University Press,1990.
[3] Buckley R.Soils and vegetation of central Australian sand ridges III.Sand ridge vegetation of the Simpson Desert[J].Australian Journal of Ecology,1981,6(4):405-422.
[4] Thomas D S G.Analysis of linear dune sediment-form relationships in the Kalahari Dune Desert[J].Earth Surface Processes and Landforms,1988,13(6):545-553.
[5] Kocurek G,Havholm K G,Deynoux M,et al.Amalgamated accumulations resulting from climatic and ecstatic changes,Akchar Erg,Mauritania[J].Sedimentology,1991,38(4):751-772.
[6] 王训明,董治宝,屈建军,等.塔克拉玛干沙漠简单线形沙丘形态动力学过程研究[J].中国沙漠,2003,23(3):257-261.
[7] 钱征宇,刘守勤.线形沙丘的风沙沉积特征与内部构造[J].中国沙漠,1994,14(3):25-30.
[8] 张克存,甲斐宪次,屈建军,等.简单线形沙丘形成环境及其动力过程研究[J].干旱区地理,2010,33(3):340-345.
[9] Livingstone I,Warren A.Aeolian Geomorphology:An Introduction[M].Harlow,UK:Longman,1996.
[10] Lancaster N.Grain-size characteristics of Namib Desert linear dunes[J].Sedimentology,1981,28(1):115-122.
[11] Li J Y,Dong Z B,Zhang Z C,et al.Grain-size characteristics of linear dunes on the northern margin of Qarhan Salt Lake,northwestern China[J].Journal of Arid Land,2015,7(4):438-449.
[12] Fork R.Longitudinal dunes of the northwestern edge of the Simpson Desert,Northern Territory,Australia,1.Geomorphology and grain size relationships[J].Sedimentology,1971,16(1/2):5-54.
[13] Lancaster N.Grain-size characteristics of linear dunes in the southwestern Kalahari[J].Journal of Sedimentary Research,1986,56(3):395-400.
[14] 曾晓青,王式功,尚可政,等.库姆塔格沙漠大尺度风场特征分析[J].中国沙漠,2009,29(3):391-396.
[15] 张正偲,董治宝,赵爱国,等.库姆塔格沙漠风沙活动特征[J].干旱区地理,2010,33(6):939-946.
[16] 董治宝,苏志珠,钱广强,等.库姆塔格沙漠风沙地貌[M].北京:科学出版社,2011:200-218.
[17] 董治宝,屈建军,钱广强,等.库姆塔格沙漠风沙地貌区划[J].中国沙漠,2011,31(4):805-814.
[18] Collias E E,Rona M R,McManus D A,et al.Machine Processing of Geological Data[R].University of Washington Technical Report Number 87.Seattle 5,Washington,USA:University of Washington department of Oceanalgraphy:119-120.
[19] 吴正.中国沙漠及其治理[M].北京:科学出版社,2009:116-119.
[20] Lancaster N.Geomorphology of Desert Dunes[M].London,UK: Routledge,1995:88-89.
[21] 李超,董治宝,崔徐甲.腾格里沙漠东南缘不同发育阶段横向沙丘粒度特征[J].中国沙漠,2015,35(1):129-135.
[22] 李恩菊,董治宝,赵景波.巴丹吉林沙漠典型高大沙山迎风坡粒度特征[J].干旱区地理,2011,34(3):471-478.
[23] 唐进年,王继和,苏志珠,等.库姆塔格沙漠羽毛状沙丘表面沙粒度分布特征[J].干旱区地理,2008,31(6):918-925.
[24] 魏怀东,王继和,徐先英,等.库姆塔格沙漠各沙丘类型沙粒粒度分析[J].甘肃科技,2007,23(5):85-88.
[25] 哈斯,王贵勇.沙坡头地区新月形沙丘粒度特征[J].中国沙漠,2001,21(3):271-275.
[26] Barndorff-Nielsen O,Dalsgaard K,Halgreen C,et al.Variation in particle size distribution over a small dune[J].Sedimentology,1982,29(1):53-65.
[27] 李振山,陈广庭,冯起,等.塔克拉玛干沙漠腹地纵向沙垅表面沙物质粒度特征[J].干旱区资源与环境,1998,12(1):21-28.
[28] 陈渭南.塔克拉玛干沙漠84°E沿线沙物质的粒度特征[J].地理学报,1993,48(1):33-46.
[29] Howard A D,Morton J B,Gad-El-Hak M.Sand transport model of barchan dune equilibrium[J].Sedimentology,1978,25(3):307-338.
[30] Watson A.Variations in wind velocity and sand transport rates on the windward flanks of desert sand dunes: comments[J].Sedimentology,1985,32(4):581-593.
[31] 俞胜清,阿布都米基提,周向玲,等.新疆喀拉库姆沙漠新月形沙丘不同部位粒度特征[J].中国沙漠,2013,33(6):1629-1635.
[32] 柳本立,屈建军,杨根生,等.库姆塔格沙漠东部复杂地貌地表沉积物化学元素组成初步研究[J].中国沙漠,2014,34(5):1194-1199.
[33] 徐志伟,鹿化煜,赵存法,等.库姆塔格沙漠地表物质组成、来源和风化过程[J].地理学报,2010,65(1):53-64.
[34] 张正偲,董治宝,赵爱国,等.库姆塔格沙漠风沙活动特征[J].干旱区地理,2010,33(6):939-946.
[35] 张春来,郝青振,邹学勇,等.新月形沙丘迎风坡形态及沉积物对表面气流的响应[J].中国沙漠,1999,19(4):359-363.