敦煌鸣沙山砂质组成与结构

Sandiness Composition and Structure of Singing Sand Mountain in Dunhuang City

敦煌鸣沙山砂质为细砂,分选性中等,粒度分布负偏,峰态曲线尖窄.该区碎屑矿物中主要轻矿物为石英、斜长石、钾长石和方解石;主要重矿物有普通角闪石、绿帘石、阳起石、透闪石、褐铁矿、石榴子石和磁铁矿等.重矿物组合为普通角闪石+绿帘石,次圆状方解石是其特征矿物.鸣沙山石英颗粒磨圆度以次棱角状为主,棱角状次之,少量次圆状,极少圆状,由此推断其搬运距离较短,风化改造时间不长.石英磨圆度较差、颗粒间的空腔摩擦作用以及干旱的气候条件是响沙的原因.鸣沙山沉积物主要来源于研究区附近的变质岩系.鸣沙山的形成与该地受南、西、东三个主要风向的共同作用、南东两侧基岩山地阻挡以及区域内部干旱、河床干涸密切相关.

Singing Sand Mountain is mainly composed of fine sand and has the medium sorting characteristics and with a negatively skewness and leptokurtic distribution.The dominant light minerals are quartz,feldspar and calcite; and the dominant heavy minerals are hornblende,epidote,actinolite,tremolite,limonite,garnet and magnetite.The main assemblages of heavy minerals are hornblende-epidote,and characteristic mineral is calcite.The shapes and surface textures of quartz are mainly composed of the subangular because of the transport distance is shorter and weathering modification time is not long.The reasons of sand can sing include：quartz grinding roundness is poorer,the cavity friction effect between particles and the dry climate conditions.The sediments of the Singing Sand Mountain mainly come from the metamorphic rocks near the study area.The Singing Sand Mountain has three main formation factors：the influence of three main wind directions,the south east side bedrock mountain,drought and the river dried up in the study area.