库布齐沙漠地表沉积物常量元素与粒度的关系

Relationship between constant elements and granularity of the surface sediment in the Kubuqi Desert

地表沉积物的风化过程引起元素在各粒级间的迁移或富集,采用粒度分级可以深度解释元素与粒度的关系。选取库布齐沙漠不同植被盖度测定粒度分布特征分级情况下的元素含量。结果表明:(1)库布齐沙漠以细砂和极细砂为主(二者占比85%以上),常量元素以SiO_(2)、Al_(2)O_(3)为主(二者占比80%以上且呈相反关系),其他元素含量较低;不同粒级组分元素富集情况不同。(2)表层沉积物的化学蚀变指标CPA(60.2~85.9)、CIA(28.08~53.06)值显示该区域处于未风化或弱风化状态;研究区表现为富SiO_(2)、CaO、Fe_(2)O_(3)、K_(2)O、TiO_(2)贫Al_(2)O_(3)、Na2O现象;SiO_(2)、K_(2)O与粒径段呈显著正相关,Fe_(2)O_(3)、CaO、Al_(2)O_(3)、MgO、TiO_(2)与粒径段呈显著负相关,Na2O不受粒度控制。(3)分级前,CaO、SiO_(2)、MgO、TiO_(2)与粒径有相关性;分级后,SiO_(2)、K_(2)O、Fe_(2)O_(3)、CaO、Al_(2)O_(3)、MgO、TiO_(2)均与粒径段具有一定的相关性,细化分级后确实能解读更多蕴含在元素中的信息。

The weathering process of surface sediments causes the migration or enrichment of elements in each grain level.Granularity classification can deeply explain the relationship between elements and granularity.The coverage of different vegetation in the Kubuqi Desert was selected to determine the element content of grain size distribution characteristics.The results show that:(1)The Kubuqi Desert is mainly dominated by fine sand and extremely fine sand(both account for more than 85%),and the constant elements are mainly SiO_(2) and Al_(2)O_(3)(accounting for more than 80%and showing the opposite relationship),while other elements have low content;the enrichment of different granular components is different.(2)CPA(60.2-85.9),CIA(28.08-53.06)value of surface sediment shows that the area is in unweathered or weakly weathered state;the study area shows rich SiO_(2),CaO,Fe_(2)O_(3),K_(2)O,TiO_(2) poor Al_(2)O_(3) and Na2O;SiO_(2) and K_(2)O are significantly positively correlated with particle size,Fe_(2)O_(3),CaO,Al_(2)O_(3),MgO and TiO_(2) are significantly negatively correlated with particle size,and Na2O is not controlled by particle size.(3)Before classification,the four elements of CaO,SiO_(2),MgO and TiO_(2) are related with the particle size;after classification,SiO_(2),K_(2)O,Fe_(2)O_(3),CaO,Al_(2)O_(3),MgO and TiO_(2) all have certain correlation with the particle size segment,detailed grading can indeed interpret more information contained in the elements.