罗布泊盐湖表层土地球化学及沉积特征

对罗布泊典型地区表层土磁性特征、粒度及地球化学特征的研究表明:(1)总体样品磁性矿物含量均较低;各样地间磁化率差异较为明显,阿奇克谷地西部磁化率值最高(2.1×10^-7 m³·kg^-1),耳轮区最低(0.47×10^-7 m³·kg^-1),该区磁化率值总体表现为东部略高于西部.(2)样品粒度组分总体以粉砂(2~63 μm)为主,平均约占74.17%,分选性较差,细颗粒占主导地位,且各粒度组分之间的含量变化幅度较小.(3)易溶性盐主要是由Cl^-、SO₄^-2、Na⁺和K⁺构成,Mg²⁺、Ca²⁺含量较低,HCO₃^-、CO₃^2-含量很低,易溶性盐类型主要为Cl^--SO₄^-2-Na⁺和K⁺型;样品总有机碳平均含量约为0.66%;pH值变化范围为6.98~8.00,且耳轮区样品值均高于阿奇克谷地西部.综上所述,该区当时气候已转向干旱化趋势发展,而且气候持续干化与补给变化对该区物质形成具有一定影响,是该区物质空间分布的主要成因.

The Characteristics of Geochemistry and Sedimentary of Surface Soil in the Salt Lakes of Lop Nor

The characteristics of magnetic and grain-size and geochemistry in surface soil of the Lop Nor area were investigated. The results showed that: (1)All samples of Magnetic mineral content were lower;there are obviously different magnetic susceptibility in different places, the maximum value of magnetic susceptibility was 2.1×10^-7 m³·kg^-1 in the Aqike Valley West, the minimum value was 0.47×10^-7 m³·kg^-1 in the helix region, overall, the magnetic susceptibility values of the eastern was slightly higher than the western in the Lop Nor Area. (2)Component of grain size in the sample was mainly silt sand (2-63 μm), the average wass 74.17%, poorly sorted,dominate particles was fine particles,and there were small magnitude changes between each particle size fractions. (3)Soluble salts were mainly composed of Cl^-, SO₄^2-, Na⁺ and K⁺, Mg²⁺, Ca²⁺ were lower content, and the lowest were HCO₃^- and CO₃^2-, the soluble salt type was mainly Cl^--SO₄^2--Na⁺ and K⁺; the average content of TOC was about 0.66%, the pH value ranged between 6.98-8.0, there were in alkaline environment, and the values in the helix region were higher than in west of Aqike Valley. To sum up, the area of climate had shifted to the drought trend, and continuous dry climate and supply variation had certain effect on the material form, this would be the main cause of the material distribution in this area.