柴达木盆地不同沉积区灌丛沙堆形态与沉积特征

柴达木盆地是我国风沙活动强烈地区.本文选择柴达木盆地灌丛沙堆,通过典型样方调查和剖面采样分析,从形态特征及剖面CaCO_3、有机质、粒度等差异对柴达木盆地灌丛沙堆发育背景进行探讨.结果表明:灌丛沙堆的长、宽、高等形态参数之间均呈现较好的相关性,高度与水平尺度、侧影面积与体积的拟合曲线及野外观测显示,湖滨地区灌丛沙堆处于增长阶段,洪积扇灌丛沙堆处于稳定阶段,绿洲边缘的坡洪积堆积区灌丛沙堆处于衰亡阶段;宗家镇和下西台灌丛沙堆沉积以细砂为主,局部存在突变现象;灌丛沙堆中CaCO_3含量与有机质含量相关性较大,CaCO_3含量高值和低值可能比有机质相应值深20~35cm,表明CaCO_3可能主要是由地下水和淋溶共同作用的结果.

Morphology and sediments of nabkha in Qaidam Basin

Qaidam Basin of China is a region of strong sandstorm activities.Typical quadrat and sediment sampling of nabkhas in Qaidam Basin was used in the present work.Development background of nabkhas was analyzed by morphology,CaCO3 ,organic matter and particle size.Data indicated good correlations among length,width and altitude of nabkhas,curve fiting showed that nabkhas around the lake was at the growth stage,in the diluvial fan areas was at the mature and stable stage,around the oasis was at the decline stage;geographic conditions and sand source affected nabkhas development.The profile sediments of nebkhas were mainly composed of fine sands in both Zongjiazhen and Xiaxitai,but local mutation phenomenon existed. Mutations of Zongjiazhen may be associated with short weak soil;then mutations of Xiaxitai may be associated with strong sandstorm activities.CaCO3 content and organic matter showed good correlation.As for the high value and the low value,CaCO3 content existed 20~35 cm deeper,results showed that CaCO3 was mainly produced by eluviation and underground water.