西风区黄土–古土壤的碳酸盐含量对磁化率影响研究

本文选择伊犁盆地塔勒德黄土– 古土壤序列，系统地开展了沉积物碳酸盐和磁化率等指 标研究，初步探讨了伊犁黄土碳酸盐含量对磁化率增减的影响机制。研究发现，塔勒德古土壤 中低频磁化率值中明显低于黄土层，且较黄土高原古土壤值小，频率磁化率也远小于黄土高原； 碳酸盐含量在S₁ 层中含量明显高于黄土，且较黄土高原古土壤高，与剖面磁化率负相关，在古 土壤中相关度更显著。去除碳酸盐的设计实验显示加入蒸馏水后沉积物磁化率值变化在10％以 内；加入醋酸（HAc）后样品磁化率值均增加，其最大增幅达12.89%（黄土），古土壤的磁化 率增加9% 以上；加入稀盐酸后影响程度不一，在黄土中约在15%，而对古土壤影响较大，最大 可达35%，表明沉积物中碳酸盐含量对磁化率的影响不仅是简单的稀释作用，还与干旱气候环 境下碳酸盐化、次生碳酸盐化作用相关。

Study on the influence of carbonate content on magnetic susceptibility of Talede loess-paleosol sequences in westerly area of China

Based on the analysis of carbonate content and magnetic susceptibility of Talede loess-paleosol sequences, the influence mechanism of carbonate content on magnetic susceptibility variation of Ili basin was discussed primarily. The results show that low frequency magnetic susceptibility in paleosol was significantly lower than the value in loess of section and the Loess Plateau (LP). The frequency magnetic susceptibility of the section is far less than its in LP. In contrast, carbonate content in the paleosol S1 was higher than the content of loess of Talede section and the same layer of LP obviously. It is negatively related to magnetic susceptibility, especially in the paleosol. The design experiment of remove carbonate interpreted that magnetic susceptibility varies within 10% after adding distilled water. The magnetic susceptibility values of all samples increased added HAc, and the increment reaches as high as 12.89%, the magnetic susceptibility of paleosol increase more than 9%. The effects of carbonate content on magnetic susceptibility of the section were different after adding HCl. The change rate of loess samples is about 15%, while it is larger influence on the paleosol samples, up to 35%. These indicate that carbonate content is not only the dilution effect on the magnetic susceptibility, also associated the carbonation and secondary carbonatization under the arid climate environment.