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通过对郧县前坊村黄土剖面常量元素及相关参数分析,采用Al为标准的变化率参数计算。结果表明:(1)古土壤S0形成时期,土壤磁化率、粘粒成分、CIA值较典型黄土L1高,Na/K值低于典型黄土L1。这表明古土壤形成时期,气候温暖湿润,土壤风化淋溶较强,反映了较强的成壤过程,在黄土堆积时期气候相对干冷,沙尘暴频繁出现,土壤的成壤作用较弱;(2)碳酸盐含量的剧烈变化是影响黄土元素分布特征很重要的因素,其中,一些元素如Mn和Fe在剖面中的含量较高,主要是碳酸盐被强烈淋溶造成的相对富集;(3)前坊村剖面中,常量元素风化成土过程中,Na、Ca、Mg、K、Si和Ti在古土壤S0为主要迁移元素,其迁移顺序为:Na>Ca>Mg>K>Si>Ti;Mn和Fe表现的轻微富集;常量元素的迁移特征指示了汉江上游谷地黄土已经完成初级的脱Ca、Na阶段,应进入了早期去K的中等风化阶段。
Based on the analysis of the major elements and related parameters of loess section in Qianfangcun, Yun County, Al was used as the standard rate of change parameter. The results show that: (1) The soil magnetic susceptibility, clay content and CIA value are higher than the typical loess L1 and the Na / K value is lower than that of the typical loess L1 during the formation of paleosol S0. This indicates that during the formation of palaeosol, the climate was warm and humid, and the weathering and leaching of soil was relatively strong, which reflected a strong process of soil formation. During the period of loess accumulation, the climate was relatively dry and cold with frequent occurrence of dust storms and weak pedogenesis. (2) The dramatic change of carbonate content is a very important factor that affects the distribution characteristics of loess elements. Some elements such as Mn and Fe are high in the profile, mainly due to the relative enrichment caused by carbonate leaching. 3) In the Qianfangcun section, Na, Ca, Mg, K, Si and Ti are mainly migrated in the soils of ancient soils in the process of weathering of the major elements. The order of migration is Na> Ca> Mg> K> Si> Ti; slight enrichment of Mn and Fe; and the migration characteristics of the major elements indicate that the primary Loess-Ca and Na stages have been completed in the upper loess valley of the Hanjiang River and should enter the middle-stage of weathering that goes to K in the early stage.