黄土高原南部全新世土壤微结构形成机理探讨

通过对黄土高原南部不同剖面土壤微结构的研究和与相邻地区的对比 ,探讨了风化成土过程的特征 ,揭示出全新世土壤S0 是由上下两个土壤层组成的复合土壤 ,显示两个较完整的成土过程。早期成土阶段形成了具棕壤特征的古土壤S0 2 ,晚期成土阶段形成了淋溶褐土型古土壤S0 1 。土壤S0 以上的部分是风尘堆积增强时期形成的风积黄土层 ,但被人类耕作活动所扰动。

Genetic and micromorphological studies of the Holoence soil complex on the southern Loess Plateau

Detailed soil micromorphological analysisin Holoence loess-palaeosol profile in southern Loess Plateau, along with comparisons withanother profile nearby, the thesis discusses the characteristics of weathering and forming processes. It indicates that the micro-texture ofthe Holoence loess-palaeosol sequence is divided into both cementing texture including type 1, type 2 and type 3, and granular textureincluding type 4, type 5 and type 6.Cementing textureisalways in the palaeosol layers and was formed in warm-humid forest environment. Granular textureisalways in typical loess layers or weathering loess layers and was formed in a dry environment. It has been discovered that the palaeosol S 0 is separated into two distinct types of soils, namely palaeosols S 02 and S 01, because of the deposition of a layer (L x) inthe aridness. Soil S 0 substantively is a polycyclic soilthat is composed of two layers interbedding a loess layer, with two remarkable soil-formingprocesses. The lower soil S 02 is brown palaeosol, with the strongest argillification and eluviation, and was formed in early soil-forming phase. Argillic horizons were identified in the soil S 02. The upper soil S 01 is leached cinnamon palaeosol, with distinct argillification and weak calcification, and was developed in late soil-forming phase. The polycyclic soilS 0indicates that pedogenic environment has distinct variations. Cover layer above the polycyclic soilS 0is not a manured aggradated layer because of continuously piling up of loessial dung. It is a loess layer because of accelerated aeolian dust deposit. The cover is divided into both lower loess L 0weakly disturbed by cultivation activities and upper plough horizon strongly disturbed by cultivation activities. It indicates that it has been a relative arid period after the ending of formation of palaeosol S 0, with clear northwestmonsoon domino effect andaccelerated aeolian dust deposit. The polycyclic soilS 0 has been buried and become palaeosol of the Holoence.