Crystallinity, polytype, and morphology of clay minerals in the Luochuan loess-palaeosols in Shaanxi Province, northwest China were studied in order to have an insight into their origin using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) methods. The SEM observations showed that the morphology of some illites seems to be lath-shaped crystals. An analysis of illite crystallinity (IC) on the Luochuan section indicated that the origin of illite was related to the rocks of an anchizone. Most illite in the Luochuan loess-palaeosol section were of 2M1 polytype, but some were of 1M polytype formed by weathering of feldspar in the process of pedogenesis. Illite in the Luochuan section has undergone both physical and chemical weathering. These results revealed that most illite were of detrital origin related to the source area of an anchizone, but parts of the illite were of an authigenic origin formed during pedogenesis after sedimentation. Chlorites in the samples of the Luochuan section were mainly composed of irregular flaky grains and their crystallinity was good. These showed that chlorite had the detrital origin formed by physical weathering. Kaolinite crystallinity was relatively good. The value of CIA on the Luochuan section ranges from 61.9 to 69, and therefore kaolinite could not be formed during weathering and pedogenesis. These results indicated that the kaolinite had a detrital origin. Morphology of smectite seems to be capillaceous. The XRD patterns of all samples contained diffraction peaks at 1.5218 Å (nontronite) and 1.5052 Å (montmorillonite), thus indicating an intermediate composition between trioctahedral and dioctahedral smectite. The smectite crystallinity was very poor. These results revealed that smectite in the study area was authigenic rather than detrital origin.

为了研究X射线衍射（XRD）分析和扫描电子显微镜（SEM）方法对黏土矿物的结晶度，多型性和形态的影响，以了解其起源。SEM观察表明，某些伊利石的形态似乎是板条状晶体。通过对洛川剖面伊利石结晶度（IC）的分析表明，伊利石的成因与安息chi岩有关。洛川黄土古土壤剖面中的伊利石多数为2M1多型，但在成岩作用过程中由长石风化形成的伊利石多为1M多型。洛川段的伊利石经历了物理和化学风化。这些结果表明，大多数伊利石是与an兰花的来源地区有关的碎屑来源，但是伊利石的某些部分是沉积后成岩过程中形成的自生来源。洛川断面样品中的亚氯酸盐主要由不规则的片状晶粒组成，且结晶度良好。这些表明绿泥石具有由自然风化形成的碎屑源。高岭石结晶度相对较好。洛川断面的CIA值在61.9-69之间，因此在风化和成岩作用中不会形成高岭石。这些结果表明高岭石具有碎屑起源。蒙脱石的形态似乎是毛细的。所有样品的X射线衍射图谱均在1.5218Å（绿脱石）和1.5052Å（蒙脱石）处有衍射峰，因此表明在三八面体和二八面体蒙脱石之间存在中间成分。绿土的结晶度非常差。这些结果表明，研究区的蒙皂石是自生的，而不是碎屑的。