The occurrence of lamellae in soils and sediments has direct implications for agricultural production, and for stratigraphic and geomorphological studies. Although lamellae have been studied for more than a century, their origin remains controversial. The aim of this study was to identify the origin and formation mechanisms of lamellae in autochthonous soils developed from metamorphic rocks in a semi-arid area of Northeast Brazil. As such, the spatial organization of soil profiles was evaluated in a topolithosequence, through structural analysis of the pedological coverage for subsequent soil sampling. Morphological, chemical, physical, sedimentological, mineralogical, and micromorphological analyses were carried out on the studied slope and in greater detail in four soil profiles. The results indicated that clay particles predominantly smaller than 0.2 µm are eluviated in a sandy soil matrix, infilling voids and coating quartz grains, which are organized in layers of densely packed fine sand, impeding clay translocation and helping form lamellae. Although the micromorphological properties of the lamellae demonstrate their pedogenic origin, the contribution of strips of polycrystalline quartz constitutes a petrogenic component of the illuviation process. Therefore, the genesis of the lamellae is better described based on a petro-pedogenic origin. We suggest a restructuring of the concept of petro-pedogenic origins, including the structural influence of metamorphic rocks, as illuviated clay deposition occurs in accordance with a physical barrier provoked by the increase and organization of fine sand particles, distributed horizontally and in parallel, arising from the disintegration of polycrystalline quartz grains, which indicates geological control in the genesis of lamellae, corresponding to petrogenic evidence. Furthermore, the morphological distinction of the lamellae seems to be more associated with the fine sand content (<0.25 mm), and its packing with larger grains of quartz in the soils.

土壤和沉积物中薄片的出现对农业生产以及地层和地貌研究具有直接影响。尽管薄片已经研究了一个多世纪，但它们的起源仍然存在争议。本研究的目的是确定巴西东北部半干旱地区变质岩发育的本土土壤中片层的起源和形成机制。因此，通过土壤覆盖的结构分析，土壤剖面的空间组织在一个拓扑序列中进行了评估，以用于随后的土壤采样。对所研究的斜坡进行了形态学、化学、物理、沉积学、矿物学和微形态学分析，并在四个土壤剖面中进行了更详细的分析。结果表明，主要小于 0.2 µm 的粘土颗粒在沙质土壤基质中被淋洗，填充空隙并覆盖石英颗粒，这些颗粒组织成密实的细砂层，阻碍粘土易位并帮助形成片层。虽然薄片的微形态特性证明了它们的成土起源，但多晶石英条的贡献构成了冲积过程的成岩成分。因此，基于岩石成土起源更好地描述了薄片的起源。我们建议重构岩石成因起源的概念，包括变质岩的结构影响，因为发光的粘土沉积是根据细砂颗粒的增加和组织引起的物理屏障发生的，水平平行分布，由多晶石英颗粒解体产生，表明在片层形成过程中受地质控制，对应于成岩证据。此外，薄片的形态差异似乎与细砂含量（<0.25 毫米）及其在土壤中填充较大的石英颗粒有关。