Micromorphological Properties Of Al-fe- Humus Soils Of The North Taiga Of Western Siberia


I. V. Kritskov, S. V. Loiko, L. I. Geras'ko, G. I. Istigechev, D. M. Kuzmina

Soil-forming rocks rock of the territory being researched consists of layers of polymict sands which is distinctly visible in the soil profile of present-day soil. The prevalent components of the sandy rocks are minerals resistant to weathering, namely quartz and feldspars. One can observe a high content of minerals that do not participate in the soil formation process; their amount can reach up to 90% of the sample’s weight. Minerals susceptible to weathering are featured in the altered feldspars which are comprised of a mixture of acid plagioclase grains partially or completely replaced by sericite particles. These particles are susceptible to various degrees of weathering due to mineralogical compositional heterogeneity. A sample of the sandy fraction was compared with the microscopic structure of soil particles selected from the primary genetic horizons. Due to the acid hydrolysis, the diagnostics of the primary mineral weathering was conducted based on eluvial horizons, where the crystal lattice of the mineral is most actively destroyed through the influence of acidic solutions, which results into a series of cavities in the dissolution area. Two main types of particle dissolution were identified and the connection between the type of weathering and soil composition was established. The intensity of illuviation was examined through the morphology of iron hydr/oxide films, as well as the description of their amount, shape, and structure. A characteristic of the primary soil processes featuring the description of the surfaces of mineral particles was revealed. In addition, current primary processes were identified; specifically, Al-Fe-humus process and superficial gleying process. A comparison between the eluvial horizon sandy particles and the particles of the parent rock material indicates a small number of mechanisms transforming them via soil processes. Consequently, coarse particles retain a greater volume of lithogenic memory.

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