Abstract:

The circulation of rocks between the earth's crust and the asthenosphere is called the rock cycle. This change in rocks and minerals is the geological processes that play a role in the shaping of the earth's crust. Therefore, the determination of soil formation processes in different natural environments allows soil to be defined better than that. The objectives of the present work were to assess the physical, chemical and mineralogical characteristics and pedolojical processes responsible for soil genesis and soil classification of four volcanic soil profiles derived volcanic parent material and to study and compare the pedogenic evolution of these soils. To achieve this, soil samples were collected from the horizons to investigate their mineralogical, geochemical and physiochemical properties. Chemical alteration Index (CIA), (CIW), Parker weathering, Index (WIP), Product Index (PI), plagioclase Alteration Index (PIA), Bases / sesquioxide Rate (Base/R2O3) are used to compare the pedogenic processes as a case study . The pedogenic processes were also evaluated used to Mass-balance analysis to quantify elemental losses, gains and transformations for soils studied. Weathering index values were distributed in harmony with the geological age in all studied profiles. This shows that the soils in question are subjected to low intensity decomposition processes depending on time. Dominat soil-forming processes include 1. desilication and loss of base cations and Al from the solum, 2. transformation of iron and aluminum from sand and silt-size fractions to secondary clay and crystalline Fe minerals. The similar and limited variation of physical, chemical and mineralogical properties in pedons, and very limited variation of the weathering indexes and mass balance pattern across pedones indicate that pedones have similar levels of weathering. Our results imply that the rate of elemental mass-balance changes is determined by factors influencing its leaching altitude, facing sites, elevational gradient and time in the studied area.

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