Abstract:Primary minerals of the parent material undergo weathering during the formation of terrestrial soils to varying extent. As a result, secondary minerals develop, which comprise, among many others, hydroxy-interlayered minerals (HIMs). These minerals have formed by interlayering of hydroxy-metal complexes (especially of Al 3+ , also Mg 2+ , Fe 2+/3+ ) into micas, expansible 2:1 phyllosilicates and forming oligomers, or by weathering of primary chlorite. The degree of interlayer filling and the stability of these… Show more
“…When taking into account the high instability of vermiculite under acidic conditions, the low pH and low amount of HIV as a weathering product of vermiculite in the studied profile, the estimated time after decarbonization in the profile based on the Finke and Hutson's (2008) simulations becomes more realistic. In agreement with the published results (reviewed by Wilson, 1999 andGeorgiadis et al, 2020), our findings (Figure 8a,b, Tables 3 and 4) pointed out the following clay mineral assemblage: illite, chloritevermiculite -HIVsmectite is on the boundaries of mineral stability. Our interpretation partly correlates with the rate of the Luvisol-forming processes, which is based on the method of chronosequences, similarly to Alexandrovskiy (2007).…”
Section: Discussionsupporting
confidence: 93%
“…A noticeable peak at about 7.5 2θ (1.18 nm) after EG solvation, however, could indicate long-range ordering R3 illite-smectite (Moore & Reynolds Jr, 1997). The HIM (hydroxy-interlayered mineral) is positioned around 7.4-7.85 2θ; 1.2-1.13 nm in magnesium and potassiumsaturated samples after heating to 300 and 550 C (Figure 8a,b; Rich, 1968;Georgiadis, Dietel, Dohrmann, & Rennert, 2020).…”
Section: Resultsmentioning
confidence: 99%
“…The hydroxy-interlayered minerals are formed by the interlayering of hydroxy-metal complexes (especially of Al 3+ , where its source could be surrounding silicates or vermiculite alone) into an expansible interlayer, forming oligomers. HIMs are represented by hydroxy-interlayered smectite (HIS) or hydroxyinterlayered vermiculite (HIV; reviewed by Georgiadis et al, 2020). The vermiculite is the most unstable phase of silicates in the investigated profile; hence, we assume that the presented hydroxyinterlayered phase is HIV.…”
The character of parent material, organic matter and climatic conditions are the crucial factors of pedogenesis. They directly influence the intensity of weathering, transformation processes, elements release and geochemical cycles. The mineral transformation in a profile of the recent soil developed on loess (Haplic Luvisols, Siltic, Epidystric, Ochric) was studied. The land area Litovelské Pomoraví was chosen because of the stability of soil‐forming factors such as topography, relief, vegetation and climate. X‐ray diffraction (XRD) quantitative analysis of the fine earth (<2 mm) and XRD analysis of clay (<2 μm) and the fine clay fraction (<0.2 μm) were applied. The obtained results showed the most significant differences between the argic horizons (Bt1 and Bt2) and other soil horizons. The lower content of quartz and feldspars and higher content of dioctahedral micas and phyllosilicates in both Bt horizons was observed. It was assumed the clay illuviation/lessivage process was preceded by long‐term leaching of carbonate in humid continental conditions during almost the whole Holocene. The distribution of the clay fraction correlates with the distribution of phyllosilicates through the profile. Major clay minerals in the clay fraction (<2 μm) were illite and kaolinite, smectite, chlorite, vermiculite and several types of mixed‐layered phases. The analysis of the finer clay fraction (<0.2 μm) identified the new phase hydroxy‐interlayered minerals as the product of illite (vermiculite) weathering in humid continental conditions.Highlights
Clay mineralogy of Haplic Luvisols on loess was studied.
XRD analysis identified the new phase of hydroxy‐interlayered minerals.
Increasing of smectites, dioctahedral micas, and goethite as a result of clay illuviation/lessivage process was observed.
“…When taking into account the high instability of vermiculite under acidic conditions, the low pH and low amount of HIV as a weathering product of vermiculite in the studied profile, the estimated time after decarbonization in the profile based on the Finke and Hutson's (2008) simulations becomes more realistic. In agreement with the published results (reviewed by Wilson, 1999 andGeorgiadis et al, 2020), our findings (Figure 8a,b, Tables 3 and 4) pointed out the following clay mineral assemblage: illite, chloritevermiculite -HIVsmectite is on the boundaries of mineral stability. Our interpretation partly correlates with the rate of the Luvisol-forming processes, which is based on the method of chronosequences, similarly to Alexandrovskiy (2007).…”
Section: Discussionsupporting
confidence: 93%
“…A noticeable peak at about 7.5 2θ (1.18 nm) after EG solvation, however, could indicate long-range ordering R3 illite-smectite (Moore & Reynolds Jr, 1997). The HIM (hydroxy-interlayered mineral) is positioned around 7.4-7.85 2θ; 1.2-1.13 nm in magnesium and potassiumsaturated samples after heating to 300 and 550 C (Figure 8a,b; Rich, 1968;Georgiadis, Dietel, Dohrmann, & Rennert, 2020).…”
Section: Resultsmentioning
confidence: 99%
“…The hydroxy-interlayered minerals are formed by the interlayering of hydroxy-metal complexes (especially of Al 3+ , where its source could be surrounding silicates or vermiculite alone) into an expansible interlayer, forming oligomers. HIMs are represented by hydroxy-interlayered smectite (HIS) or hydroxyinterlayered vermiculite (HIV; reviewed by Georgiadis et al, 2020). The vermiculite is the most unstable phase of silicates in the investigated profile; hence, we assume that the presented hydroxyinterlayered phase is HIV.…”
The character of parent material, organic matter and climatic conditions are the crucial factors of pedogenesis. They directly influence the intensity of weathering, transformation processes, elements release and geochemical cycles. The mineral transformation in a profile of the recent soil developed on loess (Haplic Luvisols, Siltic, Epidystric, Ochric) was studied. The land area Litovelské Pomoraví was chosen because of the stability of soil‐forming factors such as topography, relief, vegetation and climate. X‐ray diffraction (XRD) quantitative analysis of the fine earth (<2 mm) and XRD analysis of clay (<2 μm) and the fine clay fraction (<0.2 μm) were applied. The obtained results showed the most significant differences between the argic horizons (Bt1 and Bt2) and other soil horizons. The lower content of quartz and feldspars and higher content of dioctahedral micas and phyllosilicates in both Bt horizons was observed. It was assumed the clay illuviation/lessivage process was preceded by long‐term leaching of carbonate in humid continental conditions during almost the whole Holocene. The distribution of the clay fraction correlates with the distribution of phyllosilicates through the profile. Major clay minerals in the clay fraction (<2 μm) were illite and kaolinite, smectite, chlorite, vermiculite and several types of mixed‐layered phases. The analysis of the finer clay fraction (<0.2 μm) identified the new phase hydroxy‐interlayered minerals as the product of illite (vermiculite) weathering in humid continental conditions.Highlights
Clay mineralogy of Haplic Luvisols on loess was studied.
XRD analysis identified the new phase of hydroxy‐interlayered minerals.
Increasing of smectites, dioctahedral micas, and goethite as a result of clay illuviation/lessivage process was observed.
“…These result from weathering of primary silicates in a geochemical milieu typical of early Podzol development, i.e. pH approximately > 4.5, which prevents acidic dissolution of 2:1 layers of phyllosilicates 47 . Despite the limited duration of the experiment, mimicked weathering of the topsoil showed that masking phases were easily removed.…”
Podzols are characterised by mobilisation of metals, particularly Al and Fe, and dissolved organic matter (DOM) in topsoil horizons, and by immobilisation in subsoil horizons. We mimicked element mobilisation during early podzolisation by irrigating the AE horizon of a Dystric Arenosol with acetic acid at different flow velocities and applying flow interruptions to study rate-limited release in experiments with soil cylinders. We used eluates in batch experiments with goethite and Al-saturated montmorillonite to investigate DOM reactivity towards minerals. Both the flow velocity and flow interruptions affected element release, pointing to chemical non-equilibrium of release and to particles, containing Fe and OM mobilised at larger flow velocity, characteristic of heavy rain or snowmelt. Based on chemical extractions, the source of mobilised Al and Fe, the vast majority of which was complexed by DOM, was no oxide phase, but rather organic. Rate limitation also affected the composition of DOM released. Carboxyl and phenolic species were the most important species adsorbed by both minerals. However, DOM composition affected the extent of DOM adsorption on goethite more distinctly than that on montmorillonite. Our findings evidence that the intensity of soil percolation affects quantitative and qualitative element release during early podzolisation and adsorptive DOM retention in subsoil horizons.
“…Andrade et al (2019) ascribed the formation of HIMs to high rates of Al release during pedogenic weathering under acidic soil conditions, which influenced the interlayering of Al-polymers in the clay minerals. Interlayering is a common phenomenon in pedogenic 2:1 clay minerals, in which the interlayer materials include cations, hydrated cations, organic molecules, and hydroxide groups or sheets (Meunier 2007;Dietel et al 2019aDietel et al , 2019bGeorgiadis et al 2020). According to Rich (1968) and Meunier (2007), HIV is a fast-forming and unstable phase representing a moderately acidic and oxidizing condition that is often linked to frequent wet-dry cycles.…”
Section: Coupling Between Soil Acidity Pools and Hiv Formationmentioning
Clay-mineral evolution in supergene environments is commonly a complex process subject to hydrologic influences on clay-mineral transformations, yet these
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