The FR value was calculated as 3.54 for sandy loam and 0.22 for silty clay (Table 2).
A difference was found in Sample M.17 from Mo-1, which doesn't contain Fe but present P. Another difference observed was the identification of a manganese compound in the form of 2 to 3 μm needles embedded in layers of clay (Table 1).
Open image in new window Fig. 4 XRD patterns of local clay Table 4 Chemical composition of VT Constituent SiO2 Al2O3 Fe2O3 CaO MgO SO3 K2O Na2O LIa Wt. 63.00 14.85 5.0.06.11 2.65.1406 5.14 0.06 7.8 aLoss on ignition.
The permeability is, however, related to factors other than depth such as grain size, detrital clay content and diagenetic development, including presence of cement and authigenic clays (Table 1).
The average texture of the soil at 45 cm depth in the study site was clay loam (Table 2).
The main oxides based on elemental analysis of the local clay composition (Table 4) are silica (63%), aluminum (≈15%) and iron (≈5%).
It contains 13 wt% quartz, 23 wt% feldspar, and ≈ 12 wt% hornblende as clastic grains, and 32 wt% smectite, ≈6 wt% illite, 1.5 wt% chlorite, and ≈ 3 wt% kaolinite as clay minerals (Table 2).
It contains 32 wt% quartz, ≈39 wt% feldspar, and ≈ 9 wt% hornblende as clastic grains; ≈13 wt% calcite as the cementing material; and 3.3 wt% illite and 2.7 wt% kaolinite as clay minerals (Table 2).
It contains ≈ 64 wt% volcanic glass, ≈8 wt% quartz, and ≈ 8 wt% feldspar as clastic grains, and ≈ 12 wt% smectite, ≈3 wt% illite, and ≈ 2 wt% kaolinite as clay minerals (Table 2).
The relatively high concentrations of MgO, Na2O, CaO, and K2O in the raw bentonite indicates that Mg2+, Na+, Ca2+, and K+ are the main exchangeable cations in the clay interlayers (Table 1).
It contains ≈ 32 wt% quartz and ≈ 32 wt% feldspar as clastic grains, ≈5 wt% calcite as microfossil grains, and ≈ 22 wt% smectite, ≈5 wt% illite, and ≈ 3 wt% kaolinite as clay minerals (Table 2).
