SUMMARY

Using TEM-EDX to study about illite - smectite transformation

in Di Linh bentonite, Lâm Đồng province

Phạm Thị Nga, Jörn Kasbohm,

Nguyễn Thanh Lan, Nguvễn Ngọc Nam, Hoàng Thị Minh Thảo

Mineral characterization of Di Linh bentonite was carried out by XRD, TEM methods. Especially, chemical composition of clay particles identified by TEM-EDX measurements showed an illite-smectite transformation, which has been mainly effected by natural weathering processes. Platy illite was altered to cloudy aggregates of dioctahedral vermiculite-montmorillonite interstratifications from the margin to the center of the particle. Smectitic layer proportion of the part located in the margin is higher than that of the Central, corresponding to a higher Fe content and a lower K content. This smectitization may be caused by the oxidation of Fe²⁺ into Fe³⁺ happened in illite structure so that the bonding strength between layers was reduced. Consequently, K⁺ in the interlayer space was removed and substituted by other ions or water to form smectite. In additions, the weathering processes also removed AI in octahedral sheet and then exotic Fe was introduced.

Người biên tập: TS. Vũ Lê Tú