Identification of clay coatings in an older Quaternary Terrace of the Allier, Limagne, France.

摘要: Micromorphologically three types of coatings were observed in B horizons two planosol profiles (Albaqualfs): (a) nonlaminated isotropic limpid clay coatings, (b) anisotropic and (c) microlaminated dusty coatings. Micromorphological observations suggested that coating genetically similar, resulting from weathering neoformation. Coating type originated illuviation. Elemental compositions obtained with a scanning electron microscope-energy dispersive x-ray analyzer technique. Alumina contents decreased 38% to about 28% illuviation The Al content was inversely related K, Mg, Ca, Fe. Factor analysis indicated factors accounted for 56.5 22.8% the total elemental variance. first factor associated revealed antithetic behavior vs. Fe, 90% variability Al. second sample location explained >70% Ti Si. Chemical classification investigated samples based on similarity. Cluster same more alike than originating profile. About 83% grouped classified correctly as Clay minerals individual identified an step-scan method after sampling microquantities these microdrill. Anisotropic consisted illite kaolinite. however, found contain less Isotropic amorphous, suggesting presence Al-Fe-Si gel.