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Micromorphology and Mineralogy of Illuviated Clay in a Davidson Soil
Author(s) -
Goenadi Didiek H.,
Tan Kim H.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300030056x
Subject(s) - saprolite , kaolinite , geology , weathering , clay minerals , horizon , mineralogy , argillic alteration , soil horizon , geochemistry , feldspar , pedogenesis , soil water , soil science , volcanic rock , quartz , physics , volcano , astronomy , paleontology
Clay illuviation was studied in a highly weathered soil of the Southern Piedmont by macro‐ and micromorphological techniques. Five pedons of a Davidson soil (Rhodic Paleudult) were sampled from four counties for preparation of thin sections and analysis of soil matrix, illuviated clay and argillans. The related distribution pattern of the soil fabric in the epipedon was different than that in the argillic horizon or saprolite. A single‐spaced porphyric fabric was found in the A horizon, which had no illuvial clays. The argillic horizon exhibited an open‐spaced porphyric fabric with illuvial clay ranging in concentrations from 2.4 to 5.6%. A double‐spaced porphyric fabric was noticed in the saprolite, which contained 1.4% illuvial clay. X‐ray diffraction analysis of clays in the soil matrix vs. argillans showed strong evidence for kaolinite as the major mineral eluviated from the upper horizon. The data also suggested that, in the argillic horizon, kaolinite was formed in situ through alteration of K‐feldspar minerals. The relatively high contents of kaolinite and iron‐oxide minerals, together with the presence of prominent argillans in the argillic horizons, indicated that the soil has undergone an intensive weathering and leaching process.