Pla (1997), modeling a slope characteristic of the Western Andes of Venezuela, found that simple reforestation of a degraded pasture was not sufficient to prevent landslides--hydraulic conductivity was so low in the argillic
horizon of Ultisols that drainage ditches were required to prevent saturation-induced translational failure.
The southern part of the Deccan Peninsula in India is mainly occupied by reddish sandy soils with clay accumulation horizons (argillic
) dominated by kaolinites, illites and lesser fractions of montmorillonite, mixed with iron oxides.
Creston's mineralisation is accompanied by silicification, decalcification and possible argillic
alteration of the host rocks.
Farellon and the eastern portion of Coipa Norte possess high gold grades associated with advanced argillic
alteration and are hosted mainly by Triassic sedimentary rocks.
The Dragon Tale prospect comprises significant silver-zinc-copper mineralization exposed in argillic
sedimentary rocks along more than 0.5 km of roadcuts.
Hydrothermal alteration ranges from extensive intermediate alteration, through widespread sericitic (phyllic) alteration, to advanced argillic
alteration in the higher levels.
Preliminary spectral (PIMA) alteration analysis of the mineralized drill intersections show the Au+Ag mineralization is directly associated with vuggy and hydrothermal silica, localized within zones of strong advanced argillic
(kaolinite-dickie-alunite) alteration, possibly representing feeder zones.
Therefore, in many cases an exposed argillic
horizon was observed in the surface.
In field B, the predominant map unit, the Hilleman series, does not meet the taxonomic definition as natric; however, its pedon description clearly indicates that the soil has excessive Na levels at depths below the top 40 cm (16 in) of the argillic
Anyway, these soils are very rare in the Alpine layer, showing that the illuviation of clays to form differentiated accumulation horizons--argic (FAO) or argillic
(ST) horizons--takes more than 10,000 years.
There are extensive areas of silicification and argillic
alteration with sulphur deposits.
These typically exhibit zonation of alunitic to propylytic "argillic
" mineralization with extensive silicification and pyritization.