A Toposequence of Alpine Soils on Calcareous Micaschists, Northern Adula Region, Switzerland

Abstract

On calcareous micaschists in the northern Adula Region, Switzerland, brown soils are formed under grasses and herbs at altitudes below 2000 m. Podzols occur below Ericaceae below 2000 m and are formed irrespective of vegetation above this altitude. Calcimorphic soils are not found. Brown soils have a stable clay mineral association of chlorite and mica, while in the A horizons of podzols and in initial podzols alteration of chlorites to smectites occurs.

Clay minerals formed from micas and chlorites in some New Zealand soils

“…These might include chlorite-smectites with XRD peaks at 28 A for the air-dried Mgsaturated state, at 32 ~ for the glycerated state, at between 24 and 28 ~, for K-saturated air-dried samples and at 24 and/or 22 ~ for heated samples. Mica-chlorites, regarded as important phases in some Swiss alpine soils, where they were characterized as non-expanding 24 A phases (Buurmann et al, 1976), could also have escaped recognition in the present soils. The difficulty of drawing clear boundaries between these differentlynamed species and of identifying each of them in a mixture supports Millot's (1970) contention that 'these words are without doubt applied to a reality with more nuances than the rigorous definitions of these words would have us believe' and that 'a succession of several distinct terms, assuming they are appropriate, encompasses a reality which is more nearly continuous'.…”

“…Such a phase, which would be trioctahedral, has been reported to form from chlorite on weathering (Loveland & Bullock, 1975;Ross & Kodama, 1976). In addition, a study of Swiss alpine soils formed on schists led Buurmann et al (1976) to conclude that smectites therein had formed from chlorites. Such smectites would be montmorillonitic, according to Buurmann et al, and not beidellitic as were the smectites in, for example, Ross& Mortland's (1966) andCampbell's (1975) Studies, and in the present study.…”

“…Such smectites would be montmorillonitic, according to Buurmann et al, and not beidellitic as were the smectites in, for example, Ross& Mortland's (1966) andCampbell's (1975) Studies, and in the present study. Few, if any, other workers except Buurmann et al (1976) have proposed that chlorites are transformed to smectites in soils. Many (Kodama & Brydon, 1968;De Coninck et al, 1975;Bain, 1977), like the present author, note the disappearance of chlorite with increased weathering.…”

“…The variety and complexity of the products of weathering transformations of micas and chlorites have been described by many workers (Rich, 1956;Gjems, 1960Gjems, , 1963Gjems, , 1970Wilson, 1970;Campbell, 1975;De Coninck et al, 1975;Loveland & Bullock, t975;Moberg, 1976;Buurmann et al, 1976;Bain, 1977). The present paper describes some effects of the major soil-forming factors of vegetation and formation time upon the mineral transformations of some micas and chlorites by comparing the clay mineralogies of a number of New Zealand soils which have been arranged in pairs into two similar vegesequences and an approximate chronosequence.…”

Characterization and Genetic Interpretation of Clays in an Acid Brown Soil (Dystrochrept) Developed in a Granitic Saprolite

“…The weathering end products in the Bw and A2 horizons were not beideUite, as has been reported in other studies (Wilson, 1987). Buurman et aL (1976) have shown that smectites that had formed from chlorite in alpine soils were montmoriUonite.…”