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Experimental Evidence on the Origin of Vermiculite in Soils on Lower Palaeozoic Sediments
Author(s) -
Adams W. A.
Publication year - 1976
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/sssaj1976.03615995004000050046x
Subject(s) - vermiculite , chlorite , weathering , paleozoic , soil water , geology , podzol , illite , clay minerals , geochemistry , eluvium , mineralogy , soil science , quartz , paleontology
Vermiculite occurs as a pedogenetic product in soils on Lower Palaeozoic sediments in mid‐Wales. Iron‐rich chlorite and dioctahedral illite, both of which are present in these sediments, are possible precursors. Field evidence on the occurrence of vermiculite indicates an increase in vermiculite coincident with chlorite weathering and a maximum vermiculite content in moderately weathered horizons. The vermiculite content of highly weathered eluvial and organic horizons of podzols is low. Using an oxidation procedure involving Na 2 Cr 2 O 7 it was possible to transform chlorite to a vermiculite having similar X‐ray diffraction properties to soil vermiculite. The transformation was demonstrated on intact clay‐sized fractions of a Silurian mudstone and on chlorite separated electromagnetically from a soil derived from Lower Palaeozoic sediments.