The weathering of ferruginous chlorite in a podzol from argyllshire, Scotland

Abstract

The dominant mineral in the clay fractions from the basal horizons of a podzol developed on till derived mainly from chlorite-schists in Argyllshire is oxidized, iron-rich chlorite. Towards the profile surface, the chlorite decreases in amount, becoming absent in the A 2 horizon in which the dominant mineral is a complex dioctahedral interstratified phase formed from dioctahedral mica and composed of mica and vermiculite. The absence of any trioctahedral mineral in the A 2 horizon together with the marked loss of iron and magnesium from the clay fraction from this horizon indicates that the chlorite, a thuringite, has been destroyed, the only detectable product being goethite. In other apparently similar soils chlorite persists throughout the profiles. As the Eredine podzol contains translocated humus in the B 2 horizon, it is suggested that during podzolization, organic solutions percolated downwards from the surface, formed complexes with iron and aluminium from the chlorite structure, removing them to the B 2 horizon, and thus eventually dissolved out the chlorite from the A 2 horizon.