Premium
THE RESIDUA SYSTEM OF CHEMICAL WEATHERING: A MODEL FOR THE CHEMICAL BREAKDOWN OF SILICATE ROCKS AT THE SURFACE OF THE EARTH
Author(s) -
CHESWORTH WARD
Publication year - 1973
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1973.tb00742.x
Subject(s) - weathering , kaolinite , silicate , geology , gibbsite , mineralogy , earth (classical element) , goethite , silicate minerals , quartz , clay minerals , geochemistry , earth materials , facies , chemistry , geomorphology , soil science , adsorption , structural basin , paleontology , physics , organic chemistry , mathematical physics
Summary The residua system of chemical weathering is here defined as the chemical sink towards which the bulk of earth's surface materials (i.e. the silicate rocks) trend during weathering. Chemically the system is defined in terms of four major components, SiO 2 –Al 2 O 3 –Fe 2 O 3 –H 2 O, evidence being derived from relative solubilities of components under earth‐surface conditions; from experiments in which weathering environments have been simulated in the laboratory; and from field studies of rocks and their weathered mantle. The residua system can be used as a framework to construct mineral facies diagrams showing assemblages of the commonest earth‐surface minerals that occur within it: quartz, gibbsite, goethite, kaolinite, halloysite. In a qualitative manner the facies diagrams can then be interpreted in terms of the partial pressure of water (PH 4 O) and the temperature, T. The usefulness of this approach in systematizing studies of soil genesis is illustrated with reference to the weathering of granite.