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QUANTIFICATION OF WEATHERING, SOIL GEOCHEMISTRY AND SOIL FERTILITY
Author(s) -
KRONBERG B. I.,
NESBITT H. W.
Publication year - 1981
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.1365-2389.1981.tb01721.x
Subject(s) - weathering , kaolinite , illite , feldspar , geology , mineralogy , clay minerals , geochemistry , gibbsite , soil production function , continental crust , quartz , pedogenesis , soil water , soil science , paleontology , mantle (geology)
Summary Continental chemical weathering is discussed with reference to a diagram, in which the ratio (CaO + Na 2 O + K 2 O)/(Al 2 O 3 + CaO + Na 2 O + K 2 O) is plotted against the ratio (SiO 2 + CaO + Na 2 O + K 2 O)/(Al 2 O 3 + SiO 2 + Na 2 O + K 2 O). The former ratio is a measure of the degree of feldspar breakdown, which is accompanied by the formation of secondary minerals (illite, smectite, etc. ). The second ratio is a measure of the enrichment during weathering of Al, Si oxide phases such as kaolinite, quartz and gibbsite. The application of the diagram to a series of global examples leads to the statement: 1) Chemical weathering is the principal process by which continental surfaces are modified. 2) The extent of chemical weathering is correlated with the age of continental surfaces. 3) Global agricultural productivity is correlated with geologically recent additions of fresh rock debris by processes of volcanism, glaciation or alluviation.