Diagenetic Development of Kaolinite

C. D. Curtis* and D. A. Spears
Department of Geology, The University, Sheffield S1 3JD, England
* Session 1970/71 visiting: The Department of Geology, University of California, Los Angeles, Calif. 90024, U.S.A.

Abstract: Experimental solubility data for gibbsite and kaolinite are reviewed and applied to the problem of gibbsite stability within the natural environment. It is concluded that free alumina compounds formed (only) in lateritic soils will tend to silicify spontaneously in all sedimentary environments. This metasomatic reaction should be accompanied by massive volume expansion: unusual textures are to be anticipated.

Petrographic and field descriptions of a number of ancient kaolinitic sediments (some with, some without free alumina) are reviewed. It is concluded that silicification of hydrated aluminum oxides was an important mechanism of kaolinite formation in ancient sediments and that free alumina compounds persist only as a result of the unusual volume expansion associated with kaolinite formation.

Clays and Clay Minerals; September 1971 v. 19; no. 4; p. 219-227; DOI: 10.1346/CCMN.1971.0190403
© 1971, The Clay Minerals Society
Clay Minerals Society (www.clays.org)