An Apparatus for Measuring the Potassium and Argon Released from Clay Samples by Treatment with Quaternary Ammonium Ions

Abstract

Chaudhuri et al. (1994) and Sears et al. (1995) have demonstrated that treatment of clay samples with aqueous octadecylammoniu m chloride causes changes in the K-Ar apparent ages of the clays. Specifically, the organic ions selectively replace K ions from some illite particles while having little effect on other illite particles. Expansion of the interlayers as the large organic ions replace the K ions presumably allows concomitant escape of the associated radiogenic argon. Sears et al. (1995) summarized earlier research that has identified 'expandable illite' as clay whose interlayers will not expand upon treatment by smaller organic ions but will expand upon treatment with octadecylammonium ions. The 'expandable illite' in a clay mixture may be either detrital or diagenetic in origin, depending on the composition and history of the detritus and on the diagenetic history of the