Glauconite radiometric dating
Minerals in this group are biotite, muscovite, sanidine-anorthoclase, glauconite, illite, sericite and alunite.
It should be noted that although sanidine-anorthoclase is suitable for dating, other K-feldspars of plutonic or metamorphic origin are not (e.g., orthoclase and microcline).
ESTIMATING RATES OF RECENT GEOMORPHOLOGICAL PROCESSES affecting Cenozoic igneous rocks (e.g., uplift, denudation, laterite, silcrete and duricrust formation).
The K-Ar method is most suited to this application and the error, for Cenozoic rocks, can be less than 1 Ma so that relatively short episodes can be distinguished; All radiometric dating methods are based on the assumption of closed system behaviour of the sample throughout geological time; i.e.
The differing half-lives for the radioactive U means that two systems can be used to calculate ages and when plotted against each other provide a test for closed system behaviour; i.e.