Glauconite radiometric dating

10-Jun-2018 14:13

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 fission track density of a mineral is thus a function of its age as defined by the time since the mineral was last heated through its annealing temperature (i.e.

the temperature at which fission tracks are destroyed) and its uranium content.

Glass, however, may not retain argon quantitatively over extended periods of time, and any trend towards devitrification will result in argon leakage.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).Ages determined on such minerals are invariably too young and have no geological significance.These minerals contain potassium as a major element, which is always present in the theoretical formula.

Glass, however, may not retain argon quantitatively over extended periods of time, and any trend towards devitrification will result in argon leakage.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).Ages determined on such minerals are invariably too young and have no geological significance.These minerals contain potassium as a major element, which is always present in the theoretical formula.Minerals in this group are hornblende, plagioclase and pyroxene.