When a reasonable number of consecutive steps, carrying a substantial amount of the total argon released, give the same age, the resulting average value carries geological significance.For unmetamorphosed igneous rocks, the latter would normally represent the crystallization age.
I illustrate the use of the techniques by looking at published age data for hotspot tracks in the Atlantic Ocean (the Walvis Ridge), as well as newly published ages for the British Tertiary Igneous Province.dating laboratories has led to a large number of papers reporting age data.
However, in many instances, the published “ages” have no merit, as they fail the simple statistical tests that should be applied to all such data. In these experiments, a sample is heated in steps of increasing laboratory extraction temperature, until all the argon is released.
The argon released in each step is measured to calculate a “step age” with an associated analytical error.
The potassium-argon (K-Ar) isotopic dating method is especially useful for determining the age of lavas.
Developed in the 1950s, it was important in developing the theory of plate tectonics and in calibrating the geologic time scale.