What is potassium argon dating
Any alteration or fracturing means that the potassium or the argon or both have been disturbed.
The site also must be geologically meaningful, clearly related to fossil-bearing rocks or other features that need a good date to join the big story.
What simplifies things is that potassium is a reactive metal and argon is an inert gas: Potassium is always tightly locked up in minerals whereas argon is not part of any minerals. So assuming that no air gets into a mineral grain when it first forms, it has zero argon content.
That is, a fresh mineral grain has its K-Ar "clock" set at zero.
Developed in the 1950s, it was important in developing the theory of plate tectonics and in calibrating the geologic time scale.
With each increment in quality, more subtle sources of error have been found and taken into account.
those in very ancient volcanic rock, by using potassic minerals in the same strata as a reference: a natural radioactive isotope of potassium, K-40, decays steadily into argon, which accumulates in the minerals and is measured to determine age There are two ways of writing down or reporting what was said on any occasion.
We can repeat the actual words used( direct speech), Monica said, ‘There’s nothing we can do about it.’ or we can buil...
Three argon isotopes are measured: Ar is determined by comparison to it.
Variations in this data may point to errors anywhere in the process, which is why all the steps of preparation are recorded in detail.
But micas, plagioclase, hornblende, clays and other minerals can yield good data, as can whole-rock analyses.