Geochronology dating techniques
This flux is known as the 'J' and can be determined by the following equation: As the table above illustrates, several "undesirable" reactions occur on isotopes present within every geologic sample.These reactor produced isotopes of argon must be corrected for in order to determine an accurate age.The quantity of potassium in a rock or mineral is variable proportional to the amount of silica present.
Because the J value is extrapolated from a standard to an unknown, the accuracy and precision on that J value is critical.
However, the Argon, a noble gas, constitutes approximately 0.1-5% of the Earth's present day atmosphere.
Because it is present within the atmosphere, every rock and mineral will have some quantity of Argon.
For the J to be determined, a standard of known age must be irradiated with the samples of unknown age.
Because this (primary) standard ultimately cannot be determined by Ar, it must be first determined by another isotopic dating method.
Search for geochronology dating techniques:
Argon can mobilized into or out of a rock or mineral through alteration Ar and potassium, there is not a reliable way to determine if the assumptions are valid.