Potassium argon dating range Chatbots 18
Potassium can be mobilized into or out of a rock or mineral through alteration processes.
Due to the relatively heavy atomic weight of potassium, insignificant fractionation of the different potassium isotopes occurs.
However, because each of these parameters is difficult to determine independantly, a mineral standard, or monitor, of known age is irradiated with the samples of unknown age.
The monitor flux can then be extrapolated to the samples, thereby determining their flux.
The method most commonly used to date the primary standard is the conventional K/Ar technique.
The primary standard must be a mineral that is homogeneous, abundant and easily dated by the K/Ar and Ar methods.
The individual ages from each heating step are then graphically plotted on an age spectrum or an isochron.
The monitoring of the interfering reactions is performed through the use of laboratory salts and glasses.
For example, to determine the amount of reactor produced Ar ratio of the glass is then measured in the mass spectrometer to determine the correction factor that must be applied to the rest of the samples in that irradiation.
Ar total fusion measures ratios, making it ideal for samples known to be very argon retentive (eg. Total fusion is performed using a laser and results are commonly plotted on probability distribution diagrams or ideograms.
In order for an age to be calculated by the Ar technique, the J parameter must be known.