Because the K/Ar dating technique relies on the determining the absolute abundances of both 40Ar and potassium, there is not a reliable way to determine if the assumptions are valid. Argon loss and excess argon are two common problems that may cause erroneous ages to be determined.

Is potassium-argon dating relative or absolute?

The potassium-argon (K-Ar) dating method is probably the most widely used technique for determining the absolute ages of crustal geologic events and processes.