Potassium-argon dating definition, a method for estimating the age of a mineral or rock, based on measurement of the rate of decay of radioactive potassium into. A variant of the K–Ar dating method fundamentally based on the natural Although all three isotopes are stable, 40Ar is the only isotope that is also a The plateau age is calculated as the weighted mean of the ages of all.
Other isotopes of argon are produced from potassium, calcium, argon and chlorine. These reactor produced isotopes of argon must be corrected for in order to determine an accurate age.
Multiple argon extractions can be performed on a sample in several ways. Step-heating is the most common way and involves either a furnace or a laser to uniformily heat the sample to evolve argon. Mechanical crushing is also a technique capable of releasing argon from a single sample in multiple steps.
For example, laser spot sizes of microns or less allow a user to extract multiple argon samples from across a small mica or feldspar grain. The results from a laser probe can be plotted in several graphical ways, including a map of a grain showing lateral argon distribution. Some of these include other isotopic dating techniques e. The NMGRL does this by irradiating samples in machined aluminum disks where standards and unknowns alternate every other position.