Potassium argon dating method
(argon), the atom typically remains trapped within the lattice because it is larger than the spaces between the other atoms in a mineral crystal.But it can escape into the surrounding region when the right conditions are met, such as change in pressure and/or temperature.The amount of argon sublimation that occurs is a function of the purity of the sample, the composition of the mother material, and a number of other factors.These factors introduce error limits on the upper and lower bounds of dating, so that final determination of age is reliant on the environmental factors during formation, melting, and exposure to decreased pressure and/or open-air.The potassium-argon age of some meteorites is as old as 4,500,000,000 years, and volcanic rocks as young as 20,000 years old have been measured by this method.The potassium-argon (K-Ar) isotopic dating method is especially useful for determining the age of lavas.
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.
After the recrystallization of magma, more being the most abundant isotope.
Thus, the amount of calcium originally present is not known and can vary enough to confound measurements of the small increases produced by radioactive decay.
Potassium is a common element found in many materials, such as micas, clay minerals, tephra, and evaporites.
In these materials, the decay product is able to escape the liquid (molten) rock, but starts to accumulate when the rock solidifies (recrystallizes).