Radioisotope dating assumptions

04 Mar

Many atoms (or elements) exist as numerous varieties called isotopes, some of which are radioactive, meaning they decay over time by losing particles.Radiometric dating is based on the decay rate of these isotopes into stable nonradioactive isotopes.Potassium–argon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology.

radioisotope dating assumptions-28

The potassium is quantified by flame photometry or atomic absorption spectroscopy.

Potassium is a common element found in many materials, such as micas, clay minerals, tephra, and evaporites.

In these materials, the decay product Ar is able to escape the liquid (molten) rock, but starts to accumulate when the rock solidifies (recrystallizes).

But if there was argon in the rock when it originally formed, then the age calculated will be millions of years too high. The greater the amount of daughter isotope, the greater the apparent age.

The proportion of argon to radioactive potassium in the sample today is observable, and the decay constant of potassium is readily calculable by measuring the amount of argon produced from the decay of K after a specified time.