Ar ar dating method
Join Britannica's Publishing Partner Program and our community of experts to gain a global audience for your work! This dating method is based upon the decay of radioactive potassium-40 to radioactive argon-40 in minerals and rocks; potassium-40 also decays to calcium-40.Thus, the ratio of argon-40 and potassium-40 and radiogenic calcium-40 to potassium-40 in a mineral or rock is a measure of the age of the sample.These each have 19 protons and 21 neutrons in their nucleus.If one of these protons is hit by a beta particle, it can be converted into a neutron.But since floods jumble materials of different origins and ages together, that meant the scientists had to date dozens of different minerals.The youngest crystal in the footprint layer would represent the oldest possible age for the prints; the oldest crystal in the layer above it would represent the youngest they could be.This is actually a mini-simulator, in that it processes a different sample each time and generates different dates.
One out of every 10,000 Potassium atoms is radioactive Potassium-40 (K-40).
The calcium-potassium age method is seldom used, however, because of the great abundance of nonradiogenic calcium in minerals or rocks, which masks the presence of radiogenic calcium.
On the other hand, the abundance of argon in the Earth is relatively small because of its escape to the atmosphere during processes associated with volcanism.
One thing to keep in mind is that high-precision isotope measurements always measure ratios between isotopes, not absolute concentrations.
To understand argon-argon dating, you need to understand potassium-argon dating.