Argon argon dating

16 Jan

However, the Argon, a noble gas, constitutes approximately 0.1-5% of the Earth's present day atmosphere.Because it is present within the atmosphere, every rock and mineral will have some quantity of Argon.The quantity of potassium in a rock or mineral is variable proportional to the amount of silica present.Therefore, mafic rocks and minerals often contain less potassium than an equal amount of silicic rock or mineral.Potassium occurs in two stable isotopes (Ar atoms trapped inside minerals.What simplifies things is that potassium is a reactive metal and argon is an inert gas: Potassium is always tightly locked up in minerals whereas argon is not part of any minerals. So assuming that no air gets into a mineral grain when it first forms, it has zero argon content.That is, a fresh mineral grain has its K-Ar "clock" set at zero.The method relies on satisfying some important assumptions: Given careful work in the field and in the lab, these assumptions can be met.

Ar dating is a major method that researchers have used to understand the structural evolution of the Maria Fold and Thrust Belt.

Second, the sample is irradiated along with a standard of a known age. A major advantage of the argon-argon method is that the sample can be heated incrementally.

This process, known as "step heating", provides additional information on the age of the sample.

Reheating events and diffusion of argon from the boundaries of the grain can result in lower Ar date.

Sometimes, when a large amount of argon has been lost, this is not possible.