www executivedatingguide com - Potassium argon dating definition

Potassium (K) is one of the most abundant elements in the Earth's crust (2.4% by mass).

potassium argon dating definition-56potassium argon dating definition-8

The potassium-argon dating method has been used to measure a wide variety of ages.

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.

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.

The potassium-argon (K-Ar) isotopic dating method is especially useful for determining the age of lavas.

Developed in the 1950s, it was important in developing the theory of plate tectonics and in calibrating the geologic time scale.The rock sample to be dated must be chosen very carefully.Any alteration or fracturing means that the potassium or the argon or both have been disturbed.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.Lava flows that lie above and below rock beds with ancient human fossils are a good—and true—example.and the ages of fossil hominids, molecular dating and divergence times for mammalian lineages, meteorites and the age of the solar system, and the use of color-magnitude diagrams for assessing ages of collections of stars.

Tags: , ,