What is potassium argon dating
Developed in the 1950s, it was important in developing the theory of plate tectonics and in calibrating the geologic time scale.Potassium occurs in two stable isotopes (Ar atoms trapped inside minerals.Geologists have used this method to date rocks as much as 4 billion years old.It is based on the fact that some of the radioactive isotope of Potassium, Potassium-40 (K-40) ,decays to the gas Argon as Argon-40 (Ar-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.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.
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.
On the other hand, the abundance of argon in the is relatively small because of its escape to the atmosphere during processes associated with volcanism.
The potassium-argon dating method has been used to measure a wide variety of ages.
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. 1979, 1986 © Harper Collins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source potassium-argon dating A method of radiometric dating, involving analysis of the ratio of potassium 40 (a radioactive isotope of potassium) to argon (the product of radioactive decay of potassium 40) in a given sample.
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