Potassium argon dating definition Videochat amputee
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.
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).
It is used primarily on lava flows and tuffs and for ocean floor basalts.
Potassium, which is present in most rocks and minerals, has a single , K 40.
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Thus, the amount of calcium originally present is not known with enough accuracy to be able to measure the small increase produced by radioactive decay.
In 2013 the K–Ar method was used by the Mars Curiosity rover to date a rock on the Martian surface, the first time a rock has been dated from its mineral ingredients while situated on another planet.
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.
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.
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.