Potassium argon dating definition bethann bonner bree williamson dating

The Science Dictionary is the most comprehensive source of science definitions online with over 38K science terms written and created by our global team of scientists and academic professionals.a technique for determining the age of minerals based on the occurrence in natural potassium of a small fixed amount of radioisotope 40K that decays to the stable argon isotope 40Ar with a half-life of 1.28x109 years.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.SYNONYMS OR RELATED TERMS: K-A dating; potassium argon dating; radiopotassium dating CATEGORY: technique DEFINITION: An isotopic method of dating the age of a rock or mineral by measuring the rate at which potassium-40, a radioactive form of this element, decays into argon.Ar atoms are able to diffuse through and escape from molten magma because most crystals have melted and the atoms are no longer trapped.Entrained argon—diffused argon that fails to escape from the magma—may again become trapped in crystals when magma cools to become solid rock again.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.

In these materials, the decay product Ar is able to escape the liquid (molten) rock, but starts to accumulate when the rock solidifies (recrystallizes).The amount of Argon sublimation that occurs is a function of the purity of the sample, the composition of the mother material, and a number of other factors.These factors introduce error limits on the upper and lower bounds of dating, so that final determination of age is reliant on the environmental factors during formation, melting, and exposure to decreased pressure and/or open-air.One archeological application has been in bracketing the age of archeological deposits at Olduvai Gorge by dating lava flows above and below the deposits.Clay minerals are less than 2 micrometres thick and cannot easily be irradiated for Ar–Ar analysis because Ar recoils from the crystal lattice.