Dating method based on rate of decay of radioactive isotopes
In contrast to a method such as Radiocarbon dating, which measures the disappearance of a substance, K-Ar dating measures the accumulation of Argon in a substance from the decomposition of potassium.
Argon, being an inert gas, usually does not leech out of a mineral and is easy to measure in small samples.
This method dates the formation or time of crystallisation of the mineral that is being dated; it does not tell when the elements themselves were formed.
These scientists and many more after them discovered that atoms of uranium, radium and several other radioactive materials are unstable and disintegrate spontaneously and consistently forming atoms of different elements and emitting radiation, a form of energy in the process.Any material which is composed of carbon may be dated.Herein lies the true advantage of the radiocarbon method.Quaternary geology provides a record of climate change and geologically recent changes in environment.U-Pb geochronology of is used for determining the age of emplacement of igneous rocks of all compositions, ranging in age from Tertiary to Early Archean.Willard Libby and his colleague Ernest Anderson showed that collected from sewage works had measurable radiocarbon activity whereas methane produced from petroleum did not.Perseverance over three years of secret research to develop the radiocarbon method came into fruition and in 1960 Libby received the Nobel Prize for chemistry for turning his vision into an invaluable tool.By measuring the C concentration or residual radioactivity of a sample whose age is not known, it is possible to obtain the number of decay events per gram of Carbon.By comparing this with modern levels of activity (1890 wood corrected for decay to 1950 AD) and using the measured half-life it becomes possible to calculate a date for the death of the sample. As a result of atomic bomb usage, C ages of objects younger than 1950.Here are some of the materials that can be successfully dated using this method: Potassium-Argon Dating Potassium-Argon (K-Ar) dating is the most widely applied technique of radiometric dating.Potassium is a component in many common minerals and can be used to determine the ages of igneous and metamorphic rocks.