Potassium–argon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology.It is based on measurement of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar). Potassium is a common element found in many materials, such as micas, clay minerals, tephra, and evaporites.In these materials, the decay product 40 Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. (4) Geological dating of igneous rocks Certain elements with very long half-lives can be used to date the geological age of igneous rocks and even the age of the Earth. has a half-life of 1.3 x 10 9 years. It decays to form .; If the argon gas is trapped in the rock, the ratio of potassium-40 to argon-40 decreases over time and the ratio can be used to date the age of rock formation i.e. from. Dating - Rubidium–strontium method: The radioactive decay of rubidium-87 (87Rb) to strontium-87 (87Sr) was the first widely used dating system that utilized the isochron method. Rubidium is a relatively abundant trace element in Earth’s crust and can be found in many common rock-forming minerals in which it substitutes for the major element potassium. RADIOMETRIC DATING. he question of the ages of the Earth and its rock formations and features has fascinated philosophers, theologians, and scientists for centuries, primarily because the answers put our lives in temporal perspective. Decay & Half Life. Why is this chapter on half-life being presented? The purpose of this chapter is to explain the process of radioactive decay and its relationship to the concept of half-life. Isochron Dating By Chris Stassen The article is well illustrated and well written. There is an introduction to the generic problem of radiometric dating, but this article concentrates on one well established method called the "isochron method". Creation Versus Evolution: We compare the theory of evolution with the Bible’s creation account in easy-to-understand terms, using evidence from the fields of paleontology, geology, biology, and astronomy.We provide links and a bibliography for those who want to study both sides of the issue. It follows that uranium-lead, potassium-argon (K-Ar), and Rubidium-Strontium (Rb-Sr) decay can be used for very long time periods, whilst radiocarbon dating can only be used up to about 70,000 years. Units and significant figures Candidates should be aware that misuse of units and/or significant figures, i.e. failure to quote units where necessary, the inclusion of units in quantities defined as ratios or quoting answers to an inappropriate number of significant figures, is liable to be penalised.