K ar dating half life

22-May-2020 02:26

The K-Ar clock works primarily on igneous rocks, i.e., those that form from a rock liquid (such as lava and granite) and have simple post-formation histories.It does not work well on sedimentary rocks because these rocks are composed of debris from older rocks.

These parent isotopes decay to stable daughter isotopes at rates that can be measured experimentally and are effectively constant over time regardless of physical or chemical conditions.Sometimes these decay schemes are used individually to determine an age (e.g., Rb-Sr) and sometimes in combinations (e.g., U-Th-Pb).Each of the various decay schemes and dating methods has unique characteristics that make it applicable to particular geologic situations.For example, a method based on a parent isotope with a very long half-life, such as C method can only be used to determine the ages of certain types of young organic material and is useless on old granites.Some methods work only on closed systems, whereas others work on open systems.

These parent isotopes decay to stable daughter isotopes at rates that can be measured experimentally and are effectively constant over time regardless of physical or chemical conditions.Sometimes these decay schemes are used individually to determine an age (e.g., Rb-Sr) and sometimes in combinations (e.g., U-Th-Pb).Each of the various decay schemes and dating methods has unique characteristics that make it applicable to particular geologic situations.For example, a method based on a parent isotope with a very long half-life, such as C method can only be used to determine the ages of certain types of young organic material and is useless on old granites.Some methods work only on closed systems, whereas others work on open systems.The discovery of radioactivity in 1896 by Henri Becquerel, the isolation of radium by Marie Curie shortly thereafter, the discovery of the radioactive decay laws in 1902 by Ernest Rutherford and Frederick Soddy, the discovery of isotopes in 1910 by Soddy, and the development of the quantitative mass spectrograph in 1914 by J. Thomson all formed the foundation of modern isotopic dating methods.