Isochron dating

Isochron dating estimates a rock’s age from a straight-line relationship between isotope ratios in co-genetic minerals or samples, while accounting for initial daughter isotope abundance.

Isochron: A straight line relating isotope ratios in co-genetic materials, whose slope can encode elapsed time. Its slope is the mathematical signal from which an isochron age is calculated.
Radiometric dating: A method of estimating age from predictable changes in radioactive isotope abundances. Isochron dating is a radiometric method with an internal test for initial isotope composition.
Rubidium–strontium dating: A radiometric dating system based on the decay of rubidium-87 to strontium-87. Its parent–daughter system is a classic application of whole-rock and mineral isochrons.
Conventional radiometric dating: Radiometric age calculations that use measured parent and daughter abundances with an assumed or independently known initial daughter abundance. Unlike these calculations, an isochron estimates initial daughter abundance from the sample array.
Closed system: A system that exchanges neither relevant matter nor isotopes with its surroundings. An isochron age can be disturbed if parent or daughter isotopes entered or left after formation.
Parent isotope: A radioactive isotope that decays into another isotope over time. Its decay supplies the time-dependent change measured by the isochron.
Isotope: One of several forms of an element, distinguished by its number of neutrons. The method distinguishes isotopes of the same elements by their measured ratios.
Samarium–neodymium dating: A radiometric dating system based on the decay of samarium-147 to neodymium-143. Its isotope system can date ancient rocks and trace their source histories using isochrons.
Concordia diagram: A plot comparing uranium–lead ages derived from two uranium decay systems. It detects certain forms of lead loss through paired U–Pb ages rather than an isochron slope.
Isotope geochemistry: The study of isotope abundances and variations in geological materials. It investigates the processes that preserve, alter, or imitate isochron relationships.

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