Radiometric Dating in Geology
A geochronological technique used to determine the absolute age of rocks and minerals by measuring radioisotope parent-to-daughter ratios.
Governing formula
t = (1 / λ) ln(1 + D / P) (Parent P → Daughter D)
SI unit
Ma or Ga (Millions / Billions of Years)
In depth
When minerals crystallize, they trap radioactive parent isotopes (e.g. U-238, K-40, Rb-87). Measuring accumulated radiogenic daughter isotopes (Pb-206, Ar-40, Sr-87) and knowing half-lives yields absolute rock ages.
Examples in the real world
Uranium-Lead (U-Pb) zircon geochronology dating Earth's oldest minerals to 4.4 billion years old.