Uses of radioactive carbon dating

Posted by / 29-Mar-2017 23:09

For an element to be useful for geochronology (measuring geological time), the isotope must be reasonably abundant and produce daughter isotopes at a good rate.Either a whole rock or a single mineral grain can be dated.The relationship between the two is: T = 0.693 / λ Many different radioactive isotopes and techniques are used for dating.All rely on the fact that certain elements (particularly uranium and potassium) contain a number of different isotopes whose half-life is exactly known and therefore the relative concentrations of these isotopes within a rock or mineral can measure the age.This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.This radioactivity can be used for dating, since a radioactive 'parent' element decays into a stable 'daughter' element at a constant rate.

It is useful for dating very old igneous and metamorphic rocks and also meteorites and other cosmic fragments.Another way of expressing this is the half-life period (given the symbol T).The half-life is the time it takes for half of the parent atoms to decay.All living organisms take up carbon from their environment including a small proportion of the radioactive isotope 14C (formed from nitrogen-14 as a result of cosmic ray bombardment).The amount of carbon isotopes within living organisms reaches an equilibrium value, on death no more is taken up, and the 14C present starts to decay at a known rate.

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Radiocarbon dating is normally suitable for organic materials less than 50 000 years old because beyond that time the amount of 14C becomes too small to be accurately measured.