Radiometric dating zircon crystals
To see how we actually use this information to date rocks, consider the following: Usually, we know the amount, N, of an isotope present today, and the amount of a daughter element produced by decay, D*.
By definition, D* = N-1) (2) Now we can calculate the age if we know the number of daughter atoms produced by decay, D* and the number of parent atoms now present, N.
The energies involved are so large, and the nucleus is so small that physical conditions in the Earth (i.e. The rate of decay or rate of change of the number N of particles is proportional to the number present at any time, i.e.
The half-life is the amount of time it takes for one half of the initial amount of the parent, radioactive isotope, to decay to the daughter isotope.
The uranium and thorium decay systems offer a multitude of radiometric dating options.
Uranium 238 decays through a series of steps to Lead 206.
Radioactive decay Radioisotopic dating relies on the process of radioactive decay, in which the nuclei of radioactive atoms emit particles.
This releases energy (in the form of radiation) and often transforms one element into another.
Although it is impossible to predict when a particular unstable atom will decay, the decay rate is predictable for a very large number of atoms.Zircon is especially useful because it frequently contains uranium in substitution for zirconium, but does not incorporate lead (as shown by the absence of Lead-204).Thus all the lead in the zircon can be assumed to be radiogenic.Thus any of the radioactive isotopes and its lead daughter product can be used for dating, or a combination may be used.In addition, some of the longer-lived intermediate daughter products have uses in dating.