Start Determining absolute ages by radiometric dating

Determining absolute ages by radiometric dating

In the ideal case, the material will incorporate a parent nuclide and reject the daughter nuclide.

Finally, correlation between different isotopic dating methods may be required to confirm the age of a sample.

The precision of a method of dating depends in part on the half-life of the radioactive isotope involved.

Precision is enhanced if measurements are taken on different samples taken from the same rock body but at different locations.

Alternatively, if several different minerals can be dated from the same sample and are assumed to be formed by the same event and were in equilibrium with the reservoir when they formed, they should form an isochron.

This predictability allows the relative abundances of related nuclides to be used as a clock that measures the time from the incorporation of the original nuclide(s) into a material to the present.

The processes that form specific materials are often conveniently selective as to what elements they incorporate during their formation.

If a material that selectively rejects the daughter nuclide is heated, any daughter nuclides that have been accumulated over time will be lost through diffusion, setting the isotopic "clock" to zero.

The temperature at which this happens is known as the "blocking temperature" and is specific to a particular material.

Additionally, measurement in a mass spectrometer is subject to isotopic interference of other nuclides with the same mass number.

Corrections may have to be performed by measuring isotopic ratios of elements which interfere with the target isotope.

When a material incorporates both the parent and daughter nuclides at the time of formation, it may be necessary to assume that the initial proportions of a radioactive substance and its daughter are known.