What is the role of isotopes in radiometric dating
Radioactive dating is a method of dating rocks and minerals using radioactive isotopes.
However, both Rb and Sr easily follow fluids that move through rocks or escape during some types of metamorphism. The dual decay of potassium (K) to 40Ar (argon) and 40Ca (calcium) was worked out between 19.This technique has become more widely used since the late 1950s.Its great advantage is that most rocks contain potassium, usually locked up in feldspars, clays and amphiboles.those that form during chemical reactions without breaking down).The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.The Re-Os isotopic system was first developed in the early 1960s, but recently has been improved for accurate age determinations.
The main limitation is that it only works on certain igneous rocks as most rocks have insufficient Re and Os or lack evolution of the isotopes.
However, there is a limited range in Sm-Nd isotopes in many igneous rocks, although metamorphic rocks that contain the mineral garnet are useful as this mineral has a large range in Sm-Nd isotopes.
This technique also helps in determining the composition and evolution of the Earth's mantle and bodies in the universe.
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.
This scheme was developed in 1937 but became more useful when mass spectrometers were improved in the late 1950s and early 1960s.
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.