, shock events, and differentiation of precursor melts, in the history of rocks.
Isochron dating can be further separated into "mineral isochron dating" and "whole rock isochron dating"; both techniques are applied frequently to date terrestrial and also extraterrestrial rocks ( and non-radiogenic isotopes of the daughter element, along with some amount of the parent nuclide.
All forms of isochron dating assume that the source of the rock or rocks contained unknown amounts of both radiogenic and non-radiogenic isotopes of the daughter element, along with some amount of the parent nuclide.
Ratios are used instead of absolute concentrations because mass spectrometers usually measure the former rather than the latter.
Isochron dating is a common technique of radiometric dating and is applied to date certain events, such as crystallization, metamorphism, shock events, and differentiation of precursor melts, in the history of rocks.
The advantage of isochron dating as compared to simple radiometric dating techniques is that no assumptions are needed about the initial amount of the daughter nuclide in the radioactive decay sequence.
For rocks that start out with a small concentration of the parent, the daughter/non-radiogenic ratio will not change quickly as compared to rocks starting with a large concentration of the parent.
Isochron plots To perform mineral isochron dating, a rock is separated into several different minerals with different ratios between parent and daughter concentrations.