Nuclear-induction methods of modern isotope geochronology

A survey is made of the modern state and theoretical bases of nuclear-induction methods. The latter are based on the analysis of the ratio of daughter isotopes of spontaneous and artificially induced origin in minerals, which permits a calculation of the duration of the natural process of radioactive decay, i.e., the time of existence of the mineral. Such an approach permits avoidance of highly accurate determinations of the absolute content of isotopes, and also in a number of cases permits consideration of the losses of daughter isotopes as a result of natural geochemical and thermal influences. The principles of the application of induction methods to minerals with closed and open geochemical systems are outlined; methods of determining the flux of inducing particles are cited, and the practical realization of the methods is discussed with the argon method (40Ar-39Ar), the xenon (Xesub(s) - Xesub(n)) and krypton (Krsub(s) - Krsub(n)) methods, and the method of tracks as examples