Mobility of Radiogenic Isotopes 4Не and 3Не and Their Retention in a Mineral (by the Example of Amphibole)
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К–Аr- and U–Th–He-dating stimulated research of the migration of radiogenic isotopes 40Аr and 4He in minerals in order to obtain quantitative estimates of their mobility and to reveal the dependence on the character and quality of the mineral structure, temperature, and other physical parameters . Generally, it was assumed that the migration parameters obtained in the study of mobility of the atoms retained in a mineral refer to all atoms that were produced in it. Such an assumption was disputed earlier ; this work shows that in some cases it is unacceptable presupposition for the characteristics of the behavior of radiogenic 3,4Не.
The analysis of the U–Th–Li–4He–3He- isotopic system in the amphiboles extracted from the alkaline granites of the Ponoi massif, Kola Peninsula  showed that these minerals contain primarily radiogenic isotopes of Не that appeared in situ : 4Не was produced during the disintegration of U and Th, and 3Не – in the reaction 6Li(n, α)3H → β– → 3He (τ
This work was supported by the Russian Foundation for Basic Research, project no. 18–05–70004, Arctic Resources.
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