Radioactive and stable isotope geology / Геология радиоактивных и стабильных изотопов

Isotopic (nuclear) geology constitutes an exact, quantitative branch of the Earth sciences which has expanded rapidly to cover a wide spectrum of applications since the establishment of its basic principles by the early 1950s, in part following seminal researches by H. C. Urey, H. A. Lowenstam, S. Epstein, T. Mayeda and numerous others. This immense progress, accelerating in recent years, led to the application of isotopes in attempting to resolve a variety of geochemical and geological problems in the Earth sciences. Lunar exploration too provided rocks for analysis and their examination stimulated refinements in mass spectrometry later used for terrestrial materials as well. New geochronometric methods were devised and include those based on the radioactive decay of l47Sm to l4:tNd, l76Lu to l7f,Hf, l87Re to ,87Os and 4llK to 4(1Ca, as well as others depending upon the production and distribution of cosmogenic radionuclides such as 2(,A1, l0Be and 36C1.
The impact of all these developments has been tremendous and shed light on such diverse topics as the origin of igneous rocks, where the isotopic compositions of neodymium, strontium, lead and hafnium suggest that magmas from the Earth's mantle are often crustally contaminated. The isotopic compositions of carbon, oxygen and sulphur have proved important in elucidating aspects of petrogenesis. The study of environmental isotopes such as tritium and radiocarbon has been invaluable, not only as regards revealing the climates of the past using palaeotemperature analyses, but also in understanding the ice volume effect, the stratigraphy of ice and snow and the dating of sediments and volcanics, together with the isotopic composition of sea water, both now and through Earth history. Isotopic analyses of the l!iO composition of foraminifera from Caribbean sea-bottom cores formed the basis for C.