Читать книгу Earth Materials - John O'Brien - Страница 73

Stable isotopes contain nuclei that do not tend to change spontaneously. Instead, their nuclear configurations (number of protons and neutrons) remain constant over time. Many elements occur in the form of multiple stable isotopes with different atomic mass numbers. In many cases, these isotopes, because of their different mass, exhibit subtly different behaviors in Earth environments. These differences in behavior are recorded as differences in the ratios between isotopes that can be used to infer the conditions under which the isotopes were selectively incorporated into Earth materials. We will use oxygen and carbon isotopes to illustrate the uses of stable isotope ratios to increase our understanding of Earth materials and processes. Other stable isotopes that are commonly utilized in such studies include those of sulfur, nitrogen, and helium (Chapter 13, Box 13.2).