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Abstract

Isotopes, these sub-species of the chemical elements that differ in their mass, are the basic constituents of all matter in the planetary system, the Earth, and its organisms. The relative abundances of isotopes shift by radioactive decay, irradiation of the Earth’s surface by cosmic rays, physico-chemical reaction, and mixing. Isotope Geochemists use these principles to measure the timing of Earth’s changes, to disclose the processes of biogeochemical transformations, and to identify the sources of Earth materials. In this issue of the GFZ-Journal “System Erde” the Isotope Geochemists at GFZ provide an overview of the enormous breadth of the components of the Earth system they explore (shown in the title figure). These applications encompass the reconstruction of past climate, the speed and time of Earth surface change, how rock becomes soil, and how plants use the released metals, how biomolecules, petroleum and metal ores are formed in the geosphere with and without microbes, when life moved from sea to land billions of years ago, the measuring of rock deformation in “fossil” subduction zones, that sediment, once deposited on the seafloor, goes all the way into subduction zones and returns to the surface in volcanic eruptions, the use of rare gas isotopes to infer the structure of the Earth’s interior. This article provides an introduction into the principles and the technology used to detect isotopes.