Thermal ionization mass spectrometry (TIMS) is an analytical method for high-precision measurements of isotope ratios and isotope abundances of elements that are easy to ionize. In geology, the method is mostly applied to measure the isotope abundances of radiogenic isotopes (which in nature often strongly varies) in relation to stable isotopes of the same element. Radiogenic isotopes are the decay products of long-lived radioactive isotopes (e.g. ⁸⁷Rb, ¹⁴⁷Sm or ²³⁸U). We apply this method to …