Abstract. We describe a new method for the measurement of U/Pb ratios by isotope dilution multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for the dating of geologically young clean carbonates, particularly speleothems. The method is intended for materials containing little or no initial 232Th. We illustrate and validate the method with four examples ranging from 0.57 Ma to 20 Ma old. The new method is capable of applying the 235U-207 and 238U-234U-206Pb chronometers, common Pb and quantifiable residual 234U/238U disequilibrium permitting. These provide an alternative to the more widely used 238U-206Pb chronometer, which can be highly inaccurate for samples a few million years old, owing to uncertainties in the excess initial 234U (hence, excess radiogenic 206Pb) commonly observed in speleothems.
Rapid unseparated rare earth element analyses by isotope dilution multicollector inductively coupled plasma mass spectrometry (ID-MC-ICP-MS)
