Application of U-Pb LA-ICP-MS dating to unravel climate evolution and surface processes

Geochronological tools may play an important role in understanding the coupled evolution of biosphere and Earth surface processes. Intermittent wet periods in arid and hyper-arid environments drive mineral precipitation and mineral transformations, which have the potential to be dated with the U-Pb isotopic system.

With the knowledge and expertise gained in the last few years with the relatively new method of laser ablation U-Pb dating of carbonates, we are now embarked mainly, but not only, on the dating of sulfate phases.

We have successfully applied the method to gypsum-anhydrate nodules sampled at variable depths in soil pits. These nodules are formed by repeated hydration-dehydration events of the soil, which is formed by atmospheric deposition of sulfate. By dating them, we are able to track periods of water availability in arid to hyper-arid environments, such as the Atacama Desert. Other samples that were successfully dated to some extent, which are also linked to water supply, are calcretes and silcretes, gypsum wedges, and minerals formed in supergene Cu enrichment processes. Zircon extracted from volcanic ash layers have also been dated to constrain the timing of lake formation.