Expanding the horizons of ore deposit geochronology using carbonate U-Pb dating

We live in a resource-hungry world and as countries transition to zero carbon economies, critical metals required by green technologies are in ever-increasing demand. Rare Earth Elements (REE) concentrate in magmatic and hydrothermal processes in carbonate-bearing igneous rocks (carbonatites). This project will develop and apply new techniques to improve understanding of the timing and genesis of deposits. Carbonate is ubiquitous in REE deposits, crystallising during early high temperature melt crystallisation to late low-temperature fluid-flow events. This project will use carbonate as a novel ‘geological clock’ to date these processes using U-Pb radiometric dating. U-Pb carbonate dating is a relatively new technique that is revolutionising the timing of carbonate formation in many settings, including ore deposit formation because it allows us to date hydrothermal processes for the first time. Despite this, the technique can be challenging due to low U and high common Pb concentrations, resulting in low success rates for many studies.

In this proposal, I seek funds to increase the analytical capacity of our laser ablation mass spectrometry system. A beam expander will substantially increase the resolving power of the technique by allowing dates to be determined for ever-decreasing uranium content of calcite. This increased sample volume will improve the analytical precision, sensitivity, and success rate, allowing for dating of a wider range of processes in ore deposits for the first time. Improving timing of REE deposit models will aid exploration for these in-demand resources, reduce uncertainty and thus the footprint, environmental and social impacts of projects.