RSES Seminar Series 2024-10-24 Axel K. Schmitt (Curtin University)

The world’s youngest syenite-carbonatite system underneath Laacher See, Germany: A testbed for carbonatite genesis
Axel K. Schmitt (John de Laeter Centre, Curtin University)

Abstract: Carbonatites are the dominant source for rare earth elements. Meeting the ever-increasing global demand for these critical minerals requires identifying fertile carbonatite rock bodies, but this is hampered by a fundamental lack in understanding timescales and process rates of their formation. Moreover, zircon is the key accessory mineral to date past carbonatite formation events, but it is intrinsically unstable in carbonatite melts, limiting the interpretability of such ages. This talk addresses this conundrum from the viewpoint of uranium-series whole-rock and zircon data for the world’s youngest known syenite-carbonatite complex, which is accessible in the form of ejecta clasts in pyroclastic deposits from the c. 13,000-year-old Laacher See eruption. Through study of these clasts, the pace of silicate-carbonatite melt evolution can be established at an absolute temporal resolution unachievable in ancient carbonatites.