In-situ Lu – Hf geochronology of calcite

Abstract. The ability to constrain the age of calcite formation is of great utility to the Earth Science community, due to the ubiquity of calcite across a wide spectrum of geological systems. Here, we present the first in-situ laser ablation inductively coupled tandem mass spectrometry (LA-ICP-MS/MS) Lu–Hf ages for calcite, demonstrating geologically meaningful ages for IOCG and skarn mineralisation, carbonatite intrusion and low grade metamorphism. The analysed samples range in age between ca. 0.9 Ga and ca. 2 Ga with uncertainties between 1.4 % and 0.5 % obtained from calcite with Lu concentrations as low as ca. 0.5 ppm. The Lu–Hf system in calcite appears to be able to preserve primary precipitation ages over a significant amount of geological time, although further research is required to constrain the closure temperature. The in-situ approach allows calcite to be rapidly dated while maintaining its petrogenetic context with mineralization and other associated mineral processes. Therefore, LA-ICP-MS/MS Lu–Hf dating of calcite can be used to resolve the timing of complex mineral paragenetic sequences that are a feature of many ancient rock systems.