Technical note: Rapid phase identification of apatite and zircon grains for geochronology using X-ray micro-computed tomography

Abstract. Apatite and zircon are among the best-studied most widely used accessory minerals for geochronology thermochronology. Given that apatite often present in same lithologies, distinguishing two phases crushed mineral separates is a common task geochronology, thermochronology, petrochronology studies. Here we method efficient accurate phase identification verification using X-ray micro-computed tomography (microCT) of grain mounts provides additional three-dimensional size, shape, inclusion suite information. In this study, analyze grains from Fish Canyon Tuff samples went through methylene iodide (MEI) lithium heteropolytungstate (LST) heavy liquid density separations. We validate microCT results known standards with Raman spectroscopy, demonstrating distinguishable each other phases, e.g., titanite, based on density. recommended scanning protocols after systematically testing effects different parameters sample positions. This methodology can help to reduce time spent performing separations highly toxic chemicals visually inspecting under light microscope, improved characterization make geochronologic data more robust.