In-situ evaluation of zirconium-bearing minerals for geochronology using micro X-ray fluorescence

In this contribution we present a method for pre-screening geological materials for zircon prior to submitting samples for heavy mineral separation. The proposed workflow utilizes micro X-ray fluorescence to identify zirconium-bearing pixels in slabbed rock samples. The open-source image analysis software ImageJ™ is applied to the micro X-ray fluorescence elemental map to determine the abundance and spatial distribution of zirconium-bearing pixels in the scanned surface area. This method allows for the prediction of zircon abundance and estimation of grain size within a sample which can be used to prioritize samples for geochronology as well as inform crushing and grinding metrics for heavy mineral separation. This information can ultimately lead to improved recovery of zircon and other mineral geochronometers for geochronological studies. Advantages of the proposed workflow include: • Minimal sample preparation and rapid results; • Analytical method is non-destructive; and • In-situ grain size estimation and abundance predictions prior to initiating time-consuming and costly heavy mineral separation methods.