Work

Low‐temperature dissociation of zircon in highly alkaline conditions: A cautionary note for studies on natural glasses of debated origin

Year: 2025

Type: article

Abstract: Dissociated zircon is largely used as a robust indicator of glasses generated by impact cratering and airbursts. The reaction of zircon dissociation, i.e. ‘ZrSiO 4 → ZrO 2 + SiO 2 ’, requires high temperatures (>1670°C) only reached by extreme geological processes. Using high‐temperature experiments, this study shows that zircon can dissociate and form ZrO 2 ‐rich coronitic rims at temperatures of 900–1000°C (P = 1 bar), in the presence of a specific chemical environment made of NaCl or a mixture of NaCl and caliche soil (Ca‐sulfates). The use of silica glass vessels provides a SiO 2 ‐rich environment during the experiments. We observe that the dissociation is strongly related to the complexity of the surrounding system (e.g. the presence of other minerals that act as a flux) in which the reaction occurs. For these reasons, we suggest considering a more careful approach in using dissociated zircon as indicative of very high temperatures in glass‐forming processes.

Source: Meteoritics and Planetary Science

DOI: 10.1111/maps.14372