WJS810: A Low-Radiation-Damage Neoproterozoic (~ 817 Ma) Zircon Reference Material for Microbeam U-Pb, Hf and O Isotopic Measurement

Abstract

This study introduces WJS810, a new natural zircon reference material designed for microbeam-based U-Pb geochronology and Hf-O isotope geochemistry. Extensive analyses using secondary ion mass spectrometry (SIMS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) have confirmed that WJS810 exhibits uniform U-Pb, Hf and O isotopic ratios. Six chemical abrasion isotope dilution thermal ionisation mass spectrometry (CA-ID-TIMS) U-Pb isotopic measurements yielded weighted mean ²⁰⁶Pb/²³⁸U, ²⁰⁷Pb/²³⁵U and ²⁰⁷Pb/²⁰⁶Pb ages of 816.88 ± 0.61 Ma (2s, n = 6), 816.90 ± 0.59 Ma (2s, n = 6) and 816.79 ± 0.93 Ma (2s, n = 6), respectively. Results from SIMS and LA-ICP-MS yielded concordant ages are in agreement with the TIMS age within analytical uncertainty. The mean ¹⁷⁶Hf/¹⁷⁷Hf ratio determined by LA-MC-ICP-MS is 0.282548 ± 0.000043 (2s, n = 121), which is in good consistency with the mean of 0.282548 ± 0.000005 (2s, n = 6) determined by solution-MC-ICP-MS. The δ¹⁸O value determined by SIMS is 6.65 ± 0.36‰ (2s, n = 117), which is consistent with the mean of 6.46 ± 0.21‰ (2s, n = 8) determined by laser fluorination. Raman microspectroscopy demonstrates that WJS810 exhibits exceptionally low (minimal) radiation damage, with a mean full width at half maximum (FWHM) of 4.06 cm^-1, comparable to the widely used 91500 reference material (mean FWHM = 4.47 cm^-1). WJS810 represents a valuable addition to the existing suite of Neoproterozoic zircon reference materials for microbeam-based U-Pb geochronology and Hf-O isotope measurement.