# High-precision U-Pb data and reference age for Emerald Lake apatite

## TL;DR

This paper presents high-precision U-Pb dating of Emerald Lake apatite, establishing it as a reliable reference material for geochronology.

## Contribution

The study provides a new high-precision U-Pb age for Emerald Lake apatite, enhancing its use as a reference material.

## Key findings

- A three-dimensional isochron yields a 95.2 ± 1.1 Ma date for Emerald Lake apatite.
- Weighted mean initial Pb-corrected dates are 95.18 ± 0.10 Ma (206Pb/238U) and 95.20 ± 0.17 Ma (207Pb/235U).
- Emerald Lake apatite is recommended as a reference material for in situ U-Pb geochronology.

## Abstract

New isotope dilution thermal ionization mass spectrometry U-Pb data for Emerald Lake apatite demonstrate its potential as a reference material for geochronology. A three-dimensional 238U/206Pb-207Pb/206Pb-204Pb/206Pb isochron produces a 95.2 ± 1.1 Ma date with an initial Pb isotopic composition of 206Pb/204Pb = 18.85 ± 0.19 and 207Pb/204Pb = 15.68 ± 0.10 (n = 5, MSWD = 9.5). These data yield a weighted mean initial Pb-corrected 206Pb/238U date of 95.18 ± 0.10 Ma (n = 5, MSWD = 1.5) and a weighted mean initial Pb-corrected 207Pb/235U date of 95.20 ± 0.17 Ma (n = 5, MSWD = 0.5). The new high-precision U-Pb age of Emerald Lake apatite further enables its utility as a reference material for in situ U-Pb apatite geochronology. Aliquots of Emerald Lake apatite are available for distribution for use in future studies.