Assessing the U‐Pb, Sm‐Nd and Sr‐Sr Isotopic Compositions of the Sumé Apatite as a Reference Material for LA‐ICP‐MS Analysis

Abstract

This study has determined the trace element and the U‐Pb, Sm‐Nd and Sr‐Sr isotope composition of the Sumé apatite (from NE Brazil) to assess its suitability as a primary/secondary reference material for LA‐ICP‐MS. Reproducibility tests demonstrate that one batch (~ 100 g) of the Sumé apatite (Sumé‐570) is uniform in terms of Nd‐Nd and U‐Pb isotope compositions. Bulk isotope dilution TIMS/ICP‐MS and LA‐MC‐ICP‐MS analyses confirm that the apatite is well suited for use as quality control material for Nd isotopes and U‐Pb geochronology. U‐Pb ID‐TIMS analyses yield weighted mean ratios of 0.09211 ± 0.00053 (2s; 206Pb*/238U) and 0.06120 ± 0.00063 (2s; 207Pb*/206Pb*) and a weighted mean 206Pb*/238U date of 568 ± 3 Ma (95% c.l.). U‐Pb LA‐(SF/MC)‐ICP‐MS runs using Sumé‐570 as a primary RM and reproduces the dates of other established RMs within 1% deviation (except for Durango 2–4%). Major and trace element abundances show that Sumé‐570 is a fluorapatite derived from a syenitic source. It also strongly shows LREE‐enriched chondrite‐normalised REE patterns with significant negative Eu anomalies, due to crystallisation of plagioclase in the residue.

Khan River and Bear Lake: Two Natural Titanite Reference Materials for High‐Spatial Resolution U‐Pb Microanalysis

“…1994, Sumé apatite – Lana et al . 2022). Other titanite reference materials with small amounts of Pb c show broad variations in the 206 Pb/ 204 Pb ratios (e.g., MKED1–117% RSD, OLT1–18.9% RSD and BLR‐1 12.4% RSD).…”

“…Sumé apatite ( 147 Sm/ 144 Nd = 0.0766 ± 0.0002, 143 Nd/ 144 Nd = 0.51075 ± 0.00004, Lana et al . 2022) yielded an average 147 Sm/ 144 Nd of 0.0766 ± 0.0002 (2 s , n = 33) and 143 Nd/ 144 Nd of 0.51075 ± 0.00004 (2 s , n = 33).…”

“…2014) and Sumé apatite (an in‐house reference material – Lana et al . 2022), were used for quality control (Appendix S2). BLR‐1 titanite yielded an average 147 Sm/ 144 Nd of 0.1912 ± 0.0005 (2 s , n = 24) and 143 Nd/ 144 Nd of 0.51279 ± 0.00004 (2 s , n = 24), both within uncertainty of the values reported by Ma et al .…”

U‐Pb Saturn: New U‐Pb/Pb‐Pb Data Reduction Software for LA‐ICP‐MS

“…The U-Pb isotope compositions were measured at the Laboratório de Geoqu´ımica Isot ópica of the Universidade Federal de Ouro Preto, using a Thermo Scientific Neptune Plus multi-collector (MC)-ICP-MS coupled to a 193 nm HelEX Photon Machine laser ablation system (Lana et al 2017, Schannor et al 2021. The signals of the relevant masses were collected following Lana et al (2022). The U-Pb data were collected during 60 s of ablation with a spot size of 80 μm, a frequency of 5 Hz and a fluence of 6 J cm -2 .…”

“…The signals of the relevant masses were collected following Lana et al . (2022). The U‐Pb data were collected during 60 s of ablation with a spot size of 80 μm, a frequency of 5 Hz and a fluence of 6 J cm ‐2 .…”