Peixe Zircon as a Quality Control Reference Material in U‐Pb Geochronology byLA‐ICP‐MS

A megacryst zircon from Brazil, referred to here as Peixe#0, was evaluated as a potential reference material for LA-ICP-MS U-Pb dating. Results from multi-method characterisation – including CA-ID-TIMS, SIMS and a long-term LA-ICP-MS data set – enabled us to assess this crystal's suitability as a reference material for routine quality control in age determinations by LA-ICP-MS. Using CA-ID-TIMS, Peixe#0 yielded mean 206Pb/238U and 207Pb/235U ratios of 0.09257 ± 0.1% and 0.7561 ± 0.1%, respectively (precisions expressed as 2RSD), and weighted mean 206Pb/238U age of 570.85 ± 0.30 Ma (2s, MSWD = 0.40, n = 4). With the LA-ICP-MS compiled database (2063 individual age determinations distributed over 167 sessions spanning eight years) acquired during routine analysis at the Isotope Geology Laboratory (LAGIS) at Unicamp, Brazil, we propose a 206Pb/238U weighted mean age of 569 ± 13 Ma (2s), which includes the long-term excess variance in the total uncertainty. Oxygen isotopes presented a homogeneous distribution (δ18OSMOW = +5.13 ± 0.15‰ (1s)). The trace element chemical compositions varied substantially depending on the chosen cathodoluminescence zone containing distinct features. Approximately 4 g of Peixe#0 zircon are available for distribution upon request.