The ISOPLOT software (Ludwig, 2003) is used for reporting, interpretation and plotting of the analytical results.Ĭoncordia diagrams (left) and final ages (right) of Plesovice, Temora0 reference zircons. Reported dates for igneous rock samples are based on the weighted mean of the calculated 206Pb/ 238U dates for relatively young zircons (Phanerozoic), and on the weighted mean of the calculated 207Pb/ 206Pb dates for zircons older than 1.5 Ga. Data are reduced using Iolite software (Paton et al., 2011). Both U-Pb data for geochronology and up to 30 user-selected trace elements, including rare earth elements, are acquired from a single laser shot. Zircons are routinely analyzed from igneous rocks as well as detrital zircon or stream sediment samples. (2) An ArF excimer (λ =193 nm) laser ablation system ( NWR193UC Electro Scientific Industries/New Wave Research) coupled to a HR-SF-ICP-MS ( Element 2 Thermo Scientific). (1) An ArF excimer (λ =193 nm) laser ablation system ( RESOlution M-50LR Australian Scientific Instruments) coupled to a quadrupole ICP-MS ( 7700 Series Agilent Technologies) or a HR-SF-ICP-MS ( AttoM Nu Instruments) (Wall et al., 2016 VerHoeve et al., 2018) PCIGR performs U-Pb dating of zircons by laser ablation, using two set-ups: VG54R Concordia diagrams showing U-Pb results for EARTHTIME standard analyses conducted at PCIGR between July 2018 and December 2019. The ISOPLOT software package (Ludwig, 2003) is used for final plotting of data. Data reduction is done with U-Pbr, an Excel-based routine based on the error estimate algorithms published by Schmitz and Shoene (2007). U and Pb are loaded together on an outgassed zone-refined Re filament, and run separately in peak-hopping mode. A variety of accessory phases, including titanite, monazite, rutile, apatite, allanite and garnet, are prepared using single- or multi-grain fractions and ion exchange chromatography, and a mixed EARTHTIME or UBC spike (Scoates and Friedman, 2008 Wall et al., 2016).Īt PCIGR, U and Pb analysis of zircons is done on either a VG354S or VG54R TIMS, where both instruments employ an analogue single Daly collector. Zircons are processed with the chemical abrasion (CA-TIMS) single-grain U-Pb technique that uses EARTHTIME ET535 or a UBC 205Pb- 233-235U isotopic tracer. We have dated rocks from Pliocene to Archean in age, for clients from universities, government and industry. TIMS U-Pb geochronology is widely recognized as one of the most robust and precise dating techniques. The external morphology of mineral grains for analysis can be documented by SEM, and internal structure can be examined in polished grain mounts by cathodoluminescence imaging. Four binocular microscope workstations are available for sample picking. Samples for U-Pb dating are processed using a Rhino jaw crusher, a Bico disk grinder equipped with ceramic grinding plates, and a Wilfley wet shaker table equipped with a machined Plexiglass top, followed by conventional heavy liquid and magnetic separation using a Frantz magnetic separator.
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