U‐Pb Age Determination for Seven Standard Zircons using Inductively Coupled Plasma–Mass Spectrometry Coupled with Frequency Quintupled Nd‐YAG (λ = 213 nm) Laser Ablation System: Comparison with LA‐ICP‐MS Zircon Analyses with a NIST Glass Reference Material

Abstract

This paper evaluates the analytical precision, accuracy and long-term reliability of the U-Pb age data obtained using inductively coupled plasma -mass spectrometry (ICP-MS) with a frequency quintupled Nd-YAG ( = 213nm) laser ablation system. The U-Pb age data for seven standard zircons of various ages, from 28 Ma to 2400 Ma (FCT, SL13, 91500, AS3, FC1, QGNG and PMA7) were obtained with an ablation pit size of 30 m d iameter. For 207 Pb/ 206 Pb ratio measurement, the mean isotopic ratio obtained on National Institute of Standards and Technology (NIST) SRM610 over 4 months was 0.9105 ± 0.0014 ( n = 280, 95% confi dence), which agrees well with the published value of 0.9096. The time-profi le of Pb/U ratios during single spot ablation showed no signifi cant difference in shape from NIST SRM610 and 91500 zircon standards. These results encouraged the use of the glass standard as a calibration standard for the Pb/U ratio determination for zircons with shorter wavelength ( = 213 nm) laser ablation. But 206 Pb/ 238 U and 207 Pb/ 235 U ages obtained by this method for seven zircon standards are systematically younger than the published U-Pb ages obtained by both isotope dilution -thermal ionization mass spectrometry (ID-TIMS) and sensitive high-resolution ion-microprobe (SHRIMP). Greater discrepancies (3 -4% younger ages) were found for the 206 Pb/ 238 U ages for SL13, AS3 and 91500 zircons. The origin of the differences could be heterogeneity in Pb/U ratio on SRM610 between the different disks, but a matrix effect accuracy either in the ICP ion source or in the ablation-transport processes of the sample aerosols cannot be neglected. When the 206 Pb/ 238 U (= 0.2302) newly defi ned in the present study is used, the measured 206 Pb/ 238 U and 207 Pb/ 235 U ages for the seven zircon standards are in good agreement with those from ID-TIMS and SHRIMP within ±2%. This suggests that SRM610 glass standard is suitable for ICP-MS with laser ablation sampling (LA-ICP-MS) zircon analysis, but it is necessary to determine the correction factor for 206 Pb/ 238 U by measuring several zircon standards in individual laboratories.

New U-Pb zircon ages from Paleo-Mesoarchean TTG gneisses of the Singhbhum Craton, Eastern India

“…Abbreviations: Gp., Group; Fm., Formation. ml/min) was added to the He carrier gas. Detailed procedure and analytical precision are described in Orihashi et al (2008).…”

Zircon growth in a granitic pluton with specific mechanisms, crystallization temperatures and U–Pb ages: Implication to the ‘spatiotemporal’ formation process of the Toki granite, central Japan

“…To achieve this, charcoal filters for the removal of Hg in Ar gas (Hirata and Nesbitt, 1995;Hirata et al, 2005) and the signal smoothing device (Tunheng and Hirata, 2004) were components of our LA-ICP-MS system (Orihashi et al, 2008). Moreover, a femtosecond laser ablation system was employed to reduce the elemental fractionation during the laser ablation (Hirata and Kon, 2008).…”

Input ion optics of inductively coupled plasma quadrupole mass spectrometers. Part 3. Asymmetrical systems with local arc-shaped ion deflection

“…В Токийском технологическом институте (Япо-ния) преимущества offset-оптики [10,11] реализо-вывали с 2000 г. на стандартных серийных ИСП-масс-спектрометрах VG PQ2/S/Omega [35][36][37] и VG PQ3S [38] (производства Thermo Elemental или Thermo Electron) путем соответствующей модификации их штатной осесимметричной оптики. Для этого в центре последней [3] вместо фотонейтралостопа устанавливали группу из 5 параллельных отклоня-ющих пластин (названных chicane-lens), снабжен-ных, подобно [10,11], дугообразно смещенными от главной оси проходными отверстиями для ио-нов (см.…”