using ArF excimer laser ablation-ICPMS

• Main Authors: Tsuyoshi Iizuka, Takafumi Hirata
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.566.9393; http://www.terrapub.co.jp/journals/GJ/pdf/3803/38030229.pdf

Using a laser ablation-inductively coupled plasma mass spectrometer (LA-ICPMS), U-Pb age and rare earth element (REE) abundances have been determined simultaneously from a single 20 µm ablation pit of zircon. The laser ablation system utilizing 193 nm wave-length ArF excimer laser produces stable and reproducible signal intensities resulted in good precisions on measurements of element concentrations and isotopic ratios. Because of the higher energy density of the deep ultra-violet laser beam, ablation fractionation between Pb and U were reduced even with the prolonged ablation, and thus accuracy of Pb-U age was improved significantly. A chicane-type ion lens system was applied to a quadrupole-based ICPMS instrument. With the chicane ion lens, higher elemental sensitivity (4 times for light mass range and 3 times for mid to heavy mass range) and lower white background (<5 cps for light to mid mass range and <2 cps for heavy mass range) were achieved. This further improved analytical precisions for low concentration elements in samples. The 238U-206Pb ages for Nancy standard zircon (Nancy 91500), SHRIMP calibration standard zircon (SL13) and Antarctic zircon (PMA7) obtained in this study were 1064 ± 24 Ma, 569 ± 78 Ma and 2438 ± 101 Ma (2-sigma), respec-tively. Relative age differences from previous reports were 0.2%, 0.4 % and 3.2 % respectively, demonstrative of high reliability of the method. The REE abundances in zircon samples were calibrated using a NIST 610 glass standard refer-ence material. The resulting REE abundance data for zircons (Nancy 91500 and SL13) show good agreement with those