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Impact of air, laser pulse width and fluence on U-Pb dating of zircons by LA-ICPMS

journal contribution
posted on 2023-05-19, 18:54 authored by Thompson, JM, Sebastien MeffreSebastien Meffre, Leonid Danyushevsky
The accuracy of zircon U–Pb dating by LA-ICPMS is limited by matrix effects related to differences in U–Pb fractionation between an unknown and the calibration standard. Zircon radiation dose has a strong influence on the ablation rate, which in turn affects the amount of U–Pb fractionation and subsequent age calculations. Presented in this study is a previously unrecognized source of uncertainty in LA-ICPMS U–Pb ages due to variations of atmospheric air absorbed onto the surfaces of samples. Laser properties such as fluence (J cm−2) will change the laser ablation rate, and therefore the degree of U–Pb fractionation, and this can change the amount of zircon matrix effect. To improve the accuracy of U–Pb dating by LA-ICPMS, a systematic error component related to radiation dose needs to be included, or alternatively a correction to U–Pb dates can be applied as a function of radiation dose relative to the primary calibration standard. This study proposes a method to calculate a correction factor for the zircon matrix effect by measurement of several zircon reference materials with varying radiation dosages.

Funding

Australian Research Council

AMIRA International Ltd

ARC C of E Industry Partner $ to be allocated

Anglo American Exploration Philippines Inc

AngloGold Ashanti Australia Limited

Australian National University

BHP Billiton Ltd

Barrick (Australia Pacific) PTY Limited

CSIRO Earth Science & Resource Engineering

Mineral Resources Tasmania

Minerals Council of Australia

Newcrest Mining Limited

Newmont Australia Ltd

Oz Minerals Australia Limited

Rio Tinto Exploration

St Barbara Limited

Teck Cominco Limited

University of Melbourne

University of Queensland

Zinifex Australia Ltd

History

Publication title

Journal of Analytical Atomic Spectrometry

Volume

33

Pagination

221-230

ISSN

0267-9477

Department/School

School of Natural Sciences

Publisher

Royal Soc Chemistry

Place of publication

Thomas Graham House, Science Park, Milton Rd, Cambridge, England, Cambs, Cb4 0Wf

Rights statement

© The Royal Society of Chemistry 2018

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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