Strategies towards statistically robust interpretations of in situ U-Pb zircon geochronology

• Published in: Di xue qian yuan. Vol. 7; no. 4; pp. 581 - 589
• Main Authors: Spencer, Christopher J., Kirkland, Christopher L., Taylor, Richard J.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2016; Australian Research Council, Centre of Excellence for Core to Crust Fluid Systems, Perth, WA 6102, Australia; The Institute of Geoscience Research(TIGeR), Department of Applied Geology, Western Australian School of Mines, Curtin University, WA 6102, Australia%Centre for Exploration Targeting-Curtin Node, Department of Applied Geology, Western Australian School of Mines, Curtin University, WA 6102, Australia
• Subjects: Earth sciences; Filtering; Geochronology; Geology; Geostatistics; Ionization; Mathematical analysis; MSWD; Radioactive age determination; U-Pb; Zircon; 原位分析; 地球科学; 地质时间; 地质问题; 激光烧蚀; 统计处理; 锆石U-Pb年代学; 锆石年代学; Geochronology; U-Pb; Zircon; Geostatistics; MSWD
• ISSN: 1674-9871; 2588-9192
• DOI: 10.1016/j.gsf.2015.11.006

Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; MSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.