A stochastic sampling approach to zircon eruption age interpretation
Abstract
The accessory mineral zircon is widely used to constrain the timing of igneous processes such as magma crystallisation or eruption. However, zircon UPb ages record zircon crystallisation, which is not an instantaneous process. Zircon saturation calculations link zircon crystallisation, temperature, and melt fraction, allowing for the estimation of zircon crystallisation distributions as a function of time or temperature. Such distributions provide valuable prior information, enabling Bayesian estimates of magma eruption time and allowing for comparison of the relative accuracy of common weightedmean and youngestzircon age interpretations with synthetic datasets. We find that both traditional interpretations carry a risk of underestimating the uncertainty in eruption age; a low mean square of weighted deviates (MSWD) does not guarantee the accuracy of weightedmean interpretations. In the absence of independent confirmation that crystallisation timescale is short relative to analytical uncertainties, a Bayesian approach frequently provides the most accurate results and is least likely to underestimate uncertainty. Finally, since UPb zircon studies now routinely resolve geological age dispersion due to increasing analytical precision, such considerations are increasingly critical to future progress in resolving rates and dates of Earth processes.
 Authors:

 Berkeley Geochronology Center, Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States). Dept. of Earth and Planetary Science
 Princeton Univ., NJ (United States). Dept. of Geosciences
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Nuclear and Chemical Sciences Division
 Publication Date:
 Research Org.:
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Sponsoring Org.:
 USDOE National Nuclear Security Administration (NNSA)
 OSTI Identifier:
 1488817
 Report Number(s):
 LLNLJRNL738859
Journal ID: ISSN 24103403; 892278
 Grant/Contract Number:
 AC5207NA27344; FG0297ER25308
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Geochemical Perspectives Letters
 Additional Journal Information:
 Journal Volume: 8; Journal ID: ISSN 24103403
 Country of Publication:
 United States
 Language:
 English
 Subject:
 58 GEOSCIENCES; geochronology; Bayesian statistics; zircon age distribution
Citation Formats
Keller, C. B., Schoene, B., and Samperton, K. M. A stochastic sampling approach to zircon eruption age interpretation. United States: N. p., 2018.
Web. doi:10.7185/geochemlet.1826.
Keller, C. B., Schoene, B., & Samperton, K. M. A stochastic sampling approach to zircon eruption age interpretation. United States. doi:10.7185/geochemlet.1826.
Keller, C. B., Schoene, B., and Samperton, K. M. Tue .
"A stochastic sampling approach to zircon eruption age interpretation". United States. doi:10.7185/geochemlet.1826. https://www.osti.gov/servlets/purl/1488817.
@article{osti_1488817,
title = {A stochastic sampling approach to zircon eruption age interpretation},
author = {Keller, C. B. and Schoene, B. and Samperton, K. M.},
abstractNote = {The accessory mineral zircon is widely used to constrain the timing of igneous processes such as magma crystallisation or eruption. However, zircon UPb ages record zircon crystallisation, which is not an instantaneous process. Zircon saturation calculations link zircon crystallisation, temperature, and melt fraction, allowing for the estimation of zircon crystallisation distributions as a function of time or temperature. Such distributions provide valuable prior information, enabling Bayesian estimates of magma eruption time and allowing for comparison of the relative accuracy of common weightedmean and youngestzircon age interpretations with synthetic datasets. We find that both traditional interpretations carry a risk of underestimating the uncertainty in eruption age; a low mean square of weighted deviates (MSWD) does not guarantee the accuracy of weightedmean interpretations. In the absence of independent confirmation that crystallisation timescale is short relative to analytical uncertainties, a Bayesian approach frequently provides the most accurate results and is least likely to underestimate uncertainty. Finally, since UPb zircon studies now routinely resolve geological age dispersion due to increasing analytical precision, such considerations are increasingly critical to future progress in resolving rates and dates of Earth processes.},
doi = {10.7185/geochemlet.1826},
journal = {Geochemical Perspectives Letters},
issn = {24103403},
number = ,
volume = 8,
place = {United States},
year = {2018},
month = {10}
}
Web of Science
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