TY - JOUR
T1 - A stochastic sampling approach to zircon eruption age interpretation
AU - Keller, C. B.
AU - Schoene, B.
AU - Samperton, K. M.
N1 - Funding Information:
Thanks to B. Dyer and J.-F. Wotzlaw for discussion and to P. Vermeesch, K. Gallagher, U. Schaltegger, and T. Sheldrake for valuable reviews. CBK. was supported in part by the Department of Energy Computational Science Graduate Fellowship Program of the Office of Science and National Nuclear Security Administration under contract DE-FG02-97ER25308. Computational support was provided by the Princeton Institute for Computational Science and Engineering. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344. All source code is available at https://github.com/brenhinkeller/BayeZirChron.c
Publisher Copyright:
© 2018 Geochemical Perspectives Letters.All right reserved.
PY - 2018
Y1 - 2018
N2 - The accessory mineral zircon is widely used to constrain the timing of igneous processes such as magma crystallisation or eruption. However, zircon U-Pb 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 weighted-mean and youngest-zircon 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 weighted-mean 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. Since U-Pb 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.
AB - The accessory mineral zircon is widely used to constrain the timing of igneous processes such as magma crystallisation or eruption. However, zircon U-Pb 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 weighted-mean and youngest-zircon 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 weighted-mean 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. Since U-Pb 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.
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U2 - 10.7185/geochemlet.1826
DO - 10.7185/geochemlet.1826
M3 - Article
AN - SCOPUS:85057468253
SN - 2410-339X
VL - 8
SP - 31
EP - 35
JO - Geochemical Perspectives Letters
JF - Geochemical Perspectives Letters
ER -