Zircon crystallization patterns from U-Th dates inform U-Pb estimates of volcanic eruption ages

U-Pb dating of zircons provides time constraints on events from 4.5 Ga to < 1Ma by measuring the timing of zircon crystallization. Absolute uncertainties on U-Pb zircon dates are significant enough to obscure zircon crystallization and complicate estimating the relationship between zircon crystallization and volcanic eruption. We use published U-Th disequilibrium dates representing 137 zircon samples with ages <350 ka and maximum likelihood estimation to develop a clearer picture of zircon crystallization and estimate the gap, if one exists, between the cessation of zircon crystallization and volcanic eruption. Our maximum likelihood estimation technique produces best-fit parameters of six reasonable crystallization models for each sample and evaluates the fit of each model using Bayesian Information Criterion (BIC). Our results show that, while the crystallization history of 56 of 137 zircon data populations remains unresolved even with sub-10 ka absolute date uncertainties, most resolvable models’ crystallization histories (57%) best fit right skew distributions consistent with open-system petrologic models (e.g., Reid et al., 1997). MLE modeling of the eruption gap distribution best fits an exponential distribution with a mean of 11.6 ± 2.2 kyr (2σ). This contrasts with previous work, which suggests gaps between the cessation of zircon crystallization and volcanic eruption on the order of ± 200 ka. We propose that U-Pb geochronologists select a prior model that matches the nature of the dated magma system and produce an eruption age using the Bayesian MLE approach of Keller et al. (2018) and apply our mean eruption gap of 11.6 ± 2.2 kyr when estimating eruption ages from U-Pb zircon dates.

Grantor dc:publisher

University of Kansas

Year dc:date.issued

2024

Author dc:creator

• Sturdevant IV, Guy Clark

Advisor dc:contributor.advisor

• McLean, Noah

• Geology
• Geochemistry
• Petrology
• crystallization
• Geochronology
• Maximum Likelihood Estimation
• U-Pb
• U-Th Dates
• Zircon

Language dc:language.iso

en

Dc Identifier Other

http://dissertations.umi.com/ku:19881

OAI identifier oai:identifier

oai:kuscholarworks.ku.edu:1808/38442