Improved age estimates for Holocene Ko-g and Ma-f~j tephras in northern Japan using Bayesian statistical modelling

Chen, X.-Y., Blockley, S. P.E., Staff, R. A. , Xu, Y.-G. and Menzies, M. A. (2022) Improved age estimates for Holocene Ko-g and Ma-f~j tephras in northern Japan using Bayesian statistical modelling. Quaternary Geochronology, 67, 101229. (doi: 10.1016/j.quageo.2021.101229)

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The Ko-g and Ma-f~j tephras are two key isochronous marker layers in northern Japan, which are from the largest Plinian eruptions of Komagatake volcano (VEI = 5) and Mashu caldera (VEI = 6), respectively. Despite extensive radiocarbon studies associated with the two tephras, individual calibrated results show considerable variations and thus accurate ages of these important eruptions remain controversial. Bayesian statistical approaches to calibrating radiocarbon determinations have proven successful in increasing accuracy and sometimes precision for dating tephras, which is achieved through the incorporation of additional stratigraphic information and the combination of evidence from multiple records. Here we use Bayesian approaches to analyse the proximal and distal information associated with the two tephra markers. Through establishing phase and deposition models, we have taken into account all of the currently available stratigraphic and chronological information. The cross-referencing of phase models with the deposition model allows the refinement of eruption ages and the deposition model itself. Using this we are able to provide the most robust current age estimates for the two tephra layers. The Ko-g and Ma-f~j tephras are hereby dated to 6657-6505 (95.4%; 6586±40, μ±σ) cal yr BP, and 7670-7395 (95.4%; 7532±72, μ±σ) cal yr BP, respectively. These updated age determinations underpin the reported East Asian Holocene tephrostratigraphic framework, and allow sites where the tephra layers are present to be dated more precisely and accurately. Our results encourage further applications of Bayesian modelling techniques in the volcanically active East Asian region.

Item Type:Articles
Additional Information:This study was supported by Chinese Academy of Sciences Strategic Priority Research Program (B) (XDB18000000) and the External Cooperation Program of the Bureau of International Co-operation, CAS (Grant No. 132744KYSB20130005). XYC would like to acknowledge the RHUL-China Scholarship awarded to him by RHUL under the collaboration scheme between GIGCAS and RHUL. This is contribution No. IS-3054 from GIGCAS.
Glasgow Author(s) Enlighten ID:Staff, Dr Richard
Authors: Chen, X.-Y., Blockley, S. P.E., Staff, R. A., Xu, Y.-G., and Menzies, M. A.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Quaternary Geochronology
ISSN (Online):1878-0350
Published Online:29 August 2021
Copyright Holders:Copyright © 2021 Elsevier
First Published:First published in Quaternary Geochronology 67:101229
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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