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Temporal and spatial evolution of a waxing then waning catastrophic density current revealed by chemical mapping

Williams, Rebecca; Barry, Tiffany L.; Branney, Michael J.

Authors

Michael J. Branney

Tiffany L. Barry

Abstract

We reconstruct the behavior of a catastrophic sustained radial pyroclastic density current as it waxed then waned during its brief lifespan. By subdividing the deposit into 8 time slices using a chemical tracer, we show that the sustained current initially was topographically restricted, but that its leading edge advanced in all directions, encroaching upon and gradually ascending hills. During peak flow the current reached its maximum extent and overtopped all topographic highs. After this, and while the current direction from source was maintained, the leading edge gradually retreated sourceward. High-resolution analysis of the depositional architecture reveals how the flow dynamics evolved and runout distance of the sustained density current rapidly increased then decreased, reflecting the dominant influence of changing mass flux, as demonstrated in numerical models but not previously distinguished in a natural deposit.

Journal Article Type Article
Publication Date 2014-02
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 42
Issue 2
Pages 107-110
DOI https://doi.org/10.1130/G34830.1
Keywords Chemical mapping
Publisher URL http://geology.gsapubs.org/content/42/2/107
Copyright Statement © 2013 Geological Society of America. Gold Open Access: This paper is published under the terms of the CC-BY license (http://creativecommons.org/licenses/by/3.0/us/).
Additional Information This is a Gold Open Access article published under the terms of the CC-BY licence in Geology, 2014, v.42 issue 2.

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Copyright Statement
© 2013 Geological Society of America. Gold Open Access: This paper is published under the terms of the CC-BY license (http://creativecommons.org/licenses/by/3.0/us/).



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