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

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

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.

Citation

Williams, R., Branney, M. J., & Barry, T. L. (2014). Temporal and spatial evolution of a waxing then waning catastrophic density current revealed by chemical mapping. Geology, 42(2), 107-110. https://doi.org/10.1130/G34830.1

• Journal Article Type: Article
• Acceptance Date: Oct 14, 2013
• Publication Date: 2014-02
• Deposit Date: Nov 27, 2015
• Publicly Available Date: Nov 23, 2017
• 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
• Public URL: https://hull-repository.worktribe.com/output/381881
• Publisher URL: http://geology.gsapubs.org/content/42/2/107
• 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.