Determining the lifespan of Pumice Rafts from the 1883 Krakatau Eruption

Ward, Sarah; Fauria, Kristen; Madden-Nadeau, Amber; Watt, Sebastian; Cassidy, Michael; Mittal, Tushar; Engwell, Samantha. 2023 Determining the lifespan of Pumice Rafts from the 1883 Krakatau Eruption. [Poster] In: IAVCEI 2023, Rotorua, New Zealand, 29 Jan - 3 Feb 2023. British Geological Survey. (Unpublished)

Full text not available from this repository. (Request a copy)

Abstract/Summary

Pumice-producing eruptions near large bodies of water can create pumice rafts, which are large swaths of floating pumice tens to thousands of square kilometers in area. These rafts can transport eruptive products hundreds to thousands of kilometers from their source, influencing the grain-size and thickness of seafloor pumiceous deposits and the preservation of large eruptive events in the marine eruptive record. Although previous work has shown that pumice floats due to capillary gas trapping and isolated porosity, it is not clear if or how floatation characteristics or mechanisms evolve within a single eruption and therefore how the style and magnitude of an event may influence the formation and extent of pumice rafts. Here we quantify the textural and flotation characteristics of 25 clasts from two fall deposits, one pyroclastic flow deposit, and one deposit with both fall and flow characteristics from the 1883 eruption of Krakatau—an eruption which produced large-scale pumice rafts. We measure clasts’ total and connected porosities and assess the time it takes individual clasts to sink in the lab. While all deposits exhibit similarly high pore connectivity (0.7-1) and total porosities (77-97%), pyroclastic density current (PDC) deposits sink faster than airfall deposits. Further analysis of clast microtextures using 3D images obtained via x-ray microtomography may illuminate the degree to which clasts that floated longer are microtexturally distinct from those that sank more quickly. Overall, our results help us to discern the mechanisms that impact the lifespan of pumice rafts.

Item Type:	Publication - Conference Item (Poster)
Additional Keywords:	IGRD
Date made live:	27 Apr 2023 15:03 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/534397

Actions (login required)

View Item

Document Downloads

More statistics for this item...