Research challenges assumptions about deep-sea volcanic eruptions

ANSTO

Key Points

  • Research on pumice formed after deep-sea volcanic eruptions challenges assumptions about known depth limits and the theory that deep-sea eruptions can’t be explosive

  • The pink colourisation of the pumice supported the theory that it was launched by a powerful jet from more than a mile beneath the ocean floor at temperatures above 700 degrees Celsius

  • Spectroscopy and microscopy on the X-ray fluorescence beamline clarified how the pink colourisation could have occurred

Experiments using an advanced imaging technique at ANSTO’s Australian Synchrotron have clarified how pink porous volcanic rock, found in the ocean following an eruption, might be formed in an underwater explosion.

Researchers from the University of Louisiana Lafayette, the Australian National University, and Queensland University of Technology applied X-ray fluorescence microscopy on samples of pink and white pumice found floating following the 2012 eruption of Havre Seamount, an undersea volcano in the Southwest Pacific Ocean.

Undersea volcano
Eruption model ©Creative Commons Attribution 4.0 International License COMMUNICATIONS EARTH & ENVIRONMENT | (2022) 3:19

The investigations clarified the source of pink colouration by examining the proportion and distribution of magnetite and hematite in the pumice samples.

In research published in Communications Earth and Environment, they concluded that the pink colourisation is due to the oxidation of magnetic nanolites and microlites to haematite and that a substantial proportion of magnetic microlites and nanolites need to be available for this to occur.

The Lafayette University researchers suggested that the findings challenge the known depth limits for deep-sea eruptions and assumptions that deep-sea eruptions can’t be explosive.

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