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Sedimentation associated with glaciovolcanism: a review

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journal contribution
posted on 2022-03-24, 11:05 authored by John Laidlaw Smellie
Three discrete categories of sedimentary deposits are associated with glaciovolcanism: englacial cavity, jökulhlaup and lahar. Englacial cavity deposits are found in water-filled chambers in the lee of active glaciovolcanoes or at a locus of enhanced geothermal heat flux. The cavities provide a depocentre for the accumulation of debris, either abundant fresh juvenile debris with sparse dropstones (associated with active glaciovolcanism) or polymict basal glacial debris in which dropstones are abundant (associated with geothermal hot spots). Described examples are uncommon. By contrast, volcanogenic jökulhlaup deposits are abundant, mainly in Iceland, where they form extensive sandar sequences associated with ice-covered volcanoes. Jökulhlaups form as a result of the sudden subglacial discharge of stored meltwater. Analogous deposits known as glaciovolcanic sheet-like sequences represent the ultra-proximal lateral equivalents deposited under the ice. Glaciovolcanic lahars are associated with ice-capped volcanoes. They form as a result of explosive eruptions through relatively thin ice or following dome collapse, and they trigger mainly supraglacial rather than subglacial meltwater escape. Sediment transport and depositional processes are similar in jökulhaups and lahars and are dominated by debris flow and hyperconcentrated or supercritical flow modes during the main flood stage, although the proportions of the principal lithofacies are different.

History

Citation

Geological Society, London, Special Publications, 520, 1 March 2022, https://doi.org/10.1144/SP520-2021-135

Author affiliation

School of Geography, Geology and Environment, University of Leicester

Version

  • AM (Accepted Manuscript)

Published in

Geological Society, London, Special Publications

Volume

520

Publisher

Geological Society of London

issn

0305-8719

eissn

2041-4927

Acceptance date

2021-12-22

Copyright date

2022

Available date

2023-03-01

Language

en

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