Inflated pyroclasts in proximal fallout deposits reveal abrupt transitions in eruption behaviour.
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| Authors: | Jones, TJ; Le Moigne, Y; Russell, JK; Williams-Jones, G; Giordano, D; Dingwell, DB |
| Year: | 2022 |
| Journal: | Nature Communications 13: 2832 Website Article Link (DOI) |
| Title: | Inflated pyroclasts in proximal fallout deposits reveal abrupt transitions in eruption behaviour. |
| Abstract: | During explosive eruption of low viscosity magmas, pyroclasts are cooled predominantly by 1 forced convection. Depending on the cooling efficiency relative to other timescales, a spectrum of 2 deposits can be formed. Deposition of hot clasts, above their glass transition temperature, can form 3 spatter mounds, ramparts and clastogenic lava flows. Clasts may also be deposited cold, producing 4 tephra cones and blankets. Thus, the deposit and pyroclast type can provide information about 5 eruption dynamics and magma properties. Here we examine pyroclasts from Tseax volcano, 6 British Columbia, Canada. These newly identified inflated pyroclasts, are fluidal in form, have 7 undergone post-depositional expansion, and are found juxtaposed with scoria. Detailed field, 8 chemical and textural observations, coupled with high temperature rheometry and thermal 9 modelling, reveal that abrupt transitions in eruptive behaviour – from lava fountaining to low-10 energy bubble bursts – created these pyroclastic deposits. These findings should help identify 11 transitions in eruptive behaviour at other mafic volcanoes worldwide. |
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