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Vesiculation and fragmentation history in a submarine scoria cone-forming eruption, an example from Nishiizu (Izu Peninsula, Japan)

journal contribution
posted on 2023-05-18, 18:00 authored by Martin JutzelerMartin Jutzeler, White, JDL, Proussevitch, AA, Gordee, SM
An uplifted, >50-m-thick, half-dissected, submarine-emplaced (below wave-base) scoria cone occurs as dipping beds in coastal outcrops at Nishiizu, on the Izu Peninsula in Japan. Concentrically outward-dipping, weakly stratified, ungraded, framework-supported thin-to-very thick beds consist of brown coarse tuff to scoria lapilli-tuff, with outsized fluidal bombs throughout; accessory lithic clasts chiefly occur in the lowermost visible beds. Scoria bombs have quenched margins, weak bread-crust textures and their vesicle number densities decrease inward, which is indicative of fast surface cooling. Composite textures in the scoria bombs indicate recycling and agglutination of quenched and semi-molten pyroclasts at the submarine vent. In contrast to weak concentric gradations in vesicle size distribution in the bombs, lapilli have asymmetrical gradients in vesicle size distribution, indicating that they are fragments of coarser, quenched lumps. Three grain-size modes characterise the Nishiizu brown scoria, with coarse magma lumps ejected during magmatic fragmentation and quench-jointed upon contact with seawater, to be subsequently fragmented into lapilli and coarse ash by various styles of fragmentation where seawater plays a critical role. The cone was constructed by slow-moving fallout-fed granular flow/creep, fed directly by suspension settling focused at the crater rim but extending onto the cone flanks, with only minor resedimentation by granular flows. Nishiizu deposits yield an exceptional record of eruption and sedimentation dynamics during submarine cone-building activity, and in this study we compare their vesiculation and fragmentation mechanisms with those of potential subaerial analogues.


Publication title

Bulletin of Volcanology



Article number









School of Natural Sciences



Place of publication

175 Fifth Ave, New York, USA, Ny, 10010

Rights statement

Copyright 2016 Springer-Verlag Berlin Heidelberg

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences