Submarine eruption-fed and resedimented pumice-rich facies: the Dogashima Formation (Izu Peninsula, Japan)
Submarine eruption-fed and resedimented pumice-rich facies: the Dogashima Formation (Izu Peninsula, Japan)
In the Izu Peninsula (Japan), the Pliocene pumice-rich Dogashima Formation (4.55?±?0.87 Ma) displays exceptional preservation of volcaniclastic facies that were erupted and deposited in a below wave-base marine setting. It includes high-concentration density current deposits that contain clasts that were emplaced hot, indicating an eruption-fed origin. The lower part of the Dogashima 2 unit consists of a very thick sequence (<12 m) of massive grey andesite breccia restricted to the base of a submarine channel, gradationally overlain by pumice breccia, which is widespread but much thinner and finer in the overbank setting. These two breccias share similar mineralogy and crystal composition and are considered to be co-magmatic and derived from the destruction of a submarine dome by an explosive, pumice-forming eruption. The two breccias were deposited from a single, explosive eruption-fed, sustained, sea floor-hugging, water-supported, high-concentration density current in which the clasts were sorted according to their density. At the rim of the channel, localised good hydraulic sorting of clasts and stratification in the pumice breccia are interpreted to reflect local current expansion and unsteadiness rather than to be the result of hydraulic sorting of clasts during fall from a submarine eruption column and/or umbrella plume. A bimodal coarse (>1 m) pumice- and ash-rich bed overlying the breccias may be derived from delayed settling of pyroclasts from suspension. In Dogashima 1 and 2, thick cross- and planar-bedded facies composed of sub-rounded pumice clasts are intercalated with eruption-fed facies, implying inter-eruptive mass-wasting on the flank of a submarine volcano, and reworking and resedimentation by high-energy tractional currents in a below wave-base environment.
Submarine pumice, High-concentration density current, Hydraulic sorting, Eruption-fed, Resedimented, Dogashima Formation
867
Jutzeler, Martin
3ff7423b-ed16-439c-ad5b-1822b72d7b8c
McPhie, Jocelyn
55a4dd37-008b-441f-91ce-f7ff5bffc9a0
Allen, Sharon R.
956fd82a-0235-4410-a5b1-d2a7bb7fc63a
September 2014
Jutzeler, Martin
3ff7423b-ed16-439c-ad5b-1822b72d7b8c
McPhie, Jocelyn
55a4dd37-008b-441f-91ce-f7ff5bffc9a0
Allen, Sharon R.
956fd82a-0235-4410-a5b1-d2a7bb7fc63a
Jutzeler, Martin, McPhie, Jocelyn and Allen, Sharon R.
(2014)
Submarine eruption-fed and resedimented pumice-rich facies: the Dogashima Formation (Izu Peninsula, Japan).
Bulletin of Volcanology, 76 (10), .
(doi:10.1007/s00445-014-0867-x).
Abstract
In the Izu Peninsula (Japan), the Pliocene pumice-rich Dogashima Formation (4.55?±?0.87 Ma) displays exceptional preservation of volcaniclastic facies that were erupted and deposited in a below wave-base marine setting. It includes high-concentration density current deposits that contain clasts that were emplaced hot, indicating an eruption-fed origin. The lower part of the Dogashima 2 unit consists of a very thick sequence (<12 m) of massive grey andesite breccia restricted to the base of a submarine channel, gradationally overlain by pumice breccia, which is widespread but much thinner and finer in the overbank setting. These two breccias share similar mineralogy and crystal composition and are considered to be co-magmatic and derived from the destruction of a submarine dome by an explosive, pumice-forming eruption. The two breccias were deposited from a single, explosive eruption-fed, sustained, sea floor-hugging, water-supported, high-concentration density current in which the clasts were sorted according to their density. At the rim of the channel, localised good hydraulic sorting of clasts and stratification in the pumice breccia are interpreted to reflect local current expansion and unsteadiness rather than to be the result of hydraulic sorting of clasts during fall from a submarine eruption column and/or umbrella plume. A bimodal coarse (>1 m) pumice- and ash-rich bed overlying the breccias may be derived from delayed settling of pyroclasts from suspension. In Dogashima 1 and 2, thick cross- and planar-bedded facies composed of sub-rounded pumice clasts are intercalated with eruption-fed facies, implying inter-eruptive mass-wasting on the flank of a submarine volcano, and reworking and resedimentation by high-energy tractional currents in a below wave-base environment.
Text
Jutzeler Dogashima Japan accepted.pdf
- Accepted Manuscript
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Published date: September 2014
Keywords:
Submarine pumice, High-concentration density current, Hydraulic sorting, Eruption-fed, Resedimented, Dogashima Formation
Organisations:
Marine Geoscience
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Local EPrints ID: 373262
URI: http://eprints.soton.ac.uk/id/eprint/373262
ISSN: 0258-8900
PURE UUID: 79b9fece-b2d5-4c3d-bef9-452c2885c368
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Date deposited: 12 Jan 2015 14:40
Last modified: 14 Mar 2024 18:50
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Author:
Martin Jutzeler
Author:
Jocelyn McPhie
Author:
Sharon R. Allen
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