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Timing and emplacement dynamics of newly recognised mass flow deposits at ~8–12ka offshore Soufrière Hills volcano, Montserrat: How submarine stratigraphy can complement subaerial eruption histories

Timing and emplacement dynamics of newly recognised mass flow deposits at ~8–12ka offshore Soufrière Hills volcano, Montserrat: How submarine stratigraphy can complement subaerial eruption histories
Timing and emplacement dynamics of newly recognised mass flow deposits at ~8–12ka offshore Soufrière Hills volcano, Montserrat: How submarine stratigraphy can complement subaerial eruption histories
This contribution describes two mass movement deposits (total volume ~ 0.5 km3) identified in seven marine cores located 8 to 15 km offshore southern Montserrat, West Indies. The deposits were emplaced in the last 35 ka and have not previously been recognised in either the subaerial or distal submarine records. Age constraints, provided by radiocarbon dating, show that an explosive volcanic eruption occurred at ca 8–12 ka, emplacing a primary eruption-related deposit that overlies a large (~ 0.3 km3) reworked bioclastic and volcaniclastic flow deposit, formed from a shelf collapse between 8 and 35 ka. The origin of these deposits has been deduced through the correlation of marine sediment cores, component analysis and geochemical analysis. The 8–12 ka primary volcanic deposit was likely derived from a highly-erosive pyroclastic flow from the Soufrière Hills volcano that entered the ocean and mixed with the water column forming a water-supported density current. Previous investigations of the eruption record suggested that there was a hiatus in activity at the Soufrière Hills volcano between 16 and 6 ka. The ca 8–12 ka eruptive episode identified here shows that this hiatus was shorter than previously hypothesised, and thus highlights the importance of obtaining an accurate and complete marine record of events offshore from volcanic islands and incorporating such data into eruption history reconstructions. Comparisons with the submarine deposit characteristics of the 2003 dome collapse also suggests that the ~ 8–12 ka eruptive episode was more explosive than eruptions from the current eruptive episode.
Montserrat, Pyroclastic flow, Debris avalanche, Dome collapse, Marine geology, Soufrière Hills volcano
0377-0273
1-14
Cassidy, M.
67673759-386d-4138-a782-680799419beb
Trofimovs, J.
933c8923-03a5-4341-9cd8-3a0733bfbc15
Palmer, M.R.
d2e60e81-5d6e-4ddb-a243-602537286080
Talling, P.J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Watt, S.F.L.
76f594eb-9252-4a8b-822f-be71038b18db
Moreton, S.G.
24fea7b9-f847-42e0-ac5a-914332900564
Taylor, R.N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Cassidy, M.
67673759-386d-4138-a782-680799419beb
Trofimovs, J.
933c8923-03a5-4341-9cd8-3a0733bfbc15
Palmer, M.R.
d2e60e81-5d6e-4ddb-a243-602537286080
Talling, P.J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Watt, S.F.L.
76f594eb-9252-4a8b-822f-be71038b18db
Moreton, S.G.
24fea7b9-f847-42e0-ac5a-914332900564
Taylor, R.N.
094be7fd-ef61-4acd-a795-7daba2bc6183

Cassidy, M., Trofimovs, J., Palmer, M.R., Talling, P.J., Watt, S.F.L., Moreton, S.G. and Taylor, R.N. (2013) Timing and emplacement dynamics of newly recognised mass flow deposits at ~8–12ka offshore Soufrière Hills volcano, Montserrat: How submarine stratigraphy can complement subaerial eruption histories. Journal of Volcanology and Geothermal Research, 253, 1-14. (doi:10.1016/j.jvolgeores.2012.12.002).

Record type: Article

Abstract

This contribution describes two mass movement deposits (total volume ~ 0.5 km3) identified in seven marine cores located 8 to 15 km offshore southern Montserrat, West Indies. The deposits were emplaced in the last 35 ka and have not previously been recognised in either the subaerial or distal submarine records. Age constraints, provided by radiocarbon dating, show that an explosive volcanic eruption occurred at ca 8–12 ka, emplacing a primary eruption-related deposit that overlies a large (~ 0.3 km3) reworked bioclastic and volcaniclastic flow deposit, formed from a shelf collapse between 8 and 35 ka. The origin of these deposits has been deduced through the correlation of marine sediment cores, component analysis and geochemical analysis. The 8–12 ka primary volcanic deposit was likely derived from a highly-erosive pyroclastic flow from the Soufrière Hills volcano that entered the ocean and mixed with the water column forming a water-supported density current. Previous investigations of the eruption record suggested that there was a hiatus in activity at the Soufrière Hills volcano between 16 and 6 ka. The ca 8–12 ka eruptive episode identified here shows that this hiatus was shorter than previously hypothesised, and thus highlights the importance of obtaining an accurate and complete marine record of events offshore from volcanic islands and incorporating such data into eruption history reconstructions. Comparisons with the submarine deposit characteristics of the 2003 dome collapse also suggests that the ~ 8–12 ka eruptive episode was more explosive than eruptions from the current eruptive episode.

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More information

Published date: 1 March 2013
Keywords: Montserrat, Pyroclastic flow, Debris avalanche, Dome collapse, Marine geology, Soufrière Hills volcano
Organisations: Geology & Geophysics, Geochemistry, Marine Geoscience

Identifiers

Local EPrints ID: 346915
URI: https://eprints.soton.ac.uk/id/eprint/346915
ISSN: 0377-0273
PURE UUID: c32028f5-d0a2-440c-8954-1fa40994225b

Catalogue record

Date deposited: 11 Jan 2013 13:32
Last modified: 18 Jul 2017 05:00

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Contributors

Author: M. Cassidy
Author: J. Trofimovs
Author: M.R. Palmer
Author: P.J. Talling
Author: S.F.L. Watt
Author: S.G. Moreton
Author: R.N. Taylor

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