Multi-stage collapse events in the South Soufrière Hills, Montserrat as recorded in marine sediment cores

Cassidy, M., Trofimovs, J., Watt, S.F.L., Palmer, M.R., Taylor, R.N., Gernon, T.M., Talling, P.J., & Le Friant, A. (2014) Multi-stage collapse events in the South Soufrière Hills, Montserrat as recorded in marine sediment cores. Memoirs, 39, pp. 383-397.

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Abstract

We present new evidence for sector collapses of the South Soufrière Hills (SSH) edifice, Montserrat during the mid-Pleistocene. High-resolution geophysical data provide evidence for sector collapse, producing an approximately 1 km3 submarine collapse deposit to the south of SSH. Sedimentological and geochemical analyses of submarine deposits sampled by sediment cores suggest that they were formed by large multi-stage flank failures of the subaerial SSH edifice into the sea. This work identifies two distinct geochemical suites within the SSH succession on the basis of trace-element and Pb-isotope compositions. Volcaniclastic turbidites in the cores preserve these chemically heterogeneous rock suites. However, the subaerial chemostratigraphy is reversed within the submarine sediment cores. Sedimentological analysis suggests that the edifice failures produced high-concentration turbidites and that the collapses occurred in multiple stages, with an interval of at least 2 ka between the first and second failure. Detailed field and petrographical observations, coupled with SEM image analysis, shows that the SSH volcanic products preserve a complex record of magmatic activity. This activity consisted of episodic explosive eruptions of andesitic pumice, probably triggered by mafic magmatic pulses and followed by eruptions of poorly vesiculated basaltic scoria, and basaltic lava flows.

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ID Code: 74278
Item Type: Journal Article
Refereed: Yes
Keywords: Montserrat, submarine landslide, turbidites, stratigraphy
DOI: 10.1144/M39.20
ISSN: 2041-4722
Subjects: Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000)
Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > GEOLOGY (040300)
Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > GEOLOGY (040300) > Marine Geoscience (040305)
Divisions: Current > Schools > School of Earth, Environmental & Biological Sciences
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2014 The Geological Society of London
Deposited On: 23 Jul 2014 00:05
Last Modified: 23 Jul 2014 22:19

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