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

Cassidy, Michael; Trofimovs, Jessica; Palmer, Martin R.; Talling, Peter J.; Watt, Sebastian; Moreton, Steven G.; Taylor, Rex N.

doi:10.1016/j.jvolgeores.2012.12.002

Cited by 22 publications

(50 citation statements)

References 53 publications

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“…The eruption of Soufrière Hills volcano, which started in 1995 [ Druitt and Kokelaar , ; Wadge et al ., ], shows a succession of different eruptive styles with lava dome growth and vulcanian explosions generating abundant pyroclastic density currents. Most of the pyroclastic density currents entered the sea, where their deposits have also been studied in detail [ Le Friant et al ., ; Trofimovs et al ., ; Cassidy et al ., ]. Minor tsunamis were sometimes caused by the rapid entrance of volcanic material into the sea [ Sparks et al ., ; Mattioli et al ., ].…”

Section: Resultsmentioning

confidence: 99%

Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODPExpedition 340

Friant

Ishizuka

Boudon

et al. 2015

Geochem Geophys Geosyst

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IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form 420Geochemistry, Geophysics, Geosystems PUBLICATIONS smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.

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Section: Resultsmentioning

confidence: 99%

Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODPExpedition 340

Friant

Ishizuka

Boudon

et al. 2015

Geochem Geophys Geosyst

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“…Volcaniclastic flow deposits, whether primary or secondary, are generally less well-sorted, as the material is emplaced more quickly (Sigurdsson et al, 1980;Carey and Sigurdsson 1984;Fisher and Schminke 1994), with the caveat that some turbidite deposits become well-sorted during gradual sedimentation (Kneller and Buckee, 2000;Mulder and Alexander, 2001). This latter process is evidenced by the range of sorting index values found throughout the turbidite deposits (shown by the red and blue arrows in Figure 6; Cassidy et al, 2013Cassidy et al, , 2014.…”

Section: Distinguishing Tephra Fallout Deposits From Other Volcaniclamentioning

confidence: 99%

“…1). Montserrat is an ideal region for this type of study, because the surrounding seafloor has been extensively surveyed (Le Friant et al, 2004, 2009Lebas et al, 2011;Watt et al, 2012a,b) and cored (Trofimovs et al, 2006(Trofimovs et al, , 2008(Trofimovs et al, , 2013Le Friant et al, 2008, 2009Cassidy et al, 2013Cassidy et al, , 2014, and the subaerial record of volcanism and igneous geochemistry is particularly wellconstrained (Rea, 1974;Roobol and Smith, 1998;Harford et al, 2002;Zellmer et al, 2003;Smith et al, 2007;Cassidy et al, 2012). This earlier work has shown that marine volcaniclastic sedimentation around Montserrat encompasses a rich array of processes, and that the identification of tephra fall deposits within the stratigraphy is not a trivial task.…”

Section: Page |mentioning

confidence: 99%

“…Subaerial pyroclastic density currents can (partially) transform into turbidity currents upon entrance into the ocean (Trofimovs et al, 2006;Cassidy et al, 2013), although turbidity currents may also deposit volcaniclastic sediment via a range of other, non-eruptive processes (Schindlbeck et al, 2013). …”

Section: Sedimentology Termsmentioning

confidence: 99%

“…Most recently, this activity has originated from the currently active Soufrière Hills (282 ka -present), Page | 16 with an interlude of volcanism at South Soufrière Hills (SSH) (128 -131 ka) (Harford et al, 2002). The subaerial record of volcanism at these two centres suggests eight active episodes, dating from 174 ka (Rea, 1974;Roobol and Smith, 1997;Harford et al, 2002;Smith et al, 2007;Cassidy et al, 2013). Studies of the history of Montserrat volcanism using submarine deposits have only been undertaken recently (Le Friant et al, 2008;Trofimovs et al, 2010Trofimovs et al, , 2013Cassidy et al, 2013Cassidy et al, , 2014.…”

Section: Montserrat: the Natural Laboratorymentioning

confidence: 99%

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Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Cassidy

Watt

Palmer

et al. 2014

Earth-Science Reviews

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Detailed knowledge of the past history of an active volcano is crucial for the prediction of the timing, frequency and style of future eruptions, and for the identification of potentially at-risk areas. Subaerial volcanic stratigraphies are often incomplete, due to a lack of exposure, or burial and erosion from subsequent eruptions. However, many volcanic eruptions produce widelydispersed explosive products that are frequently deposited as tephra layers in the sea. Cores of marine sediment therefore have the potential to provide more complete volcanic stratigraphies, at least for explosive eruptions. Nevertheless, problems such as bioturbation and dispersal by currents affect the preservation and subsequent detection of marine tephra deposits.Consequently, cryptotephras, in which tephra grains are not sufficiently concentrated to form layers that are visible to the naked eye, may be the only record of many explosive eruptions.Additionally, thin, reworked deposits of volcanic clasts transported by floods and landslides, or during pyroclastic density currents may be incorrectly interpreted as tephra fallout layers, leading to the construction of inaccurate records of volcanism. This work uses samples from the volcanic island of Montserrat as a case study to test different techniques for generating volcanic eruption records from marine sediment cores, with a particular relevance to cores sampled in relatively proximal settings (i.e. tens of kilometres from the volcanic source) where volcaniclastic material may form a pervasive component of the sedimentary sequence. Visible volcaniclastic deposits identified by sedimentological logging were used to test the effectiveness of potential alternative volcaniclastic-deposit detection techniques, including point counting of grain types (component analysis), glass or mineral chemistry, colour spectrophotometry, grain size measurements, XRF core scanning, magnetic susceptibility and X-radiography. This study demonstrates that a set of time-efficient, non-destructive and high-spatial-resolution analyses (e.g. XRF core-scanning and magnetic susceptibility) can be used effectively to detect potential cryptotephra horizons in marine sediment cores. Once these horizons have been sampled, microscope image analysis of volcaniclastic grains can be used successfully to discriminate between tephra fallout deposits and other volcaniclastic deposits, by using specific criteria Page | 3 related to clast morphology and sorting. Standard practice should be employed when analysing marine sediment cores to accurately identify both visible tephra and cryptotephra deposits, and to distinguish fallout deposits from other volcaniclastic deposits.

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Late Pleistocene stratigraphy of IODP Site U1396 and compiled chronology offshore of south and south west Montserrat, Lesser Antilles

Wall-Palmer

Coussens

Talling

et al. 2014

Geochem Geophys Geosyst

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Marine sediments around volcanic islands contain an archive of volcaniclastic deposits, which can be used to reconstruct the volcanic history of an area. Such records hold many advantages over often incomplete terrestrial data sets. This includes the potential for precise and continuous dating of intervening sediment packages, which allow a correlatable and temporally constrained stratigraphic framework to be constructed across multiple marine sediment cores. Here we discuss a marine record of eruptive and masswasting events spanning 250 ka offshore of Montserrat, using new data from IODP Expedition 340, as well as previously collected cores. By using a combination of high-resolution oxygen isotope stratigraphy, AMS radiocarbon dating, biostratigraphy of foraminifera and calcareous nannofossils, and clast componentry, we identify five major events at Soufriere Hills volcano since 250 ka. Lateral correlations of these events across sediment cores collected offshore of the south and south west of Montserrat have improved our understanding of the timing, extent and associations between events in this area. Correlations reveal that powerful and potentially erosive density-currents traveled at least 33 km offshore and demonstrate that marine deposits, produced by eruption-fed and mass-wasting events on volcanic islands, are heterogeneous in their spatial distribution. Thus, multiple drilling/coring sites are needed to reconstruct the full chronostratigraphy of volcanic islands. This multidisciplinary study will be vital to interpreting the chaotic records of 3000Geochemistry, Geophysics, Geosystems PUBLICATIONS submarine landslides at other sites drilled during Expedition 340 and provides a framework that can be applied to the stratigraphic analysis of sediments surrounding other volcanic islands.

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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

Cited by 22 publications

References 53 publications

Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODPExpedition 340

Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODPExpedition 340

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Late Pleistocene stratigraphy of IODP Site U1396 and compiled chronology offshore of south and south west Montserrat, Lesser Antilles

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