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Expedition 340 summary1

Expedition 340 Scientists2


The Lesser Antilles Volcanism and Landslides project aims to elucidate the constructive and destructive processes of island arc volcanoes. The data set collected includes the first ever drilling of volcanic island landslides and cores providing a long-term re cord of volcanic eruption cycles and magmatic evolution. Processes occurring along these arcs are among the most fundamental on Earth. Styles of magmatism and eruptive activity are diverse in this geological setting not only between different arcs but also between the different islands that make up an arc. Because of the association of volcanic activity in island arcs with potentially very damaging geohazards (explosive eruptions and tsunamis), it is imperative to investigate and thus better understand the evolution of these volcanoes and the histories of their related landslides.

Knowledge of island arc volcanism has previously been limited mainly to the subaerial geological record. Combining this record with information from related submarine deposits will provide a more complete picture of volcanic activity in this geological setting. The Lesser Antilles arc lends itself well to achieving this combined record, offering a diverse range of magmatic and eruptive styles across a relatively small geographic area. In addition, the frequency of events that result in the deposition of mass transport deposits is high, with the style of processes varying along the arc.

Integrated Ocean Drilling Program Expedition 340 focused on nine strategic drill sites around Montserrat and Martinique, as they are representative of the entire eruptive activity across the Lesser Antilles arc. We recovered 434 cores containing 2384 m of seafloor sediment samples. This expedition has shown that large mass-wasting deposits around volcanic islands can comprise large volumes of seafloor sediment, which has significant implications for tsunami generation. Initial emplacement of volcanic material on the seafloor can trigger even larger secondary failures of the seafloor sediment. Offshore Montserrat, Site U1395 sampled a 7 m thick interval of stacked turbidites associated with the largest recent landslide, whereas Site U1396 provides a ~4.5 m.y. record of eruptions on the island. Offshore Martinique, Sites U1399 and U1400 penetrated chaotic deposits comprising only tilted or more strongly deformed bedded seafloor sediments. Site U1397 provides a 400 k.y. record of eruptions of Martinique and Dominica.

Data and samples acquired during this expedition are stored at the Gulf Coast Repository at Texas A&M University (USA) and will be carefully screened to further investigate magmatic evolution and eruptive activity along the Lesser Antilles arc. In addition, we hope to reach a better understanding of the mechanisms involved in both the transport and deposition of volcanic debris avalanche deposits and to assess the potential for volcanic hazards associated with these avalanches.

1 Expedition 340 Scientists, 2013. Expedition 340 summary. In Le Friant, A., Ishizuka, O., Stroncik, N.A., and the Expedition 340 Scientists, Proc. IODP, 340: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/​iodp.proc.340.101.2013

2Expedition 340 Scientists’ addresses.

Publication: 17 August 2013
MS 340-101