Expedition 340 summary

Abstract

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 record 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. 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. Data and samples acquired during this expedition 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.