Discovery of a large 2.4 Ma Plinian eruption of Basse-Terre, Guadeloupe, from the marine sediment record

Abstract

Large volcanic eruptions are major geohazards, so identifying their frequency in the geologic record is critical for making predictions and hazard assessments. Following the discovery of a thick (18 cm) tephra layer in marine sediments from Integrated Ocean Drilling Program (IODP) Site U1396 between Montserrat and Guadeloupe in the Caribbean Sea, we document here how highprecision Pb isotopes, trace elements, and grain morphological analyses of the tephra can be used, together with volcanological models, to identify a large (Volcanic Explosivity Index ~6) Plinian eruption from Basse- Terre, Guadeloupe, at ca. 2.36 Ma. This previously unrecognized eruption is believed to be the largest documented volcanic event in this region since this time. We hypothesize that this large eruption was associated with the final stage in the evolution of an individual volcanic center, which has implications for prediction of geohazards in this setting.