New insights into the recent eruptive and collapse history of Montagne Pelée (Lesser Antilles Arc) from offshore marine drilling site U1401A (IODP Expedition 340)

Abstract

Marine tephrochronology provides a good alternative to study the eruptive history of volcanic islands and overcome the problem of poorly preserved on-land outcropping. Here, we provide new observations on the recent volcanological evolution (<40 kyrs) of Montagne Pelée (Martinique, Lesser Antilles) based on the tephrochonological study of a marine core from Site U1401, sampled during IODP Expedition 340 and located 28 km from the coastline, west off Martinique Island. The core (15 m recovered length) was obtained on the top of the debris avalanche deposits due to the last flank collapse that occurred on Montagne Pelée volcano. Although it was not possible to drill through the debris avalanche deposits because of the heterogeneity of the deposit and the presence of large blocks, the sediments and volcanic deposits that covered the debris avalanche deposits were sampled. A detailed multiparameter study (geophysical data acquired on-board during the IODP cruise, lithological and geochemical data and temporal constrains through 18O stratigraphy and 14C dating) of the core U1401A provides a new age for the last flank collapse leading us to update the recent volcanological history of Montagne Pelée. The last flank collapse is now dated at ~36 cal. ka BP (older than previous studies). The flank collapse, even though relatively minor in volume (2 km3), had a significant consequence on the magma plumbing system of Montagne Pelée and produced abundant explosive eruptions of basaltic-andesite magmas, during the period 36–25 cal. ka BP. This new age range obtained for this flank collapse has important implications for the post collapse activity and allows us to rethink the recent volcanological history of Montagne Pelée.