Linking composition and emplacement mechanisms of volcaniclastic mass transport deposits offshore Fogo, Cabo Verde

Volcanic flank collapses represent one of the most hazardous mass-wasting processes at ocean-island volcanoes due to their potential to generate large tsunamis. Fogo volcano, located within the Cabo Verde Archipelago off the coast of West Africa, is a highly active volcanic system associated with multiple geohazards, including explosive eruptions, seismicity, landslides, and tsunamis caused by flank collapses. These processes result in the widespread submarine deposition of volcaniclastic material. However, the source mechanisms, emplacement dynamics and spatial distribution of these deposits remain poorly understood.

Here we present 12 sediment cores, recovered proximal to distal from Fogo during research cruise M155 aboard RV Meteor, which contain multiple volcanogenic event layers. These layers provide archives for reconstructing mass-wasting activity and offer potential for stratigraphic correlation in marine records.

This study unravels the mechanisms responsible for the formation of volcanogenic turbidites and establishes diagnostic criteria for distinguishing different types of volcaniclastic mass-transport deposits. Thereby emphasis is placed on identifying characteristic sedimentological and compositional features associated with individual event layers. We use a combined approach of structural analyses on sediment epoxy peals, quantitative sediment petrography coupled with glass-chemistry and age-modelling. This unique approach allows assigning the compositional and structural variations of volcaniclastic material to primary deposits related to flank collapses, landslides, and pyroclastic density currents from Fogo, and secondary deposits generated by other mass-wasting events and tsunami backwash in the region. Furthermore, these findings contribute to a better understanding of submarine volcanic processes and associated geohazards at ocean-island volcanoes.