Explosive activity of the Reunion Island volcanoes through the past 260,000 years as recorded in deep-sea sediments

The explosive activity of Reunion volcanoes since approximately 260 ka is i nvestigated through detailed sedimentologic, isotopic, and geochemical anal yses of three deep-sea marine cores. Twenty-four eruptions from Piton des N eiges and one from Piton de la Fournaise are identified. The marine stratig raphic record of ash layers is undisturbed, whereas corresponding tephra de posits on land may have disappeared or have been disturbed through erosion and volcano-tectonic processes. Consequently, the new data presented herein may be regarded as a reference sequence of the main explosive events of Re union. In addition, the chronology based on delta O-18 stratigraphy offers continuous time constraints with respect to other isotopic methods used for dating lavas. Explosive events were more frequent during the period 180-15 0 ka. The comparison of major element composition and chronologic data betw een known explosive deposits on land and marine ash layers allows us to pro pose correlations between marine and land data. However, most of the marine ash layers do not yet have a recognized subaerial counterpart. For the mai n explosive events known on land, we propose the following succession: Sain te Suzanne formations, greater than or equal to 257-240 ka; Dalle Soudee Fo rmation, 218 ka; Salazie formations, two groups at 165-168 ka and 80-102 ka ; Saint Gilles formations, 175 ka; Saint Louis formations, 158-161 ka; and Saint Pierre formations, 165-166 ka.