The Lesser Antilles Volcanic Arc

Several sites around the Lesser Antilles Volcanic Arc were drilled during IODP Expedition 340 to understand the volcanic history and evolution of the arc. These cores spanned a range of time scales, with one core in-particular (U1396) containing a 4.5Myr record of sedimentation. Containing a visible tephra record, and potentially an invisible cryptotephra record these sediment sequences extend the knowledge of volcanic processes occurring over the Northern part of the arc back 2Myrs beyond current terrestrial dates.

Our focus concentrates on using magnetic measurements to recover the NRM of U1395 (a 1Myr sediment record), and U1396 to construct magnetostratigraphic records and provide age control for these important records. Using ARM and magnetic susceptibility we will also generate estimations of relative paleointensity and examine the tephra record directly addressing several of the expedition objectives.

Figure 1 shows the shipboard reversal stratigraphy obtained for U1396. Note the well defined magnetic directional record preserving all 17 reversal boundaries back 4.5Myr into the Gauss chron and the highly variable magnetic susceptibility record of the ~135 m sediment record noting the frequency of tephra events. Together we can use these records to provide event return periods which is directly useful for hazard planning for the populations of Montserrat and Guadeloupe. 


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