Material transfer in an arc-ridge collision zone


  • Leg 134 Shipboard Scientific Party


The influence of colliding and subducting ridges on the structural evolution of volcanic island arcs was investigated during Leg 134 of the Ocean Drilling Program (ODP) in the Central New Hebrides Island Arc, Southwest Pacific. Documenting tectonic accretion of colliding ridges onto the forearc of the central New Hebrides Island Arc (Vanuatu) and fragmentation of the island-arc crust were the primary drilling objectives. Other objectives included studies of compressional dewatering, diagenetic alteration of pore fluids with rocks of an accretionary mass, and the tectonic evolution of a colliding guyot. Ridge-arc collisions significantly alter the morphology and structure of volcanic island arcs and continental margins; however, the processes of tectonic deformation are poorly understood. Leg 134 documented for the first time material transfer from a ridge to an arc and defined the style of deformation occurring in the forearc area of a ridge-arc collision zone.