The proposed work will test the ideas about how oceanic lithosphere deforms as it enters the subduction zone and how its composition affects the magmatism of the adjacent volcanic arc. The investigators will undertake a magnetic and multibeam bathymetric survey and dredge rock samples from the outer bulge of Tonga-Kermadec Trench for geomorphological and geochemical analyses, respectively. This will allow them to sample young exposures of old oceanic crust rpoduced by faulting and study the sample young exposures of old oceanic crust produced by faulting and study the Mesozoic deformation. A 2000-km long and 80 km wide strip will be mapped by Seabeam 2000 and ca 20-30 dredge samples will be collected.
