During a 1987 expedition to the Marquesas island chain, the principal investigators mapped part of a high ridge that lies at the intersection of the Marquesas swell with the Marquesas fracture zone. They concluded that the fracture zone is a weak zone within the Pacific plate that allowed magmas from a weak hotspot to reach the surface. This project will survey sections of the Marquesas fracture zone using multibeam bathymetric tools, gravity, magnetics, single-channel reflection, and dredging. The survey will study the magmatic expression of three hotspots before, during, and after they encounter the fracture zone. The morphology of the fracture zone at the hotspot intersections will be contrased with other segments that have not encountered hotspots. The overall goals are to better constrain the origin of fracture zone topography, the intrinsic dimension and temporal continuity of hotspots, their interaction with lithospheric discontinuities, and the azimuth and extent of the oldest sectionof the Marquesas fracture zone.
