The PIs have proposed IODP drilling expeditions to hotspot traces in the Indian Ocean (Chagos-Laccadive and Ninetyeast ridges) and Atlantic (Walvis Ridge) to complement paleomagnetic results from the Hawaiian-Emperor chain in the Pacific (ODP Leg 197). These drilling cruises will provide data for re-examining hotspot models for these seamount chains as well as testing whether or not they are fixed relative to the spin axis or mantle reference frames. To collect site survey data for the proposed drilling program and to test the hotspot hypothesis for Ninetyeast Ridge, the PIs propose the collection and analysis of geophysical data (bathymetry, magnetic and seismic) and dredge samples from nine sites along the 5000-km long ridge. The proposed project is based upon a 46-day cruise that will collect multibeam bathymetry, magnetic, and seismic data at 5 sites as well as dredges at these sites and 4 others. The study is both a site survey (i.e., it provides the required data to prepare for drilling) as well as a stand-alone project to examine the hotspot hypothesis for Ninetyeast Ridge, which is one of the Earths primary hotspot tracks. The study involves graduate and undergraduate students, involves international collaboration, and bears on the fixity of hotspots, of great current interest.
