RUI: Deep Crustal Structure of the Ivory Coast Basin: an Ocean-Bottom Seismograph Study

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This research involves the analysis and interpretation of a large- airgun OBS seismic refraction data set collected in the Gulf of Guinea, offshore West Africa. This data set is a subset of a larger one collected by French scientists in 1990. This part of the African margin is known as the Ivory Coast-Ghana Margin, and is an example of a passive margin formed through transform rifting. The crustal structures developed during transform rifting are relatively poorly understood. Seismic refraction data offer one of the best means of determining crustal thicknesses and structures resulting from this process. Information derived from the seismic refraction data analysis will also be used as part of a site survey for upcoming ODP activities in the area. %%% When continents rift apart, they may do so through divergent (major direction of motion perpendicular to continent-continent boundary line) or transform (major direction of motion parallel to continent-continent boundary line) processes. The latter process has not been studied in as much detail as the former, and is relatively poorly understood. The rifting record is contained in now-buried and submerged structures within passive margins, or trailing edges of continents. These structures can perhaps be best determined through deep seismic sounding techniques. Within the area offshore West Africa known as the Ivory Coast-Ghana Margin, lie submerged features that record the transform rifting that occurred between West Africa and Brazil in the Cretaceous. Ocean Bottom Seismometer seismic refraction data collected in 1990 will be analyzed and interpreted, resulting in a picture of subsurface structures in this region. In addition to answering fundamental questions concerning the nature of structures contained within transform passive margins, the seismic data will be used as background information for upcoming Ocean Drilling Project activities in the area.