Opening of the Central North Atlantic: Revised Seafloor Spreading Isochrons and Tectonic Map from Geosat Data (Paleoceanographic Mapping Project Progress Report No. 39-0888)

Plate reconstructions for the opening of the Central and North Atlantic were made by combining Geosat altimetry and magnetic anomaly data. Geosat deflection of the vertical (horizontal gravity) data, which reflect the short wavelength basement topography of the ocean floor allowed us to construct a much improved map of fracture zones m the Central and North Atlantic. The fabric of prominent fracture zones, as interpreted from Geosat deflection of the vertical data, was utilized to constrain the fits of corresponding magnetic anomaly lineations by using an Evans and Sutherland 3-D graphics computer system. For example, we have used the trace of the Charlie-Gibbs Fracture Zone to better constrain the spreading history between the North American and Eurasian plate. Movements of smaller plates such as in the Canadian Arctic and the western Mediterranean were tied to the relative motion of the major plates by applying a hierarchical plate analysis technique. Our tectonic model served as a base to construct a self-consistent isochron chart of the Central and North Atlantic ocean floor.