Figure 12. Key events in the geological history of the eastern margin of the Iberia Abyssal Plain. The short duration of rifting proposed in this paper is contrasted with the prolonged synrift episode identified by Boillot and Winterer (1988). The age of the onset of seafloor spreading is based on modeling surface and deep-tow magnetic data from the southeastern part of the Iberia Abyssal Plain (Whitmarsh and Miles, 1995; Whitmarsh et al., this volume). The ⁴⁰Ar/³⁹Ar date for metagabbros drilled at Site 900 is a closure age for plagioclase subjected to low-temperature shear deformation (Féraud et al., this volume). The Gradstein et al. (1994) time scale is used in this figure.