Watch this space for a new paper on the formation of hyperextended margins which should be out in the next week or two. Below a photo from the Gulf of Suez (Hamman Faraun fault block north of Abu Zenima) taken during a field trip a few years back, which illustrates how a continental rift looks like just before continents break apart.
Overview map with hillshade relief of the Gulf of Suez region (GeoMapApp) with location (red circle) and view direction (red arrow) of the photo below.
A view of the northern Gulf of Suez looking northwest from the Sinai towards the African margin. This is how the very young South Atlantic could have looked like in the Cretaceous. The photo is taken from the Hamman Faraun fault block north of Abu Zenima (Openstreetmap link) . Picture licensed under a Creative Commons Attribution-Share Alike 3.0 license.