Is the Suez Rift in its post-rift phase?

David Fernández-Blanco , Gino de Gelder , Christopher Aiden-Lee Jackson 

Failed rifts are widely assumed to enter post-rift quiescence after termination of intracontinental rifting. This remains largely untested, however, and a comprehensive, regional evaluation of the rates and patterns of post-rift tectonic (in)activity is lacking. Our quantitative, rift-scale geomorphic study of the Suez Rift, an archetypal failed rift in Egypt, synthesizes isolated observations of faulting and coastal uplift, and reveals evidence for widespread “post-rift” rifting. Stacked topographic swaths and river profiles document pervasive normal fault offsets in Plio-Quaternary rocks along the rift length, with fluvial metrics showing steep gradients consistent with active and young faulting. Quaternary shorelines uplifted along both margins constrain normal fault footwall uplift rates of up to 0.13±0.04 mm/yr, comparable to those of the Basin and Range, USA. This evidence of active extension in the Suez Rift, occurring after its presumed Pliocene failure, should motivate reevaluation of “failed” rifts and of conceptual models of continental rift evolution.