The Morton-Black hypothesis for the thinning of continental crust—revisited in Western AFAR

Mohr, P., 1983. The Morton-Black hypothesis for the thinning of continental crust-revisited in western Afar. In: P. Morgan and B.H. Baker (Editors), Processes of Continental Rifting. Tectonophysics, 94: 509–528. Geological observations along the western margin of Afar show that the Morton-Black model, in which thinning of upper continental crust at a nascent continental margin is accomplished through block faulting and tilting, is not wholly applicable. Rather, dikes are concentrated into swarms, suggestive of important direct dilatation. Faults are concentrated into sets, within which no block-tilting steeper than 45g is observed. Therefore attenuation of the Afar margins requires a significant role for processes other than block tilting, and in some margin sectors the transition from continental to neo-oceanic crust may be relatively abrupt.