Unexpected Jurasic to Neogene vertical movements in "stable" parts of NW Africa revealed by low temperature geochronology

In Morocco, it is generally considered that post-Hercynian vertical movements were limited to the Atlas system, the passive continental margin and the Rif. Apatite FT and He ages from the Moroccan Meseta (Rehamna and Zaer Massif) document instead two episodes of subsidence and exhumation in Jurassic-Early Cretaceous and during the Late Cretaceous to Neogene. The Meseta subsided to >3 km depth during the Late Triassic to Middle Jurassic and was exhumed to the surface before the Late Cretaceous, during the rift and post-rift stages of Central Atlantic opening. Erosion of the exhuming rocks is responsible for a thick package of terrigenous sands found in the Moroccan offshore and elsewhere along the NW Africa margin. About 1km of subsidence affected the Meseta during the Late Cretaceous to Eocene. During the Neogene, these areas were brought back to the surface in association with bimodal folding with wavelengths of 100-150 km and >500 km. © 2008 Blackwell Publishing