Cenozoic denudation in the Marrakech High Atlas, Morocco: insight from apatite fission-track thermochronology

In North Africa, the High Atlas belt culminates at more than 4000 m. In Morocco, recent work shows that a lithospheric thinning explains about 1000 m of the mean topography, the remaining topography being related to crustal shortening. We combine regional geology with new apatite fission-track (AFT) ages to constrain the timing of these events in the Marrakech High Atlas (MHA). In the inner belt, 10 AFT ages are comprised between 9 ± 1 and 27 ± 3 Ma. These Neogene ages indicate that the MHA underwent significant denudation during that time. In the southern foreland domain of the belt, three samples give scattered AFT ages between 27 ± 2 and 87 ± 5 Ma. Geological evidences allow us to constrain the age of a major denudation event during Middle Miocene age. We propose that it is linked to the thermal doming highlighted in the whole Moroccan Atlas domain.