A late cenozoic age for long-wavelength surface uplift of the atlas mountains of Morocco

The Atlas Mountains have been uplifted by two mechanisms: Cenozoic thickening of the crust and thinning of the mantle lithosphere due to a buoyant thermal anomaly, previously inferred by indirect criteria to have started some 15 Ma. Because crustal shortening-related uplift and mantle-related uplift affect the topography at different spatial scales, we use scattered direct surface evidence to clarify the palaeoelevation dynamics. Uplifted Messinian shallow marine sediments in the southern margin of the Saiss Basin and in the northern Middle Atlas, tilted Pliocene lacustrine deposits in the Saiss Basin and in the piedmont of the southern High Atlas and drainage-network reorganization in the Saiss Basin underscore the long-wavelength rock uplift of the Atlas domain of mantle origin. The low erosion of the aforementioned deposits indicates that such uplift is a true surface uplift that occurred in post-Miocene times at a minimum rate ranging from 0.17 to 0.22 mm yr(-1).