Geology (2013)


The Atlas Mountains of Morocco are unusually high, given that only a moderate amount of faulting has helped to build the topography. Now, seismic images show that hot mantle is upwelling beneath the Atlas Mountains, which may give the range extra buoyancy.

Meghan Miller and Thorsten Becker at the University of Southern California used seismic data to identify the boundary between the flowing asthenospheric mantle and the overlying rigid lithosphere in the North African region. Beneath the Atlas Mountains, the boundary is shallow and offset upwards relative to the surrounding area. The researchers suggest that hot mantle is rising up and being channelled beneath the mountain range. They use numerical simulations to show that the extra buoyancy provided by such hot, upwelling mantle can explain the unusual height of the Atlas Mountains.

Large Jurassic-aged faults bound the Atlas Mountains and were probably reactivated by the upwelling mantle, creating the observed offset in the lithosphere–asthenosphere boundary. The offset, which creates a ridge in the base of the lithosphere, probably helped guide and focus more rising mantle. The result implies that large, lithosphere-scale faults may play an important role in mountain building.