Hot upwelling conduit beneath the Atlas Mountains, Morocco

Abstract

The Atlas Mountains of Morocco display high topography, no deep crustal root, and regions of localized Cenozoic alkaline volcanism. Previous seismic imaging and geophysical studies have implied a hot mantle upwelling as the source of the volcanism and high elevation. However, the existence, shape, and physical properties of an associated mantle anomaly are debated. Here we use seismic waveform analysis from a broadband deployment and geodynamic modeling to define the physical properties and morphology of the anomaly. The imaged low-velocity structure extends to~200 km beneath the Atlas and appears~350 K hotter than the ambient mantle with possible partial melting. It includes a lateral conduit, which suggests that the Quaternary volcanism arises from the upper mantle. Moreover, the shape and temperature of the imaged anomaly indicate that the unusually high topography of the Atlas Mountains is due to active mantle support.

Thermal Nature of Mantle Upwellings Below the Ibero‐Western Maghreb Region Inferred From Teleseismic Tomography

“…Our findings are consistent with values derived from modeling of hotspots tracks beneath the continental lithosphere (~300 °C, Yang & Leng, ). In addition, results from seismic waveform analysis combined with geodynamic modeling reveal a strong T excess of ~350 ± 90 °C in this region (for dry mantle), which is inferred to be solely of thermal origin, although a small quantity of partial melt and volatiles may be present (Sun et al, ). d T S estimates appear to be slightly higher than d T P in the innermost parts of the low‐velocity anomaly (see Figures e and k).…”

“…We compare our temperature model with those of previous studies in the region from thermobarometry calculations (Thurner et al, ), receiver functions (Morais et al, ), waveform analysis (Sun et al, ), and geophysical‐petrological modeling (Fullea et al, and personal communication).…”

Lithospheric structure ofIberia andMorocco using finite‐frequencyRayleigh wave tomography from earthquakes and seismic ambient noise

“…Several authors have suggested a thin lithosphere beneath the High and Middle Atlas to support its elevation and to explain the strong positive geoid anomaly [Teixell et al, 2003Ayarza et al, 2005;Zeyen et al, 2005;Fullea et al, 2010]. Different processes have been proposed to explain the source of the shallow asthenosphere: (1) a mantle plume that is part of the Canary system Missenard et al, 2006;Duggen et al, 2009;Miller and Becker, 2013;Sun et al, 2014;Miller et al, 2015], (2) lateral flow of asthenospheric mantle at the edge of the Alboran slab , (3) flow caused by edge-driven convection [Missenard and Cadoux, 2012;Kaislaniemi and van Hunen, 2014], and (4) delamination of the local upper mantle beneath the High and Middle Atlas [Bezada et al, 2014]. All these processes result in a Geochemistry, Geophysics, Geosystems 10.1002/2016GC006657 thinner lithosphere.…”

Crustal Structure of Active Deformation Zones in Africa: Implications for Global Crustal Processes

“…Many recent efforts have focused on understanding the crustal‐ and lithospheric‐scale structure of the Atlas to understand the orogenesis. Structural seismological imaging suggests that the lithosphere beneath the Atlas is particularly thin or perhaps the uppermost mantle is abnormally warm with low seismic velocities found at depths of ~65–160 km (e.g., Bezada et al, ; Fullea et al, ; Miller et al, ; Palomeras et al, ; Sun et al, ). Figure shows S receiver function estimates of the Moho and lithosphere‐asthenosphere depths along a profile across the Atlas from Miller and Becker ().…”