Magnetotelluric Investigation of the Underlying Structure of Manzaz Volcanic District (Hoggar, Southern Algeria)

The main objective of this study was to model the lithospheric structure of the Manzaz volcanic district (Hoggar) using the magnetotelluric (MT) method. For this purpose, eleven MT stations forming a 70-km long NW-SE profile, intersecting the Manzaz, were modeled. The 2D resistivity model shows an anomalously conductive crust resting on a lithospheric mantle of normal resistivity. The anomalously high conductivity of the middle and lower crust results probably from magma ascent from the asthenosphere to the surface. It could correspond to the presence of partial melting, trapped fluids released by the magma and/or precipitation of mineralization. The conductive structures underlying the Manzaz could correspond to intracrustal magmatic chambers or to magmatic underplating zones at the Moho or at lower/upper crust discontinuities.