Magnetotelluric Modelling of the Central Hoggar (Tuareg Shield, NW Africa) Lithospheric Structure

The Hoggar massif (southern Algeria) with Aïr and Adrar des Iforas is part of the Touareg shield. The present study attempted to model lithospheric structure of its central part using Magnetotelluric (MT) data. MT data were collected from 17 sites in 2005. The stations form two nearly parallel NW–SE profiles approximately 200 km long. The distance between the MT sites of the order of 40 km allowed resolving the geological regional structure of the lower crust and the lithospheric mantle down to 80 km deep. The lower crust contains a number of small conductive structures probably associated with inter and intra-terrane faults. One of the most important observations that can be deduced from the MT model is that the Cenozoic volcanic districts of Manzaz/Atakor of Central Hoggar are underlain by a deep lithospheric conductive structure. This structure was interpreted as being the path taken by the magmas to go up from the base of the lithosphere to the surface.