Deep crustal electrical structure imaging in the northern UAE using Magnetotellurics: Implications for Ophiolite emplacement and collisional tectonics

Abstract

We acquired broadband magnetotelluric (BBMT) data from 74 stations for the first time in the northern UAE to image deep crustal structures. This study aims at determining the geometry of the Semail Ophiolite, the underlying thrust sheets, and the basement structure beneath the allochthonous units and the foreland basin. Frequency-dependent response functions were determined from the acquired data using a robust processing tool. The full impedance tensors were used for 3D inversion to image the surface electrical structure. The resulting model achieves greater crustal penetration, revealing electrical structures within the upper, mid, and lower crust. A resistive structure related to the Semail Ophiolite is revealed by the MT model. This high resistive structure appears thicker in the easter section and is detected under the foreland basin west of the Semail mountains. In the Dibba zone, the Haswasina-Haybi complexes are characterized by low resistivity. This conductive structure also appears underneath the resistive Ophiolite in the Khor Fakkan and Fujairah areas to the south. The foreland basin flanking the Semail Ophiolite mountains in the UAE is identified with a lower resistivity layer. The basement structure under the allochthonous units and beneath the foreland basin is identified with high resistivity in the MT model. The allochthonous units (the Semail Ophiolite and the underlying thrust sheets of the Hawasina-Haybi complexes) show an oceanward dipping as similarly indicated in the previous studies.