Abstract The NW sector of Mauritania represents the Archaean province of the Reguibat Shield. It is mainly composed of the typical Archaean cratonic association of granitoid gneisses, greenstone belts and granites. The greenstone belts contain high mineral potential, mainly gold. This is particularly the case of the Chami Greenstone Belt, which hosts the large Tasiast gold mine. The gold deposits are hosted along a NS oriented shear zone with a surface of 70 × 15 km 2 . In this study, a subsurface structural model is proposed based on the application of suitable computations on a high-resolution reduced-to-the-pole aeromagnetic anomaly map of the northern Chami area. Upward continuations, apparent magnetic susceptibility, directional derivatives, analytical signal, 3D Euler deconvolution and spectral analyses were performed to build this model. They were used to decipher the main evidenced structural features with the main NNE–SSW, NW–SE and ∼120° N directions, identified on most all computed maps combined with in situ measurements. They probably correspond to mafic dykes, faults and shears rooted up to 5 km in depth, particularly to the north, SW and NE, and southwards and westwards by spectral analyses and 3D Euler deconvolution, respectively. The basement is deeper towards the west and south and crops out towards the NE in agreement with the geological observations. In addition, the high values of magnetic susceptibility ( χ m ) measured in situ on banded iron formations (25.7–35 × 10 −3 SI) SW of Akjoujt could be the origin of metallotect sources associated with magnetic minerals for exploration of gold-bearing and base metals.

ABSTRACT Within the Canadian High Arctic, Ellesmere Island represents a key region for improving our understanding of the plate tectonic configuration during the Paleogene times when Arctic Canada and Greenland represented two independently moving plates. Here, we present 4050 line kilometers of new high-resolution aeromagnetic data gathered across an area of 7000 km 2 in the Vendom Fiord region on southern Ellesmere Island. The survey was flown with a two-kilometer line spacing and covered sedimentary rocks of the Franklinian Basin and the partly ice-covered basement rocks of the Inglefield Uplift. Magnetic domains, major lineaments, and depths of magnetic sources as well as magnetic trend lines are detected from total field data. These data and additional ground-based magnetic susceptibility measurements are integrated with exposure information and structural data in order to distinguish whether or not the ca. NNE–SSW trending Vendom Fiord Fault Zone can be related to the Wegener Fault. In addition, high-resolution aeromagnetic data and digital enhancement provide support for early Eocene deformation in the Vendom Fiord region during “Eurekan stage 1,” which seems to be decoupled from Paleocene to early Eocene deformation along the Wegener Fault. A distinct NNE–SSW trending magnetic anomaly characterized by long wavelength is bordered by the Eurekan Fold-and-Thrust Belt in the western survey area. On a regional scale, this anomaly can be traced toward the NE where it represents the boundary between the deep water and shelf sequences of the Franklinian Basin along the Archer Fiord Fault Zone. Based on aeromagnetic anomaly data, the ice-covered boundary between sediments of the Franklinian Basin and the Precambrian basement is identified. High frequency anomalies east of this boundary characterize the basement rocks and show strong similarities to the Kane Basin region in the NE. The similarity of magnetic anomaly patterns in both regions indicates that the NNE–SSW trend of the fault zones in the study area west of the Inglefield Uplift turns continuously into an E–W trend north of the uplift in the Kane Basin region.