Aeromagnetic data from the Assarag area (Ouzellagh-Siroua salient, central Anti-Atlas, Morocco): Implications for the Imourkhssen porphyry mineralization

Abstract

The Assarag region is located in the northern part of the Ouzellagh-Siroua salient, being a segment of the centralAnti-Atlas basement bulging within the High-Atlas Belt of Morocco. It consists mainly of the Late EdiacaranMagmatic Suites (LEMS) of the Ouarzazate Group (580-539 Ma). The LEMS comprise high potassic calc-alkalic I typegranitoids that host the Imourkhssen Cu-Mo-Au-Ag porphyry mineralization. The aeromagnetic data fromthe Assarag region led to describe structural features in the LEMS based on their magnetic footprints. aeromagneticdatasets were processed using several transformations including the reduction to pole (RTP), Upwardcontinuation (UC), Tilt derivative (TD), Center for Exploration Targeting (CET) and Euler deconvolution (ED)filters. RTP, TD and CET transformations allowed to map NNE-SSW, NNW-SSE and NE-SW trending faults in thenorth, in addition to a curved magnetic halo in the southwestern part of the Assarag area. The UC filter subdividedthe Assarag area into two magnetic morpho-structural domains: a northern region with low-magneticfeatures, and a southern high-magnetic region with positive curved trending patterns. The ED results matchand support the extracted lineaments. The aeromagnetic data were also processed by a 2D Spatio-SpectralFeature Extraction and Selection tool (SFES2D) using two-dimensional continuous wavelet transformations(2D CWT), principal component analysis (PCA) and independent component analysis by kurtosis and negentropymethods (k-ICA and n-ICA). The PCA results corroborate previously extracted lineaments and highlight a newENE-WSW oriented structure. Meanwhile, the CWT allowed us to conclude that NNE, NNW and NE trends areshallow and emphasized deep NW-SE and ENE-WSW structures in the southern part of the Assarag area. ICAemphasizes the ENE lineament and matches the previous results. We herein define the deeper ENE trend as a partof the South Atlas Fault (SAF), which crosscuts the LEMS in the study area. Meanwhile, the shallow NE-SW andNNE-SSW tectonic features likely served as conduits for the ore-bearing fluids, leading to the Imourkhssen Cu-Mo-Au-Ag mineralization. Consequently, these directions present a valuable approach for guiding mineralexploration in the Ouzellagh-Siroua salient, from prospect to regional scales.