Mapping mafic dyke swarms, structural features, and hydrothermal alteration zones in Atar, Ahmeyim and Chami areas (Reguibat Shield, Northern Mauritania) using high-resolution aeromagnetic and gamma-ray spectrometry data

• Published in: Journal of African earth sciences (1994) Vol. 163; p. 103749
• Main Authors: Ba, Moussa Hamath, Jaffal, Mohammed, Lo, Khalidou, Youbi, Nasrrddine, El Mokhtar Dahmada, Mohamed, Ibouh, Hassan, Boumehdi, Moulay Ahmed, Aïfa, Tahar, Amara, Massinissa, Jessell, Mark, Ernst, Richard E., Bensalah, Mohamed Khalil, Söderlund, Ulf
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2020; Elsevier
• Subjects: Earth and Related Environmental Sciences; Earth Sciences; Gamma-ray spectrometry; Geologi; Geology; Geophysics; Geovetenskap och miljövetenskap; Mafic dyke; Magnetism; Mauritania; Natural Sciences; Naturvetenskap; Reguibat shield; Sciences of the Universe; Terrane Tasiast-Tijirit; Terrane Tasiast-Tijirit; Magnetism; Gamma-ray spectrometry; Mauritania; Reguibat shield; Mafic dyke
• ISSN: 1464-343X; 1879-1956
• DOI: 10.1016/j.jafrearsci.2019.103749

Analysis of an airborne geophysical data covering the Tasiast-Tijirit Terrane in the western part of the Reguibat Shield (including the 1:200,000 geological sheets of Chami, Ahmeyim and Atar), provided an improved mapping of mafic dyke swarms, structural features, and hydrothermal alteration zones. It also extended the mapping into extensive areas covered by sand. A low-altitude (100 m) airborne survey collected high-resolution magnetic and gamma-ray spectrometry data. The magnetic data were enhanced using techniques such as reduction to the pole, analytic signal and first vertical derivative, and revealed dyke swarms with trends of NNE-SSW to NE-SW, NW-SE to WNW-ESE and E-W. The use of the Euler deconvolution method provided constraints on the continuity and the depth of magnetic sources.
Gamma-ray spectrometry which maps the three main radioactive elements, i.e. potassium, uranium and thorium helped discriminate lithological units of the Archean basement, notably felsic intrusions. The radiometric data also helped delineate potassic alteration zones, which could testify to hydrothermal activities of relevance to sulfide mineralisation.
•Mafic dykes, structures, and hydrothermal alteration zones are mapped across the West African Craton in Northern Mauritania.•This map reveals one Great Archean Dyke (the so called Ahmeyim Great Dyke) and three possibly distinct mafic dyke swarms.•This map underpins future studies of the age, geochemistry and paleomagnetism of mafic dyke swarms of the Reguibat Shield.•This study is based on the interpretation of high-resolution aeromagnetic and gamma-ray spectrometric data.