Characterizing terranes and a Neoproterozoic suture zone in Central Hoggar (Tuareg Shield, Algeria) with airborne geophysics and Landsat 8 OLI data

Abstract

Integration of multisource data into a geographic information system has been a powerful tool to characterize contrasting terranes and their boundaries, such as suture zones with oceanic rocks juxtaposed to continental blocks. We present an integration study of geological, Landsat 8 OLI, and airborne geophysical data for the Wadi Takalous region (Central Hoggar, Algeria), covering the SAA (Sérouenout, Aghefsa, Aguendis) domain, rich in juvenile oceanic rocks, flanked by two continental domains, LATEA (Laouni, Aouilène, Tefedest, Egéré-Aleksod and Azrou N'Fad) to the West, and TAI (Tazat and Assodé-Issalane) to the East. The Sérouenout terrane, comprising tectonic slices of metamafic-ultramafic rocks (including eclogites) enveloped by metapelites and covered by Eopaleozoic sandstones, stands out for its low magnetic intensities and low radiometric responses. To the East, granitic rocks with abnormally high radiometric responses and high magnetic intensities highlight the TAI domain, a basement block rich in Pan-African collisional and post-collisional intrusions. To the West of Sérouenout terrane, a heterogeneous magnetic and radiometric pattern characterizes the eastern LATEA that has been interpreted as a Neoproterozoic passive margin. Our integrated data also suggests that the Afara terrane is more likely correlated with LATEA (instead of TAI). Deep magnetic lineaments outline major shear zones marking terrane boundaries, such as the crustal-scale (hundreds-km long and dozens-km thick) 7°30′E thrust zone limiting the SAA and TAI domains. Structures and kinematic indicators related to collisional deformation point to an overall NE-SW to E-W crustal shortening which induced thrusting and tight folding, followed by strike-slip shear zones related to transpressional deformation in late orogenic stage. In this scenario, the SAA domain may represent an accretionary complex associated to a Pan-African suture zone and thrust onto the LATEA passive margin.