ARE CHAD LINEAMENTS DEFORMING THE SAHARAN METACRATON?

The Chad cratonic remnant is among the preserved cratons of the Saharan metacraton, known to have undergone complex metacratonization during the Neoproterozoic within the interior and at the margins of the former Saharan craton. This makes the Chad cratonic remnant key to characterizing the lithospheric structure of the former Saharan craton. Studying the interactions of the Chad cratonic remnant with other tectonic entities of the former Saharan craton is equally important to better understand the processes and effects of the metacratonization of the Saharan metacraton. To address these important questions, we studied the surface and the underlying lithospheric structure of the Chad cratonic remnant using the Bouguer gravity anomaly map of the World Gravity Model (WGM) – 2012 and optical and radar remote sensing data. Both the Bouguer gravity anomalies and the directional filter of the Bouguer gravity anomalies, as well as the Remote Sensing images, show the presence of arcuate lineaments, interpreted as the Chad Lineament representing the eastern margin of the Chad cratonic remnant. To the east of the Chad lineament is the Ouaddaï Massif, represented by its distinct gravity low anomalies. To the immediate west of the Chad Lineament, ring-like gravity high features are observed, interpreted as volcanic ring-complexes. Additionally, the Chad cratonic remnant shows pronounced NW-trending gravity anomalies, possibly related to the Chad sag basin that overlies the Chad cratonic remnant. The two-dimensional (2D) forward gravity models constructed across the Chad cratonic remnant, the Chad Lineament, and the Ouaddaï Massif show the presence of thicker crust and Sub-continental lithospheric mantle (SCLM) beneath the Chad sag basin and the Ouaddaï Massif, and thinner lithosphere beneath the Chad Lineament. Therefore, as our potential field and remote sensing analyses show, the eastern margin of the Chad cratonic remnant is not as intact as once thought. It is likely that it has undergone significant tectonic deformations accompanied by volcanic activity at its eastern cratonic margin. Additionally, the Chad Lineament is interpreted as an arcuate-shaped deformation zone along which the Chad cratonic remnant interacted with the tectonic entities of the former Saharan craton.