Assessing the impact of crustal architecture and along-strike rifting propagation on salt deposition and tectonics: Insights from the Moroccan Atlantic margin

Abstract

The salt-bearing conjugate rifted margins of Morocco and Nova Scotia contain one of the oldest stratigraphic records documenting the opening history of the Central Atlantic Ocean, starting in Late Triassic times. Although there is certain consensus on the Middle Jurassic to Present evolution of this ocean basin, the Early Jurassic rift to drift transition stage is still under discussion. Through the interpretation of unpublished, recently acquired deep seismic reflection data, integrated with legacy 2D surveys from offshore Morocco, this study presents new evidence supporting a revised 3D passive-margin evolutionary model with a focus on the rift-to-drift transition phase. Eight regional seismic transects illustrate the along-strike variability of crustal structural styles, magmatic budget, and the interaction between rifting and evaporite deposition. Assuming evaporite deposition was near-isochronous along the margin, the interpretation of the autochthonous salt distribution elucidates the northward propagation of rifting and breakup. We interpret that salt was deposited during the exhumation stage in the Tarfaya and southern Agadir basins (southern segment) and during late <em>syn</em>-stretching to early syn-thinning in the Safi Basin and the Mazagan Plateau (northern segment). Furthermore, structural inheritance from Paleozoic tectonic boundaries, such as the South Atlas Fault Zone, were reactivated as transfer zones during rifting, separating segments with different crustal deformation styles and extension rates. Moreover, one of these inherited structures, the Sidi Ifni Transfer Zone, is located at the boundary between rheologically distinct pre-rift units and marks the transition between a magma-rich (south) and a magma-poor (north) segment of the margin, suggesting