Evaporite mobilisation in evaporite-cored anticlines leads to topographic growth that can alter sedimentary routing in shallow marine environments. This paper analyses two evaporite-cored anticlines perpendicular to the NW Africa coast to understand how their tectonic evolution influenced sediment pathways during the Early to Middle Jurassic and Early Cretaceous exhumation of the Mesozoic margin hinterland. The Essaouira-Agadir Basin in Morocco underwent evaporite deposition during the Atlasic and Atlantic rifting. Subsequent loading and tectonics resulted in re-mobilisation and generation of a variety of evaporite structures. Structural data obtained from analysis of Google Earth images processed using Move 2D allowed derivation of the thickness of sedimentary units on both flanks of the structures. Integrated with sedimentary logs from nine locations around evaporite-cored structures and two onshore wells, this data constrains the depositional record and allow an assessment of siliciclastic flux in the Essaouira-Agadir Basin. The results show the importance of syn-sedimentary evaporite tectonics on basin morphology, which influences the distribution of clastics delivered by fluvial systems and deepwater processes into the basin. This paper constrains the evolution of the Amsittène and Imouzzer anticlines in the Early to Middle Jurassic and support that their growth is associated with halokinesis. Mesozoic syn-sedimentary fold growth would have provided an important control on sediment discharge pathways and on the location of sediment entry points on the shelf margin, that ultimately fed deep water fan systems. This knowledge is key to predict the reservoir presence on the eastern margin of the Central Atlantic Ocean and to some extent, its conjugate margin in Nova Scotia.

It is unclear how the crustal-scale erosional exhumation of continental domains of the Moroccan Atlantic margin and the excessive subsidence of its rifted domains affected the Late Jurassic-Early Cretaceous post-rift evolution of the margin. To constrain the km-scale exhumation, we study the structural evolution of the Jbel Amsittene. This anticline is located on the coastal plain of the Moroccan Atlantic margin, and is classically considered to have been developed initially in the Late Cretaceous by halokinesis, and by contraction during the Neogene. Contrarily, our structural analysis indicates that the anticline is a fault-propagation fold verging north with Triassic salts at its core and that it formed by shortening shortly after continental breakup of the Central Atlantic. The anticline grew by NNW-SSE to NNE-SSW contraction, as shown by syn-tectonic wedges, regional kinematic indicators and synsedimentary structures in Upper Jurassic to Lower Cretaceous rocks. It grew further and tightened during the Cenozoic, presumably in relation to the Atlas/Alpine contraction. Thus, our data and interpretation suggest that “tectonic-drives-salt” in the anticline early growth, which is coeval with the growth of other anticlines along the Moroccan Atlantic margin and widespread km-scale exhumation farther onshore. Anticline growth due to shortening argues for intraplate far-field stresses potentially linked to the geodynamic evolution of the African, American and European plates.

Crustal rheology and surface processes strongly influence strain distribution and shape of orogenic wedges at their front but how they influence the wedge rear is still unclear. Here, we analyse the coupled control of viscosity and sedimentation on forearc high growth during advanced stages of subduction accretion. We use 2D thermo-mechanical finite element models constrained with data of the south Anatolian margin. Our simulations show that forearc highs grow as a thermally-activated viscosity drop in the lower crust induces ductile deformation and viscous flow. Initial viscosity and the amount of sediments in the forearc basin control non-linearly the occurrence and timing of the thermally-activated viscosity drop, and thus of the growth of the forearc high. High sedimentation rates result in thicker forearc basins that stabilise the subduction wedge and delay the onset of uplift in the forearc high. Low viscosities promote earlier onset of forearc high uplift and lead to larger morphological variability along the subduction margin. Increasing either the sedimentation rate or viscosity may prevent forearc high formation entirely. The thermo-viscous forearc highs grow at an age set by wedge thermal state as a function of accretionary flux, wedge viscosity, and synorogenic sedimentation. Our models explain vertical motions in south Anatolia and potentially in other accretionary margins, like the Lesser Antilles or Cascadia, during the formation of their broad forearc highs.

We present a model for the dynamic formation of the forearc high of southern Anatolia where sedimentation in the forearc basin leads to thermally-activated deformation in the lower crust. Our thermo-mechanical models demonstrate that forearc sedimentation increases the temperature of the underlying crust by “blanketing” the heat flux and increasing Moho depth. Deformation switches from frictional to viscous with a higher strain rate led by increased temperature. Viscous deformation changes large-wavelength subsidence into coeval, short-wavelength uplift and subsidence. Models show that forearc highs are intrinsic to accretionary wedges and can grow dynamically and non-linearly at rates dependent on sediment accretion, sedimentation and temperature. The mechanism explains the uplift of the southern margin of the Central Anatolian Plateau and the Neogene vertical motions and upper-plate strain in the Anatolian margin along Central Cyprus. This system is analogous to forearc highs in other mature accretionary margins, like Cascadia, Lesser Antilles or Makran.

Geologic evidence across orogenic plateau margins enables the discrimination of the relative contributions of orogenic, epeirogenic and/or climatic processes that lead to growth and maintenance of those plateaus and their margins. Here, we discuss the mode of formation of the southern margin of the Central Anatolian Plateau (SCAP) and evaluate its time of formation using fieldwork in the onshore and seismic reflection data in the offshore. In the onshore, uplifted Miocene rocks in a dip-slope topography show monocline flexure over >100 km, km-scale asymmetric folds verging south, and outcrop-scale syn-sedimentary reverse faults. On the Turkish shelf, vertical faults transect the basal latest Messinian of a 10 km fold where on-structure syntectonic wedges and synsedimentary unconformities indicate pre-Pliocene uplift and erosion, followed by Pliocene and younger deformation. Collectively, Miocene rocks delineate a flexural monocline at plateau margin scale that is expressed along our on-offshore sections as a kink-band fold with a steep flank 20–25 km long. In these reconstructed sections, we estimate a relative vertical displacement of 3.8 km at rates of ca. 0.5 mm/y, and horizontal shortening values <1 %. We use this evidence together with our observations of shortening at outcrop, basin, plateau-margin and forearc-system scales to infer that the SCAP forms as a monoclinal flexure to accommodate deep-seated thickening and shortening since >5 Ma, and to contextualize the plateau margin as the forearc high of the Cyprus subduction system.