Abstract
Tectonic inversion of passive margins is a common but poorly documented process preceding subduction inception. We perform here a comprehensive land-sea experimental modeling of this key process by reproducing the morphotectonic and sedimentary evolution of the central Algerian margin over the last 6 Myr. Our approach is based on scaled analog models integrating interactions between crustal shortening and surface processes, including erosion, water transport, sedimentation, gravitational instabilities, and base-level changes. A challenge was to simulate the effects of the Messinian Salinity Crisis (MSC) through a major sea-level oscillation and halite deposition. By using realistic boundary conditions, adapted analog material, and robust, first-order parameters for physiography setups, we successfully reproduce the morphotectonic domains and the time-dependent geometrical relationships between fluvio-deltaic sedimentary systems, erosional surfaces, and thrust faults as observed since Messinian times. Our results highlight (1) the key role played by the MSC sea-level oscillation on an ultra-fast building, destruction and re-sedimentation of fans and deltas from the upper slope to the abyssal plain; (2) the development of a large popup structure subparallel to the coastline, with progressive strain migration from the backthrust on land toward a frontal thrust of opposite vergence at mid-slope and the margin toe; and (3) the importance of lateral changes in initial wedge shape and strain distribution for determining the non-cylindrical geometry of the margin and progradation of piggy-back basins during tectonic inversion. Our results support that the central Algerian margin is witnessing the early building of an accretionary wedge combining thin-skinned and thick-skinned tectonic styles.