Mesozoic salt tectonics in the Toulon Belt, Eastern Provence : Inversion of a salt-rich fault zone

Detailed structural and stratigraphic field mapping is used to reconstruct the Jurassic to Late Cretaceous diapiric and tectonic evolution of the Toulon Fault Zone, eastern Beausset Syncline and Toulon Belt, southern France, which represents the easternmost vestige of the Pyrenean orogen in Provence. This complex salt-rich area records a complete history from Jurassic-early Cretaceous subsidence and Aptian-Albian oblique rifting to Late Cretaceous Pyrenean-Provençal shortening. Halokinetic sequences and geometries were preserved principally on the northern flank of the Mont Caume salt diapir sourced from the Upper Triassic Keuper unit. Our field observations are best explained by a model where halokinetic activity interacted with regional deviatoric stresses from early-Jurassic to Santonian/Campanian times. Halokinetic wedges of Jurassic and Early Cretaceous carbonates thin toward the diapir, recording early salt mobilisation. Inverted relics of Apto-Albian rift depocenters are aligned along the northern margin of the Toulon Belt and the adjacent Bandol belt that lies to the west.  The Turonian-Coniacian Revest depocenter developed due to localized strong asymmetrical growth of the Mont Caume diapir. The three-dimensional form and growth of the diapir controlled lateral migration of the Revest depocenter, thickness variations, progressive unconformities, and the westward increase in stratal overturning of a flap. A component of N-S compression with related accelerated halokinetic activity can explain our observations and can be considered as the earliest expression of N-S convergence in the Provencal fold belt.  Further west, the overturned Beausset klippe can be interpreted as the remnant of a megaflap on the northern flank of the Bandol diapir. The Toulon belt salt structures are excellent field analogues to others observed in the external Alps and Pyrenees.