Intraplate episodic shortening within a subducting plate: the case of the central Syrian Arc Fold system

Inversion of passive margins located within the subducting plate is somewhat unintuitive but widely observed. Situated at the northern African margin, the 1000-km-long Syrian Arc fold system preserves a classic example of such intraplate passive margin inversion that formed during the closure of the Tethys Ocean. Although extensively studied, its evolution is still crudely documented, thus, the dynamic processes that have driven its formation are poorly understood. Here, we present new structural and temporal constraints on the evolution of the Hatira monocline situated at the central part of the arc. Our results suggest that folding occurred at an episodic manner that overlaps long-term background shortening, with one prominent short folding pulse (~79 to ~77 Ma) accounting for 25% of the total accumulated shortening, followed by two additional minor folding pulses. Most of the shortening (~50%) was accommodated by a slow and continuous deformation that started at around 90 Ma and lasted until the Miocene. The pronounced shortening pulse seems to correlate with the secession of the double subduction zone and the obduction of ophiolites along the northern Tethys. Other dynamic processes acting along the subducting slab (e.g., slab interaction with the 660 km discontinuity, slab buckling, etc.) may have triggered the long-term and short-term shortening pulses. The temporal evolution of the central Syrian Arc demonstrated here provides new insights into the role of subduction processes (margin and slab) on the internal shortening of the trailing passive margins.