The role of pre-existing diapirs in fold and thrust belt development

Evidence of salt movement prior to the main Zagros folding event lead us to question: 1. The role of pre-existing salt structures on the Zagros fold and thrust belt development; 2. The possible mechanisms accounting for rapid salt extrusion; 3. The relative location of emergent diapirs and tectonic structures; 4. the decoupling between salt plug distribution and basement fault location. We based our interpretations on analogue sand box experiments compared to geological observations. We argue that the driving mechanism of Hormuz halokinesis during the Zagros folding and erosion is the squeezing of pre-existing salt diapirs, which also influenced the location of thrusts and strike slip faults. Emergent diapirs occurred above pre-existing domes along these faults, or at the plunging axes of the fold crests. Depending on the diapir wall attitude and its thickness relative to the sedimentary column thickness, the diapirs are either shortened and localise sharp overturned folds, or else act as preferentially oriented ramps, part of the diapir being incorporated in thefold. During fold growth, erosion or rejuvenation of the diapir growth by shortening allows for the salt extrusion.