Fault-related folding in sandbox analogue models of thrust wedges

The nucleation and growth of thrust fault-related folds has been simulated using high-resolution sandbox Coulomb wedge-type analogue models. Thrust-related anticlines grew progressively from initial layerparallel shortening, to decollement folding, thrust-tip folding and eventually thrust-ramp folding. Thrust ramps nucleated in the central sector of the overturned forelimb of decollement folds, as a consequence of limb thinning. Thrust-tip folding occurred during outward migration of the ramp tips. The fault-propagation rate was greater at the lower ramp tip, which quickly joined the basal thrust flat, while folding continued beyond the upper tip. The development of the analogue model thrust fault-related folds by progressive changes in kinematics, from decollement folding to thrust-tip folding and finally thrust-ramp folding, compares well with analyses of naturally occurring thrust fault-related folds.