Numerical models of growth-sediment development above an active monocline

The deposition, erosion and deformation of growth strata associated with an actively growing monocline are modelled using mechanically based numerical experiments. The results demonstrate that the nature of the growth‐stratal record depends on (1) the interaction between the base‐level rate of change and the rate of change of the accommodation space created due to structural relief across the limbs of the monocline; and (2) the progressive folding of the growth strata. With base‐level elevation initially coincident with the upper surface of the pre‐tectonic units, constant rates of base‐level change create three growth‐stratal preservation states. If the base level rises, a growth‐sediment wedge covers both limbs of the monocline, with thinner sediment thicknesses on the upthrown limb, forming an on‐structure wedge. If the base level falls at a rate less than the rate of accommodation space creation due to structural relief, growth‐strata pinch out onto the dipping limb of the monocline, forming an off‐structure wedge. If the base level falls at a rate greater than the rate of accommodation space generation due to structural relief, no syntectonic deposition occurs and pre‐tectonic units on both sides of the monocline are eroded. Syntectonic unconformities develop within the growth‐sediment packages when the rate of accommodation space generation changes during the course of the experiment. The bedding angularity across the unconformities is greatest in the region of the dipping limb of the monocline; off structure, the bedding across the correlative event becomes parallel, forming correlative conformities or disconformities.