A general inverse method for modelling extensional sedimentary basins

A two-dimensional inverse model for extracting the spatial and temporal variation of strain rate from extensional sedimentary basins is presented and applied. This model is a generalization of a one-dimensional algorithm which minimizes the misfit between predicted and observed patterns of basin subsidence. Our calculations include the effects of two-dimensional conduction and advection of heat as well as flexural rigidity. More importantly, we make no prior assumptions about the duration, number or intensity of rifting periods. Instead, the distribution of strain rate is permitted to vary smoothly through space and time until the subsidence misfit has been minimized. We have applied this inversion algorithm to extensional sedimentary basins in a variety of geological settings. Basin stratigraphy can be accurately fitted and the resultant spatiotemporal distributions of strain rate are corroborated by independent information about the number and duration of rifting episodes. Perhaps surprisingly, the smallest misfits are achieved with flexural rigidities close to zero. Spatiotemporal strain rate distributions will help to constrain the dynamical evolution of thinning continental lithosphere. The strain rate pattern governs the heat-flow history and so two-dimensional inversion can be used to construct accurate maturation models. Finally, our inversion algorithm is a stepping stone towards a generalized three-dimensional implementation.