Mantle-related late Cenozoic surface uplift in NW Iberia revealed by 10Be cosmogenic nuclide dating and non-linear river profile inversion

During the last decade there has been an increase in the study of transient topography because it gives information about surface uplift history. The onset of transient topography forms after a gain in potential energy which leads to the creation of slopes at the outlet of catchment. It is followed by a wave of transient erosion that propagates upstream along the main river, then across tributaries, and from the tributaries to the hillslopes. Records of incision history such as topographic data and landform dating can be gathered into inversion schemes to reconstruct base-level fall and uplift history. In this study, we employ a reversible jump Markov chain Monte Carlo Bayesian algorithm to perform an inversion of topographic data, landform dates, and erosion rates in order to unravel surface uplift history. By adopting a probabilistic approach, we generate an ensemble of solutions that comprise various combinations of model parameters. This methodology enables us to estimate uncertainties in the timing and amount of changes in uplift rates. In the forward model we use the non-linear analytical solutions of the stream power incision model that states that incision I = KA^mSⁿ is simply a function of S, the local channel gradient, and A, drainage area above that point and K incapsulates climatic conditions, geometrical and hydraulic characteristics of the stream, bedrock resistance to erosion. Our inversion is constrained by new river-sands ¹⁰Be cosmogenic nuclide data, and by incision rates derived from river terraces from the literature. Millennial scale erosion rates and topographic metrics helps us to calibrate the empirical scaling parameters of the stream power incision law. We apply our model to the Atlantic rivers draining NW Iberia where canyons are incised in low-relief erosional surfaces that developed in the last 100 Ma. We show that the transient topography is compatible with a regional late Cenozoic uplift of several hundreds of meters, most likely in response to a mantle-related continental-scale uplift.