Julien Babault

Joint inversion within a Bayesian framework provides a robust means to estimate uncertainties by integrating the inherent variability of multiple data sets used in the inversion process. In this study, we reconstruct the surface uplift history of mantle origin in NW Iberia and quantify its associated uncertainties. Using a novel reversible-jump Markov chain Monte Carlo (RJ-MCMC) Bayesian algorithm, we perform a joint inversion of topographic data and river-sand 10Be concentrations in quartz to decode the uplift history. This probabilistic approach yields an ensemble of solutions that explore diverse combinations of model parameters, enabling detailed uncertainty quantification in the timing and magnitude of uplift rate changes.Our forward model employs non-linear analytical solutions of the stream power incision model, which defines incision I = KAmSn as a function of S, the local channel gradient; A, the upstream drainage area; and K, the erodibility parameter. The model is coupled with the CAIRN method (Mudd et al., 2016, Earth Surface Dynamics, 4, 655-674) to invert Be-10 concentrations at the catchment scale to calibrate the K and n parameters with erosion rates.We apply this methodology to the Atlantic rivers draining NW, where deep canyons dissect low-relief erosional surfaces formed over the last 100 million years, and apply the calibration to other settings in Central Iberia. Our results suggest that the transient topography reflects a regional late Cenozoic uplift of several hundred meters, likely driven by mantle-related, continent-scale processes. This study underscores the utility of probabilistic joint inversion in unraveling complex geodynamic histories and their uncertainties.

The topography of the Iberian Meseta located between the Pyrenees-Cantabrian Mountains and the Betics Chain is moderately high (660 m on average) compared to the high plateaus on Earth (> 1 km) albeit higher than the topography of the surrounding western European plate. The Iberian Meseta encompasses Cenozoic sedimentary basins, active or inactive Alpine mountain ranges, and low-relief erosional surfaces represented by plateaus with elevations between 600 and 1400 m asl. It is commonly accepted that ~600-700 m surface uplift occurred during the Cenozoic, but the underlaying processes and the precise timing of the onset of the plateau growth are strongly debated. The main objective of the present study is to find out to what extent the topography of the Iberian Meseta has a crustal, lithospheric or a sublithospheric origin. We used the results of a recent modelling based on the joint inversion of both the crustal and lithospheric mantle structure. It encompasses an integrated geophysical-lithological multi-data modelling. The inversion is framed within an integrated geophysical-petrological setting where mantle seismic velocities and densities are computed as a function of temperature and composition whereas crustal density, shear and compressional wave velocities are lithologically linked based on empirical relationships from global petrophysical databases.We computed the relative contribution to topography of crustal and lithospheric mantle thickness variations and density structure. The topography of the Alpine mountain belts in Iberia is largely associated with thickened crust. We find that the elevated topography in the NW Iberian Meseta (elevation > 700 m) is mostly related to the lithospheric mantle thinning. This is in agreement with Inversion of topographic data, landform dates, and erosion rates suggesting a late Cenozoic mantle-related surface uplift of several hundreds of meters in NW Iberia (EGU24-11613) and in the central Iberia (EGU24-16382). Similarly, a thin and warm lithospheric mantle is responsible for the positive elevation of the onshore Mediterranean margins. A negatively buoyant lithospheric mantle causes >1 km subsidence in the Gibraltar Arc and western Pyrenees. We solved the Stokes flow to evaluate the contribution of temperature-related buoyancy forces at asthenospheric depths. These forces cause a long wavelength topographic response located in the centre of the Iberian Peninsula reaching a maximum value of only 100-150 m, which is much lower than the values reported in previous works assuming an isostatic balance.

The Central Range, the Iberian Chain and the Toledo Mountains in central Iberia were built during the Paleogene and Neogene alpine deformation, in response to shortening and thickening of the crust. The Cenozoic Madrid Basin in central Iberia was filled under endorheic conditions, fed by clastic sediments supplied from these mountains. This sediment influx led to the accumulation of over 3km of clastic sediments, primarily occurring during the Oligocene and early Miocene epochs. Presently, the river network, connected to the Atlantic Ocean, has carved into the sedimentary basin, resulting in an incision exceeding 200 meters.The most recent endorheic lacustrine sediments in the center of the Basin are commonly believed to have been deposited during the late Miocene (~6 Ma). Recently published dating of alluvial pediments in the northwestern part of the Basin using the cosmogenic nuclide method suggests that the basin experienced a semi-endorheic period lasting around 3 Ma (~6.4 Ma to >2.4 Ma). It is proposed that the onset of glacial/interglacial oscillations at ~3.35 Ma (M2 event) would have driven the overspilling of the closed sedimentary Basin, establishing its connection to the Atlantic River network (Karampaglidis et al., 2020).We present a new stratigraphic framework based on a new magnetostratigraphic analysis of the Plio-Quaternary deposits located in the center of the Madrid sedimentary Basin, incorporating new paleontological data and absolute U-Pb carbonate dating. Our findings indicate lacustrine endorheic conditions prevailed at least until 2.6 Ma. Moreover, on top of the lacustrine deposits, an accumulation of clastic deposits and carbonated paleosoils persisted until 1.7+-0.3 Ma. Modeling the transient incision within the Basin revealed a subsequent wave of incision propagating from the South to the North along the Central System mountains. Consequently, the onset of river incision appears to be more recent than previously acknowledged and unrelated to the onset of Quaternary climate oscillations. The long-wavelength deformation and the southward tilting of the youngest lacustrine deposits, combined with the age of the overlying paleosoils, suggest a mantle-driven surface uplift of Central Iberia during the last 1.7+-0.3 Ma. Previous studies suggested that regional surface uplift and the building of the Iberian Meseta began either at 20 Ma or after 3 Ma, depending on the methodology employed. The observed incision history in the Madrid Basin aligns with the latter estimation and even suggests a more recent age for a mantle-related surface uplift and the opening of the Cenozoic Madrid Basin. Reference:Karampaglidis, T., Benito-Calvo, A., Rodés, A., Braucher, R., Pérez-González, A., Pares, J., Stuart, F., Di Nicola, L., and Bourles, D., 2020, Pliocene endorheic-exhoreic drainage transition of the Cenozoic Madrid Basin (Central Spain): Global and Planetary Change, v. 194, p. 103295.

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 = KAmSn 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.

Records of incision history such as topographic data and landform dating can be gathered in inversion schemes to reconstruct base-level fall and uplift history. Here, we use a non-linear inversion scheme and the stream power incision model to study the landscape evolution of a mountainous area to quantify whether it responds to an uplift or a capture-induced local base-level fall. Our inversion is constrained by 10Be cosmogenic nuclide data. The probabilistic approach yields an ensemble of solutions made by a combination of model parameters. We apply our model to the Draa Canyon located in the Anti-Atlas of Morocco at the outlet of the Ouarzazate Basin which was internally drained during the Miocene. We show that incision rates in the Ouarzazate Basin and the southern margin of the High Atlas are compatible with a Pleistocene age for the opening of the Basin. The forcing to drainage integration may be due to capture by regressive erosion in the proto Draa river or tilting to the south of the High Atlas, Ouarzazate basin, and Anti-Atlas as a whole in response to mantle-related continental-scale uplift, or a combination of both. The southern border of the High Atlas in this region displays a transient landscape previously interpreted as evidence for recent shortening and rock uplift. Our results suggest that the rejuvenation of the southern Central High Atlas, in the northern margin of the Ouarzazate Basin, mainly occurred in response to the opening of the Ouarzazate Basin, with only several hundreds of meters of rock uplift localized along the South Atlas front during the late Cenozoic.

Drainage networks link erosional landscapes and sedimentary basins in a source‐to‐sink system, controlling the spatial and temporal distribution of sediment flux at the outlets. Variations of accumulation rates in a sedimentary basin have been classically interpreted as changes in erosion rates driven by tectonics and/or climate. We studied the interactions between deformation, rainfall rate and the intrinsic dynamics of drainage basins in an experimental fold‐and‐thrust belt subjected to erosion and sedimentation under constant rainfall and shortening rates. The emergence of thrust sheets at the front of a prism may divert antecedent transverse channels (perpendicular to the structural grain) leading to the formation of longitudinal reaches, later uplifted and incorporated in the prism by the ongoing deformation. In the experiments, transverse incisions appear in the external slopes of the emerging thrust sheets. Headward erosion in these transverse channels results in divide migration and capture of the uplifted longitudinal channels located in the inner parts of the prism, leading to drainage network reorganization and modification of the sediment routing system. We show that the rate of drainage reorganization increases with the rainfall rate. It also increases in a nonlinear way with the rate of uplift. We explain this behaviour by an exponent > 1 on the slope variable in the framework of the stream power erosion model. Our results confirm the view that early longitudinal‐dominated networks are progressively replaced by transverse‐dominated rivers during mountain building. We show that drainage network dynamics modulate the distribution of sedimentary fluxes at the outlets of experimental wedges. We propose that under constant shortening and rainfall rates the drainage network reorganization can also modulate the composition and the spatial distribution of clastic fluxes in foreland basins.

The Betics are a key area to study an orogenic landscape disrupted by late‐orogenic extension. New low‐temperature thermochronology (LTT) data (AHe and AFT) coupled with geomorphic constraints in the Sierra de Gador (Alpujarride complex) are used to reconstruct the cooling history and evolution of relief during the Neogene. We document three stages: (1) a fast cooling event between 23 and 16 Ma associated with the well‐known extensive tectonic exhumation of the Alpujarride unit, (2) a period of slow cooling between 16 and 7.2 Ma related to a planation event and (3) a post‐7.2 Ma surface uplift associated with the inversion of the Alboran domain undetected by LTT. The planation event followed by this late uplift can explain the occurrence of inherited low‐relief surfaces overlain by Tortonian–Messinian platform deposits at the top of the range. Finally, we propose that the Sierra de Gador is a more transient landscape than the nearby Sierra Nevada.

Catchment‐wide erosion rates were defined using ¹⁰Be terrestrial cosmogenic nuclides for the Eastern Cordillera of the Colombian Andes to help determine the nature of drainage development and landscape evolution. The Eastern Cordillera, characterized by a smooth axial plateau bordered by steep flanks, has a mean erosion rate of 11 ± 1 mm/ka across the plateau and 70 ± 10 mm/ka on its flanks, with local high rates >400 mm/ka. The erosional contrast between the plateau and its flanks was produced by the increase in the orogen regional slope, derived from the progressive shortening and thickening of the Eastern Cordillera. The erosion rates together with digital topographic analysis show that the drainage network is dynamic and confirms the view that drainage divides in the Eastern Cordillera are migrating towards the interior of the mountain belt resulting in progressive drainage reorganization from longitudinal to transverse‐dominated rivers and areal reduction of the Sabana de Bogotá plateau. Copyright © 2016 John Wiley & Sons, Ltd.

The morphology of the Pyrenees is characterized by the presence of high-elevation, low-relief surfaces. The origin of these Lower-Miocene surfaces is still debated. Two major interpretations have been proposed, both assuming that these surfaces are remnants of a single composite planation surface. The first interpretation proposes that this surface corresponds to a peneplain developed near sea level before the Late Miocene, subsequently uplifted and dissected. The present-day Pyrenees is therefore supposed to rise from the Late Miocene. In the second interpretation, the rise of the efficient base level of the chain induced the progressive inhibition of erosion and the smoothing of the relief before the Late Miocene, resulting in a highly elevated peneplain. According to this latter interpretation, the high elevation of the low-relief surfaces does not equate to post-orogenic uplift. We test these two interpretations by investigating, among other considerations, the relation between the elevation of the planation surface remnants and the deep structure of the chain. We find that (1) the isostatic compensation of the dissected Pyrenean planation surface by crustal thickening and (2) the absence of thinning of the lithosphere mantle below the chain favors the second interpretation.