Detection of channel-hillslope coupling along a tectonic gradient

Hurst, Martin D.; Grieve, Stuart; Clubb, Fiona J.; Mudd, Simon M.

doi:10.1016/j.epsl.2019.06.018

Cited by 31 publications

(39 citation statements)

References 49 publications

(86 reference statements)

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“…The amount of finite deformation accommodated by these folds progressively decreases southward, such that the structure we identified could correspond to the most recently activated as an in-sequence system. Finally, while high-resolution hillslope morphology analysis has already been used to constrain rock uplift patterns in a limited number of studies (Hurst et al, 2013a(Hurst et al, , 2019Clubb et al, 2020), our results are the first to illustrate the use of such data to infer the geometry of tectonic structures at depth.…”

Section: Constraints On Tectonic Structures From Hillslope Morphologymentioning

confidence: 74%

“…This comparison illustrates the resolving power of high-resolution hillslope morphology analysis, which allows us to document short-wavelength patterns of erosion and uplift that are undersampled by scarcely distributed fluvial metrics. We note that Hurst et al (2019) observed a clear re- Figure 11. (a) Nondimensional erosion rate evolution from hilltop patches (mean and standard deviation binned every 1 km).…”

Section: Hillslopes and Channel Dynamicsmentioning

confidence: 89%

“…There is no significant inverse correlation between L H and C HT as observed by Hurst et al (2013b). The characteristic horizontal length scale of landscapes, which can be evaluated through different types of measurements such as drainage density, spacing of first-order valleys or hillslope length, has been shown to be highly sensitive to external tectonic and climatic forcings, as well as internal parameters controlling erosion processes (e.g., Perron et al, 2008a;Pelletier et al, 2016;Clubb et al, 2016;Hurst et al, 2019). For example, Clubb et al (2016) Godard et al: Hillslopes across a rock uplift gradient ied in detail the relationship between denudation rate and drainage density with analytical and numerical models as well as high-resolution topographic and cosmogenic nuclide data.…”

Section: Hillslopes and Channel Dynamicsmentioning

confidence: 98%

“…Two important differences compared to our study are the existence of transient channel adjustment along the Bolinas Ridge and the dimension of the section, which is ∼ 30 km long in their case compared to the ∼ 10 km of our profile. Combined with a longer wavelength of the underlying tectonic signal, this latter difference might be a reason for the better sampling through fluvial metrics by Hurst et al (2019), and the clearer relationship they observe with hillslope properties.…”

Section: Hillslopes and Channel Dynamicsmentioning

confidence: 99%

“…Important methodological developments were necessary to extract the relevant information from highresolution DTMs (e.g., Grieve et al, 2016b). However, while theoretically warranted, the applicability of these approaches to explore tectonic gradients has only been tested on a limited number of cases (e.g., Hurst et al, 2013aHurst et al, , 2019Clubb et al, 2020). There is, therefore, an urgent need to further investigate hillslope morphological response in various types of tectonic settings to unravel the potential of such methods as an alternative or complement to the routinely applied investigation of river profiles.…”

Section: Introductionmentioning

confidence: 99%

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Hillslope denudation and morphologic response to a rock uplift gradient

et al. 2020

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Abstract. Documenting the spatial variability of tectonic processes from topography is routinely undertaken through the analysis of river profiles, since a direct relationship between fluvial gradient and rock uplift has been identified by incision models. Similarly, theoretical formulations of hillslope profiles predict a strong dependence on their base-level lowering rate, which in most situations is set by channel incision. However, the reduced sensitivity of near-threshold hillslopes and the limited availability of high-resolution topographic data has often been a major limitation for their use to investigate tectonic gradients. Here we combined high-resolution analysis of hillslope morphology and cosmogenic-nuclide-derived denudation rates to unravel the distribution of rock uplift across a blind thrust system at the southwestern Alpine front in France. Our study is located in the Mio-Pliocene Valensole molassic basin, where a series of folds and thrusts has deformed a plateau surface. We focused on a series of catchments aligned perpendicular to the main structures. Using a 1 m lidar digital terrain model, we extracted hillslope topographic properties such as hilltop curvature CHT and nondimensional erosion rates E∗. We observed systematic variation of these metrics coincident with the location of a major underlying thrust system identified by seismic surveys. Using a simple deformation model, the inversion of the E∗ pattern allows us to propose a location and dip for a blind thrust, which are consistent with available geological and geophysical data. We also sampled clasts from eroding conglomerates at several hilltop locations for 10Be and 26Al concentration measurements. Calculated hilltop denudation rates range from 40 to 120 mm kyr−1. These denudation rates appear to be correlated with E∗ and CHT that were extracted from the morphological analysis, and these rates are used to derive absolute estimates for the fault slip rate. This high-resolution hillslope analysis allows us to resolve short-wavelength variations in rock uplift that would not be possible to unravel using commonly used channel-profile-based methods. Our joint analysis of topography and geochronological data supports the interpretation of active thrusting at the southwestern Alpine front, and such approaches may bring crucial complementary constraints to morphotectonic analysis for the study of slowly slipping faults.

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Section: Constraints On Tectonic Structures From Hillslope Morphologymentioning

confidence: 74%

Section: Hillslopes and Channel Dynamicsmentioning

confidence: 89%