Denudation rates and tectonic geomorphology of the Spanish Betic Cordillera

- We use 10Be TCN to infer denudation rates in a slow tectonic uplift area.
- We examine relations between geomorphic indices, denudation and rock uplift rates.
- Spatial pattern of denudation is well related to geomorphic indices and topography.
- Magnitude of denudation rates is consistent with longer-term uplift rates.
- Betic Cordillera probably approached topographic steady-state.

The tectonic control on landscape morphology and long-term denudation is largely documented for settings with high uplift rates. Relatively little is known about the rates of geomorphic response in areas of low tectonic uplift. Here, we evaluate spatial variations in denudation of the Spanish Betic Cordillera based on cosmogenic 10Be-derived denudation rates. Denudation rates are compared to published data on rock uplift and exhumation of the Betic Cordillera to evaluate steady-state topography. The spatial patterns of catchment-wide denudation rates (n=20) are then analysed together with topographic metrics of hillslope and channel morphology. Catchments draining the Betic ranges have relatively low denudation rates (64±54 mmkyr−1), but also show large variation as they range from 14 to 246 mm kyr−1. Catchment-wide denudation is linearly proportional to the mean hillslope gradient and local relief. Despite large spatial variation in denudation, the magnitude and spatial pattern of denudation rates are generally consistent with longer-term local uplift rates derived from elevated marine deposits, fission-track measurements and vertical fault slip rates. This might be indicative of a steady-state topography where rock uplift is balanced by denudation.