Quaternary landscape evolution and erosion rates for an intramontane Neogene basin (Guadix-Baza basin, SE Spain)

The landscape evolution in Neogene intramontane basins is a result of the interaction of climatic lithologic, and tectonic factors. When sedimentation ceases and a basin enters an erosional stage, estimating erosion rates across the entire basin can offer a good view of landscape evolution. In this work, the erosion rates in the Guadix-Baza basin have been calculated based on a volumetric estimate of sediment loss by river erosion since the Late Pleistocene. To do so, the distribution of a glacis surface at ca. 43 kyr, characterised by a calcrete layer that caps the basin infilling, has been reconstructed. To support this age, new radiometric data of the glacis are presented. The volume of sediment loss by water erosion has been calculated for the entire basin by comparing the reconstructed geomorphic surface and the present-day topography. The resulting erosion rates vary between 428 and 6.57 m(3) ha(-1) yr(-1), and are the consequence of the interaction of climatic, lithologic, topographic, and tectonic factors. Individual erosion rates for the Guadix and Baza sub-basins (11.80 m(3) ha(-1) yr(-1) and 1.77 m(3) ha(-1) yr(-1) respectively) suggest different stages of drainage pattern evolution in the two sub-basins. We attribute the lower values obtained in the Baza sub-basin to the down-throw of this sub-basin caused by very recent activity along the Baza fault. (C) 2008 Elsevier B.V. All rights reserved.