From landscape to mantle: Decoding the geomorphic expression of lithospheric subduction and tearing under the Betic Cordillera (southeast Spain)

The Betic Cordillera (southeast Spain) experienced a kilometric topographic uplift since the late Miocene that led to widespread emergence of marine sediment and to the isolation of the Mediterranean Sea from the Atlantic Ocean at the end of the Miocene. Previous studies based on geophysical data have linked this uplift to the dynamics of a lithospheric slab under the region. However, the regional geomorphic signature of these events has been only patchily studied. Here we perform topographic analysis, knickpoint mapping and river profile metrics to constrain the landscape evolution and uplift history of the Betic Cordillera. We first identify an obliquity between the trend of maximum elevation and the main tectonic structures, in contrast to other Mediterranean orogens. This anomalous elevation trend matches the area of lithospheric slab detachment under the Betics previously derived from seismic tomography. Our analysis then reveals an orogenic-scale topographic transient state characterized by a high contrast in both k sn and χ-values across the main drainage divide. This suggests an active migration of the main divide towards the Atlantic catchments, as confirmed by the presence of wind gaps and fluvial captures. Knickpoint distribution adds to this evidence to suggest an increase in landscape disequilibrium towards the SW. These findings provide independent evidence for epeirogenic uplift under the Betics, driven by slab tearing and propagating westwards at a rate of 100–160 km/My. • Betic Cordillera topography under regional transient state • Active main divide migration towards the Atlantic catchments • Provide independent evidence for epeirogenic uplift under the Betics • Westward tearing of a lithospheric slab driving process of landscape transience • Suggest a lateral migration rate of slab tearing of 100–160 km/My since late Tortonian