Morpho-Tectonic Evolution of the Southern Apennines and Calabrian Arc: Insights From Pollino Range and Surrounding Extensional Intermontane Basins

The evolution of topography in forearc regions results from the complex interplay of crustal and mantle processes. The Southern Apennines represent a well-studied forearc region that experienced several tectonic phases, initially marked by compressional deformation followed by extension and large-scale uplift. We present a new structural, geomorphic and fluvial analysis of the Pollino Massif and surrounding intermontane basins (Mercure, Campotenese and Castrovillari) to unravel their evolution since the Pliocene. We constrain multiple tectonic transport directions, evolution of the drainage, and magnitude and timing of long-term incision following base level falls. Two sets of knickpoints suggest two phases of base level lowering and allow to estimate similar to 500 m of long-term uplift (late Pleistocene), as observed in the Sila Massif. On a smaller spatial scale, the evolution and formation of topographic relief, sedimentation, and opening of intermontane basins is strongly controlled by the recent increase in rock uplift rate and fault activity. At the regional scale, an along-strike, long-wavelength uplift pattern from north to south can be explained by progressive lateral slab tearing and inflow of asthenospheric mantle beneath Pollino and Sila, which in turn may have promoted extensional tectonics. The lower uplift of Le Serre Massif may be explained as result of weak plate coupling due to narrowing of the Calabrian slab. The onset of uplift in the Pollino Massif, ranging from 400 to 800 ka, is consistent with that one proposed in the southern Calabrian forearc, suggesting a possible synchronism of uplift, and lateral tearing of the Calabrian slab.Topographic evolution constrained by structural, geomorphic and river analysis of the Pollino range and surrounding extensional basins At short spatial scale, increase in rock uplift and fault activity controls the endorheic-exorheic transition At regional scale, uplift increases between 400 and 800 ka, due to progressive lateral slab tearing, and inflow asthenospheric mantle