Surface and Crustal Response to Deep Subduction Dynamics: Insights From the Apennines, Italy

Abstract

The topography of orogenic belts responds to several contributions operating at short and long temporal and spatial (i.e., wavelengths) scales, from the surface to the deep mantle. Here, we aim to investigate the connection between morphometric characteristics, exhumation, and crustal deformation along and across the Italian Apennines, by comparing superficial with deeper data. Specifically, we present four sets of observations that are constructed by gathering previous data and adding new analyses and inferences, that include: (a) a new geomorphological set of analyses; (b) a database of available low temperature thermochronological cooling ages; (c) a reconstruction of drainage divide evolution in time and space based on the age of the youngest lacustrine deposits within each extensional basin; (d) Moho depth from receiver functions, gathering previous estimates and 13 new ones. From these sets of data, it emerges that across the main drainage divide of the Apennines, the morphological characteristics, the style of deformation and the spatial distribution of exhumation correlate with the geometries of the Moho and are associated with a strong asymmetry in the Northern‐Apennines and a clear symmetry in the Central‐Apennines. We interpret these results as evidence of a strong coupling between shallower and deeper geometries, that are most likely related to complex along‐strike variations in the Apennines geodynamic setting.

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

“…Stage a: The Southern Apennines wedge was partially uplifted, and therefore eroded and exhumed since the late Miocene due to orogenic accretion related to the subduction of the Adria-Ionian plate. This is well attested also by low-temperature thermochronology data and syn-sedimentary deposits (Lanari, Boutoux, et al, 2023;Lanari, Reitano, et al, 2023 andreferences therein Corrado et al, 2005;Invernizzi et al, 2008;Mazzoli et al, 2008;Vignaroli et al, 2012;Olivetti et al, 2017). Subsequently, the uplifted range was progressively eroded, promoting the development of low-relief topography, which may be diachronous from the inner to the outer portion of the chain (Amato & Cinque, 1999;Ascione & Cinque, 1999;Olivetti et al, 2017).…”

“…Our topographic and geomorphic analysis favors the model of slab detachment and decoupling followed by upwelling of the asthenospheric mantle, which can be associated with toroidal flow around the subducting Ionian slab. The link between regional uplift and extensional tectonics, currently active on the Southern Apennines, may be interpreted as surface response of slab break off, as proposed for the Central Apennines (Faccenna et al, 2011;Fellin et al, 2022;Lanari, Reitano, et al, 2023).…”

“…The break-point separates the deeply incised valleys from the terrace surfaces, suggesting their migration following base level lowering after the endorheic-exorheic transition (e.g., Struth et al, 2019). The drainage connection to the sea of the intermontane basins is considered the youngest geological event, even if it might not have occurred coevally from north to south (see the compilation of lacustrine deposits in Lanari, Reitano, et al, 2023). For instance, the external drainage connection of the Mercure Basin is younger than ∼500 Kyr (Robustelli et al, 2014), but it is reasonable to infer that it occurred earlier than the external connection of the Castrovillari Basin, whose basin infill hasn't been fully incised yet.…”

“…The Southern Apennines of Italy are an ideal case study for deciphering the mutual influence between crustal and deep processes in a forearc setting. The mountain range is located at the transition between active subduction of the Calabrian arc and the Central Apennines, where slab is completely or partially detached (Lanari, Reitano, et al, 2023;Maesano et al, 2017;Wortel & Spakman, 2000). Here, a combination of crustal shortening, recent extensional tectonic activity and large-scale regional uplift resulted in the complex topography of the Pollino range (Brozzetti et al, 2017a;Cowie et al, 2017;Faure Walker et al, 2012;Ferranti et al, 2006;Roda-Boluda & Whittaker, 2017;Schiattarella et al, 2003).…”

The Atlas of Morocco: A Plume‐Assisted Orogeny

“…In addition, to qualitatively test whether large wavelength processes are supporting the topography of the Atlas, we filtered the topography signal through a “circle average” consisting of averaging each pixel with areas with diameters of 10, 50, 100, and 150 km (Figures 4a–4d). This well‐established method has been applied to several other locations (e.g., Apennines; Lanari, Reitano, et al., 2023; Carpathians; Molin et al., 2012) and qualitatively allows differentiating regional‐scale features from short wavelength topographic characteristics supported by tectonic or elastic flexure (Roy et al., 2009; Wegmann et al., 2007). If the large wavelength topography matches the actual one, it is then possible to deduce that the actual topography is likely sustained by the mantle.…”