Comment on “Gravity modeling reveals a Messinian foredeep depocenter beneath the intermontane Fucino basin (Central Apennines)” by Mancinelli et al., 2021

The Fucino Pliocene-Quaternary extensional basin represents a puzzling tectonic structure in the central part of the Apennine chain (Italy). Bordered by seismogenetic faults responsible for strong earthquakes in the last millennium (Mw = 6–7), differently from other elongated intermontane basins in this area, it has a rounded shape and extends for 15–20 km both in the E-W and N-S directions. This structural peculiarity is also demonstrated by the very intense gravity low, with amplitude >30 mGal (e.g., Cella et al., 2021), associated with this basin. Available reflection seismic data in this area are often considered of low quality (e.g., Compagnia Mediterranea Idrocarburi, 1999), and no deep well (i.e., >200 m depth) is present in this basin, so that its structure at depth results poorly constrained. In a recent paper, Mancinelli et al. (2021; hereafter this paper will be referred to as MSPM), by forward modelling residual gravity data try to confirm a recent 2D seismic stratigraphic interpretation (Patruno and Scisciani, 2021) and the relative model of the Fucino basin structure. In this interpretation of seismic data, the Pliocene-Quaternary units infilling the basin overlies an older (Messinian) siliciclastic flysch, instead of a carbonate substrate as hypothesized in previous studies (e. g., Cavinato et al., 2002; Cella et al., 2021). The forward gravity modelling attempted in MSPM would confirm the presence of huge volumes of Miocene sediments, with a thickness up to 1000 m, and would support the hypothesis of the presence of a, rapidly filled, transient Messinian foredeep basin. However, we have concerns about the quality of the gravity modelling proposed in MSPM, and consequently we are doubtful about the geological conclusions that are drawn from it.