GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Rheological behaviour along the Hellenic Wadat-Beniof zone D. Russo 1,2 and R. Caputo 1,2 1 Department of Physics and Earth Sciences, University of Ferrara, Italy 2 Centro Interuniversitario per La Sismotetonica Tridimensionale, CRUST-UR Ferrara, Italy Following the method and the working fow proposed by Maggini et al. (2023) for reconstructng the 3D thermo-rheological modelling of the broader Aegean Region, the present note is focused on the rheological characteristcs in correspondence of the Wadat-Beniof zone of the Hellenic subducton. The geometry of the interface has been reconstructed based on the results of Bocchini et al. (2018) and Halpaap et al. (2018). Figure 1a shows the isobaths, while Figure 1b the slope distributon. The rheological model of Maggini et al. (2023) is based on a simplifed approach, assuming frictonal sliding and power-law creep as dominatng deformatonal mechanisms for describing the britle and the ductle behaviour, respectvely. Calculatons have been performed by means of several purposedly writen MATLAB scripts (Maggini, 2020; Maggini and Caputo, 2020a, 2020b, 2021) allowing to calculate and reproduce the thermo-rheological features. In order to obtain a 3D cover for the whole investgated area, a number of 1D vertcal logs were reconstructed in correspondence of the nodes of a horizontal regular grid (115 x 115 pixels) and were than interpolated to reconstruct a pseudo 3D model. Using common GIS tools, all the input parameters considered in the modelling (see Maggini et al., 2023 for details) were properly averaged at the selected pixel size of 10 x 10 km. Based on the general results and for the purpose of the present note, we investgated a 500 m- thick volume on either side of the modelled slab interface (Figure 1a) conceptually corresponding to the core of the Wadat-Beniof zone separatng the two plates. In partcular, we implemented a dedicated MATLAB script to analyse the rheological behaviour of the lowermost porton of the upper plate and the uppermost one of the lower plate. Although, four diferent combinatons between britle versus ductle and upper versus lower plate could in principle occur, the results show that three conditons dominate the whole subducton zone, each uniformly and regularly covering wide sectors of the interface zone. Figure 1c clearly shows that the most external and shallower zone (blue in Figure 1c), grossly at the base of the actve accretonary wedge, is characterised by a britle behaviour in both sides of the interface. In a progressively deeper sector, the model results indicate the contact between britle rocks in the upper plate with ductle ones in the lower plate (purple zone in Figure 1c). Further deeper along the Wadat-Beniof zone, the modelled behaviour is ductle on either side (pink area in Figure 1c). Taking into account the resoluton of the rheological model (10 x 10 km), only in a