Crustal image of the Ionian basin and its Calabrian margins

Propagation of a lithospheric tear fault (STEP) through the western boundary of the Calabrian accretionary wedge offshore eastern Sicily (Southern Italy)

“…These syntectonic deposits were interpreted as Pleistocene in age (Cernobori et al, 1996;Hirn et al, 1997;Nicolich et al, 2000).…”

“…Offshore Sicily, in the Ionian Sea, the evidence of vertical motion between the more steeply Ionian oceanic subducting segment of the African downgoing plate and the adjacent Sicilian continental portion of the African plate was also reported (Cernobori et al, 1996;Hirn et al, 1997;Argnani, 2000;Nicolich et al, 2000;Argnani and Bonazzi, 2005;Govers and Wortel, 2005;Argnani, 2009;Polonia et al, 2011). Two distinct interpretations are still proposed concerning the position of the STEP fault beneath the Ionian Sea ( Figure 2): first along the NNW-SSE oriented Malta escarpment (Argnani, 2000;Argnani and Bonazzi, 2005;Govers and Wortel, 2005;Argnani, 2009), second along a NW-SE crustal fault 50 km further to the east of this escarpment (Figure 2) (Cernobori et al, 1996;Hirn et al, 1997;Nicolich et al, 2000;Polonia et al, 2011).…”

“…Two distinct interpretations are still proposed concerning the position of the STEP fault beneath the Ionian Sea ( Figure 2): first along the NNW-SSE oriented Malta escarpment (Argnani, 2000;Argnani and Bonazzi, 2005;Govers and Wortel, 2005;Argnani, 2009), second along a NW-SE crustal fault 50 km further to the east of this escarpment (Figure 2) (Cernobori et al, 1996;Hirn et al, 1997;Nicolich et al, 2000;Polonia et al, 2011). Below, we offer new constraints that favour one of these interpretations and then discuss the geodynamic implications of the presence of a STEP fault (lithospheric tear fault) at the edge of the Ionian slab.…”

TOPO-EUROPE: The geoscience of coupled deep Earth-surface processes

“…(ii) Shallow geometry of the subducting slab: At depths shallower than about 50-70 km, the geometry of the subducting slab is poorly known. Reflection-seismic data show a 15°dipping reflector beneath the Calabrian orogenic wedge that is interpreted as the Moho and that can be traced over a distance of about 60 km (Cernobori et al, 1996). In contrast, at deeper levels, the geometry of the slab is constrained by the WadatiBenioff plane (Selvaggi and Chiarabba, 1995).…”

The Ionian and Alfeo–Etna fault zones: New segments of an evolving plate boundary in the central Mediterranean Sea?

“…The transition from a nearly pure strike-slip regime near the AEF to a combination of strike-slip and normal faulting across the IF is highlighted by the distributions of P-and T-axes shown in Figure 13b. In particular, normal faulting earthquakes with focal depths of 36, 40 and 42 km (see earthquakes 13, 16 and 23 in Table 2 (ii) LET showing accumulation of highly-fractured fluid-enriched low-Vp high Vp/Vs materials closely over the de-hydrating retreating subduction slab (Barberi et al, 2004), (iii) velocity structure modeling based on joint analysis of data from active and passive seismology and (iv) the lack of any eventual evidence of Ionian crust at depths deeper than the unique Moho discontinuity appearing in the vertical sections crossing the study area (Nicolich et al, 2000;Dezes and Ziegler, 2001;Barberi et al, 2004;Cassinis et al, 2005;Pontevivo and Panza, 2006;Neri et al, 2009 and.…”