Spreading pulses of the Tyrrhenian Sea during the narrowing of the Calabrian slab

Abstract

The opening of the Tyrrhenian Sea has been punctuated by short-lived episodes of oceanic\ud accretion on separate small backarc basins during early Pliocene (Vavilov basin) and early\ud Pleistocene (Marsili basin) time. These spreading pulses are related to slab rollback and are\ud synchronous with the reduction of the subduction zone width during the formation of the\ud narrow Calabrian arc. Using laboratory models, we investigated the long-term and transient\ud effects of the reduction of slab width on the subduction kinematics. We found that the abrupt\ud reduction in slab width results in a pulse of acceleration of the trench retreat velocity, as the\ud balance between driving and resisting forces acting on the slab is temporarily modifi ed. Our\ud fi ndings also show that the time scale and amplitude of spreading observed in the Tyrrhenian\ud Sea can be experimentally fi tted if the scaled viscosity of the uppermost part of the mantle\ud ranges between 1019 and 1020 Pa s

The dynamics of laterally variable subductions: laboratory models applied to the Hellenides

“…In the following, we only discuss results from the end-member (model 11). During stage 2, the trench migrates slightly faster in model 11 than in model 5 (5.5-6 vs. 5 cm yr −1 ), in agreement with previous models that show that narrower slabs retreat faster (Guillaume et al, 2010). At the beginning of stage 3 after 18 Myr, trench retreat velocity decreases all along the subduction zone.…”

“…The lateral continuity of the subducting lithosphere is not entirely resolved, and may vary from one subduction zone to another: tear faults may occasionally adjust the geometry of the slab to the differential motion between the low and high buoyancy units (e.g. Govers and Wortel, 2005;Rosenbaum et al, 2008;Guillaume et al, 2010;Baes et al, 2011). Alternatively, the slab may not be disrupted by tear faults and instead distort, at least during the earlier stages of continental subduction, in order to accommodate the lateral variations in subducting rates (e.g.…”

Onshore to offshore correlation of regional unconformities in the Plio-Pleistocene sedimentary successions of the Calabrian Arc (central Mediterranean)

“…1). Episodic subduction zone retreat has taken place due to changes in the geometry of the downgoing slab, involving stepwise narrowing conditioned by interference with continental blocks of the adjacent southern Apennines, Apulia and Sicily (Faccenna et al, 2001(Faccenna et al, , 2004Chiarabba et al, 2008;Guillaume et al, 2010). This complex Neogene geodynamic evolution has had consequences for the structural and stratigraphic records of the Apennines that are difficult to unravel, as reflected in the range of reconstructions that have been proposed (e.g., Rehault et al, 1987;Patacca et al, 1990;Sartori, 1990;Knott and Turco, 1991;Van Dijk and Scheepers, 1995;Schettino and Turco, 2011).…”

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

“…This leads to the opening of the Liguro--Provençal basin between 30-16 Ma and after a period of tectonic quiescence, of the Tyrrhenian basin from 12-10 Ma to the present ( (Faccenna et al, 2001a;Faccenna et al, 2004) and references cited in these papers). Spreading in the Tyrrhenian back-arc basin occurred during two distinct episodes: first within the Vavilov basin (4.3-2.6 Ma) (Kastens and Mascle, 1990) and second within the Marsili basin ( 2-1 Ma) ( Figure 2) (Nicolosi et al, 2006;Guillaume et al, 2010).…”