Active tectonics of the Calabrian subduction revealed by new multi-beam bathymetric data and high-resolution seismic profiles in the Ionian Sea (Central Mediterranean)

Marc-André M-A Gutscher (1) , H. Kopp (2) , S. Krastel (3) , G. Bohrmann (4) , Th. Garlan (5) , S. Zaragosi (6) , I. Klaucke (2) , P. Wintersteller (4) , B. Loubrieu (7) , Y. Le Faou (5) , L. San Pedro (1) , S. Dominguez (8) , M. Rovere (9) , B. Mercier de Lepinay (10) , C. Ranero (11) , V. Sallares (12)

1 LDO - Domaines Océaniques
2 GEOMAR - Helmholtz Centre for Ocean Research [Kiel]
3 CAU - Christian-Albrechts-Universität zu Kiel = Christian-Albrechts University of Kiel = Université Christian-Albrechts de Kiel
4 MARUM - Center for Marine Environmental Sciences [Bremen]
5 SHOM - Service Hydrographique et Océanographique de la Marine
6 EPOC - Environnements et Paléoenvironnements OCéaniques
7 GM - Unité Géosciences Marines
8 Géosciences Montpellier
9 Institute for marine sciences
10 GEOAZUR 7329 - Géoazur
11 ICREA - Institució Catalana de Recerca i Estudis Avançats = Catalan Institution for Research and Advanced Studies
12 UTM - Unitat de Tecnologia Marina

The detailed morphology and internal structure of the Calabrian accretionary wedge and adjacent Eastern Sicily margin are imaged in unprecedented detail by a combined dataset of multi-beam bathymetry and high-resolution seismic profiles. The bathymetric data represent the results of 6 recent marine geophysical surveys since 2010 as well as a compilation of earlier surveys presented as a 2 arc-sec (60 m) grid. Several distinct morpho-tectonic provinces are identified including: the deeply incised Malta–Hyblean Escarpment, numerous submarine canyons, broad regions of relatively flat seafloor dominated by fields of sediment waves, the gently undulating anticlinal fold-and-thrust belts of the external Calabrian accretionary wedge and the adjacent portion of the Western Mediterranean Ridge. The Calabrian arc can be divided into 4 domains (from SE to NW): 1) the undeformed Ionian abyssal plain, 2) the external evaporitic wedge, 3) the internal clastic wedge, 4) the Calabrian backstop (Variscan crystalline basement). The Calabrian accretionary wedge can also be divided laterally into two major lobes, the NE- and the SW lobes, and two minor lobes. The kinematics of the limit between the two major lobes is investigated and shown to be sinistral in the external (evaporitic) wedge. A network of radial slip lines within the southernmost external wedge unequivocally demonstrate ongoing dextral displacement of a rigid indenter (representing the corner of the clastic wedge) into the evaporitic wedge thereby confirming the geodynamic model of an active lateral slab tear fault here off eastern Sicily. The slab tear produces a series of major sub-parallel dextral strike-slip faults offshore Mt. Etna and south of the Straits of Messina consistent with the relative motions between Calabria and the Peloritan domain (NE Sicily). Abundant strike-slip faulting, and wide-spread folding and thrusting observed throughout the entire accretionary wedge, indicate regional shortening between the Ionian abyssal plain (foreland) and the Calabrian–Peloritan backstop caused by active subduction.

Domaines: Sciences de la Terre

Marc-André M-A Gutscher, H. Kopp, S. Krastel, G. Bohrmann, Th. Garlan, et al.. Active tectonics of the Calabrian subduction revealed by new multi-beam bathymetric data and high-resolution seismic profiles in the Ionian Sea (Central Mediterranean). Earth and Planetary Science Letters, 2017, 461, pp.61 - 72. ⟨10.1016/j.epsl.2016.12.020⟩. ⟨hal-01523990⟩